Criteria for the Certification and Recertification of the Waste Isolation Pilot Plant's Compliance With the Disposal Regulations; Recertification Decision, 33106-33122 [2017-15182]
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33106
Federal Register / Vol. 82, No. 137 / Wednesday, July 19, 2017 / Notices
ENVIRONMENTAL PROTECTION
AGENCY
[EPA–HQ–OAR–2014–0609; FRL–9965–08–
OAR]
Criteria for the Certification and
Recertification of the Waste Isolation
Pilot Plant’s Compliance With the
Disposal Regulations; Recertification
Decision
Environmental Protection
Agency (EPA).
ACTION: Notice; recertification decision.
AGENCY:
With this notice, the
Environmental Protection Agency (EPA
or the Agency) recertifies that the U.S.
Department of Energy’s (DOE) Waste
Isolation Pilot Plant (WIPP) continues to
comply with the ‘‘Environmental
Standards for the Management and
Disposal of Spent Nuclear Fuel, HighLevel and Transuranic (TRU)
Radioactive Waste.’’
This action represents the Agency’s
third periodic evaluation of the WIPP’s
continued compliance with the disposal
regulations and WIPP Compliance
Criteria. The WIPP Compliance Criteria
implement and interpret the disposal
regulations specifically for the WIPP. As
directed by Congress in the WIPP Land
Withdrawal Act (WIPP LWA), this
‘‘recertification’’ process is required
every five years following the WIPP’s
initial receipt of TRU waste on March
26, 1999 (e.g., March 2004, March 2009),
until the end of the decommissioning
phase. For each recertification—
including the one being announced with
this action—the DOE must submit
documentation of the site’s continuing
compliance with the disposal
regulations to the EPA for review.
This recertification decision is based
on a thorough review of information
submitted by the DOE, independent
technical analyses, and public
comments. The Agency has determined
that the DOE continues to meet all
applicable requirements of the WIPP
Compliance Criteria, and with this
action, recertifies the WIPP facility. This
recertification decision does not
otherwise amend or affect the EPA’s
radioactive waste disposal regulations
or the WIPP Compliance Criteria. In
addition, recertification is not subject to
rulemaking or judicial review, nor is it
linked to the resumption of disposal
activities at the WIPP facility. The EPA
has also identified areas in which the
DOE’s technical analyses and
justifications could be improved for the
next recertification application.
FOR FURTHER INFORMATION CONTACT: Ray
Lee, Radiation Protection Division, Mail
Code 6608T, U.S. Environmental
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SUMMARY:
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Protection Agency, 1200 Pennsylvania
Avenue Washington, DC 20460;
telephone number: (202) 343–9463; fax
number: (202) 343–2305; email address:
lee.raymond@epa.gov. Copies of the
Compliance Application Review
Documents (CARDs) supporting this
action and all other recertificationrelated documentation can be found in
the Agency’s electronic docket found at
www.regulations.gov (Docket ID No.
EPA–HQ–OAR–2014–0609).
SUPPLEMENTARY INFORMATION:
Table of Contents
I. General Information
II. What is the WIPP?
A. Background
B. Impacts of the February 2014 Incidents
on the Repository
III. Compliance Certification History
A. 1998 Certification Decision
B. 2006 Recertification Decision
C. 2010 Recertification Decision
IV. With which regulations must the WIPP
comply?
A. Compliance with Radioactive Waste
Disposal Regulations & the WIPP
Compliance Criteria
B. Compliance with Other Environmental
Laws and Regulations
V. Continuing Compliance with the WIPP
Compliance Criteria
A. Annual Change Reports
B. Monitoring the Conditions of
Compliance
1. Panel Closure Rulemaking
2. Quality Assurance
3. Waste Characterization
4. Passive Institutional Controls
C. Inspections
V. What is the EPA’s 2017 Recertification
Decision?
A. Performance Assessment and the EPA’s
Standards
B. Summary of the EPA’s Review
C. What information did the Agency
examine to make the final decision?
D. Content of the Compliance
Recertification Application (§§ 194.14
and 194.15)
1. Changes to the Disposal System
Identified by the DOE
a. Update to the Drilling Rate and Borehole
Plugging Patterns
b. Replacement of Option D Panel Closure
System With Run-of-Mine Salt Panel
Closure Design
c. Modeling of Open Areas in the
Repository
d. The DOE’s Revised Estimate of the
Probability of Encountering Pressurized
Brine
e. Revised Corrosion Rate of Steel
f. Revised Effective Shear Strength of the
WIPP Waste
g. Revised Repository Water Balance
h. Variable Brine Volume
i. Revised Colloid Parameters
j. New Actinide Solubility Code (EQ3/6)
2. Other Key Issues Identified by the EPA
During Review
a. Actinide Solubilities
b. Solubility Uncertainty Distribution
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c. Plutonium Oxidation States
E. Performance Assessment: Modeling and
Containment Requirements (§§ 194.14,
194.15, 194.23, 194.31 through 194.34)
1. Overview
2. Sensitivity Studies
a. The SEN1 Study
b. The SEN2 Study
c. The SEN3 Study
d. The SEN4 Study
i. Overview
ii. Cumulative Effects of the Changes
Evaluated by Release Pathway
aa. Direct Brine Releases
bb. Spallings Releases
cc. Cuttings and Cavings Releases
dd. Releases From the Culebra
ee. Insights from the SEN4 Study
3. How the Four Sensitivity Studies Affect
the WIPP Compliance
F. Additional Requirements
1. Waste Characterization (Waste Inventory
(§ 194.24)
2. Peer Review (§ 194.27)
G. Individual and Groundwater Protection
Requirements (§§ 194.51 Through
194.55)
VII. How has the public been involved in the
EPA’s WIPP Recertification activities?
A. Public Information
B. Stakeholder Meetings
C. Public Comments on Recertification
VIII. Where can I get more information about
the EPA’s WIPP-related activities?
A. Supporting Documents for
Recertification
B. The WIPP Web site & WIPP–NEWS
Email Listserv
C. Dockets
IX. What is the EPA’s role in future WIPP
activities?
Abbreviations
CARD Compliance Application Review
Document
CFR Code of Federal Regulations
DOE U.S. Department of Energy
EPA U.S. Environmental Protection Agency
FR Federal Register
NMED New Mexico Environment
Department
OAR Office of Air and Radiation
Pa Pascal
PBRINE Parameter: Probability Distribution
of Encountering Brine
RCRA Resource Conservation and Recovery
Act
SEN Sensitivity Study
TRU Transuranic
TSD Technical Support Document
WIPP Waste Isolation Pilot Plant
WIPP LWA WIPP Land Withdrawal Act
I. General Information
A. How can I get copies of this
document and other related
information?
1. Docket. The EPA has established a
docket for this action under Docket ID
No. EPA–HQ–OAR–2014–0609.
Publicly available docket materials are
available either electronically at https://
www.regulations.gov or in hard copy at
the Air and Radiation Docket in the EPA
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Federal Register / Vol. 82, No. 137 / Wednesday, July 19, 2017 / Notices
Docket Center, (EPA/DC) EPA West,
Room B102, 1301 Constitution Ave.
NW., Washington, DC. The EPA Docket
Center Public Reading Room is open
from 8:30 a.m. to 4:30 p.m., Monday
through Friday, excluding legal
holidays. The telephone number for the
Public Reading Room is (202) 566–1744,
and the telephone number for the Air
and Radiation Docket is (202) 566–1742.
As provided in the EPA’s regulations at
40 CFR part 2, and in accordance with
normal EPA docket procedures, if
copies of any docket materials are
requested, a reasonable fee may be
charged for photocopying.
2. Electronic Access. You may access
this Federal Register document
electronically through the U.S.
Government Publishing Office Web site
at https://www.gpo.gov/fdsys/browse/
collection.action?collectionCode=FR.
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II. What is the WIPP?
A. Background
The Waste Isolation Pilot Plant
(WIPP) is a disposal system for defenserelated transuranic (TRU) radioactive
waste. The WIPP Land Withdrawal Act
(WIPP LWA) of 1992 defines TRU waste
as materials containing alpha-emitting
radioisotopes, with half-lives greater
than twenty years, in concentrations
greater than 100 nanocuries per gram
(nCi/g), except for (A) high-level
radioactive waste; (B) waste that the
Secretary has determined, with the
concurrence of the Administrator, does
not need the degree of isolation required
by the disposal regulations; or (C) waste
that the Nuclear Regulatory Commission
has approved for disposal on a case-bycase basis in accordance with part 61 of
title 10, Code of Federal Regulations
(CFR). Developed by the U.S.
Department of Energy (DOE), the WIPP
is located near Carlsbad in southeastern
New Mexico. At the WIPP, the DOE
disposes of radioactive waste 655 meters
(2,150 feet) underground in an ancient
salt layer which will eventually creep
and encapsulate the waste. The WIPP
has a total capacity to dispose of 6.2
million cubic feet of waste.
Congress initially authorized the
development and construction of the
WIPP in 1980 ‘‘for the express purpose
of providing a research and
development facility to demonstrate the
safe disposal of radioactive wastes
resulting from the defense activities and
programs of the United States.’’ 1 To
further facilitate the development and
operation of the WIPP, Congress passed
1 Department of Energy National Security and
Military Applications of Nuclear Energy
Authorization Act of 1980, Pub. L. 96–164, section
213.
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the WIPP LWA in 1992 and amended it
in 1996. The WIPP LWA only allows
TRU radioactive waste generated by
defense activities associated with
nuclear weapons to be emplaced in the
WIPP and explicitly prohibits high-level
waste or spent nuclear fuel from being
disposed of at the WIPP.
Most TRU waste proposed for
disposal at the WIPP consists of items
that have become contaminated as a
result of activities associated with the
production of nuclear weapons or with
the clean-up of weapons production
facilities, e.g., rags, equipment, tools,
protective gear and organic or inorganic
sludges. Some TRU waste contains
hazardous chemicals used during
weapons production, research and
development and cleaning/
maintenance/deactivation activities.
Some of the waste proposed for disposal
at the WIPP is known as legacy waste
and has been stored for decades at
various federal facilities across the
United States, including major generator
sites such as the Idaho National
Laboratory, Los Alamos National
Laboratory and Oak Ridge National
Laboratory, and smaller generators such
as Argonne National Laboratory and
Lawrence Livermore National
Laboratory. These facilities continue to
generate small quantities of TRU waste.
All TRU waste which the DOE plans to
ship to the WIPP is subjected to the
EPA’s WIPP waste characterization
requirements at 40 CFR 194.24.
The WIPP LWA provides the EPA the
authority to oversee and regulate the
WIPP. The WIPP LWA requires the EPA
to conduct three main tasks, to be
completed sequentially, to reach an
initial compliance certification decision.
First, the WIPP LWA requires the EPA
to finalize general regulations for the
disposal of highly-radioactive waste.2
The EPA published these disposal
regulations, located at subparts B and C
of 40 CFR part 191, in the Federal
Register in 1985 and 1993.3
Second, the WIPP LWA requires the
EPA to develop criteria, via rulemaking,
to interpret and implement the general
radioactive waste disposal regulations
specifically as they apply to the WIPP.
In 1996, the Agency issued the WIPP
Compliance Criteria (40 CFR part 194).4
Third, the WIPP LWA requires the
EPA to review the information
submitted by the DOE every five years
to demonstrate continued compliance
with the disposal regulations and
determine whether or not the WIPP
LWA, section 8(b).
FR 38066–38089 (September 19, 1985) and
58 FR 66398–66416 (December 20, 1993).
4 61 FR 5224–5245 (February 9, 1996).
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3 50
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continues to be in compliance.5 The
Agency issued the initial certification
decision on May 18, 1998 (63 FR 27354–
27406).
B. Impacts of February 2014 Incidents
on the Repository
Since the EPA’s initial certification,
operation of the WIPP proceeded
without substantial interruption until
2014. However, two events took place at
the WIPP in February 2014 that led the
DOE to suspend emplacement of
additional waste in the facility for
nearly three years. On February 5, a salt
haul truck caught fire. Workers were
evacuated, and the underground portion
of the WIPP was shut down. On
February 14, a second event occurred
when a continuous air monitor alarmed
during the night shift, signaling a
detection of radiation. The continuous
air monitor was measuring exhaust from
waste panel 7, where waste
emplacement had recently begun.
Radiological contamination of the
underground caused an indefinite
suspension of waste handling activities.
After implementing numerous
corrective actions, the DOE resumed
limited waste emplacement on January
4, 2017, and also resumed limited
shipments from waste generator sites.
Resumption of waste emplacement at
the WIPP is unrelated to the EPA’s
recertification decision, which is
primarily concerned with compliance
with the EPA’s long-term disposal
requirements. However, the DOE has
acknowledged that recovery from the
radiological release will result in design
changes to the repository, which will
need to be considered from that longerterm perspective. These changes include
installation of a new ventilation shaft
and modification of the waste panel
layout to accommodate the premature
closure of planned waste emplacement
capacity in panel 9. The DOE is still
reviewing options and has not provided
any specific plans to the EPA. The EPA
will review these changes as more
information becomes available and they
are incorporated into future
recertification applications. The EPA
recognizes that the current
recertification decision is based on a
repository design that is likely to
change, but the current application
contains the information necessary to
reach a decision without knowing the
details of the future changes. It is not
unprecedented for the EPA to conduct
a recertification review with the
knowledge that the DOE will submit a
request to change an aspect of the
disposal system design.
5 WIPP
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The EPA expects that any issues
associated with repository design
changes will be appropriately addressed
in responding to change requests from
the DOE and in subsequent
recertification applications. However,
because these design changes are likely
to be substantial, the EPA believes it is
necessary for the DOE to ensure that
future compliance recertification
applications are as robust and
technically defensible as possible. To
that end, the EPA discusses in Section
VI.D specific aspects of future
compliance recertification applications
that the Agency believes would benefit
from independent technical review, or
otherwise from thorough consideration
of more recent scientific information
and understanding of chemical
processes anticipated to take place
within the repository. The EPA strongly
believes that incorporating such reviews
and information into future applications
will increase public confidence in the
DOE’s compliance demonstrations and
facilitate the Agency’s review.
III. Compliance Certification History
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A. 1998 Certification Decision
The WIPP LWA, as amended,
required the EPA to evaluate whether
the WIPP complied with the EPA’s
standards for the disposal of radioactive
waste. On May 18, 1998 (63 FR 27354–
27406), the EPA determined that the
WIPP met the standards for radioactive
waste disposal. This decision allowed
the DOE to begin placing radioactive
waste in the WIPP, provided that all
other applicable health and safety
standards, and other legal requirements,
were met. The WIPP received the first
shipment of TRU waste on March 26,
1999. The complete record and basis for
the EPA’s 1998 certification decision
can be found in Air Docket A–93–02.
Although the EPA determined that the
DOE met all of the applicable
requirements of the WIPP Compliance
Criteria in the original certification
decision, the EPA also found that it was
necessary for the DOE to take additional
steps to ensure that the measures
actually implemented at the WIPP (and
thus the circumstances expected to exist
there) were consistent with the DOE’s
compliance certification application and
with the basis for the EPA’s compliance
certification. As a result, the EPA
included four explicit conditions in the
WIPP certification of compliance (see 40
CFR part 194, Appendix A; WIPP
Recertification Background Document
in Docket No. EPA–HQ–OAR–2014–
0609). These conditions are discussed in
Section V.C of this document.
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B. 2006 Recertification Decision
The first recertification process,
which occurred in 2004–2006, included
an EPA review of all changes made at
the WIPP facility since the original 1998
certification decision. The Agency
received the DOE’s first compliance
recertification application on March 26,
2004. The EPA issued the completeness
determination 6 for the 2004 Compliance
Recertification Application by letter to
the DOE on September 29, 2005 (see 70
FR 61107–61111, October 20, 2005). On
March 29, 2006, the EPA officially
recertified the WIPP facility for the first
time (71 FR 18010–18021, April 10,
2006).
C. 2010 Recertification Decision
Following receipt of the DOE’s second
compliance recertification application
on March 24, 2009, the EPA requested
additional information from the DOE
and the DOE responded with the
requested supplemental information.
All pertinent 2009 Compliance
Recertification Application
correspondence was placed in the
docket (Docket ID No. OAR–2009–0330
on www.regulations.gov) and linked to
on the WIPP Web site (https://
www.epa.gov/radiation/certificationand-recertification-wipp#tab2). On June
29, 2010, the EPA sent a letter to the
DOE announcing that the DOE’s
recertification application was complete
(75 FR 41421–41424, July 16, 2010). The
EPA’s second recertification of the WIPP
compliance was published on
November 18, 2010 (75 FR 70584).
IV. With which regulations must the
WIPP comply?
A. Compliance With Radioactive Waste
Disposal Regulations & the WIPP
Compliance Criteria
The WIPP must comply with the
EPA’s radioactive waste disposal
regulations, located at subparts B and C
of 40 CFR part 191. These regulations
limit the amount of radioactive material
which may escape from a disposal
facility, and protect individuals and
ground water resources from dangerous
levels of radioactive contamination. In
addition, the compliance recertification
application and other information
6 A ‘‘completeness determination’’ is an
administrative step by the Agency to notify the DOE
and the public that the Agency has enough
information to conduct a final technical review of
the DOE’s application. It does not reflect any
conclusion regarding the WIPP’s continued
compliance with the radioactive waste disposal
regulations at 40 CFR part 191 and the compliance
criteria at 40 CFR part 194. The completeness
determination represents the start of the six-month
period specified in the WIPP LWA for issuance of
the recertification decision.
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submitted by the DOE must meet the
requirements of the WIPP Compliance
Criteria at 40 CFR part 194. The WIPP
Compliance Criteria implement and
interpret the general disposal
regulations specifically for the WIPP,
and clarify the basis on which the EPA
makes the certification decision.
B. Compliance With Other
Environmental Laws and Regulations
In addition to the EPA’s radioactive
waste disposal regulations, the WIPP
must also comply with a number of
other federal laws and regulations
pertaining to public health and safety or
the environment, including, for
example, the Solid Waste Disposal Act
(also known as the Resource
Conservation and Recovery Act (RCRA))
(42 U.S.C. 6901 et seq.) and the EPA’s
environmental standards for the
management and storage of radioactive
waste (subpart A of 40 CFR part 191).
Various regulatory agencies are
responsible for overseeing the
enforcement of these federal laws and
regulations. For example, enforcement
of some parts of the hazardous waste
management regulations has been
delegated to the State of New Mexico.
The State is authorized by the EPA to
carry out the State’s RCRA programs in
lieu of the equivalent federal programs,
and New Mexico’s Environment
Department (NMED) reviews the DOE’s
permit applications for treatment,
storage, and disposal facilities for
hazardous waste, under Subtitle C of
RCRA. NMED’s RCRA authority, such as
issuing a hazardous waste operating
permit for the WIPP, is not affected by
the EPA’s recertification decision. The
DOE is responsible for biennially
reporting to the EPA and the State of
New Mexico on the WIPP’s compliance
with all applicable federal laws
pertaining to public health and safety
(WIPP LWA § 9).7 This action does not
address the WIPP’s compliance with
environmental or public health and
safety laws and regulations other than
the EPA’s radioactive waste disposal
regulations (40 CFR part 191) and the
WIPP Compliance Criteria (40 CFR part
194).
V. Continuing Compliance With the
WIPP Compliance Criteria
The EPA monitors and ensures
continuing compliance with the EPA
regulations through a variety of
activities, including the following:
review and evaluation of the DOE’s
annual change reports, monitoring of
7 Compliance with these laws and regulations is
addressed in the site’s Biennial Environmental
Compliance Report (BECR).
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A. Annual Change Reports
In addition to reporting significant
changes to the WIPP disposal system,
the DOE is required to report at least
annually other changes to the
conditions or activities concerning the
WIPP disposal system (40 CFR
194.4(b)(4)). The DOE submitted the
first annual change report in November
1998.
The DOE’s annual change reports
reflect the progress of quality assurance
and waste characterization inspections,
minor changes to the DOE documents,
information on monitoring activities
and any additional EPA approvals for
changes in activities. All
correspondence and approvals regarding
the annual change reports can be found
in hard copy in the Air Docket A–98–
49, Categories II–B2 and II–B3.
Condition 1 required the DOE to
implement the Option D panel closure
system at the WIPP, using Salado mass
concrete.8 By final action published
October 8, 2014, the EPA modified
Condition 1 to remove the specific
reference to Option D and generally
require that the DOE close filled waste
panels as specifically approved by the
EPA (40 CFR part 194, Appendix A, as
amended; 79 FR 60750–60756). With
the same action, the EPA approved a
design which primarily consists of 100
feet of run-of-mine salt. The DOE
submitted a performance assessment 9 to
support its request to change the panel
closure system design. The DOE
asserted that the performance
assessment demonstrated that a panel
closure design using run-of-mine salt
would be compliant with the EPA’s
disposal regulations (40 CFR part 191).
The modification to the WIPP
Certification Condition 1 also removed
the requirement for the Agency to make
future panel closure design changes by
formal rulemaking.
2. Quality Assurance. Certification
Condition 2 requires each TRU
generator site to establish and execute a
quality assurance program for waste
characterization activities. Section
194.22 establishes quality assurance
requirements for the WIPP. The DOE
must adhere to a quality assurance
program that implements the
requirements of ASME NQA–1–1989
edition, ASME NQA–2a–1990 addenda,
part 2.7, to ASME NQA–2–1989 edition,
and ASME NQA–3–1989 edition
(excluding Section 2.1 (b) and (c), and
Section 17.1).The EPA determined that
the 2014 Compliance Recertification
Application provides adequate
information to verify the establishment
and implementation of each of the
applicable elements of the ASME NQA–
1–1989.The EPA has also verified the
continued proper implementation of the
Nuclear Quality Assurance Program
through periodic audits conducted in
accordance with § 194.22(e).
B. Monitoring the Conditions of
Compliance
1. Panel Closure Rulemaking. Waste
panel closure systems are required by
the State of New Mexico during the
WIPP’s operational phase. Since they
are a feature of the disposal system
design, the EPA requires panel closures
to be included in the long-term
modeling of the repository. The panel
closures impact long-term disposal
system performance because they can
impede brine and gas flow between
waste panels. As originally
promulgated, the WIPP Certification
8 ‘‘Salado’’ mass concrete refers to concrete made
using Salado brines instead of fresh water.
9 Performance assessment is an important tool
used in various contexts or evaluations relating to
the WIPP and such assessments are mentioned in
different circumstances throughout this notice,
especially in Section VI.E. In general, performance
assessment means: ‘‘an analysis that: (1) Identifies
the processes and events that might affect the
disposal system; (2) examines the effects of those
processes and events on the performance of the
disposal system; and (3) estimates the cumulative
release of radionuclides, considering the associated
uncertainties, caused by all significant processes
and events’’ (40 CFR 191.12). Performance
assessment, for example, is required to show
compliance with containment requirements (40
CFR 191.13).
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the conditions of compliance,
addressing planned change requests,
inspections of the WIPP site and
inspections of waste characterization
operations. Because of the 2014
incident, the EPA also reviewed health
and monitoring data to ensure the
radiological releases remained below
the limits of subpart A of 40 CFR part
191 and the Clean Air Act National
Emissions Standards for Hazardous Air
Pollutants at 40 CFR part 61, subpart H.
The DOE must timely report any
planned or unplanned changes in
activities or conditions pertaining to the
disposal system that differ significantly
from the most recent compliance
application and, at least annually, report
any other changes in disposal system
conditions or activities (40 CFR
194.4(b)(3), (4)). The Department must
also report any releases of radioactive
material from the disposal system (40
CFR 194.4(b)(3)(iii)). In addition, the
EPA may request additional information
from the DOE at any time (§ 194.4(b)(2)).
These requirements assist the EPA with
monitoring the performance of the
disposal system and evaluating whether
the certification should be modified,
suspended or revoked.
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The EPA’s determination of
compliance with 40 CFR 194.22 can be
found in Table 1 of the 2014
Compliance Recertification Application
CARD 22. Between March 2008 and
April 2012, the EPA conducted several
quality assurance audits and found the
site-specific quality assurance programs
to be adequate. The EPA conducted
quality assurance audits at several waste
generator sites and entities supporting
the WIPP Performance Assessment
activities at Los Alamos and Sandia
Laboratories. The EPA also audited the
quality assurance program of the
Carlsbad Field Office.
3. Waste Characterization.
Certification Condition 3 requires TRU
waste generator sites to have waste
characterization systems approved by
the EPA. The Agency has conducted
numerous audits and inspections at
waste generator sites in order to
implement Condition 3 and the relevant
provisions of 40 CFR part 194, including
§ 194.8. The EPA inspected site-specific
TRU waste characterization programs
implemented to (a) characterize
physical and radiological components
in individual waste containers and (b)
demonstrate compliance with the WIPP
waste disposal requirements at 40 CFR
194.24.
To support the 2014 Compliance
Recertification Application, the DOE
reported the EPA’s waste
characterization inspections and
approvals between January 2007 and
December 2012 (see Table 1 in CARD 8).
The EPA evaluated previously approved
site-specific waste characterization
program for continued compliance in
accordance with 40 CFR 194.24, as well
as changes to the systems of controls
approved as part of the baseline (initial)
approvals, and concluded them to be
technically adequate. The TRU waste
sites approved by the EPA to ship
contact-handled TRU waste to the WIPP
facility in accordance with the
requirements of § 194.8 since the 2009
Compliance Recertification Application
are as follows: Advanced Mixed Waste
Treatment Project, Hanford’s Richland
Laboratory, Idaho National Laboratory,
Los Alamos National Laboratory, Oak
Ridge National Laboratory and
Savannah River Site. Since the 2009
Compliance Recertification Application,
the TRU waste sites approved by the
EPA to ship remote-handled TRU waste
to the WIPP facility in accordance with
the requirements of § 194.8 are Argonne
National Laboratory, Bettis Atomic
Power Laboratory, General Electric
Vallecitos Nuclear Center, Idaho
National Laboratory, Oak Ridge National
Laboratory and Savannah River Site.
Since the 2009 Compliance
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Recertification Application, no waste
characterization occurred at Bettis
Atomic Power Laboratory, General
Electric Vallecitos Nuclear Center,
Hanford’s Richland Laboratory and Oak
Ridge National Laboratory.
During the period covered by the 2014
Compliance Recertification Application,
all site-specific waste characterization
systems of controls at active TRU waste
generator sites had necessary baseline
approvals. Over the years, when
warranted, the EPA approved
modification to waste characterization
program components. Notices
announcing the EPA inspections or
audits are routinely published in the
Federal Register and also announced on
the Agency’s WIPP Web site (https://
www.epa.gov/radiation/epas-role-wasteisolation-pilot-plant-wipp) and WIPPNEWS email listserv.10
Records of the EPA’s quality
assurance correspondences and waste
characterization approvals can be found
in Air Docket A–98–49, Categories II–A1
and II–A4, respectively, as well as
online in Docket ID No. EPA–HQ–OAR–
2001–0012 on www.regulations.gov.
4. Passive Institutional Controls.
Certification Condition 4 requires the
DOE to submit a schedule and plan for
implementing passive institutional
controls, including markers and other
measures indicating the presence of the
repository. The standards under the
WIPP Certification Condition 4 do not
require the submission of any reports
until the final compliance recertification
application prior to closure of the WIPP.
The EPA has not received any
submissions from the DOE during the
period addressed by the 2014
Compliance Recertification Application
and has not taken any actions relating
to Condition 4. The EPA anticipates that
it will evaluate the DOE’s compliance
with Condition 4 of the certification
when the DOE submits a revised
schedule and additional documentation
regarding the implementation of passive
institutional controls. Once received,
the information will be placed in the
EPA’s public dockets, and the Agency
will evaluate the adequacy of the
documentation. After receiving
Condition 4 submissions from the DOE,
and during the operational period when
waste is being emplaced in the WIPP
(and before the site has been sealed and
decommissioned), the EPA will verify
that specific actions identified by the
DOE in the compliance certification
application, and supplementary
information (and in any additional
documentation submitted in accordance
10 For more information on the WIPP–NEWS
email listserv, see Section VIII.B below.
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with Condition 4) are being taken to test
and implement passive institutional
controls.
C. Inspections
The WIPP Compliance Criteria
provide the EPA the authority to
conduct inspections of activities at the
WIPP and at off-site facilities which
provide information relevant to
compliance applications (40 CFR
194.21). The Agency has conducted
periodic inspections to verify the
adequacy of information relevant to
certification applications. The EPA has
conducted annual inspections at the
WIPP site to review and ensure that the
monitoring program meets the
requirements of § 194.42. The EPA has
also inspected the emplacement and
tracking of waste in the repository. The
Agency’s inspection reports can be
found in Air Docket A–98–49,
Categories II–A1 and II–A4, as well as
online at www.regulations.gov, Docket
ID No. EPA–HQ–OAR–2001–0012.
VI. What is the EPA’s 2017
Recertification Decision?
The EPA determines, in accordance
with WIPP LWA § 8(f)(2), that the WIPP
facility is in compliance with the final
disposal regulations, subparts B and C
of 40 CFR part 191. Compliance
recertification ensures that accurate and
up-to-date information is considered in
the determination that WIPP remains in
compliance with these radioactive waste
disposal regulations. The EPA makes
this recertification and determination of
continued compliance following the
‘‘Criteria for the Certification and
Recertification of the WIPP’s
Compliance with the 40 CFR part 191
Disposal Regulations’’ (WIPP
Compliance Criteria, 40 CFR part 194),
including the WIPP certification
conditions (40 CFR part 194, Appendix
A).
A. Performance Assessment and the
EPA’s Standards
The disposal regulations at 40 CFR
part 191 include requirements for
containment of radionuclides. The
containment requirements at 40 CFR
191.13 specify that releases of
radionuclides to the accessible
environment 11 must be unlikely to
exceed specific limits for 10,000 years
after disposal. The DOE assesses the
likelihood that the WIPP will meet these
11 The accessible environment is defined in 40
CFR 191.12 as (1) The atmosphere: (2) land
surfaces; (3) surface waters; (4) oceans; and (5) all
of the lithosphere that is beyond the controlled
area.
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release limits through a process known
as performance assessment.
The disposal regulations provide that
there must be a reasonable expectation
that cumulative releases of
radionuclides from the WIPP and into
the environment over 10,000 years will
not exceed specified quantities of these
radionuclides (40 CFR 191.13 and
Appendix A). A reasonable expectation
standard is used because of the long
time period involved and the nature of
the events and processes at radioactive
waste disposal facilities leads to
uncertainties about future performance.
The DOE’s probabilistic performance
assessments assess the likelihood of
environmental radionuclide release so
that future uncertainties are accounted
for in the calculations through the use
of alternative scenarios and variations in
values of uncertain parameters via
probability distributions.
The containment requirements in 40
CFR 191.13 are expressed in terms of
‘‘normalized releases.’’ At the WIPP, the
specific release limits are based on the
estimated amount of waste in the
repository at the time of closure, and the
projected releases are ‘‘normalized’’
against these limits (§ 194.31).
Normalized releases are expressed as
‘‘EPA units’’. The EPA units are
calculated by dividing all the combined
projected releases by the total combined
radioactivity of all the waste in the
repository.
The DOE must demonstrate, in each
5-year compliance recertification
application, that the total average of
combined releases are below two
compliance criteria at a higher
probability of occurrence and a lower
probability of occurrence. These
compliance points are as follows:
1. For a probability of 0.1 (a 1 in 10
chance) in 10,000 years, releases to the
accessible environment will not exceed
1 EPA unit, and
2. For a probability of 0.001 (a 1 in
1,000 chance) in 10,000 years, releases
to the accessible environment will not
exceed 10 EPA units.
DOE evaluates four release
mechanisms in the WIPP performance
assessment modeling:
Cuttings and cavings. This consists of
material that gets brought to the surface
when a borehole intersects waste in a
WIPP waste panel. The cuttings are the
material intersected by the borehole
itself and the cavings material is waste
that fails around the borehole, collapses
into it and is brought to the surface.
Spallings. This is solid material that
fails and gets brought to the surface
under high pressure conditions in the
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repository. This only occurs when the
pressure is above 8 megapascal 12 (MPa).
Direct Brine Releases. This is a release
of dissolved actinides in brine when
there is sufficient brine and high
pressure in the repository (i.e., above 8
MPa) and brine saturations are above
residual saturation (i.e., brine is not
‘‘trapped’’ between pore spaces) as a
borehole intersects a waste panel. The
contaminated fluid is brought to the
surface over a period of hours to days.
Releases to the Culebra. This occurs
when contaminated brine from
repository is introduced via a borehole
to the Culebra Dolomite and then moves
to the edge of the accessible
environment (i.e., the boundary
established by the WIPP LWA).
The DOE estimates the potential
releases from these release mechanisms,
i.e., the cumulative releases, for
comparison with the specified limits
provided in 40 CFR part 191, Appendix
A. The DOE is to provide in the
application overall mean calculated
releases and the upper 95th confidence
limit of that mean.
B. Summary of the EPA’s Review
After reviewing the DOE’s
documentation and additional studies
that the DOE conducted at EPA’s
request, the aspects of the performance
assessment of most interest to EPA are
those that affect the direct brine release
mechanism, by which actinides 13
dissolved in brine are transported to the
surface during a drilling intrusion.
Direct brine release is the overall
dominant release mechanism at the low
probability compliance point, and is
influenced primarily by the availability
of liquid (i.e., brine) in the repository,
the availability of radionuclides to
dissolve in that liquid (i.e., inventory
and solubility) and the pressure in the
repository (providing a motivating force
for dissolved radionuclides to move out
of the repository).
The key issues involving these aspects
of the repository are: (1) The actinide
solubility, which is addressed through
changes to the geochemical database,
colloid contribution updates and the
determination of the actinide solubility
uncertainty; (2) the probability of hitting
a brine pocket under the repository; (3)
the steel corrosion rate and steel’s
interactions with hydrogen sulfide and
magnesium oxide (affecting the gas
12 ‘‘Pascal’’ is a unit of pressure, defined as 1 kg/
m-sec2.
13 Actinide means any of the series of fifteen
metallic elements from actinium (atomic number
89) to lawrencium (atomic number 103) in the
periodic table. They are all radioactive, the heavier
members being extremely unstable and not of
natural occurrence.
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pressure); and (4) the overall modeling
of direct brine releases that involve the
interactions of items 1–3 plus the
conditions of the repository (e.g., panel
and drift permeability and porosity) that
can influence the pressure
characteristics of the waste areas. These
issues are discussed in more detail in
Section VI.D, along with other issues
that are noteworthy but have more
limited impact on performance
assessment results.
The following information describes
the EPA’s compliance evaluation related
to the disposal regulations and
Compliance Criteria.
C. What information did the Agency use
to make the decision?
In general, compliance applications
must include information relevant to
demonstrating compliance with each of
the individual sections of 40 CFR part
194 to determine if the WIPP will
comply with the Agency’s radioactive
waste disposal regulations at 40 CFR
part 191, subparts B and C. The EPA
begins the compliance recertification
evaluation once the EPA receives a
complete compliance recertification
application (40 CFR 194.11).
To make this decision, the EPA
evaluated basic information about the
WIPP site and disposal system design,
as well as information which addressed
the various compliance criteria. As
required by 40 CFR 194.15(a), the DOE’s
2014 Compliance Recertification
Application updated the previous
submission in 2009.
On March 26, 2014, the DOE
submitted the compliance recertification
application. The EPA began to identify
areas of the application where
additional information was needed. On
October 10, 2014, the EPA gave public
notice of the compliance recertification
application and opened the official
public comment period (79 FR 61268).
On January 13, 2017, the EPA sent a
letter to the DOE stating that the DOE’s
recertification application was
complete. On March 10, 2017, the EPA
issued a Federal Register notice
announcing the completeness
determination and stating that the
public comment period would close one
month later, on April 10, 2017 (82 FR
13282). The compliance recertification
application completeness-related
correspondence can be found in Docket
ID No. EPA–HQ–OAR–2014–0609 on
www.regulations.gov.
The EPA relied on materials prepared
by the Agency or submitted by the DOE
in response to the EPA requests. For
example, the EPA requested that the
DOE conduct specific, additional
modeling calculations for the
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performance assessment, known as
sensitivity studies. The purpose of these
studies was to evaluate the impact on
performance assessment results of
changing specific parameter values. The
studies aided the EPA in determining
how significant the differences in some
parameter values were to a
demonstration of compliance. The four
sensitivity studies and the EPA’s
evaluation of them are discussed in
more detail in Section VI.E.
To determine whether the WIPP
facility continues to be in compliance
with the final disposal regulations, the
EPA engaged in a technical review of
the compliance recertification
application against the WIPP
Compliance Criteria. The Agency
focused the review on areas of change
identified by the DOE since the 2010
recertification decision.
The Agency produced many
documents during the technical review
and evaluation of the compliance
recertification application. The EPA’s
Compliance Application Review
Documents (CARDs) correspond in
number to the sections of 40 CFR part
194 to which the documents primarily
relate. Each CARD enumerates all
changes made by the DOE relating to a
particular section of the rule or
certification criterion, and describes the
EPA’s process and conclusions. The
EPA also prepared technical support
documents (TSDs) to address specific
topics in greater detail. Both the CARDs
and the TSDs for this recertification
decision can be found in Docket ID No.
EPA–HQ–OAR–2014–0609 on
www.regulations.gov. Together, the
CARDs and TSDs thoroughly document
the EPA’s review of the DOE’s
compliance recertification application
and the technical rationale for the
Agency’s decisions.
In summary, the EPA’s recertification
decision is based on the entire record
available to the Agency, which is
located in the public docket dedicated
to this recertification (Docket ID No.
EPA–HQ–OAR–2014–0609 on
www.regulations.gov). The record
consists of the 2014 Compliance
Recertification Application,
supplementary information submitted
by the DOE in response to the EPA
requests for additional information,
technical reports generated by the EPA,
the EPA audit and inspection reports,
and comments submitted on the DOE’s
application and the EPA’s completeness
review during the public comment
period. All pertinent 2014 Compliance
Recertification Application
correspondence was placed in the
docket and linked to via the EPA’s WIPP
Web site (https://www.epa.gov/
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radiation/certification-andrecertification-wipp).
D. Content of the Compliance
Recertification Application (§§ 194.14
and 194.15)
The DOE’s WIPP compliance
applications must include, at a
minimum, basic information about the
WIPP site and disposal system design,
including information about the
following topics: the geology,
hydrology, hydrogeology and
geochemistry of the WIPP disposal
system and the WIPP vicinity; the WIPP
materials of construction; standards
applied to design and construction;
background radiation in air, soil and
water; and past and current
climatological and meteorological
conditions (40 CFR 194.14). Section
194.15 states that the DOE’s
recertification applications shall update
this information to provide sufficient
information for the EPA to determine
whether or not the WIPP facility
continues to be in compliance with the
disposal regulations.
1. Changes to the Disposal System
Identified by the DOE. In Section 15 of
the 2014 Compliance Recertification
Application, the DOE identified changes
to the disposal system between the 2009
Compliance Recertification Application
and 2014 Compliance Recertification
Application and changes to technical
information relevant to §§ 194.14 and
194.15. Noteworthy changes identified
by the DOE in the 2014 Compliance
Recertification Application include the
following: an update to the parameters
defining drilling rate and plugging
pattern, revisions to the calculations of
the probability of encountering a
pressurized brine reservoir, replacing
the Option D panel closure design with
run-of-mine salt, modeling open areas in
the repository, revision of the steel
corrosion rate, revision of the effective
shear strength of waste, revisions of the
repository water balance including
variable brine volumes for radionuclides
to dissolve and revisions of the colloid
parameters.
Before determining that the
compliance recertification application
was complete, the EPA raised numerous
technical questions with the DOE, as
described below. For each topic, a brief
summary is provided of how the DOE
addressed the issue in the 2014
application, followed by the EPA’s
perspective on the change, including
any follow-up analyses requested. The
DOE also updated the waste inventory.
This topic is discussed in Section
VI.F.1.
Since the initial Compliance
Certification performance assessment,
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the DOE’s calculated releases in
performance assessments have
increased with every performance
assessment until the 2014 Compliance
Recertification Application performance
assessment. The changes the DOE made
to the performance assessment in the
current application reduce the
calculated releases. For example, the
calculated release of radionuclides at
the low probability compliance point (a
likelihood of less than a one in 1,000
chance), was assessed by the DOE in the
2009 Compliance Recertification
Application as 0.72 EPA Units, but in
the 2014 Compliance Recertification
Application, the similar calculated
release initially was assessed as 0.261
EPA Units.
Changes that reduce the calculated
releases involve the shear strength of the
waste, revised steel corrosion rate,
incorporating water balance as part of
the chemical model implementation as
it relates to steel corrosion and
interactions with the magnesium oxide
engineered barrier, correcting errors
associated with brine volume mass
balance and calculation of actinide
solubility and the change to how the
DOE calculates the probability of hitting
a brine pocket under the repository. In
general, the result of the DOE’s
methodology changes is to reduce
calculated releases by about a factor of
two between the 2009 and 2014
Compliance Recertification
Applications at both the 0.1 and 0.001
probability compliance points.
The EPA has identified issues with
some of these changes, but even with
changes the EPA asked the DOE to
investigate, projected releases stay well
under the numerical release limits. For
example, at the 0.001 probability
compliance point where the EPA
normalized release limit is 10 EPA
units, the changes the EPA requested
resulted in increased releases from
0.261 EPA units in the DOE’s 2014
performance assessment to 0.299 EPA
units in sensitivity study SEN3 and
0.541 EPA units in sensitivity study
SEN4. The sensitivity studies are
discussed in depth in Section VI.E.
a. Update to the Drilling Rate and
Borehole Plugging Patterns. As with
previous recertification applications, the
DOE updated the Delaware basin
drilling rates based on the methodology
previously approved. For the 2014
Compliance Recertification Application,
the drilling rate increased to 0.00673
boreholes per km2 per year (equivalent
to 67.3 boreholes/km2 over the 10,000year regulatory period) compared to that
used in the 2009 performance
assessment baseline calculation, which
was .00598 boreholes per km2 per year
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(or 59.8 boreholes/km2 over 10,000
years). The Agency accepted the DOE’s
drilling rate increase.
The DOE also updated information on
the type of plugs installed in
exploratory, disposal and resource
extraction boreholes. There are three
types of borehole plugs used in the
Delaware basin. There are boreholes that
are continuously plugged through the
entire salt section, and the DOE reports
a slight increase in the use of this
design. There are boreholes plugged
with a two-plug configuration (at the
Salado/Rustler and the Bell Canyon/
Castile Formation interfaces). This twoplug design also slightly increased from
that used in the 2009 application. There
is also a three-plug configuration (i.e.,
borehole plugs at the Rustler/Salado,
Salado/Castile and Castile/Bell Canyon
interfaces); the DOE reports a slight
decrease in this configuration. The
Agency accepted the DOE’s update to
the change in the plugging patterns.
b. Replacement of Option D Panel
Closure System with the Run-of-Mine
Salt Panel Closure Design. Part of the
design for the WIPP includes the use of
a closure system to separate the waste
rooms in a panel from active areas in the
mine, which can affect long-term brine
and gas flows within the repository. As
part of the design, the panel closure
system that is installed needs to be
represented in the modeling of longterm performance.
On September 28, 2011, the DOE
provided a change request to the EPA
(Docket EPA–HQ–OAR–2013–0684) to
modify the panel closure system design
specified in Appendix A of 40 CFR part
194 from that of a concrete monolith
plug, noted as Option D, to a 100-foot
long barrier consisting of run-of-mine
salt (EPA 2013; 2014). The panel closure
system performance assessment release
calculations were well within the
numerical limits established in 40 CFR
191.13. The EPA approved the DOE’s
use of the proposed run-of-mine salt
closure design (79 FR 60750, Oct. 8,
2014) (Docket EPA–HQ–OAR–2013–
0684–0004 on www.regulations.gov).
The DOE incorporated the run-ofmine salt design for panel closures into
the 2014 Compliance Recertification
Application. To evaluate this change,
the Agency reviewed a broad set of
information related to the evolution of
salt repository properties, including
run-of-mine salt and adjacent disturbed
rock zone in the WIPP repository setting
(Salt Characteristics TSD 14). From this
14 ‘‘Technical Support Document for Section
194.23: Technical Review of Salt Aggregate,
Disturbed Rock Zone, and Open Drift Healing
Characteristics’’ in Docket ID No. EPA–HQ–OAR–
2014–0609.
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review, the Agency’s interpretation of
the data is that healing of the run-ofmine salt in the panel closures, the
surrounding disturbed rock zone and
open areas should occur within about
the first 200 years of post-closure
instead of the relatively asymptotic
closure for the 200–10,000 years used by
the DOE. The DOE’s use of the longer
period of time assumes permeability
and porosity for the salt will be low
within 200 years, but not at the very low
end state properties of intact halite.
To identify the potential effect of the
difference in the repository properties
between what the EPA has identified
may be applicable and what the DOE
modeled, the Agency requested that the
DOE analyze the repository performance
using parameter values for the run-ofmine salt panel closure system and
adjacent disturbed rock zone that
simulate complete healing. The DOE did
this in the sensitivity study SEN3
discussed in Section VI.E. The
calculated releases increased for direct
brine releases and spallings releases in
SEN3, but overall releases remained
well within the numerical limits of 40
CFR 191.13 and the EPA concludes that
there is a reasonable expectation that
the repository remains in compliance
with the numerical limits at 40 CFR
191.13, and 40 CFR part 191, Appendix
A.
If the DOE determines, in light of the
announced decision to abandon the area
previously designated for panel 9, that
worker safety considerations preclude
installing panel closures in affected
areas of the repository, the DOE’s
treatment of panel closures in
performance assessment may be more
appropriately addressed in the context
of modeling open areas representative of
no panel closures. The Agency will
review future panel closure modeling in
the context of future facility design
changes.
c. Modeling of Open Areas in the
Repository. In the 2014 Compliance
Recertification Application, the DOE
increased the modeled volume of the
open rooms and drifts by approximately
forty percent to accommodate future
planned experiments. These new areas
are located north of the waste area drifts
and are to be separated from the waste
area by two sets of run-of-mine salt
panel closures. For the 2014
Compliance Recertification Application
performance assessment, the DOE
modeled these areas as open for the
entire 10,000-year regulatory period
even though it is expected that the creep
closure process will close the open areas
within a few hundred years (Overview
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TSD 15). The Agency evaluated the
impact of the DOE’s assumption to
model these areas as open (relatively
large porosity and high permeability) by
requesting the DOE perform sensitivity
study SEN2, where the non-waste rooms
and open drifts are assumed to have
creep closed during the entire 10,000year regulatory period.
The results from the SEN2 studies
indicate modeling creep closure and
healing of the operations and
experimental areas (i.e., non-waste
areas) of the repository was shown to
have little effect on the prediction of
total releases from the repository
although, relative to the 2014
Compliance Recertification Application
performance assessment, a slight
increase in spallings releases does occur
if these areas are assumed to creep
closed. This is a result of higher
pressures occurring in panels. See
Section VI.E for discussion of the SEN2
study.
If, in the future, there are repository
design changes that result in more nonwaste drifts mined or left open in the
facility, the issue of open areas will
need to be re-evaluated in the context of
those design changes, as releases could
be expected to increase in that
circumstance. The DOE’s plan to
abandon panel 9 would leave large areas
of open space in the repository in the
panel 9 drifts and possibly no panel
closures for multiple panels.
Performance assessment modeling
should address these expected future
repository conditions. The EPA believes
that an independent technical review of
issues related to salt behavior and
modeling of open areas would be of
benefit to the DOE as it further develops
its plans.
d. The DOE’s Revised Estimate of the
Probability of Encountering Pressurized
Brine. Highly pressurized zones of brine
(i.e., pressurized brine reservoirs) occur
in the Castile Formation below the
Salado Formation, which is the
formation that hosts the WIPP. If a
future driller encounters a Castile
pressurized brine reservoir and brine
enters the waste panels, it can dissolve
radionuclides that then could be
transported up a borehole to the surface.
In the modeling of the repository, the
probability of a future borehole
intersecting a waste panel and a Castile
brine reservoir below the repository is
denoted by the parameter name
PBRINE. Because the probability of
hitting a brine pocket is uncertain, it is
represented by a probability
15 ‘‘Overview of Changes Between PABC–2009
and CRA–2014 WIPP Performance Assessments’’ in
Docket ID No. EPA–HQ–OAR–2014–0609.
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distribution, and the actual value of the
PBRINE parameter for an individual
model run is sampled from the PBRINE
probability distribution.
In the 2014 Compliance
Recertification Application, the DOE
changed the basis it used to develop the
probability distribution for parameter
PBRINE. The DOE’s revision to the
estimated probability of a future driller
encountering pressurized brine relies
heavily on voluntarily reported drilling
logs 16 combined with an updated
probability distribution. The DOE
eliminated from consideration sitespecific data collected through
geophysical detection methods, which
had previously been incorporated into
the PBRINE parameter.
The EPA has several concerns
regarding the DOE’s update to the
PBRINE parameter,17 including the
DOE’s elimination of the site
geophysical data leading to estimates of
the potential for brine encounters based
only on the voluntary data reported by
the driller, and that more recent site
data supports the potential for more
brine under the repository than the DOE
or the EPA had previously considered.
For a more in-depth discussion of these
issues, see the PBRINE TSD.18 The
EPA’s concerns were significant enough
that the EPA developed a modified
methodology for determining the
probability distribution for parameter
PBRINE in the WIPP performance
assessment calculations.
The Agency’s revision to the PBRINE
parameter was incorporated into
Sensitivity Study SEN4. The study
results indicate the modified PBRINE
probability distribution contributed to
an increase in estimated direct brine
releases and increased the total releases
at the 0.001 low probability compliance
point to roughly double those in the
2014 Compliance Recertification
Application performance assessment.19
Because the Agency is unable to accept
the DOE approach used to define the
PBRINE parameter, the EPA views the
updated probability distribution used in
16 Kirchner, T., T. Zeitler, and R. Kirkes. 2012.
Evaluating the Data in Order to Derive a Value for
GLOBAL:PBRINE. Memorandum to Sean Dunagan
dated December 11, 2012. ERMS 558724. Carlsbad,
NM: Sandia National Laboratories.; EPA
Completeness Comment 1–23–6; Docket EPA–HQ–
OAR–2014–0609–0004.
17 See Completeness Question 1–23–6, Probability
of Encountering a Castile Brine Pocket and
subsequent clarifying questions, as well as the
PBRINE TSD, for more detail in Docket ID No. EPA–
HQ–OAR–2014–0609.
18 ‘‘Probability of Encountering Castile Brine
Beneath the WIPP Waste Panels Using the TDEM
Block Method.’’
19 DOE 2014 Appendix PA, Sections PA–9.3 and
PA–9.5 Kirchner 2013 and the EPA, 2017 Technical
Support Document.
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the SEN4 study as the baseline for
PBRINE in future performance
assessments. The EPA will evaluate
alternative approaches proposed by the
DOE. See Section VI.E for more
discussion of the SEN4 study.
e. Revised Corrosion Rate of Steel.
The WIPP corrosion rate model includes
anoxic corrosion (i.e., corrosion in the
absence of oxygen) of iron in the waste
containers. This corrosion is caused by
hydrogen sulfide gas produced from the
microbial degradation of cellulosic,
plastics and rubber materials from the
contaminated rubber gloves and
KimwipesTM included in the waste.
The EPA reviewed the 2014
Compliance Recertification Application
model and had concerns with the way
the model addressed expected
repository carbon dioxide
concentrations in the experimental
derivation of corrosion rates. The EPA
also found that the model did not
incorporate hydrogen sulfide induced
steel passivation,20 which could result
in an overestimation of corrosion in the
longer-term. Once steel is passivated,
hydrogen sulfide consumption will
decrease significantly as corrosion will
be limited by the ability for the gas to
diffuse through the iron sulfide coating
the outer surface of the container.
In addition, other components of this
model, which the DOE considered to be
minor, may have more impact.
Calculations of the potential lead
inventories at the WIPP only include
current waste containers without
accounting for the maximum potential
of future containers.
To address the EPA’s concerns about
corrosion, part of the DOE’s SEN4
sensitivity study involved turning off
the hydrogen sulfide corrosion
parameter to simulate steel passivation.
These changes resulted in a slight
increase in gas pressures as well as a
decrease in the saturation of the waste
area because both hydrogen gas and
water were eliminated from the end
products. Results from this study
indicated that projected releases would
remain within the limits of 40 CFR
191.13. Therefore, the EPA accepts the
corrosion approach incorporated in the
2014 Compliance Recertification
Application. See Section VI.E for more
discussion of the SEN4 study.
To ensure that future performance
assessments adequately address the
mechanisms that affect gas generation in
the repository, it would be appropriate
for the DOE to update the corrosion
model to better address steel passivation
20 Passivation refers to the creation of an outer
coating layer on the steel canisters due to the
interaction of iron and sulfide.
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and account for radiolysis and address
lead corrosion to be consistent with the
expected inventory of the repository.
f. Revised Effective Shear Strength of
the WIPP Waste. The parameter
TAUFAIL represents waste shear
strength and is used in calculating
potential releases of waste materials
from the WIPP repository when a
drilling operator drills a borehole
through the waste. The drilling mud
will apply a hydrodynamic shear stress
to the punctured waste and cause it to
erode and be transported up the
borehole to the surface. The sheared
waste transmitted to the surface is
called ‘‘cavings’’. A higher shear
strength means the material is less likely
to break into pieces and be transported
up a borehole. The parameter TAUFAIL
has an uncertain value which is
sampled from a range of experimental
values for individual model runs. In the
2014 Compliance Recertification
Application, the DOE updated the mean
and lower bound for the TAUFAIL
parameter value distribution based on a
suite of laboratory flume tests
specifically designed to represent the
range of values for the WIPP waste.
In the 2009 Compliance
Recertification Application the lower
bound value was 0.05 Pa, while for the
2014 Compliance Recertification
Application the lower bound of the
distribution was increased to 2.22 Pa
(the mean value from the laboratory
flume tests). The upper bound of the
distribution, 77 Pa, remained the same.
The EPA believes the DOE’s overall
approach of using experimental data to
revise the TAUFAIL parameter is
reasonable; however, the EPA had
concerns with the DOE’s lower
‘‘bounding’’ range value derived from
the experiments. The Agency was
concerned that three of the five low
shear-strength tests had highly scattered
results. The DOE attributed the scatter
to pre-test sample damage and/or a high
degree of variability in sample
preparation, rather than testing an
equivalent suite of samples. As a result,
the mean of the low shear strength test
results may not be truly representative
of low shear strength samples.
In the SEN4 study, the EPA requested
the DOE include the lowest shearstrength flume test results (1.6 Pa) as the
bounding value, rather than the average
(2.22 Pa). The SEN4 results indicate
modifying the lower range to include
the lowest value as the bounding value
insignificantly impacted releases. This
is due to the fact that the change from
2.22 Pa to 1.6 Pa (i.e., from the mean of
experimental values to the lowest
experimental value) is much less than
would be the change from the 0.05 Pa
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used in previous performance
assessments to either the 1.6 Pa or the
2.22 Pa values. Based on these results,
the EPA accepts the DOE’s range of
values used in the 2014 Compliance
Recertification Application, though for
future performance assessments the EPA
believes it is more appropriate for the
DOE to use the lower-bound result
instead of the mean. See Section VI.E for
more discussion of the SEN4 study. See
also the TAUFAIL TSD.21
g. Revised Repository Water Balance.
Repository water balance is the
culmination of multiple chemical
reactions that produce or consume
water and affect actinide concentrations
in the brine. These reactions include
microbial degradation of the cellulosic,
plastic and rubber materials, the anoxic
corrosion of iron in the steel waste
canisters, and reactions of the
magnesium oxide (MgO) used to control
carbon dioxide (CO2) buildup in the
repository. Magnesium oxide, in
particular, reacts with brine and results
in hydromagnesite
(Mg5(CO3)4(OH)2•4H2O), which
consumes water in the process.
Previous compliance recertification
applications only included anoxic
corrosion in water balance calculations.
The 2014 Compliance Recertification
Application includes an assessment of
the microbial degradation of the
cellulosic, plastic and rubber material,
the anoxic corrosion of iron in the steel
waste canisters and reactions of the
engineered barrier. The DOE did not
change the rates for microbial cellulosic,
plastic and rubber material degradation
and water production from the 2009
Compliance Recertification Application.
As discussed previously, the DOE
revised steel corrosion rates. The DOE
developed magnesium reaction rates for
the compliance recertification
application based on previous studies
(Chemistry TSD 22).
Although changes to each of these
parameters is minor, the reactions will
have a cumulative effect. Based on
previous exchanges with the DOE (see
comment 2–C–5 in Docket ID No. EPA–
HQ–OAR–2014–0609) as well as the
SEN4 sensitivity study, the water
balance updates do not appear to
significantly affect the WIPP
performance. However, the EPA
21 ‘‘Technical Support Document for Section
194.23: EPA Review of Proposed Modification to
the Waste Shear Strength Parameter TAUFAIL’’ in
Docket ID No. EPA–HQ–OAR–2014–0609.
22 ‘‘Technical Support Document for Section
194.24: Evaluation of the Compliance
Recertification Actinide Source Term, Gas
Generation, Backfill Efficacy, Water Balance and
Culebra Dolomite Distribution Coefficient Values’’
in Docket ID No. EPA–HQ–OAR–2014–0609.
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recommends that the DOE re-evaluate
the water balance issue for future
performance assessments to address
questions associated with interactions
involving magnesium oxide (e.g.,
hydration rates in the water balance
calculations), and as previously
discussed in Section VI.D.1.e, the
associated steel corrosion model and
passivation processes.
h. Variable Brine Volume. Brine
volume plays an important role in
calculating actinide and organic ligand
concentrations. In previous performance
assessments, the DOE calculated
concentrations of these species using
the minimum brine volume needed for
a direct brine release, regardless of how
much brine is projected to be released.
This failed to account for dilution and
thus resulted in an overestimation of
organic ligand concentrations as well as
actinide releases. To correct for this in
the 2014 Compliance Recertification
Application, the DOE adjusted actinide
and organic ligand concentration
calculations to incorporate multiple
brine volumes. The DOE continues to
calculate actinides and organic ligand
concentrations at the minimum brine
volume required for a release. However,
the DOE now also calculates
concentrations by dissolving these
species at volumes 2, 3, 4 and 5 times
the minimum volume to simulate larger
volume releases. Thus, concentrations at
5 times the volume will be lower than
those calculated at the minimum
volume because more brine will be
present to dilute these aqueous species.
The EPA finds that this approach
realistically addresses the issue of
variable brine volumes involved in a
direct brine release and accepts this
model for the compliance recertification
application.
i. Revised Colloid Parameters.
Colloids are particles larger than
molecules that can be suspended in the
WIPP brine. Because colloids migrate
more rapidly through the subsurface
than actinides dissolved in solution,
colloids are an important contribution
to actinide mobility during a direct
brine release. Intrinsic colloids are
actinide macromolecules that eventually
increase in size. Microorganisms are
considered large colloids capable of
mobilizing actinides because of actinide
sorption to their charged cell walls or
because of actinide bio-uptake.
In the original Compliance
Certification Application, the colloid
parameters were based on
experimentally derived values
examining actinide macromolecules or
actinides sorbed onto biomass (e.g.,
Completeness Comment 3–C–9 in EPA–
HQ–OAR–2014–0609–0010). Since
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then, the DOE has performed multiple
new investigations to update the
intrinsic and microbial colloid
parameters. These investigations
prompted the DOE to reduce the
contribution of colloids in the 2014
performance assessment.
Because of issues with experimental
data used to develop the 2014 colloid
contributions to actinide solubility, the
2014 performance assessment
calculations using those experimental
results may underestimate colloidal
concentrations, and therefore, actinide
solubility. However, the EPA finds that
the use of an updated uncertainty
distribution for actinide solubility in the
SEN4 sensitivity study provides
adequate information to determine that
an increase in colloid concentrations
would not cause releases to exceed the
disposal standards. The EPA
recommends that additional review of
the experimental results would benefit
the DOE’s treatment of colloid formation
mechanisms in future performance
assessments. The EPA’s review of this
topic is provided in the Chemistry TSD.
See Section VI.E of this document for
discussion of the SEN4 study.
j. New Actinide Solubility Code (EQ3/
6). Prior to the 2014 Compliance
Recertification Application, the DOE
used the Fracture Matrix Transport
(FMT) geochemical modeling code for
actinide solubility calculations. The
DOE has since moved actinide solubility
calculations to the EQ3/6 code using the
database DATA0.FM1, which contains
the values needed to calculate chemical
speciation of the ions, actinides and
minerals present in the WIPP. The move
to EQ3/6 is logical as the program is
widespread and has been used in other
the DOE projects. EQ3/6 can provide
more robust calculations than FMT,
particularly in dynamic reaction-path
calculations. The EPA accepts the move
to the EQ3/6 code. For additional
discussion on this topic see the EQ3/6
TSD.23
2. Other Key Issues Identified by the
EPA During Review. The EPA identified
three key topics where the Agency
believes new information can be
incorporated into future compliance
recertification applications. These
topics relate to the chemical conditions
within the repository and are of
fundamental importance in determining
the potential for releases of
radionuclides from the disposal system.
These topics are discussed in more
detail in the Chemistry TSD.
a. Chemical Database. Actinide
solubility, or the ability for actinide
23 ‘‘EQ3/6 Computer Code Evaluation’’ in Docket
ID No. EPA–HQ–OAR–2014–0609.
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solids to dissolve in brine, is important
in calculating releases. In performance
assessment calculations, these
radionuclides include americium,
curium, neptunium, plutonium,
thorium, and uranium. Americium(III)
solubility is used to predict
plutonium(III) and curium(III)
concentrations while thorium(IV) is
used to predict plutonium(IV),
neptunium(IV) and uranium(IV).
The EPA’s review identified that the
DOE’s update of the chemical
assumptions used in the actinide
solubility database (DATA0.FM1) did
not reflect all data available prior to the
DOE’s data cut-off date of December 31,
2012.The EPA raised several issues (in
Docket ID No. EPA–HQ–OAR–2014–
0609–0010) about americium and
thorium solubility and speciation and in
response, the DOE modified the
database to produce DATA0.FM2.
However, the EPA identified flaws in
the modified database that need to be
corrected before it can be considered to
be of sufficient quality for use in
recertification. The EPA concluded that,
even with identified data gaps, the
original DATA0.FM1 database was of
higher quality and provided sufficient
information to support a determination
of continued compliance. The DOE’s
updates of the chemical database for
future performance assessments should
more comprehensively incorporate
recent data.
b. Revised Radionuclide Uncertainty
Distribution. The DOE also examined
the uncertainty distribution used to
model the +III and +IV actinide
concentrations in the performance
assessment by comparing modeled
solubility calculations to experimental
data from multiple reports and peerreviewed studies. These studies include
solubility measurements from
americium, thorium and their analogues
using a specific set of criteria
(Chemistry TSD; 2014 Compliance
Recertification Application, Appendix
SOTERM–2014 Section 5.1.3). During
the performance assessment solubility
calculations, this uncertainty
distribution is sampled and used in
calculating dissolved actinides in a
release.
After reviewing the actinide solubility
uncertainty distribution for the 2014
Compliance Recertification Application,
the EPA identified relevant studies that
were not considered in developing this
distribution, as well as identifying
studies that should have been excluded
from consideration, based on the DOE’s
evaluation criteria. Using relevant
studies would result in a revised
actinide solubility uncertainty
distribution with overall higher +III
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actinide solubility. The DOE included a
revised solubility uncertainty
distribution based on the EPA’s input in
the sensitivity study SEN4. The higher
actinide solubility used in the SEN4
study contributed to higher releases
compared to the 2014 performance
assessment, although releases in the
SEN4 study still remain below the
regulatory limits. See Section VI.E for
more discussion of the SEN4 study.
The EPA recommends that updating
the actinide solubility uncertainty
distribution should be part of the update
to the geochemical database. This would
include incorporating new solubility
data for thorium and americium under
the WIPP repository conditions, and reevaluating how studies are included in
or excluded from the DOE’s analyses.
c. Plutonium Oxidation State.
Oxidation states refer to an actinide
ion’s charge. Actinides with a higher
charge likely exist in environments with
greater oxygen content while actinides
with lower charges likely exist where
there is less oxygen. Although
plutonium has multiple oxidation states
including +VI, +V, +IV, and +III, the
WIPP model assumes plutonium
oxidation state is dominated by the +III
or +IV charge in the aqueous phase due
to the rapid removal of oxygen in the
repository. Identifying the dominant
oxidation state is particularly important
as plutonium(III) is much more soluble
than plutonium(IV). To address this
uncertainty, the plutonium oxidation
state model does not calculate oxidation
state but instead considers
plutonium(III) in 50% of the realizations
and plutonium(IV) in the other 50%.
Since the 2009 Compliance
Recertification Application,
experiments have verified that the iron
metal corrosion of the WIPP waste
containers largely mediate the
conditions conducive to plutonium(IV)
and plutonium(III) oxidation states.
While experiments have confirmed the
WIPP conditions post-closure, the
debate has shifted towards whether
plutonium(IV) or plutonium(III) is
dominant in the WIPP conditions, or
whether they will be present in equal
proportions. More recent experimental
information leads the EPA to believe
that, under the WIPP conditions,
aqueous plutonium(III) will be the
dominant state of plutonium and will
exist in equilibrium with the different
solid plutonium phases present. In
addition, organic ligands, iron and
microbial processes will also increase
the likelihood that plutonium(III) will
dominate in solutions.
While the sensitivity studies did not
directly test the presumption that +III
and +IV species would be equally
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present, the SEN4 study indirectly
examined this proposition by including
a modified solubility uncertainty
distribution that was more heavily
weighted toward higher +III solubility
(see Section VI.E.2.d). Both the
compliance recertification application
and the SEN4 study indicate plutonium
release levels will be below the
compliance points. Combined with the
related analysis of the actinide
solubility uncertainty distributions, the
Agency can accept the DOE’s
assumption that the plutonium(III) and
plutonium(IV) oxidation states will each
occur 50% of the time in performance
assessment calculations for the current
recertification. However, because of the
available data that the EPA has
identified supporting the presence of
plutonium(III) over plutonium(IV), the
EPA believes this issue is of sufficient
significance to benefit from independent
technical review of the available data
and the assumption that both plutonium
oxidation states will occur equally
under the WIPP conditions. The EPA’s
review of the plutonium oxidation state
issue is addressed more thoroughly in
the Chemistry TSD.
E. Performance Assessment: Modeling
and Containment Requirements
(§§ 194.14, 194.15, 194.23, 194.31
through 194.34)
1. Overview. Section VI.A provided a
basic description of the requirements in
40 CFR 191.13 and the performance
assessment process required to show
compliance with those standards. This
section provides additional information
on performance assessment and how it
is evaluated by the EPA in the
compliance recertification application.
As described earlier, the DOE must use
the performance assessment to
demonstrate compliance with the
containment requirements in 40 CFR
191.13. The containment requirements
are expressed in terms of ‘‘normalized
releases.’’ The DOE assembles the
results of the performance assessment
into complementary cumulative
distribution functions, which indicate
the probability of exceeding various
levels of normalized releases (§ 194.34).
For both of the DOE’s 2004 and 2009
Compliance Recertification
Applications, the EPA requested that
the DOE modify those respective
performance assessments to (1) address
completeness and technical issues
raised during the EPA review process
and with these modifications, and (2)
assure the disposal regulations were
met.
These additional sets of calculations
have been termed by the DOE to be
performance assessment ‘‘baseline
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calculations’’ and the EPA has
considered these calculations as
updated ‘‘baselines’’ for each respective
compliance recertification application.
The EPA then used these baseline
calculations for the comparison
performance assessment in each of the
DOE’s subsequent five-year compliance
recertification applications.
In this recertification review process,
the Agency proceeded differently than
in the past. During the completeness
review, the EPA identified issues with
parameters or approaches used by the
DOE in the calculations. These have
been discussed in Section VI.D. The
Agency requested that the DOE conduct
additional calculations so the EPA
could better understand how alternative
parameter values would affect
repository performance. These
calculations, or sensitivity studies as
they have been referred to, are
summarized below and are the subject
of a TSD.24 With the completion of these
sensitivity studies, the Agency has
decided not to request another set of
performance assessment baseline
calculations as was done for previous
recertifications. The Agency believes
that the sensitivity studies, coupled
with the DOE’s documentation, provide
a reasonable expectation that the WIPP
complies with the radioactive waste
disposal regulations at 40 CFR part 191
and the compliance criteria at 40 CFR
part 194. Further, with the February
2014 incidents and the DOE’s resulting
need to change the facility design,25 the
Agency felt it was not necessary or
appropriate at this time to conduct
additional calculations using a facility
design that will be changed in the near
future.
The Agency requested that the DOE
conduct four sensitivity studies (labeled
as SEN1, SEN2, SEN3 and SEN4) to
address technical concerns raised
during the EPA’s 2014 Compliance
Recertification Application review. The
EPA has compared these sensitivity
results to the DOE’s 2014 performance
assessment calculations. The purpose of
these sensitivity studies is to provide an
understanding of how repository
24 ‘‘Review of EPA Sensitivity Studies of the DOE
CRA–2014 WIPP Compliance Recertification
Performance Assessment’’ in Docket ID No. EPA–
HQ–OAR–2014–0609.
25 The DOE has stated that it intends to abandon
plans to use the area previously designated as waste
panel 9 for waste emplacement because of worker
safety issues (‘‘Installation of Ventilation Barriers
and Prohibiting Personnel Access to Equivalent
Panel 9 Areas,’’ Letter from Todd Shrader, DOE, to
Alan Perrin, EPA dated April 18, 2017, Docket ID
No. EPA–HQ–OAR–2014–0609). The DOE also
plans to develop a new ventilation shaft to increase
airflow in the mine, which is limited after the
February 2014 incidents.
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compliance would be affected when
modifying specific inputs in the 2014
performance assessment calculations. A
brief explanation of those selected
parameters is provided below.
The ability of salt openings and
aggregates to quickly compress,
consolidate and ‘‘heal’’ within a few
hundred years, mostly due to the creepclosure process, is one of the unique
properties of bedded salt geologic units
that make them potentially suitable to
use as nuclear waste repositories. The
DOE’s 2014 performance assessment
parameter values assigned to the nonwaste rooms, the panel closure system
and the adjacent disturbed rock zone
did not reflect the creep-closure and
rapid healing of these areas that the EPA
expects to occur. That is, the DOE did
not use permeability, porosity, residual
gas and brine saturations and capillary
pressures reflective of in-situ (i.e.,
undisturbed) conditions.
Three of the EPA requested sensitivity
studies, SEN1, SEN2 and SEN3, focused
on modifying parameters to test how
assuming complete creep-closure and
healing of these areas would impact
long-term performance through
modifying values related to the
permeability, porosity and two-phase
flow parameter values for the run-ofmine salt panel closure system, the
disturbed rock zone and non-waste
areas for the 10,000-year modeled
period. The fourth sensitivity study,
SEN4, investigated the cumulative
effects and impact on repository
performance by making changes to five
important parameter values as well as
using an updated numerical code.
As with the 2014 performance
assessment, all of the sensitivity studies
had three replicate calculation sets and
included the same future scenarios. The
four scenarios are briefly described
below:
(1) The undisturbed scenario—where
the repository is not impacted by human
activities,
(2) The E1 Scenario—where one or
more boreholes penetrate a Castile brine
reservoir and also intersect a repository
waste panel,
(3) The E2 Scenario—where one or
more boreholes intersect a repository
waste panel but not a brine reservoir,
and
(4) The E1/E2 Scenario—where there
are multiple penetrations of waste
panels by boreholes of either the E1 or
E2 type, at many possible combinations
of intrusion times and locations for
either E1 or E2 drilling type of event.
2. Sensitivity Studies
a. The SEN1 Study. The intention of
the SEN1 study was to determine the
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impact on repository performance by
modeling the stepped (i.e., gradual)
reduction in porosity, permeability,
residual gas and brine saturation, and
capillary pressures that reflect creepclosure and healing of the open rooms
and disturbed rock zone during the first
200 years after repository closure. The
DOE was then to model these areas,
from 200 years to 10,000 years, as fully
healed.
This study had to be terminated
because the numerical flow code used
in these calculations produced nonphysical and unrealistic results when
these parameters were modified in timeintervals to reflect healing. The Agency
accepted termination of this study, in
part, because modeling changes in these
values for the first 200 years, a relatively
short time compared to the 10,000-year
regulatory time period, would not be as
important to long-term repository
performance. The Agency considered
that the SEN2 and SEN3 studies
described below adequately addressed
the issues targeted by the SEN1 study
because the latter two studies both
modeled the open and disturbed areas
as fully healed for the entire 10,000-year
regulatory time period, essentially
bounding the conditions specified for
the SEN1 study.
b. The SEN2 Study. This study tested
the impacts on repository performance
by modeling the non-waste areas and
open drifts as completely creep-closed
during the entire 10,000-year regulatory
period. In this study, parameter values
for all the non-waste areas (i.e., the
operations and experimental room open
drifts) and adjacent disturbed rock
zones were modified. The permeability
and porosity were reduced to that of
intact halite. The residual brine and gas
saturations were also increased to better
reflect healed conditions and capillary
pressures (the pressure needed for fluid
to flow between pores) were increased.
Compared to the 2014 Compliance
Recertification Application performance
assessment, the SEN2 study waste room
pressures generally increased and brine
saturations decreased. The most affected
primary release mechanism saw an
increase in solid waste moving up a
borehole (spallings) because this release
mechanism increases when waste panel
pressure increase. All other release
mechanisms remained essentially
unchanged from the 2014 performance
assessment calculations. Total spallings
releases remained small compared with
cuttings, cavings and direct brine
releases. Spallings releases therefore did
not materially contribute to total
repository releases in either SEN2 or the
2014 Compliance Recertification
Application.
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c. The SEN3 Study. For the SEN3
study, the DOE assumed that the panel
closure system, the adjacent disturbed
rock zone and the non-waste areas and
open drifts are healed for the 10,000year regulatory period. The DOE
reduced porosity and permeability in
the repository, increasing initial
residual brine and gas saturations, and
invoking two-phase flow parameters for
intact halite. Using these modifications
effectively isolated the individual waste
panels and the non-waste areas from
one another for the entire modeled
period due to limited brine and gas
flows between areas of the repository.
The modifications made in the SEN3
study caused increases in waste-panel
pressures and decreases in waste panel
saturations. The dominant releases were
from spallings, which are only
dependent on a waste panel pressure
high enough to force solids to the
surface, and direct brine releases, which
are dependent on having sufficient brine
in the waste panels coupled with high
enough pressure to force brine to the
surface. The release mechanism that
increased the most was for spallings,
and the increase was seen at both the
low and high probability compliance
points. The impact on direct brine
release was primarily at low
probabilities because this release
depends on both high waste panel
pressure and high saturation conditions,
the combination of which were less
likely to occur in this study.
Factoring in all combined releases,
the total mean and low-probability
(0.001 probability) releases increased by
approximately 15% from the initial
2014 Compliance Recertification
Application results, although the upper
bound of the 95% confidence interval
was essentially the same as in the 2014
Compliance Recertification Application
(0.384 EPA Units in the 2014
Compliance Recertification Application
and 0.387 EPA Units in SEN3). Total
releases did not exceed the EPA’s WIPP
release limits.
The parameter values used in the
SEN3 study created a ‘‘tight’’ repository
(panel closure system, disturbed rock
zone and non-waste rooms) in which
brine and gas flow is limited. The study
results indicate that such conditions
may produce calculated releases higher
than the more open and brine- and gasconducive set of conditions presented
by the DOE in the 2014 Compliance
Recertification Application.
d. The SEN4 Study
i. Overview. The fourth sensitivity
study was intended to understand the
cumulative effects on repository
performance by making changes to
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several parameters that the Agency
questioned in the completeness review.
This study also incorporated a DOEcorrected version of the DRSPALL code,
which calculates waste that is released
up a borehole to the surface. This study
does not address all of the EPA’s
completeness questions, but provides
significant insights as to the degree in
which some parameter values of interest
to the EPA impact releases. Note, the
parameter changes in SEN2 and SEN3
representing creep closure were not
made in the SEN4 study, so the results
reflect the 2014 Compliance
Recertification Application creep
closure assumptions. The modifications
requested for this study are provided
below:
• Use the EPA’s updated distribution
for the probability of intersecting a
waste panel and a Castile brine
reservoir, denoted as the PBRINE
parameter and discussed in Section
VI.D.1.d previously.
• Use the revised data set for the
plutonium oxidation state uncertainty
distribution discussed in Section
VI.D.2.c.
• Modify the lower limit for the
parameter that predicts waste strength,
denoted as the parameter TAUFAIL
discussed in Section VI.D.1.f.
• Use the updated version of the
computer code DRSPALL that models
waste carried up a borehole. After the
2014 performance assessment
calculations had been completed and
submitted to the EPA, the DOE
discovered an error in the computer
code, DRSPALL. The DOE corrected this
error and reported it to the EPA. For the
SEN4 study, the EPA requested that the
DOE use the corrected version.
• Eliminate the hydrogen sulfide
reaction with iron as discussion in
Section VI.D.1.e.
• Use the correct modeled length for
north panel closure. The WIPP
repository design includes two sets of
panel closures emplaced at the north
end of the repository. For the 2014
performance assessment calculations,
the DOE modeled the ‘‘effective’’ length
of only one panel closure rather than
two. The EPA requested that the DOE
increase the effective length of the
modeled north waste panel to be
consistent with the facility design.
ii. Cumulative effects of the changes
evaluated by release pathway.
aa. Direct Brine Releases. Direct brine
releases are a function of actinide
solubility, repository pressure and brine
saturation. Of these changes, the most
significant are the revised solubility
uncertainty distributions that increase
the concentration of the more soluble
plutonium(III) in repository brine, the
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increased likelihood of a higher
probability of hitting a brine pocket and
the iron sulfidation reaction
stoichiometric coefficient changes. The
combined effects of these changes
increased direct brine calculated
releases and total mean low probability
(0.001) repository releases to about
twice those of the 2014 Compliance
Recertification Application performance
assessment (0.541 EPA Units for SEN4
versus 0.261 EPA Units for 2014
performance assessment).
bb. Spallings Releases. Spallings
releases are affected in SEN4 by a
combination of corrections using the
updated version of the DRSPALL code
as well as increases in repository
pressure. Repository pressure was
generally increased in SEN4 as a result
of the updated distribution of the
PBRINE parameter, the increased length
of the northernmost panel closure and
the updated iron sulfidation reaction
stoichiometric coefficients. The
combined effect of these changes was to
increase spallings releases by about half
an order of magnitude. However,
spallings releases remained low
compared to direct brine releases and
the effect of this increase in spallings on
total mean releases was minimal.
cc. Cuttings and Cavings Releases.
Cavings releases were affected by the
Agency’s requested reduction of the
lower bound of the distribution for the
TAUFAIL parameter. The small
reduction in the lower bound did not
have a meaningful effect on total mean
releases.
dd. Releases from the Culebra.
Releases from lateral flow through the
Culebra Dolomite are a function of
actinide solubility, repository pressure,
and brine saturation. These are affected
by the revised solubility uncertainty
distributions, the increased likelihood
of sampling higher values for the
PBRINE parameter, the increased length
of the northernmost panel closure and
removal of the iron sulfidation
reactions. The combined effect of these
changes on Culebra releases was too
small to have a meaningful effect on
total mean repository releases.
ee. Insights from the SEN4 Study. In
the SEN4 study, the most significant
effects on repository performance were
an increase in direct brine releases and,
by extension, an increase in total low
probability repository releases. The
Agency concludes that these increases
were primarily the result of updating
the solubility uncertainty distributions,
updating the distribution of PBRINE and
incorporating hydrogen sulfide steel
passivation. The remaining changes,
updating the TAUFAIL lower bound,
using the corrections in the code
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DRSPALL and correcting the panel
closure length, provided important
updates and corrections to the
performance calculation but had only a
negligible effect on total mean releases.
As in the previous sensitivity studies,
the total mean releases, the upper 95%
confidence limit on those means and all
individual vectors in the three replicates
remained below regulatory limits in
SEN4.
3. How the Four Sensitivity Studies
Affect the WIPP’s Compliance. The
results indicate that modifications to the
selected parameters reported in these
evaluations increased calculated
releases. However, the total mean
releases, the upper 95% confidence
limit on those means, and all individual
vectors in the three replicates remained
below the EPA’s WIPP release limits.
These sensitivity studies were
intended to address a subset of the EPA
technical issues. These studies do not
address all the technical issues
identified in the EPA’s 2014
Compliance Recertification Application
review. The major issues identified in
the EPA’s review primarily influence
the direct brine releases and how the
performance assessment addresses those
releases. The EPA recommends that,
especially with respect to calculating
direct brine releases, the DOE reevaluate the implementation of features,
events and processes, along with model
assumptions, to ensure their appropriate
integration in the 2019 Compliance
Recertification Application. The EPA
has identified two areas in particular
(modeling of open areas and plutonium
oxidation states) that the Agency
believes would greatly benefit from
independent technical review for
consideration in the DOE’s 2019
Compliance Recertification Application.
F. Additional Requirements
This section summarizes the EPA’s
review as it relates to specific sections
of the WIPP Compliance Criteria in 40
CFR part 194 that do not directly
involve performance assessment.
Information on continuing
compliance activities related to waste
characterization (40 CFR 194.8 and
194.24), inspections (§ 194.21) and
quality assurance (§ 194.22) may be
found in Section V of this document.
The DOE did not conduct any
activities during the period covered by
the 2014 Compliance Recertification
Application related to future state
assumptions (§ 194.25), expert judgment
(§ 194.26) or assurance requirements
(§ 194.41–46). See the corresponding
CARDs for more discussion. Information
on passive institutional controls, which
is an element of the assurance
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requirements, may also be found in
Section V.B.4.
1. Waste Characterization (Waste
Inventory) (§ 194.24). Section 194.24
generally requires the DOE to identify,
quantify and track the important
chemical, radiological and physical
components of the waste destined for
disposal at the WIPP. The DOE collects
data from generator sites and compiles
the waste inventory on an annual basis.
The DOE’s 2012 Annual Transuranic
Waste Inventory Report (ATWIR 2012),
which was used for the 2014
Compliance Recertification Application,
reflects the disposal intentions of the
waste generator sites as of December 31,
2010. The DOE classified the wastes as
emplaced, stored or projected (to-begenerated). The DOE used data from the
WIPP database to identify the
characteristics of the waste that has
been emplaced at the WIPP. The
projected wastes were categorized
similarly to existing waste (e.g.,
heterogeneous debris, filter material,
soil).
The EPA reviewed the compliance
recertification application and
supplemental information to determine
whether these documents provided a
sufficiently complete estimate and
description of the chemical, radiological
and physical composition of the
emplaced, stored and projected wastes
proposed for disposal in the WIPP. The
Agency also reviewed the DOE’s
description of the approximate
quantities of waste components (for
both existing and projected wastes). The
EPA found that the radionuclides,
cellulosic, plastic and rubber materials,
organic ligands, oxyanions and cements
in the waste are being appropriately
tracked and characterized. In the 2014
Compliance Recertification Application,
there is an update on the inventory of
curium and neptunium, which remain
in concentrations well below their
solubility limits even after accounting
for decay. The EPA accepts this updated
inventory, which is relatively similar to
the one used in the 2009 Compliance
Recertification Application. See the
Baseline Inventory TSD 26 for more
information.
2. Peer Review (§ 194.27). Section
194.27 of the WIPP Compliance Criteria
requires the DOE to conduct peer review
evaluations, when warranted, of
conceptual models, waste
characterization analyses, and a
comparative study of engineered
barriers. The required peer reviews must
26 ‘‘Technical Support Document for Section
194.24: Review of the Baseline Inventory Used in
the Compliance Recertification Application (CRA–
2014)’’ in Docket ID No. EPA–HQ–OAR–2014–0609.
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be performed in accordance with the
Nuclear Regulatory Commission’s
NUREG–1297, ‘‘Peer Review for HighLevel Nuclear Waste Repositories,’’
which establishes guidelines for the
conduct of a peer review exercise. The
DOE has conducted one peer review
since the 2009 Compliance
Recertification Application to establish
radiological properties for two waste
streams, titled the ‘‘Savannah River Site
Historical Radiochemistry Data Peer
Review,’’ demonstrating its compliance
with the requirements of § 194.27.
Based on a review and evaluation of
the 2014 Compliance Recertification
Application and supplemental
information provided by the DOE
(Docket ID No. EPA–HQ–OAR–2014–
0609–0330), the EPA determines that
the DOE continues to comply with the
requirements of 40 CFR 194.27.
G. Individual and Groundwater
Protection Requirements (§§ 194.51
Through 194.55)
Sections 194.51 through 194.55 of the
WIPP Compliance Criteria implement
the individual protection requirements
of 40 CFR 191.15 and the groundwater
protection requirements of subpart C of
40 CFR part 191. Assessment of the
likelihood that the WIPP will meet the
individual dose limits and radionuclide
concentration limits for ground water is
conducted through a process known as
compliance assessment. Compliance
assessment uses methods similar to
those of performance assessment (for the
containment requirements in 40 CFR
191.13 and Appendix A) but is required
to address only undisturbed
performance of the disposal system.
That is, compliance assessment does not
include human intrusion scenarios (i.e.,
drilling or mining for resources).
Compliance assessment can be
considered a ‘‘subset’’ of performance
assessment, since it considers only
natural (undisturbed) conditions and
past or near-future human activities
(such as existing boreholes), but does
not include the long-term future human
activities that are addressed in the
performance assessment.
In the 2014 Compliance
Recertification Application, the DOE reevaluated each of the individual and
groundwater requirements. The DOE
updated the data for ground water
quantity determination to define an
underground source of drinking water
for purposes of calculating groundwater
concentrations and doses. In the 2014
Compliance Recertification Application,
the DOE used 2011 (U.S. Bureau of
Census 2013) census data to update the
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number of persons per household.27 The
DOE continued to use the 2009
compliance recertification application
data for the average household water
consumption values. The water
consumption data show that the average
per capita consumption is 273 gallons
per day.28 The DOE concludes that the
sub-criterion of 5 gallons per minute
rate of production from a well continues
to accurately define an underground
source of drinking water 29 and any
change in this sub-criterion is not
warranted as a result of applying more
current water-consumption data to the
calculation.
The updates made by the DOE in the
2014 Compliance Recertification
Application did not significantly impact
the conclusions regarding the
groundwater standard in the
Compliance Certification Application.
The DOE did not change the criteria for
making underground source of drinking
water determinations, and for the 2014
Compliance Recertification Application
evaluation, the maximum potential dose
remains below the Compliance
Certification Application value
calculated and continued compliance
with the individual protection standard
is maintained. The DOE states that the
conservative bounding analysis used for
the 1998 certification decision
compliance assessment is still
applicable for 2014 Compliance
Recertification Application.30
The EPA finds the DOE in continued
compliance with 40 CFR 194.51–194.55
requirements.
VII. How has the public been involved
in the EPA’s WIPP recertification
activities?
A. Public Information
The EPA interacts with the public
through various means. The EPA’s main
mechanism for distributing information
is the EPA Web site and email messages
via the WIPP–NEWS listserv. The EPA
will also occasionally have meetings, in
person or via teleconferences or
webinars.
Throughout the recertification
process, the Agency posted pertinent
new information and updates on the
EPA WIPP Web site (https://
www.epa.gov/radiation/epas-role-wasteisolation-pilot-plant-wipp). All
pertinent recertification documents
27 2014 Compliance Recertification Application
Appendix IGP–2014, Table IGP–3
28 2014 Compliance Recertification Application
Appendix IGP–2014, Table IGP–3
29 2014 Compliance Recertification Application
Appendix IGP–2014, Section IGP–3.1.1)
30 2014 Compliance Recertification Application
Appendix IGP–2014, Section IGP–4.0
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(including the DOE-submitted
recertification materials,
correspondence, Federal Register
notices, outreach materials, hearing
transcripts as well as TSDs) are
available for review or download (in
Adobe PDF format) via the electronic
docket dedicated to the 2014–2017
recertification process (https://
www.regulations.gov, Docket ID No.
EPA–HQ–OAR–2014–0609).
Since October 2014, the EPA has sent
out numerous announcements regarding
the recertification schedule and
availability of any WIPP-related
documents on the EPA WIPP Web site
and the dockets, as well as details for
the Agency’s June 2015 stakeholder
meetings in New Mexico and January
2017 stakeholder webinar (via Adobe
Connect).
B. Stakeholder Meetings
As discussed in the WIPP LWA, the
recertification process is not a
rulemaking and public hearings are not
required. However, the EPA held a
series of stakeholder meetings in June
2015 (Carlsbad and Albuquerque, NM)
as well as a stakeholder webinar in
January 2017 (via Adobe Connect
software, with public hosting locations
in Carlsbad and Albuquerque, NM) to
provide information and updates about
the recertification process. In an effort to
make these meetings as informative as
possible to all attending parties, the EPA
listened to stakeholder input and
concerns and tailored the meetings
around the public as much as possible.
The first meeting was held on June 16,
2015, in Carlsbad, New Mexico and
consisted of one three-hour afternoon
session. The second public meeting was
held on June 17, 2015, in Albuquerque,
New Mexico, with afternoon and
evening sessions.
The main purpose of these meetings
was to discuss the EPA’s recertification
process and timeline, as well as the
DOE’s application and important
changes at the WIPP since the last
recertification in 2010. The meetings
featured brief presentations on the
aforementioned topics, as well as a
facilitated discussion. In response to
stakeholder suggestions, the DOE staff
members were also on hand to provide
information and answer any stakeholder
questions. Staff from the New Mexico
Environment Department (NMED) were
present as observers. Public participants
were encouraged to provide comments
to the EPA for consideration during
review of the DOE’s 2014 Compliance
Recertification Application.
The EPA also held a stakeholder
webinar using the Adobe Connect
software on January 12, 2017. The
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Agency hosted the webinar from
Washington, DC, with physical hosting
locations set up in both Carlsbad and
Albuquerque, NM, to accommodate
members of the public as well as the
DOE and NMED staff. The main purpose
of this webinar was to inform the public
of the current recertification schedule
and provide updated technical
information related to stakeholder
questions and comments received at the
June 2015 meetings.
All of the issues raised at these
meetings have been addressed by the
EPA in Section VII.C of this document
or in the CARDs under the relevant
section and are available in the public
docket (www.regulations.gov, Docket ID
No. EPA–HQ–OAR–2014–0609).
C. Public Comments on Recertification
The EPA posted the recertification
application on the Web site immediately
following receipt. The EPA formally
announced receipt of the recertification
application in the Federal Register on
October 10, 2014. The notice also
officially opened the public comment
period on the recertification application.
For recertification, the EPA sought
public comments and input related to
changes in the DOE’s application that
may have a potential impact on the
WIPP’s ability to remain in compliance
with the EPA’s disposal regulations.
The comment period for the
recertification application closed on
April 10, 2017, approximately two years
and six months after it initially opened.
This closing date was 30 days after the
EPA’s announcement in the Federal
Register that the recertification
application was complete.
The EPA received 17 sets of written
public comments during the public
comment period. The EPA considered
significant comments from the written
submissions and the stakeholder
meetings in the evaluation of continuing
compliance. The EPA addresses these
comments in CARDs that are relevant to
each topic. In addition, a listing of all
comments received and responses to
each is included in Appendix 15–C of
CARD 15. Two specific comments are
addressed here.
Comment: One comment addressed
shipment of waste from Argonne
National Lab. Citing the EPA’s
inspection reports, the commenter
stated that he believed that the DOE had
shipped and emplaced at the WIPP
waste from the Lab that contained spent
nuclear fuel and high level waste. He
correctly stated that the WIPP LWA
bans the transport to and disposal at the
WIPP of high level radioactive waste
and spent nuclear fuel. He wanted to
know (a) how the EPA failed to uncover
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that the Argonne Lab was to ship spent
nuclear fuel to the WIPP and approved
this disposal, (b) how the EPA assures
that this waste will not be sent to the
WIPP, (c) how much of this waste has
been sent to the WIPP, and the identity
of all waste of these types, (d) what
authority allowed the shipment and
disposal of these prohibited wastes, and
(e) how the EPA did not bar the DOE’s
shipment and disposal of these wastes.
In a related comment, on February 3,
2017, the DOE, responded to this
commenter and stated that the Argonne
Lab waste is derived from atomic energy
defense activities and did not contain
any spent nuclear fuel (see EPA–HQ–
OAR–2014–0609–0042). The DOE
acknowledged that the WIPP LWA
prohibits the disposal at WIPP of spent
nuclear fuel and also acknowledged that
some of the waste from the Argonne Lab
was debris from specimens taken from
fuel pins that were originally irradiated
in commercial nuclear reactors.
However, the DOE commented that the
statutory definition of spent nuclear fuel
does not speak directly to the issue of
whether debris from specimens of
commercial fuel rods is spent nuclear
fuel. The DOE explained that, here, the
debris—although including material
that originated from fuel pins that had
been irradiated in nuclear reactors—
resulted from research and development
activities at Argonne. The DOE stated
that to try to segregate debris originating
from irradiated fuel pins from other
waste would be technically infeasible
and cost prohibitive and would increase
worker exposure. The DOE asserted that
resolution of whether the material
should be considered spent nuclear fuel
was within its discretion and that it was
its longstanding practice to classify such
debris as waste and not spent nuclear
fuel. In response to the DOE’s February
3, 2017 comment, the original
commenter resubmitted his original
comment.
EPA Response: Under the WIPP LWA,
the focus of the EPA’s present
recertification determination is whether
the WIPP continues to comply with the
final disposal regulations. Although—as
the commenter notes and the DOE
acknowledges—the WIPP LWA bans
disposal at the WIPP of spent nuclear
fuel, the disposal regulations,
themselves, currently do not expressly
address disposal of spent nuclear fuel.
The WIPP LWA incorporates the
definition of spent nuclear fuel found in
the Nuclear Waste Policy Act of 1982:
‘‘fuel that has been withdrawn from a
nuclear reactor following irradiation,
the constituent elements of which have
not been separated by reprocessing.’’ 42
U.S.C. 10101(23) (as incorporated by
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WIPP LWA §2(15)). There seems to be
no dispute that waste from the Argonne
Lab includes some quantity of material
that is not presently in the intact
physical form of fuel withdrawn from a
reactor following irradiation,31 but is
fragments of or particulates from fuel
pins withdrawn from a reactor following
irradiation. The DOE states that the
fragments or particulates resulted from
research and development activities on
test specimens from fuel pins
withdrawn from a reactor following
irradiation and claims that treatment of
such material as other than spent
nuclear fuel is consistent with the intent
of the WIPP LWA. The DOE also asserts
that attempting to segregate the fuel pin
fragments and particulates from other
debris shipped to the WIPP is infeasible
and cost prohibitive and would increase
worker exposure.
Reasonable contentions may be made
that fragments and particulates resulting
from research and development
activities on specimens from fuel
withdrawn from a nuclear reactor
following irradiation (‘‘pieces of pieces’’
of fuel pins) do not meet the statutory
definition of spent nuclear fuel. The
practical considerations of feasibility,
cost, and worker safety associated with
attempting to segregate such particulates
from other waste shipped to the WIPP
bear consideration. It is not essential,
however, to the EPA’s present
recertification decision to attempt to
definitively resolve this issue, because
the current disposal regulations do not
expressly address disposal of spent
nuclear fuel.
On an on-going basis, aside from the
periodic recertification of the WIPP, the
EPA communicates with the DOE
concerning the characterization of WIPP
waste. The DOE provides the EPA with
documentation relating to WIPP waste
streams, including but not limited to,
waste from the Argonne National
Laboratory, and including
documentation for both contact handled
and remote handled TRU waste streams.
The relevant information is confirmed
by analyzing individual waste
containers using the EPA approved
processes, procedures and equipment.
These steps allow the DOE to
demonstrate that waste containers for
WIPP disposal meet the EPA’s WIPP
waste limits for physical and
radiological contents of the waste. So,
concerning the waste shipped from
Argonne National Laboratory, the EPA
evaluated the waste characteristic
information prepared for remote
31 There also seems to be no doubt that, as to the
material in question, the ‘‘constituent elements’’
have not been ‘‘separated by reprocessing.’’
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handled waste. The DOE provided
historical information to document that
waste generated from laboratory
experiments at Argonne was defense
related, and through radiological assay
concluded that the waste in question
met the definition of TRU waste and
was appropriate for disposal at the
WIPP. Following this determination,
Argonne provided this waste for
characterization. Radiological and
physical characterization confirmed that
the TRU waste in question (a) is remote
handled waste; (b) exhibits the
characteristics of debris waste; and (c)
meets the regulatory limits of the EPA’s
WIPP waste acceptance requirements at
40 CFR 194.24.
The EPA thoroughly inspects and
approves the waste characterization
processes in place at all waste
characterization sites including Argonne
National Laboratory. As part of the
waste characterization inspections and
approvals, the EPA is responsible for
evaluating the adequacy of
characterization methods used to
identify and measure radiological and
physical contents of the TRU waste that
affect the long term containment and
isolation of waste at the WIPP and for
ensuring that the WIPP-bound waste
meets the disposal requirements under
40 CFR 194.24.
Comment: Another commenter
disagreed with the DOE’s proposed
revision of the PBRINE parameter. The
commenter noted that the DOE’s 2014
approach resulted in a lower probability
of intersecting a brine pocket than was
used in the original certification and
previous recertifications, and finds this
to be ‘‘invalid.’’ The commenter
recommends using a fixed value of 60%
probability, based on historical well
testing and geophysical data. The
commenter also disputes a number of
the DOE’s underlying assumptions for
revising the approach, including the
DOE’s view of the geophysical data as
unreliable and what the commenter sees
as the DOE’s misinterpretation of more
recent drilling data.
EPA Response: The EPA agrees with
the commenter that the DOE’s revised
approach raises concerns. In particular,
the EPA does not agree with the DOE’s
conclusions regarding the geophysical
data. However, after reviewing the data
again, the EPA disagrees with the
commenter that a fixed probability of
60% is necessary. The EPA notes that
60% was the high end of the probability
distribution used in performance
assessments prior to 2014, with a mean
probability of 30.5%, as recognized by
the commenter. The updated approach
developed by the EPA uses the
geophysical data, but also incorporates
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newer drilling information into the
probability distribution. The EPA
believes this approach is sound and is
acceptable for use in future performance
assessments. The EPA will evaluate
future proposals by the DOE to update
the method for determining PBRINE.
The EPA’s review is discussed further in
Section VI.D.1.d of this document and
in the PBRINE TSD.
VIII. Where can I get more information
about the EPA’s WIPP-related
activities?
A. Supporting Documents for
Recertification
The CARDs discuss DOE’s
compliance with each of the individual
requirements of the WIPP Compliance
Criteria. The CARDs also list the EPA
TSDs and any other references used by
the EPA in rendering the decision on
compliance. All TSDs and references are
available in the Agency’s dockets, via
www.regulations.gov (Docket ID No.
EPA–HQ–OAR–2014–0609), with the
exception of generally available
references and those documents already
maintained by the DOE or its
contractors in locations accessible to the
public. For more detailed information
on the technical issues considered in
the EPA’s recertification decision, see
the TSDs.
B. The WIPP Web site & WIPP–NEWS
Email Listserv
For more general information and
updates on the EPA’s WIPP activities,
please visit the WIPP internet homepage
at .
All pertinent recertification-related
documents (including the DOEsubmitted recertification materials,
letters, Federal Register notices,
outreach materials, etc.) are available for
review or download in Adobe PDF
format. The Agency’s WIPP–NEWS
email listserv, which automatically
sends messages to subscribers with upto-date WIPP announcements and
information, is also available online.
Any individuals wishing to subscribe to
the listserv can join by visiting and
providing all requested information to
register.
C. Dockets
In accordance with 40 CFR 194.67,
the EPA maintains public dockets via
www.regulations.gov (Docket ID No.
EPA–HQ–OAR–2014–0609) that contain
all the information used to support the
Agency’s decision on recertification.
The Agency maintains the formal hard
E:\FR\FM\19JYN1.SGM
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33122
Federal Register / Vol. 82, No. 137 / Wednesday, July 19, 2017 / Notices
asabaliauskas on DSKBBXCHB2PROD with NOTICES
copy/paper docket in Washington, DC,
as well as informational dockets in three
locations in the State of New Mexico
(Carlsbad, Albuquerque, and Santa Fe).
The docket consists of all relevant,
significant information received to date
from outside parties and all significant
information considered by the EPA in
reaching a recertification decision
regarding whether the WIPP facility
continues to comply with the disposal
regulations.
IX. What is the EPA’s role in future
WIPP activities?
The EPA’s regulatory role at the WIPP
does not end with this recertification
decision. The Agency’s future WIPP
activities include additional
recertifications every five years (the next
being scheduled to be submitted by the
DOE in March 2019), review of the DOE
reports on conditions and activities at
the WIPP, assessment of waste
characterization and quality assurance
programs at waste generator sites,
announced and unannounced
inspections of the WIPP and other
facilities and, if necessary, modification,
revocation or suspension of the
certification.
As a result of the February 2014
incidents at the WIPP, the DOE will be
making changes to the repository
design. The DOE has indicated that it no
longer plans to use panel 9 for waste
operations due to the worker safety
hazards in that location, so an
alternative panel will be needed. This
decision may also have implications for
panel closures in the panels accessed
through the panel 9 drifts (i.e., panels 3–
6). In addition, the DOE is planning a
new ventilation shaft that will allow for
increased airflow through the
underground operations area. The EPA
will be keeping abreast of the DOE’s
requested changes and will make that
information available as it is received.
As described in Section VI of this
notice, the EPA’s review of the 2014
Compliance Recertification Application
identified where the DOE’s technical
basis for the modeling has limitations
with assumptions used or with the basis
for some parameter values. The EPA
concerns with these limitations were
generally addressed by the results of the
SEN studies. While this approach of
using a series of sensitivity studies to
examine identified limitations was
sufficient in the context of this
compliance recertification application,
it was to some extent driven by the
known upcoming physical changes in
the repository. The EPA would prefer to
be able to evaluate a complete revised
performance assessment in future
compliance recertification application
VerDate Sep<11>2014
18:49 Jul 18, 2017
Jkt 241001
reviews. The EPA recommends that the
performance assessment technical basis
be evaluated for improvement in these
areas: (1) Calculations of actinide
solubility, (2) modeling the chemical
conditions in the repository, and (3)
modeling direct brine releases.
Although not required by the
Administrative Procedure Act (APA),
the WIPP LWA or the WIPP Compliance
Criteria, the EPA intends to continue
docketing all inspection or audit reports
and annual reports and other significant
documents on conditions and activities
at the WIPP, as well as formal
communications between the two
agencies.
The EPA plans to conduct future
recertification processes using an
administrative process generally similar
to that described in today’s action.
Dated: July 10, 2017.
Sarah Dunham,
Acting Assistant Administrator, Office of Air
and Radiation.
[FR Doc. 2017–15182 Filed 7–18–17; 8:45 am]
BILLING CODE 6560–50–P
ENVIRONMENTAL PROTECTION
AGENCY
[9965–03–OEI]
Cross-Media Electronic Reporting:
Authorized Program Revision
Approval, Territory of U.S. Virgin
Islands
Environmental Protection
Agency (EPA).
ACTION: Notice.
AGENCY:
This notice announces EPA’s
approval of the Territory of U.S. Virgin
Islands’ request to revise its EPA
Administered Permit Programs: The
National Pollutant Discharge
Elimination System EPA-authorized
program to allow electronic reporting.
DATES: EPA’s approval is effective July
19, 2017.
FOR FURTHER INFORMATION CONTACT:
Karen Seeh, U.S. Environmental
Protection Agency, Office of
Environmental Information, Mail Stop
2823T, 1200 Pennsylvania Avenue NW.,
Washington, DC 20460, (202) 566–1175,
seeh.karen@epa.gov.
SUPPLEMENTARY INFORMATION: On
October 13, 2005, the final Cross-Media
Electronic Reporting Rule (CROMERR)
was published in the Federal Register
(70 FR 59848) and codified as part 3 of
title 40 of the CFR. CROMERR
establishes electronic reporting as an
acceptable regulatory alternative to
paper reporting and establishes
requirements to assure that electronic
SUMMARY:
PO 00000
Frm 00083
Fmt 4703
Sfmt 9990
documents are as legally dependable as
their paper counterparts. Subpart D of
CROMERR requires that state, tribal or
local government agencies that receive,
or wish to begin receiving, electronic
reports under their EPA-authorized
programs must apply to EPA for a
revision or modification of those
programs and obtain EPA approval.
Subpart D provides standards for such
approvals based on consideration of the
electronic document receiving systems
that the state, tribe, or local government
will use to implement the electronic
reporting. Additionally, § 3.1000(b)
through (e) of 40 CFR part 3, subpart D
provides special procedures for program
revisions and modifications to allow
electronic reporting, to be used at the
option of the state, tribe or local
government in place of procedures
available under existing programspecific authorization regulations. An
application submitted under the subpart
D procedures must show that the state,
tribe or local government has sufficient
legal authority to implement the
electronic reporting components of the
programs covered by the application
and will use electronic document
receiving systems that meet the
applicable subpart D requirements.
On July 7, 2017, the U.S. Virgin
Islands Department of Planning &
Natural Resources (VI DPNR) submitted
an application titled ‘‘NPDES eReporting Tool’’ for revision to its EPAapproved program under title 40 CFR to
allow new electronic reporting. EPA
reviewed VI DPNR’s request to revise its
EPA-authorized Part 123—EPA
Administered Permit Programs: The
National Pollutant Discharge
Elimination System program and, based
on this review, EPA determined that the
application met the standards for
approval of authorized program
revision/modification set out in 40 CFR
part 3, subpart D. In accordance with 40
CFR 3.1000(d), this notice of EPA’s
decision to approve U.S. Virgin Islands’
request to revise its Part 123—EPA
Administered Permit Programs: The
National Pollutant Discharge
Elimination System program to allow
electronic reporting under 40 CFR parts
122 and 125 is being published in the
Federal Register.
VI DPNR was notified of EPA’s
determination to approve its application
with respect to the authorized program
listed above.
Matthew Leopard,
Director, Office of Information Management.
[FR Doc. 2017–15164 Filed 7–18–17; 8:45 am]
BILLING CODE 6560–50–P
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Agencies
[Federal Register Volume 82, Number 137 (Wednesday, July 19, 2017)]
[Notices]
[Pages 33106-33122]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-15182]
[[Page 33106]]
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ENVIRONMENTAL PROTECTION AGENCY
[EPA-HQ-OAR-2014-0609; FRL-9965-08-OAR]
Criteria for the Certification and Recertification of the Waste
Isolation Pilot Plant's Compliance With the Disposal Regulations;
Recertification Decision
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice; recertification decision.
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SUMMARY: With this notice, the Environmental Protection Agency (EPA or
the Agency) recertifies that the U.S. Department of Energy's (DOE)
Waste Isolation Pilot Plant (WIPP) continues to comply with the
``Environmental Standards for the Management and Disposal of Spent
Nuclear Fuel, High-Level and Transuranic (TRU) Radioactive Waste.''
This action represents the Agency's third periodic evaluation of
the WIPP's continued compliance with the disposal regulations and WIPP
Compliance Criteria. The WIPP Compliance Criteria implement and
interpret the disposal regulations specifically for the WIPP. As
directed by Congress in the WIPP Land Withdrawal Act (WIPP LWA), this
``recertification'' process is required every five years following the
WIPP's initial receipt of TRU waste on March 26, 1999 (e.g., March
2004, March 2009), until the end of the decommissioning phase. For each
recertification--including the one being announced with this action--
the DOE must submit documentation of the site's continuing compliance
with the disposal regulations to the EPA for review.
This recertification decision is based on a thorough review of
information submitted by the DOE, independent technical analyses, and
public comments. The Agency has determined that the DOE continues to
meet all applicable requirements of the WIPP Compliance Criteria, and
with this action, recertifies the WIPP facility. This recertification
decision does not otherwise amend or affect the EPA's radioactive waste
disposal regulations or the WIPP Compliance Criteria. In addition,
recertification is not subject to rulemaking or judicial review, nor is
it linked to the resumption of disposal activities at the WIPP
facility. The EPA has also identified areas in which the DOE's
technical analyses and justifications could be improved for the next
recertification application.
FOR FURTHER INFORMATION CONTACT: Ray Lee, Radiation Protection
Division, Mail Code 6608T, U.S. Environmental Protection Agency, 1200
Pennsylvania Avenue Washington, DC 20460; telephone number: (202) 343-
9463; fax number: (202) 343-2305; email address: lee.raymond@epa.gov.
Copies of the Compliance Application Review Documents (CARDs)
supporting this action and all other recertification-related
documentation can be found in the Agency's electronic docket found at
www.regulations.gov (Docket ID No. EPA-HQ-OAR-2014-0609).
SUPPLEMENTARY INFORMATION:
Table of Contents
I. General Information
II. What is the WIPP?
A. Background
B. Impacts of the February 2014 Incidents on the Repository
III. Compliance Certification History
A. 1998 Certification Decision
B. 2006 Recertification Decision
C. 2010 Recertification Decision
IV. With which regulations must the WIPP comply?
A. Compliance with Radioactive Waste Disposal Regulations & the
WIPP Compliance Criteria
B. Compliance with Other Environmental Laws and Regulations
V. Continuing Compliance with the WIPP Compliance Criteria
A. Annual Change Reports
B. Monitoring the Conditions of Compliance
1. Panel Closure Rulemaking
2. Quality Assurance
3. Waste Characterization
4. Passive Institutional Controls
C. Inspections
V. What is the EPA's 2017 Recertification Decision?
A. Performance Assessment and the EPA's Standards
B. Summary of the EPA's Review
C. What information did the Agency examine to make the final
decision?
D. Content of the Compliance Recertification Application
(Sec. Sec. 194.14 and 194.15)
1. Changes to the Disposal System Identified by the DOE
a. Update to the Drilling Rate and Borehole Plugging Patterns
b. Replacement of Option D Panel Closure System With Run-of-Mine
Salt Panel Closure Design
c. Modeling of Open Areas in the Repository
d. The DOE's Revised Estimate of the Probability of Encountering
Pressurized Brine
e. Revised Corrosion Rate of Steel
f. Revised Effective Shear Strength of the WIPP Waste
g. Revised Repository Water Balance
h. Variable Brine Volume
i. Revised Colloid Parameters
j. New Actinide Solubility Code (EQ3/6)
2. Other Key Issues Identified by the EPA During Review
a. Actinide Solubilities
b. Solubility Uncertainty Distribution
c. Plutonium Oxidation States
E. Performance Assessment: Modeling and Containment Requirements
(Sec. Sec. 194.14, 194.15, 194.23, 194.31 through 194.34)
1. Overview
2. Sensitivity Studies
a. The SEN1 Study
b. The SEN2 Study
c. The SEN3 Study
d. The SEN4 Study
i. Overview
ii. Cumulative Effects of the Changes Evaluated by Release
Pathway
aa. Direct Brine Releases
bb. Spallings Releases
cc. Cuttings and Cavings Releases
dd. Releases From the Culebra
ee. Insights from the SEN4 Study
3. How the Four Sensitivity Studies Affect the WIPP Compliance
F. Additional Requirements
1. Waste Characterization (Waste Inventory (Sec. 194.24)
2. Peer Review (Sec. 194.27)
G. Individual and Groundwater Protection Requirements
(Sec. Sec. 194.51 Through 194.55)
VII. How has the public been involved in the EPA's WIPP
Recertification activities?
A. Public Information
B. Stakeholder Meetings
C. Public Comments on Recertification
VIII. Where can I get more information about the EPA's WIPP-related
activities?
A. Supporting Documents for Recertification
B. The WIPP Web site & WIPP-NEWS Email Listserv
C. Dockets
IX. What is the EPA's role in future WIPP activities?
Abbreviations
CARD Compliance Application Review Document
CFR Code of Federal Regulations
DOE U.S. Department of Energy
EPA U.S. Environmental Protection Agency
FR Federal Register
NMED New Mexico Environment Department
OAR Office of Air and Radiation
Pa Pascal
PBRINE Parameter: Probability Distribution of Encountering Brine
RCRA Resource Conservation and Recovery Act
SEN Sensitivity Study
TRU Transuranic
TSD Technical Support Document
WIPP Waste Isolation Pilot Plant
WIPP LWA WIPP Land Withdrawal Act
I. General Information
A. How can I get copies of this document and other related information?
1. Docket. The EPA has established a docket for this action under
Docket ID No. EPA-HQ-OAR-2014-0609. Publicly available docket materials
are available either electronically at https://www.regulations.gov or in
hard copy at the Air and Radiation Docket in the EPA
[[Page 33107]]
Docket Center, (EPA/DC) EPA West, Room B102, 1301 Constitution Ave.
NW., Washington, DC. The EPA Docket Center Public Reading Room is open
from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal
holidays. The telephone number for the Public Reading Room is (202)
566-1744, and the telephone number for the Air and Radiation Docket is
(202) 566-1742. As provided in the EPA's regulations at 40 CFR part 2,
and in accordance with normal EPA docket procedures, if copies of any
docket materials are requested, a reasonable fee may be charged for
photocopying.
2. Electronic Access. You may access this Federal Register document
electronically through the U.S. Government Publishing Office Web site
at https://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR.
II. What is the WIPP?
A. Background
The Waste Isolation Pilot Plant (WIPP) is a disposal system for
defense-related transuranic (TRU) radioactive waste. The WIPP Land
Withdrawal Act (WIPP LWA) of 1992 defines TRU waste as materials
containing alpha-emitting radioisotopes, with half-lives greater than
twenty years, in concentrations greater than 100 nanocuries per gram
(nCi/g), except for (A) high-level radioactive waste; (B) waste that
the Secretary has determined, with the concurrence of the
Administrator, does not need the degree of isolation required by the
disposal regulations; or (C) waste that the Nuclear Regulatory
Commission has approved for disposal on a case-by-case basis in
accordance with part 61 of title 10, Code of Federal Regulations (CFR).
Developed by the U.S. Department of Energy (DOE), the WIPP is located
near Carlsbad in southeastern New Mexico. At the WIPP, the DOE disposes
of radioactive waste 655 meters (2,150 feet) underground in an ancient
salt layer which will eventually creep and encapsulate the waste. The
WIPP has a total capacity to dispose of 6.2 million cubic feet of
waste.
Congress initially authorized the development and construction of
the WIPP in 1980 ``for the express purpose of providing a research and
development facility to demonstrate the safe disposal of radioactive
wastes resulting from the defense activities and programs of the United
States.'' \1\ To further facilitate the development and operation of
the WIPP, Congress passed the WIPP LWA in 1992 and amended it in 1996.
The WIPP LWA only allows TRU radioactive waste generated by defense
activities associated with nuclear weapons to be emplaced in the WIPP
and explicitly prohibits high-level waste or spent nuclear fuel from
being disposed of at the WIPP.
---------------------------------------------------------------------------
\1\ Department of Energy National Security and Military
Applications of Nuclear Energy Authorization Act of 1980, Pub. L.
96-164, section 213.
---------------------------------------------------------------------------
Most TRU waste proposed for disposal at the WIPP consists of items
that have become contaminated as a result of activities associated with
the production of nuclear weapons or with the clean-up of weapons
production facilities, e.g., rags, equipment, tools, protective gear
and organic or inorganic sludges. Some TRU waste contains hazardous
chemicals used during weapons production, research and development and
cleaning/maintenance/deactivation activities. Some of the waste
proposed for disposal at the WIPP is known as legacy waste and has been
stored for decades at various federal facilities across the United
States, including major generator sites such as the Idaho National
Laboratory, Los Alamos National Laboratory and Oak Ridge National
Laboratory, and smaller generators such as Argonne National Laboratory
and Lawrence Livermore National Laboratory. These facilities continue
to generate small quantities of TRU waste. All TRU waste which the DOE
plans to ship to the WIPP is subjected to the EPA's WIPP waste
characterization requirements at 40 CFR 194.24.
The WIPP LWA provides the EPA the authority to oversee and regulate
the WIPP. The WIPP LWA requires the EPA to conduct three main tasks, to
be completed sequentially, to reach an initial compliance certification
decision. First, the WIPP LWA requires the EPA to finalize general
regulations for the disposal of highly-radioactive waste.\2\ The EPA
published these disposal regulations, located at subparts B and C of 40
CFR part 191, in the Federal Register in 1985 and 1993.\3\
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\2\ WIPP LWA, section 8(b).
\3\ 50 FR 38066-38089 (September 19, 1985) and 58 FR 66398-66416
(December 20, 1993).
---------------------------------------------------------------------------
Second, the WIPP LWA requires the EPA to develop criteria, via
rulemaking, to interpret and implement the general radioactive waste
disposal regulations specifically as they apply to the WIPP. In 1996,
the Agency issued the WIPP Compliance Criteria (40 CFR part 194).\4\
---------------------------------------------------------------------------
\4\ 61 FR 5224-5245 (February 9, 1996).
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Third, the WIPP LWA requires the EPA to review the information
submitted by the DOE every five years to demonstrate continued
compliance with the disposal regulations and determine whether or not
the WIPP continues to be in compliance.\5\ The Agency issued the
initial certification decision on May 18, 1998 (63 FR 27354-27406).
---------------------------------------------------------------------------
\5\ WIPP LWA, section 8(d).
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B. Impacts of February 2014 Incidents on the Repository
Since the EPA's initial certification, operation of the WIPP
proceeded without substantial interruption until 2014. However, two
events took place at the WIPP in February 2014 that led the DOE to
suspend emplacement of additional waste in the facility for nearly
three years. On February 5, a salt haul truck caught fire. Workers were
evacuated, and the underground portion of the WIPP was shut down. On
February 14, a second event occurred when a continuous air monitor
alarmed during the night shift, signaling a detection of radiation. The
continuous air monitor was measuring exhaust from waste panel 7, where
waste emplacement had recently begun. Radiological contamination of the
underground caused an indefinite suspension of waste handling
activities.
After implementing numerous corrective actions, the DOE resumed
limited waste emplacement on January 4, 2017, and also resumed limited
shipments from waste generator sites. Resumption of waste emplacement
at the WIPP is unrelated to the EPA's recertification decision, which
is primarily concerned with compliance with the EPA's long-term
disposal requirements. However, the DOE has acknowledged that recovery
from the radiological release will result in design changes to the
repository, which will need to be considered from that longer-term
perspective. These changes include installation of a new ventilation
shaft and modification of the waste panel layout to accommodate the
premature closure of planned waste emplacement capacity in panel 9. The
DOE is still reviewing options and has not provided any specific plans
to the EPA. The EPA will review these changes as more information
becomes available and they are incorporated into future recertification
applications. The EPA recognizes that the current recertification
decision is based on a repository design that is likely to change, but
the current application contains the information necessary to reach a
decision without knowing the details of the future changes. It is not
unprecedented for the EPA to conduct a recertification review with the
knowledge that the DOE will submit a request to change an aspect of the
disposal system design.
[[Page 33108]]
The EPA expects that any issues associated with repository design
changes will be appropriately addressed in responding to change
requests from the DOE and in subsequent recertification applications.
However, because these design changes are likely to be substantial, the
EPA believes it is necessary for the DOE to ensure that future
compliance recertification applications are as robust and technically
defensible as possible. To that end, the EPA discusses in Section VI.D
specific aspects of future compliance recertification applications that
the Agency believes would benefit from independent technical review, or
otherwise from thorough consideration of more recent scientific
information and understanding of chemical processes anticipated to take
place within the repository. The EPA strongly believes that
incorporating such reviews and information into future applications
will increase public confidence in the DOE's compliance demonstrations
and facilitate the Agency's review.
III. Compliance Certification History
A. 1998 Certification Decision
The WIPP LWA, as amended, required the EPA to evaluate whether the
WIPP complied with the EPA's standards for the disposal of radioactive
waste. On May 18, 1998 (63 FR 27354-27406), the EPA determined that the
WIPP met the standards for radioactive waste disposal. This decision
allowed the DOE to begin placing radioactive waste in the WIPP,
provided that all other applicable health and safety standards, and
other legal requirements, were met. The WIPP received the first
shipment of TRU waste on March 26, 1999. The complete record and basis
for the EPA's 1998 certification decision can be found in Air Docket A-
93-02.
Although the EPA determined that the DOE met all of the applicable
requirements of the WIPP Compliance Criteria in the original
certification decision, the EPA also found that it was necessary for
the DOE to take additional steps to ensure that the measures actually
implemented at the WIPP (and thus the circumstances expected to exist
there) were consistent with the DOE's compliance certification
application and with the basis for the EPA's compliance certification.
As a result, the EPA included four explicit conditions in the WIPP
certification of compliance (see 40 CFR part 194, Appendix A; WIPP
Recertification Background Document in Docket No. EPA-HQ-OAR-2014-
0609). These conditions are discussed in Section V.C of this document.
B. 2006 Recertification Decision
The first recertification process, which occurred in 2004-2006,
included an EPA review of all changes made at the WIPP facility since
the original 1998 certification decision. The Agency received the DOE's
first compliance recertification application on March 26, 2004. The EPA
issued the completeness determination \6\ for the 2004 Compliance
Recertification Application by letter to the DOE on September 29, 2005
(see 70 FR 61107-61111, October 20, 2005). On March 29, 2006, the EPA
officially recertified the WIPP facility for the first time (71 FR
18010-18021, April 10, 2006).
---------------------------------------------------------------------------
\6\ A ``completeness determination'' is an administrative step
by the Agency to notify the DOE and the public that the Agency has
enough information to conduct a final technical review of the DOE's
application. It does not reflect any conclusion regarding the WIPP's
continued compliance with the radioactive waste disposal regulations
at 40 CFR part 191 and the compliance criteria at 40 CFR part 194.
The completeness determination represents the start of the six-month
period specified in the WIPP LWA for issuance of the recertification
decision.
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C. 2010 Recertification Decision
Following receipt of the DOE's second compliance recertification
application on March 24, 2009, the EPA requested additional information
from the DOE and the DOE responded with the requested supplemental
information. All pertinent 2009 Compliance Recertification Application
correspondence was placed in the docket (Docket ID No. OAR-2009-0330 on
www.regulations.gov) and linked to on the WIPP Web site (https://www.epa.gov/radiation/certification-and-recertification-wipp#tab2). On
June 29, 2010, the EPA sent a letter to the DOE announcing that the
DOE's recertification application was complete (75 FR 41421-41424, July
16, 2010). The EPA's second recertification of the WIPP compliance was
published on November 18, 2010 (75 FR 70584).
IV. With which regulations must the WIPP comply?
A. Compliance With Radioactive Waste Disposal Regulations & the WIPP
Compliance Criteria
The WIPP must comply with the EPA's radioactive waste disposal
regulations, located at subparts B and C of 40 CFR part 191. These
regulations limit the amount of radioactive material which may escape
from a disposal facility, and protect individuals and ground water
resources from dangerous levels of radioactive contamination. In
addition, the compliance recertification application and other
information submitted by the DOE must meet the requirements of the WIPP
Compliance Criteria at 40 CFR part 194. The WIPP Compliance Criteria
implement and interpret the general disposal regulations specifically
for the WIPP, and clarify the basis on which the EPA makes the
certification decision.
B. Compliance With Other Environmental Laws and Regulations
In addition to the EPA's radioactive waste disposal regulations,
the WIPP must also comply with a number of other federal laws and
regulations pertaining to public health and safety or the environment,
including, for example, the Solid Waste Disposal Act (also known as the
Resource Conservation and Recovery Act (RCRA)) (42 U.S.C. 6901 et seq.)
and the EPA's environmental standards for the management and storage of
radioactive waste (subpart A of 40 CFR part 191). Various regulatory
agencies are responsible for overseeing the enforcement of these
federal laws and regulations. For example, enforcement of some parts of
the hazardous waste management regulations has been delegated to the
State of New Mexico. The State is authorized by the EPA to carry out
the State's RCRA programs in lieu of the equivalent federal programs,
and New Mexico's Environment Department (NMED) reviews the DOE's permit
applications for treatment, storage, and disposal facilities for
hazardous waste, under Subtitle C of RCRA. NMED's RCRA authority, such
as issuing a hazardous waste operating permit for the WIPP, is not
affected by the EPA's recertification decision. The DOE is responsible
for biennially reporting to the EPA and the State of New Mexico on the
WIPP's compliance with all applicable federal laws pertaining to public
health and safety (WIPP LWA Sec. 9).\7\ This action does not address
the WIPP's compliance with environmental or public health and safety
laws and regulations other than the EPA's radioactive waste disposal
regulations (40 CFR part 191) and the WIPP Compliance Criteria (40 CFR
part 194).
---------------------------------------------------------------------------
\7\ Compliance with these laws and regulations is addressed in
the site's Biennial Environmental Compliance Report (BECR).
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V. Continuing Compliance With the WIPP Compliance Criteria
The EPA monitors and ensures continuing compliance with the EPA
regulations through a variety of activities, including the following:
review and evaluation of the DOE's annual change reports, monitoring of
[[Page 33109]]
the conditions of compliance, addressing planned change requests,
inspections of the WIPP site and inspections of waste characterization
operations. Because of the 2014 incident, the EPA also reviewed health
and monitoring data to ensure the radiological releases remained below
the limits of subpart A of 40 CFR part 191 and the Clean Air Act
National Emissions Standards for Hazardous Air Pollutants at 40 CFR
part 61, subpart H.
The DOE must timely report any planned or unplanned changes in
activities or conditions pertaining to the disposal system that differ
significantly from the most recent compliance application and, at least
annually, report any other changes in disposal system conditions or
activities (40 CFR 194.4(b)(3), (4)). The Department must also report
any releases of radioactive material from the disposal system (40 CFR
194.4(b)(3)(iii)). In addition, the EPA may request additional
information from the DOE at any time (Sec. 194.4(b)(2)). These
requirements assist the EPA with monitoring the performance of the
disposal system and evaluating whether the certification should be
modified, suspended or revoked.
A. Annual Change Reports
In addition to reporting significant changes to the WIPP disposal
system, the DOE is required to report at least annually other changes
to the conditions or activities concerning the WIPP disposal system (40
CFR 194.4(b)(4)). The DOE submitted the first annual change report in
November 1998.
The DOE's annual change reports reflect the progress of quality
assurance and waste characterization inspections, minor changes to the
DOE documents, information on monitoring activities and any additional
EPA approvals for changes in activities. All correspondence and
approvals regarding the annual change reports can be found in hard copy
in the Air Docket A-98-49, Categories II-B2 and II-B3.
B. Monitoring the Conditions of Compliance
1. Panel Closure Rulemaking. Waste panel closure systems are
required by the State of New Mexico during the WIPP's operational
phase. Since they are a feature of the disposal system design, the EPA
requires panel closures to be included in the long-term modeling of the
repository. The panel closures impact long-term disposal system
performance because they can impede brine and gas flow between waste
panels. As originally promulgated, the WIPP Certification Condition 1
required the DOE to implement the Option D panel closure system at the
WIPP, using Salado mass concrete.\8\ By final action published October
8, 2014, the EPA modified Condition 1 to remove the specific reference
to Option D and generally require that the DOE close filled waste
panels as specifically approved by the EPA (40 CFR part 194, Appendix
A, as amended; 79 FR 60750-60756). With the same action, the EPA
approved a design which primarily consists of 100 feet of run-of-mine
salt. The DOE submitted a performance assessment \9\ to support its
request to change the panel closure system design. The DOE asserted
that the performance assessment demonstrated that a panel closure
design using run-of-mine salt would be compliant with the EPA's
disposal regulations (40 CFR part 191). The modification to the WIPP
Certification Condition 1 also removed the requirement for the Agency
to make future panel closure design changes by formal rulemaking.
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\8\ ``Salado'' mass concrete refers to concrete made using
Salado brines instead of fresh water.
\9\ Performance assessment is an important tool used in various
contexts or evaluations relating to the WIPP and such assessments
are mentioned in different circumstances throughout this notice,
especially in Section VI.E. In general, performance assessment
means: ``an analysis that: (1) Identifies the processes and events
that might affect the disposal system; (2) examines the effects of
those processes and events on the performance of the disposal
system; and (3) estimates the cumulative release of radionuclides,
considering the associated uncertainties, caused by all significant
processes and events'' (40 CFR 191.12). Performance assessment, for
example, is required to show compliance with containment
requirements (40 CFR 191.13).
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2. Quality Assurance. Certification Condition 2 requires each TRU
generator site to establish and execute a quality assurance program for
waste characterization activities. Section 194.22 establishes quality
assurance requirements for the WIPP. The DOE must adhere to a quality
assurance program that implements the requirements of ASME NQA-1-1989
edition, ASME NQA-2a-1990 addenda, part 2.7, to ASME NQA-2-1989
edition, and ASME NQA-3-1989 edition (excluding Section 2.1 (b) and
(c), and Section 17.1).The EPA determined that the 2014 Compliance
Recertification Application provides adequate information to verify the
establishment and implementation of each of the applicable elements of
the ASME NQA-1-1989.The EPA has also verified the continued proper
implementation of the Nuclear Quality Assurance Program through
periodic audits conducted in accordance with Sec. 194.22(e).
The EPA's determination of compliance with 40 CFR 194.22 can be
found in Table 1 of the 2014 Compliance Recertification Application
CARD 22. Between March 2008 and April 2012, the EPA conducted several
quality assurance audits and found the site-specific quality assurance
programs to be adequate. The EPA conducted quality assurance audits at
several waste generator sites and entities supporting the WIPP
Performance Assessment activities at Los Alamos and Sandia
Laboratories. The EPA also audited the quality assurance program of the
Carlsbad Field Office.
3. Waste Characterization. Certification Condition 3 requires TRU
waste generator sites to have waste characterization systems approved
by the EPA. The Agency has conducted numerous audits and inspections at
waste generator sites in order to implement Condition 3 and the
relevant provisions of 40 CFR part 194, including Sec. 194.8. The EPA
inspected site-specific TRU waste characterization programs implemented
to (a) characterize physical and radiological components in individual
waste containers and (b) demonstrate compliance with the WIPP waste
disposal requirements at 40 CFR 194.24.
To support the 2014 Compliance Recertification Application, the DOE
reported the EPA's waste characterization inspections and approvals
between January 2007 and December 2012 (see Table 1 in CARD 8). The EPA
evaluated previously approved site-specific waste characterization
program for continued compliance in accordance with 40 CFR 194.24, as
well as changes to the systems of controls approved as part of the
baseline (initial) approvals, and concluded them to be technically
adequate. The TRU waste sites approved by the EPA to ship contact-
handled TRU waste to the WIPP facility in accordance with the
requirements of Sec. 194.8 since the 2009 Compliance Recertification
Application are as follows: Advanced Mixed Waste Treatment Project,
Hanford's Richland Laboratory, Idaho National Laboratory, Los Alamos
National Laboratory, Oak Ridge National Laboratory and Savannah River
Site. Since the 2009 Compliance Recertification Application, the TRU
waste sites approved by the EPA to ship remote-handled TRU waste to the
WIPP facility in accordance with the requirements of Sec. 194.8 are
Argonne National Laboratory, Bettis Atomic Power Laboratory, General
Electric Vallecitos Nuclear Center, Idaho National Laboratory, Oak
Ridge National Laboratory and Savannah River Site. Since the 2009
Compliance
[[Page 33110]]
Recertification Application, no waste characterization occurred at
Bettis Atomic Power Laboratory, General Electric Vallecitos Nuclear
Center, Hanford's Richland Laboratory and Oak Ridge National
Laboratory.
During the period covered by the 2014 Compliance Recertification
Application, all site-specific waste characterization systems of
controls at active TRU waste generator sites had necessary baseline
approvals. Over the years, when warranted, the EPA approved
modification to waste characterization program components. Notices
announcing the EPA inspections or audits are routinely published in the
Federal Register and also announced on the Agency's WIPP Web site
(https://www.epa.gov/radiation/epas-role-waste-isolation-pilot-plant-wipp) and WIPP-NEWS email listserv.\10\
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\10\ For more information on the WIPP-NEWS email listserv, see
Section VIII.B below.
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Records of the EPA's quality assurance correspondences and waste
characterization approvals can be found in Air Docket A-98-49,
Categories II-A1 and II-A4, respectively, as well as online in Docket
ID No. EPA-HQ-OAR-2001-0012 on www.regulations.gov.
4. Passive Institutional Controls. Certification Condition 4
requires the DOE to submit a schedule and plan for implementing passive
institutional controls, including markers and other measures indicating
the presence of the repository. The standards under the WIPP
Certification Condition 4 do not require the submission of any reports
until the final compliance recertification application prior to closure
of the WIPP. The EPA has not received any submissions from the DOE
during the period addressed by the 2014 Compliance Recertification
Application and has not taken any actions relating to Condition 4. The
EPA anticipates that it will evaluate the DOE's compliance with
Condition 4 of the certification when the DOE submits a revised
schedule and additional documentation regarding the implementation of
passive institutional controls. Once received, the information will be
placed in the EPA's public dockets, and the Agency will evaluate the
adequacy of the documentation. After receiving Condition 4 submissions
from the DOE, and during the operational period when waste is being
emplaced in the WIPP (and before the site has been sealed and
decommissioned), the EPA will verify that specific actions identified
by the DOE in the compliance certification application, and
supplementary information (and in any additional documentation
submitted in accordance with Condition 4) are being taken to test and
implement passive institutional controls.
C. Inspections
The WIPP Compliance Criteria provide the EPA the authority to
conduct inspections of activities at the WIPP and at off-site
facilities which provide information relevant to compliance
applications (40 CFR 194.21). The Agency has conducted periodic
inspections to verify the adequacy of information relevant to
certification applications. The EPA has conducted annual inspections at
the WIPP site to review and ensure that the monitoring program meets
the requirements of Sec. 194.42. The EPA has also inspected the
emplacement and tracking of waste in the repository. The Agency's
inspection reports can be found in Air Docket A-98-49, Categories II-A1
and II-A4, as well as online at www.regulations.gov, Docket ID No. EPA-
HQ-OAR-2001-0012.
VI. What is the EPA's 2017 Recertification Decision?
The EPA determines, in accordance with WIPP LWA Sec. 8(f)(2), that
the WIPP facility is in compliance with the final disposal regulations,
subparts B and C of 40 CFR part 191. Compliance recertification ensures
that accurate and up-to-date information is considered in the
determination that WIPP remains in compliance with these radioactive
waste disposal regulations. The EPA makes this recertification and
determination of continued compliance following the ``Criteria for the
Certification and Recertification of the WIPP's Compliance with the 40
CFR part 191 Disposal Regulations'' (WIPP Compliance Criteria, 40 CFR
part 194), including the WIPP certification conditions (40 CFR part
194, Appendix A).
A. Performance Assessment and the EPA's Standards
The disposal regulations at 40 CFR part 191 include requirements
for containment of radionuclides. The containment requirements at 40
CFR 191.13 specify that releases of radionuclides to the accessible
environment \11\ must be unlikely to exceed specific limits for 10,000
years after disposal. The DOE assesses the likelihood that the WIPP
will meet these release limits through a process known as performance
assessment.
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\11\ The accessible environment is defined in 40 CFR 191.12 as
(1) The atmosphere: (2) land surfaces; (3) surface waters; (4)
oceans; and (5) all of the lithosphere that is beyond the controlled
area.
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The disposal regulations provide that there must be a reasonable
expectation that cumulative releases of radionuclides from the WIPP and
into the environment over 10,000 years will not exceed specified
quantities of these radionuclides (40 CFR 191.13 and Appendix A). A
reasonable expectation standard is used because of the long time period
involved and the nature of the events and processes at radioactive
waste disposal facilities leads to uncertainties about future
performance. The DOE's probabilistic performance assessments assess the
likelihood of environmental radionuclide release so that future
uncertainties are accounted for in the calculations through the use of
alternative scenarios and variations in values of uncertain parameters
via probability distributions.
The containment requirements in 40 CFR 191.13 are expressed in
terms of ``normalized releases.'' At the WIPP, the specific release
limits are based on the estimated amount of waste in the repository at
the time of closure, and the projected releases are ``normalized''
against these limits (Sec. 194.31). Normalized releases are expressed
as ``EPA units''. The EPA units are calculated by dividing all the
combined projected releases by the total combined radioactivity of all
the waste in the repository.
The DOE must demonstrate, in each 5-year compliance recertification
application, that the total average of combined releases are below two
compliance criteria at a higher probability of occurrence and a lower
probability of occurrence. These compliance points are as follows:
1. For a probability of 0.1 (a 1 in 10 chance) in 10,000 years,
releases to the accessible environment will not exceed 1 EPA unit, and
2. For a probability of 0.001 (a 1 in 1,000 chance) in 10,000
years, releases to the accessible environment will not exceed 10 EPA
units.
DOE evaluates four release mechanisms in the WIPP performance
assessment modeling:
Cuttings and cavings. This consists of material that gets brought
to the surface when a borehole intersects waste in a WIPP waste panel.
The cuttings are the material intersected by the borehole itself and
the cavings material is waste that fails around the borehole, collapses
into it and is brought to the surface.
Spallings. This is solid material that fails and gets brought to
the surface under high pressure conditions in the
[[Page 33111]]
repository. This only occurs when the pressure is above 8 megapascal
\12\ (MPa).
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\12\ ``Pascal'' is a unit of pressure, defined as 1 kg/m-sec\2\.
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Direct Brine Releases. This is a release of dissolved actinides in
brine when there is sufficient brine and high pressure in the
repository (i.e., above 8 MPa) and brine saturations are above residual
saturation (i.e., brine is not ``trapped'' between pore spaces) as a
borehole intersects a waste panel. The contaminated fluid is brought to
the surface over a period of hours to days.
Releases to the Culebra. This occurs when contaminated brine from
repository is introduced via a borehole to the Culebra Dolomite and
then moves to the edge of the accessible environment (i.e., the
boundary established by the WIPP LWA).
The DOE estimates the potential releases from these release
mechanisms, i.e., the cumulative releases, for comparison with the
specified limits provided in 40 CFR part 191, Appendix A. The DOE is to
provide in the application overall mean calculated releases and the
upper 95th confidence limit of that mean.
B. Summary of the EPA's Review
After reviewing the DOE's documentation and additional studies that
the DOE conducted at EPA's request, the aspects of the performance
assessment of most interest to EPA are those that affect the direct
brine release mechanism, by which actinides \13\ dissolved in brine are
transported to the surface during a drilling intrusion. Direct brine
release is the overall dominant release mechanism at the low
probability compliance point, and is influenced primarily by the
availability of liquid (i.e., brine) in the repository, the
availability of radionuclides to dissolve in that liquid (i.e.,
inventory and solubility) and the pressure in the repository (providing
a motivating force for dissolved radionuclides to move out of the
repository).
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\13\ Actinide means any of the series of fifteen metallic
elements from actinium (atomic number 89) to lawrencium (atomic
number 103) in the periodic table. They are all radioactive, the
heavier members being extremely unstable and not of natural
occurrence.
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The key issues involving these aspects of the repository are: (1)
The actinide solubility, which is addressed through changes to the
geochemical database, colloid contribution updates and the
determination of the actinide solubility uncertainty; (2) the
probability of hitting a brine pocket under the repository; (3) the
steel corrosion rate and steel's interactions with hydrogen sulfide and
magnesium oxide (affecting the gas pressure); and (4) the overall
modeling of direct brine releases that involve the interactions of
items 1-3 plus the conditions of the repository (e.g., panel and drift
permeability and porosity) that can influence the pressure
characteristics of the waste areas. These issues are discussed in more
detail in Section VI.D, along with other issues that are noteworthy but
have more limited impact on performance assessment results.
The following information describes the EPA's compliance evaluation
related to the disposal regulations and Compliance Criteria.
C. What information did the Agency use to make the decision?
In general, compliance applications must include information
relevant to demonstrating compliance with each of the individual
sections of 40 CFR part 194 to determine if the WIPP will comply with
the Agency's radioactive waste disposal regulations at 40 CFR part 191,
subparts B and C. The EPA begins the compliance recertification
evaluation once the EPA receives a complete compliance recertification
application (40 CFR 194.11).
To make this decision, the EPA evaluated basic information about
the WIPP site and disposal system design, as well as information which
addressed the various compliance criteria. As required by 40 CFR
194.15(a), the DOE's 2014 Compliance Recertification Application
updated the previous submission in 2009.
On March 26, 2014, the DOE submitted the compliance recertification
application. The EPA began to identify areas of the application where
additional information was needed. On October 10, 2014, the EPA gave
public notice of the compliance recertification application and opened
the official public comment period (79 FR 61268). On January 13, 2017,
the EPA sent a letter to the DOE stating that the DOE's recertification
application was complete. On March 10, 2017, the EPA issued a Federal
Register notice announcing the completeness determination and stating
that the public comment period would close one month later, on April
10, 2017 (82 FR 13282). The compliance recertification application
completeness-related correspondence can be found in Docket ID No. EPA-
HQ-OAR-2014-0609 on www.regulations.gov.
The EPA relied on materials prepared by the Agency or submitted by
the DOE in response to the EPA requests. For example, the EPA requested
that the DOE conduct specific, additional modeling calculations for the
performance assessment, known as sensitivity studies. The purpose of
these studies was to evaluate the impact on performance assessment
results of changing specific parameter values. The studies aided the
EPA in determining how significant the differences in some parameter
values were to a demonstration of compliance. The four sensitivity
studies and the EPA's evaluation of them are discussed in more detail
in Section VI.E.
To determine whether the WIPP facility continues to be in
compliance with the final disposal regulations, the EPA engaged in a
technical review of the compliance recertification application against
the WIPP Compliance Criteria. The Agency focused the review on areas of
change identified by the DOE since the 2010 recertification decision.
The Agency produced many documents during the technical review and
evaluation of the compliance recertification application. The EPA's
Compliance Application Review Documents (CARDs) correspond in number to
the sections of 40 CFR part 194 to which the documents primarily
relate. Each CARD enumerates all changes made by the DOE relating to a
particular section of the rule or certification criterion, and
describes the EPA's process and conclusions. The EPA also prepared
technical support documents (TSDs) to address specific topics in
greater detail. Both the CARDs and the TSDs for this recertification
decision can be found in Docket ID No. EPA-HQ-OAR-2014-0609 on
www.regulations.gov. Together, the CARDs and TSDs thoroughly document
the EPA's review of the DOE's compliance recertification application
and the technical rationale for the Agency's decisions.
In summary, the EPA's recertification decision is based on the
entire record available to the Agency, which is located in the public
docket dedicated to this recertification (Docket ID No. EPA-HQ-OAR-
2014-0609 on www.regulations.gov). The record consists of the 2014
Compliance Recertification Application, supplementary information
submitted by the DOE in response to the EPA requests for additional
information, technical reports generated by the EPA, the EPA audit and
inspection reports, and comments submitted on the DOE's application and
the EPA's completeness review during the public comment period. All
pertinent 2014 Compliance Recertification Application correspondence
was placed in the docket and linked to via the EPA's WIPP Web site
(https://www.epa.gov/
[[Page 33112]]
radiation/certification-and-recertification-wipp).
D. Content of the Compliance Recertification Application (Sec. Sec.
194.14 and 194.15)
The DOE's WIPP compliance applications must include, at a minimum,
basic information about the WIPP site and disposal system design,
including information about the following topics: the geology,
hydrology, hydrogeology and geochemistry of the WIPP disposal system
and the WIPP vicinity; the WIPP materials of construction; standards
applied to design and construction; background radiation in air, soil
and water; and past and current climatological and meteorological
conditions (40 CFR 194.14). Section 194.15 states that the DOE's
recertification applications shall update this information to provide
sufficient information for the EPA to determine whether or not the WIPP
facility continues to be in compliance with the disposal regulations.
1. Changes to the Disposal System Identified by the DOE. In Section
15 of the 2014 Compliance Recertification Application, the DOE
identified changes to the disposal system between the 2009 Compliance
Recertification Application and 2014 Compliance Recertification
Application and changes to technical information relevant to Sec. Sec.
194.14 and 194.15. Noteworthy changes identified by the DOE in the 2014
Compliance Recertification Application include the following: an update
to the parameters defining drilling rate and plugging pattern,
revisions to the calculations of the probability of encountering a
pressurized brine reservoir, replacing the Option D panel closure
design with run-of-mine salt, modeling open areas in the repository,
revision of the steel corrosion rate, revision of the effective shear
strength of waste, revisions of the repository water balance including
variable brine volumes for radionuclides to dissolve and revisions of
the colloid parameters.
Before determining that the compliance recertification application
was complete, the EPA raised numerous technical questions with the DOE,
as described below. For each topic, a brief summary is provided of how
the DOE addressed the issue in the 2014 application, followed by the
EPA's perspective on the change, including any follow-up analyses
requested. The DOE also updated the waste inventory. This topic is
discussed in Section VI.F.1.
Since the initial Compliance Certification performance assessment,
the DOE's calculated releases in performance assessments have increased
with every performance assessment until the 2014 Compliance
Recertification Application performance assessment. The changes the DOE
made to the performance assessment in the current application reduce
the calculated releases. For example, the calculated release of
radionuclides at the low probability compliance point (a likelihood of
less than a one in 1,000 chance), was assessed by the DOE in the 2009
Compliance Recertification Application as 0.72 EPA Units, but in the
2014 Compliance Recertification Application, the similar calculated
release initially was assessed as 0.261 EPA Units.
Changes that reduce the calculated releases involve the shear
strength of the waste, revised steel corrosion rate, incorporating
water balance as part of the chemical model implementation as it
relates to steel corrosion and interactions with the magnesium oxide
engineered barrier, correcting errors associated with brine volume mass
balance and calculation of actinide solubility and the change to how
the DOE calculates the probability of hitting a brine pocket under the
repository. In general, the result of the DOE's methodology changes is
to reduce calculated releases by about a factor of two between the 2009
and 2014 Compliance Recertification Applications at both the 0.1 and
0.001 probability compliance points.
The EPA has identified issues with some of these changes, but even
with changes the EPA asked the DOE to investigate, projected releases
stay well under the numerical release limits. For example, at the 0.001
probability compliance point where the EPA normalized release limit is
10 EPA units, the changes the EPA requested resulted in increased
releases from 0.261 EPA units in the DOE's 2014 performance assessment
to 0.299 EPA units in sensitivity study SEN3 and 0.541 EPA units in
sensitivity study SEN4. The sensitivity studies are discussed in depth
in Section VI.E.
a. Update to the Drilling Rate and Borehole Plugging Patterns. As
with previous recertification applications, the DOE updated the
Delaware basin drilling rates based on the methodology previously
approved. For the 2014 Compliance Recertification Application, the
drilling rate increased to 0.00673 boreholes per km\2\ per year
(equivalent to 67.3 boreholes/km\2\ over the 10,000-year regulatory
period) compared to that used in the 2009 performance assessment
baseline calculation, which was .00598 boreholes per km\2\ per year (or
59.8 boreholes/km\2\ over 10,000 years). The Agency accepted the DOE's
drilling rate increase.
The DOE also updated information on the type of plugs installed in
exploratory, disposal and resource extraction boreholes. There are
three types of borehole plugs used in the Delaware basin. There are
boreholes that are continuously plugged through the entire salt
section, and the DOE reports a slight increase in the use of this
design. There are boreholes plugged with a two-plug configuration (at
the Salado/Rustler and the Bell Canyon/Castile Formation interfaces).
This two-plug design also slightly increased from that used in the 2009
application. There is also a three-plug configuration (i.e., borehole
plugs at the Rustler/Salado, Salado/Castile and Castile/Bell Canyon
interfaces); the DOE reports a slight decrease in this configuration.
The Agency accepted the DOE's update to the change in the plugging
patterns.
b. Replacement of Option D Panel Closure System with the Run-of-
Mine Salt Panel Closure Design. Part of the design for the WIPP
includes the use of a closure system to separate the waste rooms in a
panel from active areas in the mine, which can affect long-term brine
and gas flows within the repository. As part of the design, the panel
closure system that is installed needs to be represented in the
modeling of long-term performance.
On September 28, 2011, the DOE provided a change request to the EPA
(Docket EPA-HQ-OAR-2013-0684) to modify the panel closure system design
specified in Appendix A of 40 CFR part 194 from that of a concrete
monolith plug, noted as Option D, to a 100-foot long barrier consisting
of run-of-mine salt (EPA 2013; 2014). The panel closure system
performance assessment release calculations were well within the
numerical limits established in 40 CFR 191.13. The EPA approved the
DOE's use of the proposed run-of-mine salt closure design (79 FR 60750,
Oct. 8, 2014) (Docket EPA-HQ-OAR-2013-0684-0004 on
www.regulations.gov).
The DOE incorporated the run-of-mine salt design for panel closures
into the 2014 Compliance Recertification Application. To evaluate this
change, the Agency reviewed a broad set of information related to the
evolution of salt repository properties, including run-of-mine salt and
adjacent disturbed rock zone in the WIPP repository setting (Salt
Characteristics TSD \14\). From this
[[Page 33113]]
review, the Agency's interpretation of the data is that healing of the
run-of-mine salt in the panel closures, the surrounding disturbed rock
zone and open areas should occur within about the first 200 years of
post-closure instead of the relatively asymptotic closure for the 200-
10,000 years used by the DOE. The DOE's use of the longer period of
time assumes permeability and porosity for the salt will be low within
200 years, but not at the very low end state properties of intact
halite.
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\14\ ``Technical Support Document for Section 194.23: Technical
Review of Salt Aggregate, Disturbed Rock Zone, and Open Drift
Healing Characteristics'' in Docket ID No. EPA-HQ-OAR-2014-0609.
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To identify the potential effect of the difference in the
repository properties between what the EPA has identified may be
applicable and what the DOE modeled, the Agency requested that the DOE
analyze the repository performance using parameter values for the run-
of-mine salt panel closure system and adjacent disturbed rock zone that
simulate complete healing. The DOE did this in the sensitivity study
SEN3 discussed in Section VI.E. The calculated releases increased for
direct brine releases and spallings releases in SEN3, but overall
releases remained well within the numerical limits of 40 CFR 191.13 and
the EPA concludes that there is a reasonable expectation that the
repository remains in compliance with the numerical limits at 40 CFR
191.13, and 40 CFR part 191, Appendix A.
If the DOE determines, in light of the announced decision to
abandon the area previously designated for panel 9, that worker safety
considerations preclude installing panel closures in affected areas of
the repository, the DOE's treatment of panel closures in performance
assessment may be more appropriately addressed in the context of
modeling open areas representative of no panel closures. The Agency
will review future panel closure modeling in the context of future
facility design changes.
c. Modeling of Open Areas in the Repository. In the 2014 Compliance
Recertification Application, the DOE increased the modeled volume of
the open rooms and drifts by approximately forty percent to accommodate
future planned experiments. These new areas are located north of the
waste area drifts and are to be separated from the waste area by two
sets of run-of-mine salt panel closures. For the 2014 Compliance
Recertification Application performance assessment, the DOE modeled
these areas as open for the entire 10,000-year regulatory period even
though it is expected that the creep closure process will close the
open areas within a few hundred years (Overview TSD \15\). The Agency
evaluated the impact of the DOE's assumption to model these areas as
open (relatively large porosity and high permeability) by requesting
the DOE perform sensitivity study SEN2, where the non-waste rooms and
open drifts are assumed to have creep closed during the entire 10,000-
year regulatory period.
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\15\ ``Overview of Changes Between PABC-2009 and CRA-2014 WIPP
Performance Assessments'' in Docket ID No. EPA-HQ-OAR-2014-0609.
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The results from the SEN2 studies indicate modeling creep closure
and healing of the operations and experimental areas (i.e., non-waste
areas) of the repository was shown to have little effect on the
prediction of total releases from the repository although, relative to
the 2014 Compliance Recertification Application performance assessment,
a slight increase in spallings releases does occur if these areas are
assumed to creep closed. This is a result of higher pressures occurring
in panels. See Section VI.E for discussion of the SEN2 study.
If, in the future, there are repository design changes that result
in more non-waste drifts mined or left open in the facility, the issue
of open areas will need to be re-evaluated in the context of those
design changes, as releases could be expected to increase in that
circumstance. The DOE's plan to abandon panel 9 would leave large areas
of open space in the repository in the panel 9 drifts and possibly no
panel closures for multiple panels. Performance assessment modeling
should address these expected future repository conditions. The EPA
believes that an independent technical review of issues related to salt
behavior and modeling of open areas would be of benefit to the DOE as
it further develops its plans.
d. The DOE's Revised Estimate of the Probability of Encountering
Pressurized Brine. Highly pressurized zones of brine (i.e., pressurized
brine reservoirs) occur in the Castile Formation below the Salado
Formation, which is the formation that hosts the WIPP. If a future
driller encounters a Castile pressurized brine reservoir and brine
enters the waste panels, it can dissolve radionuclides that then could
be transported up a borehole to the surface. In the modeling of the
repository, the probability of a future borehole intersecting a waste
panel and a Castile brine reservoir below the repository is denoted by
the parameter name PBRINE. Because the probability of hitting a brine
pocket is uncertain, it is represented by a probability distribution,
and the actual value of the PBRINE parameter for an individual model
run is sampled from the PBRINE probability distribution.
In the 2014 Compliance Recertification Application, the DOE changed
the basis it used to develop the probability distribution for parameter
PBRINE. The DOE's revision to the estimated probability of a future
driller encountering pressurized brine relies heavily on voluntarily
reported drilling logs \16\ combined with an updated probability
distribution. The DOE eliminated from consideration site-specific data
collected through geophysical detection methods, which had previously
been incorporated into the PBRINE parameter.
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\16\ Kirchner, T., T. Zeitler, and R. Kirkes. 2012. Evaluating
the Data in Order to Derive a Value for GLOBAL:PBRINE. Memorandum to
Sean Dunagan dated December 11, 2012. ERMS 558724. Carlsbad, NM:
Sandia National Laboratories.; EPA Completeness Comment 1-23-6;
Docket EPA-HQ-OAR-2014-0609-0004.
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The EPA has several concerns regarding the DOE's update to the
PBRINE parameter,\17\ including the DOE's elimination of the site
geophysical data leading to estimates of the potential for brine
encounters based only on the voluntary data reported by the driller,
and that more recent site data supports the potential for more brine
under the repository than the DOE or the EPA had previously considered.
For a more in-depth discussion of these issues, see the PBRINE TSD.\18\
The EPA's concerns were significant enough that the EPA developed a
modified methodology for determining the probability distribution for
parameter PBRINE in the WIPP performance assessment calculations.
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\17\ See Completeness Question 1-23-6, Probability of
Encountering a Castile Brine Pocket and subsequent clarifying
questions, as well as the PBRINE TSD, for more detail in Docket ID
No. EPA-HQ-OAR-2014-0609.
\18\ ``Probability of Encountering Castile Brine Beneath the
WIPP Waste Panels Using the TDEM Block Method.''
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The Agency's revision to the PBRINE parameter was incorporated into
Sensitivity Study SEN4. The study results indicate the modified PBRINE
probability distribution contributed to an increase in estimated direct
brine releases and increased the total releases at the 0.001 low
probability compliance point to roughly double those in the 2014
Compliance Recertification Application performance assessment.\19\
Because the Agency is unable to accept the DOE approach used to define
the PBRINE parameter, the EPA views the updated probability
distribution used in
[[Page 33114]]
the SEN4 study as the baseline for PBRINE in future performance
assessments. The EPA will evaluate alternative approaches proposed by
the DOE. See Section VI.E for more discussion of the SEN4 study.
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\19\ DOE 2014 Appendix PA, Sections PA-9.3 and PA-9.5 Kirchner
2013 and the EPA, 2017 Technical Support Document.
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e. Revised Corrosion Rate of Steel. The WIPP corrosion rate model
includes anoxic corrosion (i.e., corrosion in the absence of oxygen) of
iron in the waste containers. This corrosion is caused by hydrogen
sulfide gas produced from the microbial degradation of cellulosic,
plastics and rubber materials from the contaminated rubber gloves and
KimwipesTM included in the waste.
The EPA reviewed the 2014 Compliance Recertification Application
model and had concerns with the way the model addressed expected
repository carbon dioxide concentrations in the experimental derivation
of corrosion rates. The EPA also found that the model did not
incorporate hydrogen sulfide induced steel passivation,\20\ which could
result in an overestimation of corrosion in the longer-term. Once steel
is passivated, hydrogen sulfide consumption will decrease significantly
as corrosion will be limited by the ability for the gas to diffuse
through the iron sulfide coating the outer surface of the container.
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\20\ Passivation refers to the creation of an outer coating
layer on the steel canisters due to the interaction of iron and
sulfide.
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In addition, other components of this model, which the DOE
considered to be minor, may have more impact. Calculations of the
potential lead inventories at the WIPP only include current waste
containers without accounting for the maximum potential of future
containers.
To address the EPA's concerns about corrosion, part of the DOE's
SEN4 sensitivity study involved turning off the hydrogen sulfide
corrosion parameter to simulate steel passivation. These changes
resulted in a slight increase in gas pressures as well as a decrease in
the saturation of the waste area because both hydrogen gas and water
were eliminated from the end products. Results from this study
indicated that projected releases would remain within the limits of 40
CFR 191.13. Therefore, the EPA accepts the corrosion approach
incorporated in the 2014 Compliance Recertification Application. See
Section VI.E for more discussion of the SEN4 study.
To ensure that future performance assessments adequately address
the mechanisms that affect gas generation in the repository, it would
be appropriate for the DOE to update the corrosion model to better
address steel passivation and account for radiolysis and address lead
corrosion to be consistent with the expected inventory of the
repository.
f. Revised Effective Shear Strength of the WIPP Waste. The
parameter TAUFAIL represents waste shear strength and is used in
calculating potential releases of waste materials from the WIPP
repository when a drilling operator drills a borehole through the
waste. The drilling mud will apply a hydrodynamic shear stress to the
punctured waste and cause it to erode and be transported up the
borehole to the surface. The sheared waste transmitted to the surface
is called ``cavings''. A higher shear strength means the material is
less likely to break into pieces and be transported up a borehole. The
parameter TAUFAIL has an uncertain value which is sampled from a range
of experimental values for individual model runs. In the 2014
Compliance Recertification Application, the DOE updated the mean and
lower bound for the TAUFAIL parameter value distribution based on a
suite of laboratory flume tests specifically designed to represent the
range of values for the WIPP waste.
In the 2009 Compliance Recertification Application the lower bound
value was 0.05 Pa, while for the 2014 Compliance Recertification
Application the lower bound of the distribution was increased to 2.22
Pa (the mean value from the laboratory flume tests). The upper bound of
the distribution, 77 Pa, remained the same. The EPA believes the DOE's
overall approach of using experimental data to revise the TAUFAIL
parameter is reasonable; however, the EPA had concerns with the DOE's
lower ``bounding'' range value derived from the experiments. The Agency
was concerned that three of the five low shear-strength tests had
highly scattered results. The DOE attributed the scatter to pre-test
sample damage and/or a high degree of variability in sample
preparation, rather than testing an equivalent suite of samples. As a
result, the mean of the low shear strength test results may not be
truly representative of low shear strength samples.
In the SEN4 study, the EPA requested the DOE include the lowest
shear-strength flume test results (1.6 Pa) as the bounding value,
rather than the average (2.22 Pa). The SEN4 results indicate modifying
the lower range to include the lowest value as the bounding value
insignificantly impacted releases. This is due to the fact that the
change from 2.22 Pa to 1.6 Pa (i.e., from the mean of experimental
values to the lowest experimental value) is much less than would be the
change from the 0.05 Pa used in previous performance assessments to
either the 1.6 Pa or the 2.22 Pa values. Based on these results, the
EPA accepts the DOE's range of values used in the 2014 Compliance
Recertification Application, though for future performance assessments
the EPA believes it is more appropriate for the DOE to use the lower-
bound result instead of the mean. See Section VI.E for more discussion
of the SEN4 study. See also the TAUFAIL TSD.\21\
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\21\ ``Technical Support Document for Section 194.23: EPA Review
of Proposed Modification to the Waste Shear Strength Parameter
TAUFAIL'' in Docket ID No. EPA-HQ-OAR-2014-0609.
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g. Revised Repository Water Balance. Repository water balance is
the culmination of multiple chemical reactions that produce or consume
water and affect actinide concentrations in the brine. These reactions
include microbial degradation of the cellulosic, plastic and rubber
materials, the anoxic corrosion of iron in the steel waste canisters,
and reactions of the magnesium oxide (MgO) used to control carbon
dioxide (CO2) buildup in the repository. Magnesium oxide, in
particular, reacts with brine and results in hydromagnesite
(Mg5(CO3)4(OH)24H2
O), which consumes water in the process.
Previous compliance recertification applications only included
anoxic corrosion in water balance calculations. The 2014 Compliance
Recertification Application includes an assessment of the microbial
degradation of the cellulosic, plastic and rubber material, the anoxic
corrosion of iron in the steel waste canisters and reactions of the
engineered barrier. The DOE did not change the rates for microbial
cellulosic, plastic and rubber material degradation and water
production from the 2009 Compliance Recertification Application. As
discussed previously, the DOE revised steel corrosion rates. The DOE
developed magnesium reaction rates for the compliance recertification
application based on previous studies (Chemistry TSD \22\).
---------------------------------------------------------------------------
\22\ ``Technical Support Document for Section 194.24: Evaluation
of the Compliance Recertification Actinide Source Term, Gas
Generation, Backfill Efficacy, Water Balance and Culebra Dolomite
Distribution Coefficient Values'' in Docket ID No. EPA-HQ-OAR-2014-
0609.
---------------------------------------------------------------------------
Although changes to each of these parameters is minor, the
reactions will have a cumulative effect. Based on previous exchanges
with the DOE (see comment 2-C-5 in Docket ID No. EPA-HQ-OAR-2014-0609)
as well as the SEN4 sensitivity study, the water balance updates do not
appear to significantly affect the WIPP performance. However, the EPA
[[Page 33115]]
recommends that the DOE re-evaluate the water balance issue for future
performance assessments to address questions associated with
interactions involving magnesium oxide (e.g., hydration rates in the
water balance calculations), and as previously discussed in Section
VI.D.1.e, the associated steel corrosion model and passivation
processes.
h. Variable Brine Volume. Brine volume plays an important role in
calculating actinide and organic ligand concentrations. In previous
performance assessments, the DOE calculated concentrations of these
species using the minimum brine volume needed for a direct brine
release, regardless of how much brine is projected to be released. This
failed to account for dilution and thus resulted in an overestimation
of organic ligand concentrations as well as actinide releases. To
correct for this in the 2014 Compliance Recertification Application,
the DOE adjusted actinide and organic ligand concentration calculations
to incorporate multiple brine volumes. The DOE continues to calculate
actinides and organic ligand concentrations at the minimum brine volume
required for a release. However, the DOE now also calculates
concentrations by dissolving these species at volumes 2, 3, 4 and 5
times the minimum volume to simulate larger volume releases. Thus,
concentrations at 5 times the volume will be lower than those
calculated at the minimum volume because more brine will be present to
dilute these aqueous species. The EPA finds that this approach
realistically addresses the issue of variable brine volumes involved in
a direct brine release and accepts this model for the compliance
recertification application.
i. Revised Colloid Parameters. Colloids are particles larger than
molecules that can be suspended in the WIPP brine. Because colloids
migrate more rapidly through the subsurface than actinides dissolved in
solution, colloids are an important contribution to actinide mobility
during a direct brine release. Intrinsic colloids are actinide
macromolecules that eventually increase in size. Microorganisms are
considered large colloids capable of mobilizing actinides because of
actinide sorption to their charged cell walls or because of actinide
bio-uptake.
In the original Compliance Certification Application, the colloid
parameters were based on experimentally derived values examining
actinide macromolecules or actinides sorbed onto biomass (e.g.,
Completeness Comment 3-C-9 in EPA-HQ-OAR-2014-0609-0010). Since then,
the DOE has performed multiple new investigations to update the
intrinsic and microbial colloid parameters. These investigations
prompted the DOE to reduce the contribution of colloids in the 2014
performance assessment.
Because of issues with experimental data used to develop the 2014
colloid contributions to actinide solubility, the 2014 performance
assessment calculations using those experimental results may
underestimate colloidal concentrations, and therefore, actinide
solubility. However, the EPA finds that the use of an updated
uncertainty distribution for actinide solubility in the SEN4
sensitivity study provides adequate information to determine that an
increase in colloid concentrations would not cause releases to exceed
the disposal standards. The EPA recommends that additional review of
the experimental results would benefit the DOE's treatment of colloid
formation mechanisms in future performance assessments. The EPA's
review of this topic is provided in the Chemistry TSD. See Section VI.E
of this document for discussion of the SEN4 study.
j. New Actinide Solubility Code (EQ3/6). Prior to the 2014
Compliance Recertification Application, the DOE used the Fracture
Matrix Transport (FMT) geochemical modeling code for actinide
solubility calculations. The DOE has since moved actinide solubility
calculations to the EQ3/6 code using the database DATA0.FM1, which
contains the values needed to calculate chemical speciation of the
ions, actinides and minerals present in the WIPP. The move to EQ3/6 is
logical as the program is widespread and has been used in other the DOE
projects. EQ3/6 can provide more robust calculations than FMT,
particularly in dynamic reaction-path calculations. The EPA accepts the
move to the EQ3/6 code. For additional discussion on this topic see the
EQ3/6 TSD.\23\
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\23\ ``EQ3/6 Computer Code Evaluation'' in Docket ID No. EPA-HQ-
OAR-2014-0609.
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2. Other Key Issues Identified by the EPA During Review. The EPA
identified three key topics where the Agency believes new information
can be incorporated into future compliance recertification
applications. These topics relate to the chemical conditions within the
repository and are of fundamental importance in determining the
potential for releases of radionuclides from the disposal system. These
topics are discussed in more detail in the Chemistry TSD.
a. Chemical Database. Actinide solubility, or the ability for
actinide solids to dissolve in brine, is important in calculating
releases. In performance assessment calculations, these radionuclides
include americium, curium, neptunium, plutonium, thorium, and uranium.
Americium(III) solubility is used to predict plutonium(III) and
curium(III) concentrations while thorium(IV) is used to predict
plutonium(IV), neptunium(IV) and uranium(IV).
The EPA's review identified that the DOE's update of the chemical
assumptions used in the actinide solubility database (DATA0.FM1) did
not reflect all data available prior to the DOE's data cut-off date of
December 31, 2012.The EPA raised several issues (in Docket ID No. EPA-
HQ-OAR-2014-0609-0010) about americium and thorium solubility and
speciation and in response, the DOE modified the database to produce
DATA0.FM2. However, the EPA identified flaws in the modified database
that need to be corrected before it can be considered to be of
sufficient quality for use in recertification. The EPA concluded that,
even with identified data gaps, the original DATA0.FM1 database was of
higher quality and provided sufficient information to support a
determination of continued compliance. The DOE's updates of the
chemical database for future performance assessments should more
comprehensively incorporate recent data.
b. Revised Radionuclide Uncertainty Distribution. The DOE also
examined the uncertainty distribution used to model the +III and +IV
actinide concentrations in the performance assessment by comparing
modeled solubility calculations to experimental data from multiple
reports and peer-reviewed studies. These studies include solubility
measurements from americium, thorium and their analogues using a
specific set of criteria (Chemistry TSD; 2014 Compliance
Recertification Application, Appendix SOTERM-2014 Section 5.1.3).
During the performance assessment solubility calculations, this
uncertainty distribution is sampled and used in calculating dissolved
actinides in a release.
After reviewing the actinide solubility uncertainty distribution
for the 2014 Compliance Recertification Application, the EPA identified
relevant studies that were not considered in developing this
distribution, as well as identifying studies that should have been
excluded from consideration, based on the DOE's evaluation criteria.
Using relevant studies would result in a revised actinide solubility
uncertainty distribution with overall higher +III
[[Page 33116]]
actinide solubility. The DOE included a revised solubility uncertainty
distribution based on the EPA's input in the sensitivity study SEN4.
The higher actinide solubility used in the SEN4 study contributed to
higher releases compared to the 2014 performance assessment, although
releases in the SEN4 study still remain below the regulatory limits.
See Section VI.E for more discussion of the SEN4 study.
The EPA recommends that updating the actinide solubility
uncertainty distribution should be part of the update to the
geochemical database. This would include incorporating new solubility
data for thorium and americium under the WIPP repository conditions,
and re-evaluating how studies are included in or excluded from the
DOE's analyses.
c. Plutonium Oxidation State. Oxidation states refer to an actinide
ion's charge. Actinides with a higher charge likely exist in
environments with greater oxygen content while actinides with lower
charges likely exist where there is less oxygen. Although plutonium has
multiple oxidation states including +VI, +V, +IV, and +III, the WIPP
model assumes plutonium oxidation state is dominated by the +III or +IV
charge in the aqueous phase due to the rapid removal of oxygen in the
repository. Identifying the dominant oxidation state is particularly
important as plutonium(III) is much more soluble than plutonium(IV). To
address this uncertainty, the plutonium oxidation state model does not
calculate oxidation state but instead considers plutonium(III) in 50%
of the realizations and plutonium(IV) in the other 50%. Since the 2009
Compliance Recertification Application, experiments have verified that
the iron metal corrosion of the WIPP waste containers largely mediate
the conditions conducive to plutonium(IV) and plutonium(III) oxidation
states. While experiments have confirmed the WIPP conditions post-
closure, the debate has shifted towards whether plutonium(IV) or
plutonium(III) is dominant in the WIPP conditions, or whether they will
be present in equal proportions. More recent experimental information
leads the EPA to believe that, under the WIPP conditions, aqueous
plutonium(III) will be the dominant state of plutonium and will exist
in equilibrium with the different solid plutonium phases present. In
addition, organic ligands, iron and microbial processes will also
increase the likelihood that plutonium(III) will dominate in solutions.
While the sensitivity studies did not directly test the presumption
that +III and +IV species would be equally present, the SEN4 study
indirectly examined this proposition by including a modified solubility
uncertainty distribution that was more heavily weighted toward higher
+III solubility (see Section VI.E.2.d). Both the compliance
recertification application and the SEN4 study indicate plutonium
release levels will be below the compliance points. Combined with the
related analysis of the actinide solubility uncertainty distributions,
the Agency can accept the DOE's assumption that the plutonium(III) and
plutonium(IV) oxidation states will each occur 50% of the time in
performance assessment calculations for the current recertification.
However, because of the available data that the EPA has identified
supporting the presence of plutonium(III) over plutonium(IV), the EPA
believes this issue is of sufficient significance to benefit from
independent technical review of the available data and the assumption
that both plutonium oxidation states will occur equally under the WIPP
conditions. The EPA's review of the plutonium oxidation state issue is
addressed more thoroughly in the Chemistry TSD.
E. Performance Assessment: Modeling and Containment Requirements
(Sec. Sec. 194.14, 194.15, 194.23, 194.31 through 194.34)
1. Overview. Section VI.A provided a basic description of the
requirements in 40 CFR 191.13 and the performance assessment process
required to show compliance with those standards. This section provides
additional information on performance assessment and how it is
evaluated by the EPA in the compliance recertification application. As
described earlier, the DOE must use the performance assessment to
demonstrate compliance with the containment requirements in 40 CFR
191.13. The containment requirements are expressed in terms of
``normalized releases.'' The DOE assembles the results of the
performance assessment into complementary cumulative distribution
functions, which indicate the probability of exceeding various levels
of normalized releases (Sec. 194.34).
For both of the DOE's 2004 and 2009 Compliance Recertification
Applications, the EPA requested that the DOE modify those respective
performance assessments to (1) address completeness and technical
issues raised during the EPA review process and with these
modifications, and (2) assure the disposal regulations were met.
These additional sets of calculations have been termed by the DOE
to be performance assessment ``baseline calculations'' and the EPA has
considered these calculations as updated ``baselines'' for each
respective compliance recertification application. The EPA then used
these baseline calculations for the comparison performance assessment
in each of the DOE's subsequent five-year compliance recertification
applications.
In this recertification review process, the Agency proceeded
differently than in the past. During the completeness review, the EPA
identified issues with parameters or approaches used by the DOE in the
calculations. These have been discussed in Section VI.D. The Agency
requested that the DOE conduct additional calculations so the EPA could
better understand how alternative parameter values would affect
repository performance. These calculations, or sensitivity studies as
they have been referred to, are summarized below and are the subject of
a TSD.\24\ With the completion of these sensitivity studies, the Agency
has decided not to request another set of performance assessment
baseline calculations as was done for previous recertifications. The
Agency believes that the sensitivity studies, coupled with the DOE's
documentation, provide a reasonable expectation that the WIPP complies
with the radioactive waste disposal regulations at 40 CFR part 191 and
the compliance criteria at 40 CFR part 194. Further, with the February
2014 incidents and the DOE's resulting need to change the facility
design,\25\ the Agency felt it was not necessary or appropriate at this
time to conduct additional calculations using a facility design that
will be changed in the near future.
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\24\ ``Review of EPA Sensitivity Studies of the DOE CRA-2014
WIPP Compliance Recertification Performance Assessment'' in Docket
ID No. EPA-HQ-OAR-2014-0609.
\25\ The DOE has stated that it intends to abandon plans to use
the area previously designated as waste panel 9 for waste
emplacement because of worker safety issues (``Installation of
Ventilation Barriers and Prohibiting Personnel Access to Equivalent
Panel 9 Areas,'' Letter from Todd Shrader, DOE, to Alan Perrin, EPA
dated April 18, 2017, Docket ID No. EPA-HQ-OAR-2014-0609). The DOE
also plans to develop a new ventilation shaft to increase airflow in
the mine, which is limited after the February 2014 incidents.
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The Agency requested that the DOE conduct four sensitivity studies
(labeled as SEN1, SEN2, SEN3 and SEN4) to address technical concerns
raised during the EPA's 2014 Compliance Recertification Application
review. The EPA has compared these sensitivity results to the DOE's
2014 performance assessment calculations. The purpose of these
sensitivity studies is to provide an understanding of how repository
[[Page 33117]]
compliance would be affected when modifying specific inputs in the 2014
performance assessment calculations. A brief explanation of those
selected parameters is provided below.
The ability of salt openings and aggregates to quickly compress,
consolidate and ``heal'' within a few hundred years, mostly due to the
creep-closure process, is one of the unique properties of bedded salt
geologic units that make them potentially suitable to use as nuclear
waste repositories. The DOE's 2014 performance assessment parameter
values assigned to the non-waste rooms, the panel closure system and
the adjacent disturbed rock zone did not reflect the creep-closure and
rapid healing of these areas that the EPA expects to occur. That is,
the DOE did not use permeability, porosity, residual gas and brine
saturations and capillary pressures reflective of in-situ (i.e.,
undisturbed) conditions.
Three of the EPA requested sensitivity studies, SEN1, SEN2 and
SEN3, focused on modifying parameters to test how assuming complete
creep-closure and healing of these areas would impact long-term
performance through modifying values related to the permeability,
porosity and two-phase flow parameter values for the run-of-mine salt
panel closure system, the disturbed rock zone and non-waste areas for
the 10,000-year modeled period. The fourth sensitivity study, SEN4,
investigated the cumulative effects and impact on repository
performance by making changes to five important parameter values as
well as using an updated numerical code.
As with the 2014 performance assessment, all of the sensitivity
studies had three replicate calculation sets and included the same
future scenarios. The four scenarios are briefly described below:
(1) The undisturbed scenario--where the repository is not impacted
by human activities,
(2) The E1 Scenario--where one or more boreholes penetrate a
Castile brine reservoir and also intersect a repository waste panel,
(3) The E2 Scenario--where one or more boreholes intersect a
repository waste panel but not a brine reservoir, and
(4) The E1/E2 Scenario--where there are multiple penetrations of
waste panels by boreholes of either the E1 or E2 type, at many possible
combinations of intrusion times and locations for either E1 or E2
drilling type of event.
2. Sensitivity Studies
a. The SEN1 Study. The intention of the SEN1 study was to determine
the impact on repository performance by modeling the stepped (i.e.,
gradual) reduction in porosity, permeability, residual gas and brine
saturation, and capillary pressures that reflect creep-closure and
healing of the open rooms and disturbed rock zone during the first 200
years after repository closure. The DOE was then to model these areas,
from 200 years to 10,000 years, as fully healed.
This study had to be terminated because the numerical flow code
used in these calculations produced non-physical and unrealistic
results when these parameters were modified in time-intervals to
reflect healing. The Agency accepted termination of this study, in
part, because modeling changes in these values for the first 200 years,
a relatively short time compared to the 10,000-year regulatory time
period, would not be as important to long-term repository performance.
The Agency considered that the SEN2 and SEN3 studies described below
adequately addressed the issues targeted by the SEN1 study because the
latter two studies both modeled the open and disturbed areas as fully
healed for the entire 10,000-year regulatory time period, essentially
bounding the conditions specified for the SEN1 study.
b. The SEN2 Study. This study tested the impacts on repository
performance by modeling the non-waste areas and open drifts as
completely creep-closed during the entire 10,000-year regulatory
period. In this study, parameter values for all the non-waste areas
(i.e., the operations and experimental room open drifts) and adjacent
disturbed rock zones were modified. The permeability and porosity were
reduced to that of intact halite. The residual brine and gas
saturations were also increased to better reflect healed conditions and
capillary pressures (the pressure needed for fluid to flow between
pores) were increased.
Compared to the 2014 Compliance Recertification Application
performance assessment, the SEN2 study waste room pressures generally
increased and brine saturations decreased. The most affected primary
release mechanism saw an increase in solid waste moving up a borehole
(spallings) because this release mechanism increases when waste panel
pressure increase. All other release mechanisms remained essentially
unchanged from the 2014 performance assessment calculations. Total
spallings releases remained small compared with cuttings, cavings and
direct brine releases. Spallings releases therefore did not materially
contribute to total repository releases in either SEN2 or the 2014
Compliance Recertification Application.
c. The SEN3 Study. For the SEN3 study, the DOE assumed that the
panel closure system, the adjacent disturbed rock zone and the non-
waste areas and open drifts are healed for the 10,000-year regulatory
period. The DOE reduced porosity and permeability in the repository,
increasing initial residual brine and gas saturations, and invoking
two-phase flow parameters for intact halite. Using these modifications
effectively isolated the individual waste panels and the non-waste
areas from one another for the entire modeled period due to limited
brine and gas flows between areas of the repository.
The modifications made in the SEN3 study caused increases in waste-
panel pressures and decreases in waste panel saturations. The dominant
releases were from spallings, which are only dependent on a waste panel
pressure high enough to force solids to the surface, and direct brine
releases, which are dependent on having sufficient brine in the waste
panels coupled with high enough pressure to force brine to the surface.
The release mechanism that increased the most was for spallings, and
the increase was seen at both the low and high probability compliance
points. The impact on direct brine release was primarily at low
probabilities because this release depends on both high waste panel
pressure and high saturation conditions, the combination of which were
less likely to occur in this study.
Factoring in all combined releases, the total mean and low-
probability (0.001 probability) releases increased by approximately 15%
from the initial 2014 Compliance Recertification Application results,
although the upper bound of the 95% confidence interval was essentially
the same as in the 2014 Compliance Recertification Application (0.384
EPA Units in the 2014 Compliance Recertification Application and 0.387
EPA Units in SEN3). Total releases did not exceed the EPA's WIPP
release limits.
The parameter values used in the SEN3 study created a ``tight''
repository (panel closure system, disturbed rock zone and non-waste
rooms) in which brine and gas flow is limited. The study results
indicate that such conditions may produce calculated releases higher
than the more open and brine- and gas-conducive set of conditions
presented by the DOE in the 2014 Compliance Recertification
Application.
d. The SEN4 Study
i. Overview. The fourth sensitivity study was intended to
understand the cumulative effects on repository performance by making
changes to
[[Page 33118]]
several parameters that the Agency questioned in the completeness
review. This study also incorporated a DOE-corrected version of the
DRSPALL code, which calculates waste that is released up a borehole to
the surface. This study does not address all of the EPA's completeness
questions, but provides significant insights as to the degree in which
some parameter values of interest to the EPA impact releases. Note, the
parameter changes in SEN2 and SEN3 representing creep closure were not
made in the SEN4 study, so the results reflect the 2014 Compliance
Recertification Application creep closure assumptions. The
modifications requested for this study are provided below:
Use the EPA's updated distribution for the probability of
intersecting a waste panel and a Castile brine reservoir, denoted as
the PBRINE parameter and discussed in Section VI.D.1.d previously.
Use the revised data set for the plutonium oxidation state
uncertainty distribution discussed in Section VI.D.2.c.
Modify the lower limit for the parameter that predicts
waste strength, denoted as the parameter TAUFAIL discussed in Section
VI.D.1.f.
Use the updated version of the computer code DRSPALL that
models waste carried up a borehole. After the 2014 performance
assessment calculations had been completed and submitted to the EPA,
the DOE discovered an error in the computer code, DRSPALL. The DOE
corrected this error and reported it to the EPA. For the SEN4 study,
the EPA requested that the DOE use the corrected version.
Eliminate the hydrogen sulfide reaction with iron as
discussion in Section VI.D.1.e.
Use the correct modeled length for north panel closure.
The WIPP repository design includes two sets of panel closures emplaced
at the north end of the repository. For the 2014 performance assessment
calculations, the DOE modeled the ``effective'' length of only one
panel closure rather than two. The EPA requested that the DOE increase
the effective length of the modeled north waste panel to be consistent
with the facility design.
ii. Cumulative effects of the changes evaluated by release pathway.
aa. Direct Brine Releases. Direct brine releases are a function of
actinide solubility, repository pressure and brine saturation. Of these
changes, the most significant are the revised solubility uncertainty
distributions that increase the concentration of the more soluble
plutonium(III) in repository brine, the increased likelihood of a
higher probability of hitting a brine pocket and the iron sulfidation
reaction stoichiometric coefficient changes. The combined effects of
these changes increased direct brine calculated releases and total mean
low probability (0.001) repository releases to about twice those of the
2014 Compliance Recertification Application performance assessment
(0.541 EPA Units for SEN4 versus 0.261 EPA Units for 2014 performance
assessment).
bb. Spallings Releases. Spallings releases are affected in SEN4 by
a combination of corrections using the updated version of the DRSPALL
code as well as increases in repository pressure. Repository pressure
was generally increased in SEN4 as a result of the updated distribution
of the PBRINE parameter, the increased length of the northernmost panel
closure and the updated iron sulfidation reaction stoichiometric
coefficients. The combined effect of these changes was to increase
spallings releases by about half an order of magnitude. However,
spallings releases remained low compared to direct brine releases and
the effect of this increase in spallings on total mean releases was
minimal.
cc. Cuttings and Cavings Releases. Cavings releases were affected
by the Agency's requested reduction of the lower bound of the
distribution for the TAUFAIL parameter. The small reduction in the
lower bound did not have a meaningful effect on total mean releases.
dd. Releases from the Culebra. Releases from lateral flow through
the Culebra Dolomite are a function of actinide solubility, repository
pressure, and brine saturation. These are affected by the revised
solubility uncertainty distributions, the increased likelihood of
sampling higher values for the PBRINE parameter, the increased length
of the northernmost panel closure and removal of the iron sulfidation
reactions. The combined effect of these changes on Culebra releases was
too small to have a meaningful effect on total mean repository
releases.
ee. Insights from the SEN4 Study. In the SEN4 study, the most
significant effects on repository performance were an increase in
direct brine releases and, by extension, an increase in total low
probability repository releases. The Agency concludes that these
increases were primarily the result of updating the solubility
uncertainty distributions, updating the distribution of PBRINE and
incorporating hydrogen sulfide steel passivation. The remaining
changes, updating the TAUFAIL lower bound, using the corrections in the
code DRSPALL and correcting the panel closure length, provided
important updates and corrections to the performance calculation but
had only a negligible effect on total mean releases. As in the previous
sensitivity studies, the total mean releases, the upper 95% confidence
limit on those means and all individual vectors in the three replicates
remained below regulatory limits in SEN4.
3. How the Four Sensitivity Studies Affect the WIPP's Compliance.
The results indicate that modifications to the selected parameters
reported in these evaluations increased calculated releases. However,
the total mean releases, the upper 95% confidence limit on those means,
and all individual vectors in the three replicates remained below the
EPA's WIPP release limits.
These sensitivity studies were intended to address a subset of the
EPA technical issues. These studies do not address all the technical
issues identified in the EPA's 2014 Compliance Recertification
Application review. The major issues identified in the EPA's review
primarily influence the direct brine releases and how the performance
assessment addresses those releases. The EPA recommends that,
especially with respect to calculating direct brine releases, the DOE
re-evaluate the implementation of features, events and processes, along
with model assumptions, to ensure their appropriate integration in the
2019 Compliance Recertification Application. The EPA has identified two
areas in particular (modeling of open areas and plutonium oxidation
states) that the Agency believes would greatly benefit from independent
technical review for consideration in the DOE's 2019 Compliance
Recertification Application.
F. Additional Requirements
This section summarizes the EPA's review as it relates to specific
sections of the WIPP Compliance Criteria in 40 CFR part 194 that do not
directly involve performance assessment.
Information on continuing compliance activities related to waste
characterization (40 CFR 194.8 and 194.24), inspections (Sec. 194.21)
and quality assurance (Sec. 194.22) may be found in Section V of this
document.
The DOE did not conduct any activities during the period covered by
the 2014 Compliance Recertification Application related to future state
assumptions (Sec. 194.25), expert judgment (Sec. 194.26) or assurance
requirements (Sec. 194.41-46). See the corresponding CARDs for more
discussion. Information on passive institutional controls, which is an
element of the assurance
[[Page 33119]]
requirements, may also be found in Section V.B.4.
1. Waste Characterization (Waste Inventory) (Sec. 194.24). Section
194.24 generally requires the DOE to identify, quantify and track the
important chemical, radiological and physical components of the waste
destined for disposal at the WIPP. The DOE collects data from generator
sites and compiles the waste inventory on an annual basis. The DOE's
2012 Annual Transuranic Waste Inventory Report (ATWIR 2012), which was
used for the 2014 Compliance Recertification Application, reflects the
disposal intentions of the waste generator sites as of December 31,
2010. The DOE classified the wastes as emplaced, stored or projected
(to-be-generated). The DOE used data from the WIPP database to identify
the characteristics of the waste that has been emplaced at the WIPP.
The projected wastes were categorized similarly to existing waste
(e.g., heterogeneous debris, filter material, soil).
The EPA reviewed the compliance recertification application and
supplemental information to determine whether these documents provided
a sufficiently complete estimate and description of the chemical,
radiological and physical composition of the emplaced, stored and
projected wastes proposed for disposal in the WIPP. The Agency also
reviewed the DOE's description of the approximate quantities of waste
components (for both existing and projected wastes). The EPA found that
the radionuclides, cellulosic, plastic and rubber materials, organic
ligands, oxyanions and cements in the waste are being appropriately
tracked and characterized. In the 2014 Compliance Recertification
Application, there is an update on the inventory of curium and
neptunium, which remain in concentrations well below their solubility
limits even after accounting for decay. The EPA accepts this updated
inventory, which is relatively similar to the one used in the 2009
Compliance Recertification Application. See the Baseline Inventory TSD
\26\ for more information.
---------------------------------------------------------------------------
\26\ ``Technical Support Document for Section 194.24: Review of
the Baseline Inventory Used in the Compliance Recertification
Application (CRA-2014)'' in Docket ID No. EPA-HQ-OAR-2014-0609.
---------------------------------------------------------------------------
2. Peer Review (Sec. 194.27). Section 194.27 of the WIPP
Compliance Criteria requires the DOE to conduct peer review
evaluations, when warranted, of conceptual models, waste
characterization analyses, and a comparative study of engineered
barriers. The required peer reviews must be performed in accordance
with the Nuclear Regulatory Commission's NUREG-1297, ``Peer Review for
High-Level Nuclear Waste Repositories,'' which establishes guidelines
for the conduct of a peer review exercise. The DOE has conducted one
peer review since the 2009 Compliance Recertification Application to
establish radiological properties for two waste streams, titled the
``Savannah River Site Historical Radiochemistry Data Peer Review,''
demonstrating its compliance with the requirements of Sec. 194.27.
Based on a review and evaluation of the 2014 Compliance
Recertification Application and supplemental information provided by
the DOE (Docket ID No. EPA-HQ-OAR-2014-0609-0330), the EPA determines
that the DOE continues to comply with the requirements of 40 CFR
194.27.
G. Individual and Groundwater Protection Requirements (Sec. Sec.
194.51 Through 194.55)
Sections 194.51 through 194.55 of the WIPP Compliance Criteria
implement the individual protection requirements of 40 CFR 191.15 and
the groundwater protection requirements of subpart C of 40 CFR part
191. Assessment of the likelihood that the WIPP will meet the
individual dose limits and radionuclide concentration limits for ground
water is conducted through a process known as compliance assessment.
Compliance assessment uses methods similar to those of performance
assessment (for the containment requirements in 40 CFR 191.13 and
Appendix A) but is required to address only undisturbed performance of
the disposal system. That is, compliance assessment does not include
human intrusion scenarios (i.e., drilling or mining for resources).
Compliance assessment can be considered a ``subset'' of performance
assessment, since it considers only natural (undisturbed) conditions
and past or near-future human activities (such as existing boreholes),
but does not include the long-term future human activities that are
addressed in the performance assessment.
In the 2014 Compliance Recertification Application, the DOE re-
evaluated each of the individual and groundwater requirements. The DOE
updated the data for ground water quantity determination to define an
underground source of drinking water for purposes of calculating
groundwater concentrations and doses. In the 2014 Compliance
Recertification Application, the DOE used 2011 (U.S. Bureau of Census
2013) census data to update the number of persons per household.\27\
The DOE continued to use the 2009 compliance recertification
application data for the average household water consumption values.
The water consumption data show that the average per capita consumption
is 273 gallons per day.\28\ The DOE concludes that the sub-criterion of
5 gallons per minute rate of production from a well continues to
accurately define an underground source of drinking water \29\ and any
change in this sub-criterion is not warranted as a result of applying
more current water-consumption data to the calculation.
---------------------------------------------------------------------------
\27\ 2014 Compliance Recertification Application Appendix IGP-
2014, Table IGP-3
\28\ 2014 Compliance Recertification Application Appendix IGP-
2014, Table IGP-3
\29\ 2014 Compliance Recertification Application Appendix IGP-
2014, Section IGP-3.1.1)
---------------------------------------------------------------------------
The updates made by the DOE in the 2014 Compliance Recertification
Application did not significantly impact the conclusions regarding the
groundwater standard in the Compliance Certification Application. The
DOE did not change the criteria for making underground source of
drinking water determinations, and for the 2014 Compliance
Recertification Application evaluation, the maximum potential dose
remains below the Compliance Certification Application value calculated
and continued compliance with the individual protection standard is
maintained. The DOE states that the conservative bounding analysis used
for the 1998 certification decision compliance assessment is still
applicable for 2014 Compliance Recertification Application.\30\
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\30\ 2014 Compliance Recertification Application Appendix IGP-
2014, Section IGP-4.0
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The EPA finds the DOE in continued compliance with 40 CFR 194.51-
194.55 requirements.
VII. How has the public been involved in the EPA's WIPP recertification
activities?
A. Public Information
The EPA interacts with the public through various means. The EPA's
main mechanism for distributing information is the EPA Web site and
email messages via the WIPP-NEWS listserv. The EPA will also
occasionally have meetings, in person or via teleconferences or
webinars.
Throughout the recertification process, the Agency posted pertinent
new information and updates on the EPA WIPP Web site (https://www.epa.gov/radiation/epas-role-waste-isolation-pilot-plant-wipp). All
pertinent recertification documents
[[Page 33120]]
(including the DOE-submitted recertification materials, correspondence,
Federal Register notices, outreach materials, hearing transcripts as
well as TSDs) are available for review or download (in Adobe PDF
format) via the electronic docket dedicated to the 2014-2017
recertification process (https://www.regulations.gov, Docket ID No. EPA-
HQ-OAR-2014-0609).
Since October 2014, the EPA has sent out numerous announcements
regarding the recertification schedule and availability of any WIPP-
related documents on the EPA WIPP Web site and the dockets, as well as
details for the Agency's June 2015 stakeholder meetings in New Mexico
and January 2017 stakeholder webinar (via Adobe Connect).
B. Stakeholder Meetings
As discussed in the WIPP LWA, the recertification process is not a
rulemaking and public hearings are not required. However, the EPA held
a series of stakeholder meetings in June 2015 (Carlsbad and
Albuquerque, NM) as well as a stakeholder webinar in January 2017 (via
Adobe Connect software, with public hosting locations in Carlsbad and
Albuquerque, NM) to provide information and updates about the
recertification process. In an effort to make these meetings as
informative as possible to all attending parties, the EPA listened to
stakeholder input and concerns and tailored the meetings around the
public as much as possible. The first meeting was held on June 16,
2015, in Carlsbad, New Mexico and consisted of one three-hour afternoon
session. The second public meeting was held on June 17, 2015, in
Albuquerque, New Mexico, with afternoon and evening sessions.
The main purpose of these meetings was to discuss the EPA's
recertification process and timeline, as well as the DOE's application
and important changes at the WIPP since the last recertification in
2010. The meetings featured brief presentations on the aforementioned
topics, as well as a facilitated discussion. In response to stakeholder
suggestions, the DOE staff members were also on hand to provide
information and answer any stakeholder questions. Staff from the New
Mexico Environment Department (NMED) were present as observers. Public
participants were encouraged to provide comments to the EPA for
consideration during review of the DOE's 2014 Compliance
Recertification Application.
The EPA also held a stakeholder webinar using the Adobe Connect
software on January 12, 2017. The Agency hosted the webinar from
Washington, DC, with physical hosting locations set up in both Carlsbad
and Albuquerque, NM, to accommodate members of the public as well as
the DOE and NMED staff. The main purpose of this webinar was to inform
the public of the current recertification schedule and provide updated
technical information related to stakeholder questions and comments
received at the June 2015 meetings.
All of the issues raised at these meetings have been addressed by
the EPA in Section VII.C of this document or in the CARDs under the
relevant section and are available in the public docket
(www.regulations.gov, Docket ID No. EPA-HQ-OAR-2014-0609).
C. Public Comments on Recertification
The EPA posted the recertification application on the Web site
immediately following receipt. The EPA formally announced receipt of
the recertification application in the Federal Register on October 10,
2014. The notice also officially opened the public comment period on
the recertification application.
For recertification, the EPA sought public comments and input
related to changes in the DOE's application that may have a potential
impact on the WIPP's ability to remain in compliance with the EPA's
disposal regulations.
The comment period for the recertification application closed on
April 10, 2017, approximately two years and six months after it
initially opened. This closing date was 30 days after the EPA's
announcement in the Federal Register that the recertification
application was complete.
The EPA received 17 sets of written public comments during the
public comment period. The EPA considered significant comments from the
written submissions and the stakeholder meetings in the evaluation of
continuing compliance. The EPA addresses these comments in CARDs that
are relevant to each topic. In addition, a listing of all comments
received and responses to each is included in Appendix 15-C of CARD 15.
Two specific comments are addressed here.
Comment: One comment addressed shipment of waste from Argonne
National Lab. Citing the EPA's inspection reports, the commenter stated
that he believed that the DOE had shipped and emplaced at the WIPP
waste from the Lab that contained spent nuclear fuel and high level
waste. He correctly stated that the WIPP LWA bans the transport to and
disposal at the WIPP of high level radioactive waste and spent nuclear
fuel. He wanted to know (a) how the EPA failed to uncover that the
Argonne Lab was to ship spent nuclear fuel to the WIPP and approved
this disposal, (b) how the EPA assures that this waste will not be sent
to the WIPP, (c) how much of this waste has been sent to the WIPP, and
the identity of all waste of these types, (d) what authority allowed
the shipment and disposal of these prohibited wastes, and (e) how the
EPA did not bar the DOE's shipment and disposal of these wastes.
In a related comment, on February 3, 2017, the DOE, responded to
this commenter and stated that the Argonne Lab waste is derived from
atomic energy defense activities and did not contain any spent nuclear
fuel (see EPA-HQ-OAR-2014-0609-0042). The DOE acknowledged that the
WIPP LWA prohibits the disposal at WIPP of spent nuclear fuel and also
acknowledged that some of the waste from the Argonne Lab was debris
from specimens taken from fuel pins that were originally irradiated in
commercial nuclear reactors. However, the DOE commented that the
statutory definition of spent nuclear fuel does not speak directly to
the issue of whether debris from specimens of commercial fuel rods is
spent nuclear fuel. The DOE explained that, here, the debris--although
including material that originated from fuel pins that had been
irradiated in nuclear reactors--resulted from research and development
activities at Argonne. The DOE stated that to try to segregate debris
originating from irradiated fuel pins from other waste would be
technically infeasible and cost prohibitive and would increase worker
exposure. The DOE asserted that resolution of whether the material
should be considered spent nuclear fuel was within its discretion and
that it was its longstanding practice to classify such debris as waste
and not spent nuclear fuel. In response to the DOE's February 3, 2017
comment, the original commenter resubmitted his original comment.
EPA Response: Under the WIPP LWA, the focus of the EPA's present
recertification determination is whether the WIPP continues to comply
with the final disposal regulations. Although--as the commenter notes
and the DOE acknowledges--the WIPP LWA bans disposal at the WIPP of
spent nuclear fuel, the disposal regulations, themselves, currently do
not expressly address disposal of spent nuclear fuel. The WIPP LWA
incorporates the definition of spent nuclear fuel found in the Nuclear
Waste Policy Act of 1982: ``fuel that has been withdrawn from a nuclear
reactor following irradiation, the constituent elements of which have
not been separated by reprocessing.'' 42 U.S.C. 10101(23) (as
incorporated by
[[Page 33121]]
WIPP LWA Sec. 2(15)). There seems to be no dispute that waste from the
Argonne Lab includes some quantity of material that is not presently in
the intact physical form of fuel withdrawn from a reactor following
irradiation,\31\ but is fragments of or particulates from fuel pins
withdrawn from a reactor following irradiation. The DOE states that the
fragments or particulates resulted from research and development
activities on test specimens from fuel pins withdrawn from a reactor
following irradiation and claims that treatment of such material as
other than spent nuclear fuel is consistent with the intent of the WIPP
LWA. The DOE also asserts that attempting to segregate the fuel pin
fragments and particulates from other debris shipped to the WIPP is
infeasible and cost prohibitive and would increase worker exposure.
---------------------------------------------------------------------------
\31\ There also seems to be no doubt that, as to the material in
question, the ``constituent elements'' have not been ``separated by
reprocessing.''
---------------------------------------------------------------------------
Reasonable contentions may be made that fragments and particulates
resulting from research and development activities on specimens from
fuel withdrawn from a nuclear reactor following irradiation (``pieces
of pieces'' of fuel pins) do not meet the statutory definition of spent
nuclear fuel. The practical considerations of feasibility, cost, and
worker safety associated with attempting to segregate such particulates
from other waste shipped to the WIPP bear consideration. It is not
essential, however, to the EPA's present recertification decision to
attempt to definitively resolve this issue, because the current
disposal regulations do not expressly address disposal of spent nuclear
fuel.
On an on-going basis, aside from the periodic recertification of
the WIPP, the EPA communicates with the DOE concerning the
characterization of WIPP waste. The DOE provides the EPA with
documentation relating to WIPP waste streams, including but not limited
to, waste from the Argonne National Laboratory, and including
documentation for both contact handled and remote handled TRU waste
streams. The relevant information is confirmed by analyzing individual
waste containers using the EPA approved processes, procedures and
equipment. These steps allow the DOE to demonstrate that waste
containers for WIPP disposal meet the EPA's WIPP waste limits for
physical and radiological contents of the waste. So, concerning the
waste shipped from Argonne National Laboratory, the EPA evaluated the
waste characteristic information prepared for remote handled waste. The
DOE provided historical information to document that waste generated
from laboratory experiments at Argonne was defense related, and through
radiological assay concluded that the waste in question met the
definition of TRU waste and was appropriate for disposal at the WIPP.
Following this determination, Argonne provided this waste for
characterization. Radiological and physical characterization confirmed
that the TRU waste in question (a) is remote handled waste; (b)
exhibits the characteristics of debris waste; and (c) meets the
regulatory limits of the EPA's WIPP waste acceptance requirements at 40
CFR 194.24.
The EPA thoroughly inspects and approves the waste characterization
processes in place at all waste characterization sites including
Argonne National Laboratory. As part of the waste characterization
inspections and approvals, the EPA is responsible for evaluating the
adequacy of characterization methods used to identify and measure
radiological and physical contents of the TRU waste that affect the
long term containment and isolation of waste at the WIPP and for
ensuring that the WIPP-bound waste meets the disposal requirements
under 40 CFR 194.24.
Comment: Another commenter disagreed with the DOE's proposed
revision of the PBRINE parameter. The commenter noted that the DOE's
2014 approach resulted in a lower probability of intersecting a brine
pocket than was used in the original certification and previous
recertifications, and finds this to be ``invalid.'' The commenter
recommends using a fixed value of 60% probability, based on historical
well testing and geophysical data. The commenter also disputes a number
of the DOE's underlying assumptions for revising the approach,
including the DOE's view of the geophysical data as unreliable and what
the commenter sees as the DOE's misinterpretation of more recent
drilling data.
EPA Response: The EPA agrees with the commenter that the DOE's
revised approach raises concerns. In particular, the EPA does not agree
with the DOE's conclusions regarding the geophysical data. However,
after reviewing the data again, the EPA disagrees with the commenter
that a fixed probability of 60% is necessary. The EPA notes that 60%
was the high end of the probability distribution used in performance
assessments prior to 2014, with a mean probability of 30.5%, as
recognized by the commenter. The updated approach developed by the EPA
uses the geophysical data, but also incorporates newer drilling
information into the probability distribution. The EPA believes this
approach is sound and is acceptable for use in future performance
assessments. The EPA will evaluate future proposals by the DOE to
update the method for determining PBRINE. The EPA's review is discussed
further in Section VI.D.1.d of this document and in the PBRINE TSD.
VIII. Where can I get more information about the EPA's WIPP-related
activities?
A. Supporting Documents for Recertification
The CARDs discuss DOE's compliance with each of the individual
requirements of the WIPP Compliance Criteria. The CARDs also list the
EPA TSDs and any other references used by the EPA in rendering the
decision on compliance. All TSDs and references are available in the
Agency's dockets, via www.regulations.gov (Docket ID No. EPA-HQ-OAR-
2014-0609), with the exception of generally available references and
those documents already maintained by the DOE or its contractors in
locations accessible to the public. For more detailed information on
the technical issues considered in the EPA's recertification decision,
see the TSDs.
B. The WIPP Web site & WIPP-NEWS Email Listserv
For more general information and updates on the EPA's WIPP
activities, please visit the WIPP internet homepage at <https://www.epa.gov/radiation/epas-role-waste-isolation-pilot-plant-wipp>. All
pertinent recertification-related documents (including the DOE-
submitted recertification materials, letters, Federal Register notices,
outreach materials, etc.) are available for review or download in Adobe
PDF format. The Agency's WIPP-NEWS email listserv, which automatically
sends messages to subscribers with up-to-date WIPP announcements and
information, is also available online. Any individuals wishing to
subscribe to the listserv can join by visiting <https://lists.epa.gov/read/all_forums/subscribe?name=wipp-news> and providing all requested
information to register.
C. Dockets
In accordance with 40 CFR 194.67, the EPA maintains public dockets
via www.regulations.gov (Docket ID No. EPA-HQ-OAR-2014-0609) that
contain all the information used to support the Agency's decision on
recertification. The Agency maintains the formal hard
[[Page 33122]]
copy/paper docket in Washington, DC, as well as informational dockets
in three locations in the State of New Mexico (Carlsbad, Albuquerque,
and Santa Fe). The docket consists of all relevant, significant
information received to date from outside parties and all significant
information considered by the EPA in reaching a recertification
decision regarding whether the WIPP facility continues to comply with
the disposal regulations.
IX. What is the EPA's role in future WIPP activities?
The EPA's regulatory role at the WIPP does not end with this
recertification decision. The Agency's future WIPP activities include
additional recertifications every five years (the next being scheduled
to be submitted by the DOE in March 2019), review of the DOE reports on
conditions and activities at the WIPP, assessment of waste
characterization and quality assurance programs at waste generator
sites, announced and unannounced inspections of the WIPP and other
facilities and, if necessary, modification, revocation or suspension of
the certification.
As a result of the February 2014 incidents at the WIPP, the DOE
will be making changes to the repository design. The DOE has indicated
that it no longer plans to use panel 9 for waste operations due to the
worker safety hazards in that location, so an alternative panel will be
needed. This decision may also have implications for panel closures in
the panels accessed through the panel 9 drifts (i.e., panels 3-6). In
addition, the DOE is planning a new ventilation shaft that will allow
for increased airflow through the underground operations area. The EPA
will be keeping abreast of the DOE's requested changes and will make
that information available as it is received.
As described in Section VI of this notice, the EPA's review of the
2014 Compliance Recertification Application identified where the DOE's
technical basis for the modeling has limitations with assumptions used
or with the basis for some parameter values. The EPA concerns with
these limitations were generally addressed by the results of the SEN
studies. While this approach of using a series of sensitivity studies
to examine identified limitations was sufficient in the context of this
compliance recertification application, it was to some extent driven by
the known upcoming physical changes in the repository. The EPA would
prefer to be able to evaluate a complete revised performance assessment
in future compliance recertification application reviews. The EPA
recommends that the performance assessment technical basis be evaluated
for improvement in these areas: (1) Calculations of actinide
solubility, (2) modeling the chemical conditions in the repository, and
(3) modeling direct brine releases.
Although not required by the Administrative Procedure Act (APA),
the WIPP LWA or the WIPP Compliance Criteria, the EPA intends to
continue docketing all inspection or audit reports and annual reports
and other significant documents on conditions and activities at the
WIPP, as well as formal communications between the two agencies.
The EPA plans to conduct future recertification processes using an
administrative process generally similar to that described in today's
action.
Dated: July 10, 2017.
Sarah Dunham,
Acting Assistant Administrator, Office of Air and Radiation.
[FR Doc. 2017-15182 Filed 7-18-17; 8:45 am]
BILLING CODE 6560-50-P