Notice of Availability of the Final License Renewal Interim Staff Guidance-LR-ISG-2006-01: Plant-Specific Aging Management Program for Inaccessible Areas of Boiling Water Reactor (BWR) Mark I Steel Containment Drywell Shell, 67923-67925 [E6-19838]
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Federal Register / Vol. 71, No. 226 / Friday, November 24, 2006 / Notices
himself or herself by stating their name,
city and state of residence, and stating
whether they have any affiliation (such
as employment, consultancy, or
membership) with any of the parties
(USEC or the NRC).
C. Submitting a Request To Make an
Oral Limited Appearance Statement
Persons wishing to make an oral
statement who have submitted a timely
written request to do so will be given
priority over those who have not filed
such a request. To be considered timely,
a written request to make an oral
statement must either be mailed, faxed,
or sent by e-mail so as to be received by
5 p.m. EST on January 2, 2007. Written
requests to make an oral statement
should be submitted to:
Mail: Office of the Secretary,
Rulemakings and Adjudications Staff,
U.S. Nuclear Regulatory Commission,
Washington, DC 20555–0001.
Fax: (301) 415–1101 (verification
(301) 415–1966).
E-mail: hearingdocket@nrc.gov.
In addition, using the same method of
service, a copy of the written request to
make an oral statement should be sent
to the Chairman of this Licensing Board
as follows:
Mail: Administrative Judge Lawrence
G. McDade, c/o: Debra Wolf, Esq. Law
Clerk, Atomic Safety and Licensing
Board Panel, Mail Stop T–3 F23, U.S.
Nuclear Regulatory Commission,
Washington, D.C. 20555–0001.
Fax: (301) 415–5599 (verification
(301) 415–6094).
E-mail: daw1@nrc.gov.
cprice-sewell on PROD1PC66 with NOTICES
D. Submitted Written Limited
Appearance Statements
A written limited appearance
statement may be submitted to the
Board regarding this proceeding at any
time, either in lieu of or in addition to
any oral statement. Such statements
should be sent to the Office of the
Secretary using the methods prescribed
above, with a copy to the Licensing
Board Chairman.
E. Availability of Documentary
Information Regarding the Proceeding
Documents relating to this proceeding
are available for public inspection at the
Commission’s Public Document Room
(PDR), located at One White Flint North,
11555 Rockville Pike (first floor),
Rockville, Maryland, or electronically
from the publicly available records
component of NRC’s document system
(ADAMS). ADAMS is accessible from
the NRC Web site at https://www.nrc.gov/
reading-rm/adams.html (Electronic
Reading Room). Persons who do not
have access to ADAMS or who
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13:24 Nov 22, 2006
Jkt 211001
encounter problems in accessing the
documents located in ADAMS should
contact the NRC PDR reference staff by
telephone at (800) 397–4209 or (301)
415–4737, or by e-mail to pdr@nrc.gov.
F. Scheduling Information Updates
Updated/revised scheduling
information regarding the limited
appearance session can be found on the
NRC Web site at https://www.nrc.gov/
public-involve/public-meetings/
index.cfm or by calling (800) 368–5642,
extension 5036, or (301) 415–5036.
Dated in Rockville, Maryland, on
November 17, 2006.
For the Atomic Safety and Licensing
Board.2
Lawrence G. McDade,
Chairman, Administrative Judge.
[FR Doc. E6–19839 Filed 11–22–06; 8:45 am]
BILLING CODE 7590–01–P
NUCLEAR REGULATORY
COMMISSION
Notice of Availability of the Final
License Renewal Interim Staff
Guidance—LR–ISG–2006–01: PlantSpecific Aging Management Program
for Inaccessible Areas of Boiling Water
Reactor (BWR) Mark I Steel
Containment Drywell Shell
Nuclear Regulatory
Commission.
ACTION: Notice of availability.
AGENCY:
SUMMARY: The NRC is issuing its Final
License Renewal Interim Staff Guidance
LR–ISG–2006–01. This LR–ISG provides
interim guidance to applicants for
license renewal for a plant with a BWR
Mark I steel containment to provide a
plant-specific aging management
program that addresses the potential
loss of material due to corrosion in the
inaccessible areas of their Mark I steel
containment drywell shell for the period
of extended operation.
The NRC staff issues LR–ISGs to
facilitate timely implementation of the
license renewal rule and to review
activities associated with a license
renewal application. The NRC staff will
also incorporate the approved LR–ISG
into the next revision of the license
renewal guidance documents.
ADDRESSES: The NRC maintains an
Agencywide Documents Access and
Management System (ADAMS), which
provides text and image files of NRC’s
public documents. These documents
may be accessed through the NRC’s
Public Electronic Reading Room on the
2 Copies of this Notice were sent this date by
Internet electronic mail transmission to counsel for
(1) USEC; and (2) the NRC Staff.
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67923
Internet at https://www.nrc.gov/readingrm/adams.html. Persons who do not
have access to ADAMS or who
encounter problems in accessing the
documents located in ADAMS should
contact the NRC Public Document Room
(PDR) reference staff at 1–800–397–
4209, 301–415–4737, or by e-mail at
pdr@nrc.gov.
Ms.
Linh Tran, License Renewal Project
Manager, Office of Nuclear Reactor
Regulation, U.S. Nuclear Regulatory
Commission, Washington, DC, 20555–
0001, telephone 301–415–4103 or by email at lnt@nrc.gov.
SUPPLEMENTARY INFORMATION:
Attachment 1 to this Federal Register
notice, entitled Staff Position and
Rationale for the Final License Renewal
Interim Staff Guidance—LR–ISG–2006–
01: Plant-specific Aging Management
Program for Inaccessible Areas of
Boiling Water Reactor Mark I Steel
Containment Drywell Shell contains the
NRC staff’s rationale for publishing the
Final LR–ISG–2006–01. Attachment 2,
entitled Final License Renewal Interim
Staff Guidance—LR–ISG–2006–01:
Plant-specific Aging Management
Program for Inaccessible Areas of BWR
Mark I Steel Containment Drywell Shell,
contains the guidance for developing
the plant-specific aging management
program. The NRC staff approves this
LR–ISG for NRC and industry use. The
NRC staff will also incorporate the
approved LR–ISG into the next revision
of the license renewal guidance
documents.
FOR FURTHER INFORMATION CONTACT:
For the Nuclear Regulatory Commission.
Dated at Rockville, Maryland, this 16th day
of November 2006.
Frank P. Gillespie,
Director, Division of License Renewal, Office
of Nuclear Reactor Regulation.
Attachment 1—Staff Position and
Rationale for the Final License Renewal
Interim Staff Guidance—LR–ISG–2006–
01: Plant-Specific Aging Management
Program for Inaccessible Areas of BWR
Mark I Steel Containment Drywell
Shell
Staff Position
The NRC staff determined that a
plant-specific aging management
program (AMP) is needed to address the
potential loss of material due to
corrosion in the inaccessible areas of the
Mark I steel containment drywell shell
for the period of extended operation.
Rationale
The current license renewal guidance
documents (LRGDs) do not provide
sufficient guidance to address
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Federal Register / Vol. 71, No. 226 / Friday, November 24, 2006 / Notices
inaccessible areas of the Mark I steel
containment drywell shell. Specifically,
the inaccessible areas where the drywell
shell is surrounded by a concrete
structure with a narrow distance
between the steel shell and the
surrounding concrete inhibit visual
inspection. Past operating experience in
Mark I steel containments indicates that
when water is discovered in the bottom
outside areas of the drywell (for
example in the sand-bed area), the most
likely cause would be the water seeping
through the space between the drywell
shell and the shield concrete.
In addition, numerous requests for
additional information (RAIs) were
necessary on previous and current
license renewal applications (LRAs) to
obtain the information needed by the
staff to perform its review. The purpose
of this LR–ISG is to provide guidance on
the information that should be provided
in the LRA to reduce the number of
RAIs issued to the applicants.
Specifically, the staff has determined
that a plant-specific aging management
program (AMP) is needed to address the
potential loss of material due to
corrosion in the inaccessible areas of the
Mark I steel containment drywell shell
for the period of extended operation.
The drywell shell is a passive, longlived structure subject to aging
degradation. Pursuant to 10 CFR 54.21,
the applicant must demonstrate that the
effects of aging will be adequately
managed so that the intended function
will be consistent with the current
licensing basis (CLB) for the period of
extended operation.
cprice-sewell on PROD1PC66 with NOTICES
Attachment 2—Final License Renewal
Interim Staff Guidance—LR–ISG–2006–
01: Plant-Specific Aging Management
Program for Inaccessible Areas of
Boiling Water Reactor Mark I Steel
Containment Drywell Shell
Introduction
Line Item II.B1.1–2 of NUREG–1801,
Volume 2, Revision 1, includes a
provision for aging management of the
Mark I steel containment drywell shells.
However, the line item requires
additional detail to address the
inaccessible areas of the Mark I steel
containment drywell shells.
Specifically, the line item does not
provide guidance when the distance
between the steel drywell shell and the
surrounding concrete structure is too
small for the successful performance of
visual examination.
All Mark I containment drywells are
free-standing steel construction, except
for Brunswick, Units 1 and 2. The
Brunswick Mark I containment consists
of a reinforced concrete drywell and a
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13:24 Nov 22, 2006
Jkt 211001
reinforced concrete torus with a steel
liner. A drywell shell is a free-standing
steel structure with no concrete backing,
whereas the steel liner of a drywell is a
leak-tight membrane in direct contact
with the concrete containment.
Historical Background
Information Notice (IN) 86–99,
‘‘Degradation of Steel Containments,’’
dated December 8, 1986, described an
event related to the degradation of the
drywell shell at Oyster Creek Nuclear
Generating Station. IN 86–99,
Supplement 1, dated February 14, 1991,
explained that the most likely cause of
corrosion of the drywell shell in sandpocket areas (near the bottom of the
drywell) and in the spherical portion of
the drywell at higher elevations, was the
water in the gap between the drywell
and the concrete shield. The source of
water was noted as leakage through the
seal between the drywell and the
refueling cavity. The IN supplement
noted that the stainless steel liners in
the refueling cavity and equipment pool
developed cracks along the perimeter of
the liner plates where they were welded
to embedded channels. The IN
supplement also noted that ultrasonic
testing (UT) discovered minor corrosion
in the cylindrical portion of the drywell,
and significant corrosion in the sandbed region of the shell.
Discussion
Generic Letter (GL) 87–05, ‘‘Request
for Additional Information-Assessment
of Licensee Measures to Mitigate And/
Or Identify Potential Degradation of
Mark I Drywells,’’ requested additional
information regarding licensee actions
to mitigate and/or identify potential
degradation of boiling water reactor
Mark I drywells. As a result, a number
of licensees performed UT of their
carbon steel drywell shells adjacent to
the sand-bed region. In addition, many
licensees established leakage monitoring
programs for drain lines to identify
leakage that may have resulted from
refueling or spillage of water into the
gap between the drywell and the
surrounding concrete. UT performed as
a result of GL 87–05 provided a set of
data points to determine the drywell
shell thickness that could be compared
to the nominal fabrication thickness and
the minimum thickness required to
withstand the postulated loads. These
UT measurements taken during the
1987–1988 time frame fall
approximately near the mid-point of the
current 40-year operating license period
for most plants with Mark I steel
containments.
The drywell shell is a passive, longlived structure within the scope of
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Frm 00079
Fmt 4703
Sfmt 4703
license renewal that is subject to aging
degradation. Pursuant to 10 CFR 54.21,
the applicant must demonstrate that the
effects of aging will be adequately
managed so that the intended function
will be maintained consistent with the
current licensing basis for the period of
extended operation. On the basis of
license renewal application reviews and
industry operating experience, the NRC
staff determined that a plant-specific
aging management program (AMP) is
needed to address the potential loss of
material due to corrosion in the
inaccessible areas of the Mark I steel
containment drywell shell for the period
of extended operation.
Recommended Action
In addressing Line Item II.B1.1–2 of
NUREG–1801, Volume 2, Revision 1,
applicants for license renewal for plants
with a Mark I steel containment should
perform an aging management review of
the inaccessible areas of its containment
drywell shell and provide a plantspecific aging management program that
addresses the potential loss of material
due to corrosion for the period of
extended operation.
In conducting the aging management
review and developing the plantspecific aging management program for
the drywell shell, the applicant should
consider the following recommended
actions based upon plant design and
operating experience:
(1) Develop a corrosion rate that can
be reasonably inferred from past UT
examinations or establish a corrosion
rate using representative samples in
similar operating conditions, materials,
and environments. If degradation has
occurred, provide a technical basis
using the developed or established
corrosion rate to demonstrate that the
drywell shell will have sufficient wall
thickness to perform its intended
function through the period of extended
operation.
(2) Demonstrate that UT
measurements performed in response to
GL 87–05 did not show degradation
inconsistent with the developed or
established corrosion rate.
(3) Where degradation has been
identified in the accessible areas of the
drywell, provide an evaluation that
addresses the condition of the
inaccessible areas for similar conditions,
that is, the applicant should evaluate
the acceptability of inaccessible areas
when conditions exist in the adjacent
accessible areas that could indicate the
presence of or could result in
degradation to such inaccessible areas.
(4) To assure that there are no
circumstances that would result in
degradation of the drywell, demonstrate
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Federal Register / Vol. 71, No. 226 / Friday, November 24, 2006 / Notices
cprice-sewell on PROD1PC66 with NOTICES
that moisture levels associated with
accelerated corrosion rates do not exist
in the exterior portion of the drywell
shell, for example: (1) The sand pocket
area drains and/or the refueling seal
drains are monitored periodically; (2)
the top of the sand pocket area is sealed
to exclude water accumulation in the
sand pocket area; and/or alarms are
used to monitor regions for moisture/
leakage.
(5) If moisture has been detected or
suspected 1 in the inaccessible area on
the exterior of the drywell shell or the
source of moisture cannot be
determined subsequent to root cause
analyses:
(a) Include in the scope of license
renewal any components that are
identified as a source of moisture, if
applicable, such as the refueling seal or
cracks in the stainless steel liners of the
refueling cavity pool walls, and perform
an aging management review.
(b) Identify surface areas requiring
examination by implementing
augmented inspections for the period of
extended operation in accordance with
the American Society of Mechanical
Engineers (ASME) Section XI IWE–1240
as identified in Table IWE–2500–1,
Examination Category E–C.
(c) Use examination methods, that are
in accordance with ASME Section XI
IWE–2500, which specifies:
(i) surface areas accessible from both
sides shall be visually examined using
a VT–1 visual examination method,
(ii) surface areas accessible from one
side only shall be examined for wall
thinning using an ultrasonic thickness
measurement method,
(iii) when ultrasonic thickness
measurements are performed, one foot
square grids shall be used, unless
justified otherwise, and
(iv) ultrasonic measurements shall be
used to determine the minimum wall
thickness within each grid. The location
of the minimum wall thickness shall be
marked such that periodic
reexamination of that location can be
performed.
(d) Demonstrate through use of
augmented inspections performed in
accordance with ASME Section XI IWE
that corrosion is not occurring, or that
corrosion is progressing so slowly that
the age-related degradation will not
jeopardize the intended function of the
drywell shell through the period of
extended operation.
1 The term ‘‘suspected’’ refers to surface areas
likely to experience accelerated degradation and
aging as described in IWE–1241(a) of Section XI of
the ASME Code. Specifically, typical locations are
those areas exposed to standing water, repeated
wetting and drying, persistent leakage, and those
with geometries that permit water accumulation,
condensation, and microbiological attack.
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13:24 Nov 22, 2006
Jkt 211001
(6) If the intended function of the
drywell shell cannot be demonstrated
for the period of extended operation
(i.e., wall thickness is less than the
minimum required thickness), identify
actions that will be taken as part of the
aging management program to ensure
that the integrity of the drywell shell
will be maintained through the period
of extended operation.
[FR Doc. E6–19838 Filed 11–22–06; 8:45 am]
BILLING CODE 7590–01–P
NUCLEAR REGULATORY
COMMISSION
[EA–06–244]
In the Matter of Dairyland Power
Cooperative and All Other Persons
Who Seek or Obtain Access to
Safeguards Information Described
Herein; Order Imposing Fingerprinting
and Criminal History Records Check
Requirements for Access to
Safeguards Information (Effective
Immediately)
I
The Licensee, Dairyland Power
Cooperative, holds a license issued in
accordance with the Atomic Energy Act
(AEA) of 1954, as amended, by the U.S.
Nuclear Regulatory Commission (NRC
or Commission), authorizing it to engage
in an activity subject to regulation by
the Commission. On August 8, 2005, the
Energy Policy Act of 2005 (EPAct) was
enacted. Section 652 of the EPAct
amended Section 149 of the AEA to
require fingerprinting and a Federal
Bureau of Investigation (FBI)
identification and criminal history
records check of any person who is to
be permitted to have access to
Safeguards Information (SGI) 1. The
NRC’s implementation of this
requirement cannot await the
completion of the SGI rulemaking,
which is underway, because the EPAct
fingerprinting and criminal history
records check requirements for access to
SGI were immediately effective upon
enactment of the EPAct. Although the
EPAct permits the Commission by rule
to except certain categories of
individuals from the fingerprinting
requirement, which the Commission has
done (see 10 CFR 73.59, 71 FR 33989
(June 13, 2006)), it is unlikely that
licensee employees or others are
excepted from the fingerprinting
requirement by the ‘‘fingerprinting
relief’’ rule. Individuals relieved from
1 Safeguards Information is a form of sensitive,
unclassified, security-related information that the
Commission has the authority to designate and
protect under section 147 of the AEA.
PO 00000
Frm 00080
Fmt 4703
Sfmt 4703
67925
fingerprinting and criminal history
records checks under the relief rule
include Federal, State, and local
officials and law enforcement
personnel; Agreement State inspectors
who conduct security inspections on
behalf of the NRC; members of Congress
and certain employees of members of
Congress or Congressional Committees,
and representatives of the International
Atomic Energy Agency (IAEA) or certain
foreign government organizations. In
addition, individuals who have a
favorably-decided U.S. Government
criminal history records check within
the last five (5) years, or individuals
who have active federal security
clearances (provided in either case that
they make available the appropriate
documentation), have satisfied the
EPAct fingerprinting requirement and
need not be fingerprinted again.
Therefore, in accordance with Section
149 of the AEA, as amended by the
EPAct, the Commission is imposing
additional requirements for access to
SGI, as set forth by this Order, so that
affected licensees can obtain and grant
access to SGI. This Order also imposes
requirements for access to SGI by any
person, from any person 2, whether or
not a Licensee, Applicant, or Certificate
Holder of the Commission or Agreement
States.
II
The Commission has broad statutory
authority to protect and prohibit the
unauthorized disclosure of SGI. Section
147 of the AEA grants the Commission
explicit authority to issue such Orders
as necessary to prohibit the
unauthorized disclosure of SGI.
Furthermore, Section 652 of the EPAct
amended Section 149 of the AEA to
require fingerprinting and an FBI
identification and criminal history
records check of each individual who
seeks access to SGI. In addition, no
person may have access to SGI unless
the person has an established need-toknow the information and satisfies the
trustworthy and reliability requirements
described in Attachment 2 to Order EA–
06–243.
In order to provide assurance that the
Licensee is implementing appropriate
2 Person means (1) any individual, corporation,
partnership, firm, association, trust, estate, public
or private institution, group, government agency
other than the Commission or the Department of
Energy, except that the Department of Energy shall
be considered a person with respect to those
facilities of the Department of Energy specified in
section 202 of the Energy Reorganization Act of
1974 (88 Stat. 1244), any State or any political
subdivision of, or any political entity within a State,
any foreign government or nation or any political
subdivision of any such government or nation, or
other entity; and (2) any legal successor,
representative, agent, or agency of the foregoing.
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]]>Agencies
[Federal Register Volume 71, Number 226 (Friday, November 24, 2006)]
[Notices]
[Pages 67923-67925]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E6-19838]
-----------------------------------------------------------------------
NUCLEAR REGULATORY COMMISSION
Notice of Availability of the Final License Renewal Interim Staff
Guidance--LR-ISG-2006-01: Plant-Specific Aging Management Program for
Inaccessible Areas of Boiling Water Reactor (BWR) Mark I Steel
Containment Drywell Shell
AGENCY: Nuclear Regulatory Commission.
ACTION: Notice of availability.
-----------------------------------------------------------------------
SUMMARY: The NRC is issuing its Final License Renewal Interim Staff
Guidance LR-ISG-2006-01. This LR-ISG provides interim guidance to
applicants for license renewal for a plant with a BWR Mark I steel
containment to provide a plant-specific aging management program that
addresses the potential loss of material due to corrosion in the
inaccessible areas of their Mark I steel containment drywell shell for
the period of extended operation.
The NRC staff issues LR-ISGs to facilitate timely implementation of
the license renewal rule and to review activities associated with a
license renewal application. The NRC staff will also incorporate the
approved LR-ISG into the next revision of the license renewal guidance
documents.
ADDRESSES: The NRC maintains an Agencywide Documents Access and
Management System (ADAMS), which provides text and image files of NRC's
public documents. These documents may be accessed through the NRC's
Public Electronic Reading Room on the Internet at https://www.nrc.gov/
reading-rm/adams.html. Persons who do not have access to ADAMS or who
encounter problems in accessing the documents located in ADAMS should
contact the NRC Public Document Room (PDR) reference staff at 1-800-
397-4209, 301-415-4737, or by e-mail at pdr@nrc.gov.
FOR FURTHER INFORMATION CONTACT: Ms. Linh Tran, License Renewal Project
Manager, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory
Commission, Washington, DC, 20555-0001, telephone 301-415-4103 or by e-
mail at lnt@nrc.gov.
SUPPLEMENTARY INFORMATION: Attachment 1 to this Federal Register
notice, entitled Staff Position and Rationale for the Final License
Renewal Interim Staff Guidance--LR-ISG-2006-01: Plant-specific Aging
Management Program for Inaccessible Areas of Boiling Water Reactor Mark
I Steel Containment Drywell Shell contains the NRC staff's rationale
for publishing the Final LR-ISG-2006-01. Attachment 2, entitled Final
License Renewal Interim Staff Guidance--LR-ISG-2006-01: Plant-specific
Aging Management Program for Inaccessible Areas of BWR Mark I Steel
Containment Drywell Shell, contains the guidance for developing the
plant-specific aging management program. The NRC staff approves this
LR-ISG for NRC and industry use. The NRC staff will also incorporate
the approved LR-ISG into the next revision of the license renewal
guidance documents.
For the Nuclear Regulatory Commission.
Dated at Rockville, Maryland, this 16th day of November 2006.
Frank P. Gillespie,
Director, Division of License Renewal, Office of Nuclear Reactor
Regulation.
Attachment 1--Staff Position and Rationale for the Final License
Renewal Interim Staff Guidance--LR-ISG-2006-01: Plant-Specific Aging
Management Program for Inaccessible Areas of BWR Mark I Steel
Containment Drywell Shell
Staff Position
The NRC staff determined that a plant-specific aging management
program (AMP) is needed to address the potential loss of material due
to corrosion in the inaccessible areas of the Mark I steel containment
drywell shell for the period of extended operation.
Rationale
The current license renewal guidance documents (LRGDs) do not
provide sufficient guidance to address
[[Page 67924]]
inaccessible areas of the Mark I steel containment drywell shell.
Specifically, the inaccessible areas where the drywell shell is
surrounded by a concrete structure with a narrow distance between the
steel shell and the surrounding concrete inhibit visual inspection.
Past operating experience in Mark I steel containments indicates that
when water is discovered in the bottom outside areas of the drywell
(for example in the sand-bed area), the most likely cause would be the
water seeping through the space between the drywell shell and the
shield concrete.
In addition, numerous requests for additional information (RAIs)
were necessary on previous and current license renewal applications
(LRAs) to obtain the information needed by the staff to perform its
review. The purpose of this LR-ISG is to provide guidance on the
information that should be provided in the LRA to reduce the number of
RAIs issued to the applicants. Specifically, the staff has determined
that a plant-specific aging management program (AMP) is needed to
address the potential loss of material due to corrosion in the
inaccessible areas of the Mark I steel containment drywell shell for
the period of extended operation.
The drywell shell is a passive, long-lived structure subject to
aging degradation. Pursuant to 10 CFR 54.21, the applicant must
demonstrate that the effects of aging will be adequately managed so
that the intended function will be consistent with the current
licensing basis (CLB) for the period of extended operation.
Attachment 2--Final License Renewal Interim Staff Guidance--LR-ISG-
2006-01: Plant-Specific Aging Management Program for Inaccessible Areas
of Boiling Water Reactor Mark I Steel Containment Drywell Shell
Introduction
Line Item II.B1.1-2 of NUREG-1801, Volume 2, Revision 1, includes a
provision for aging management of the Mark I steel containment drywell
shells. However, the line item requires additional detail to address
the inaccessible areas of the Mark I steel containment drywell shells.
Specifically, the line item does not provide guidance when the distance
between the steel drywell shell and the surrounding concrete structure
is too small for the successful performance of visual examination.
All Mark I containment drywells are free-standing steel
construction, except for Brunswick, Units 1 and 2. The Brunswick Mark I
containment consists of a reinforced concrete drywell and a reinforced
concrete torus with a steel liner. A drywell shell is a free-standing
steel structure with no concrete backing, whereas the steel liner of a
drywell is a leak-tight membrane in direct contact with the concrete
containment.
Historical Background
Information Notice (IN) 86-99, ``Degradation of Steel
Containments,'' dated December 8, 1986, described an event related to
the degradation of the drywell shell at Oyster Creek Nuclear Generating
Station. IN 86-99, Supplement 1, dated February 14, 1991, explained
that the most likely cause of corrosion of the drywell shell in sand-
pocket areas (near the bottom of the drywell) and in the spherical
portion of the drywell at higher elevations, was the water in the gap
between the drywell and the concrete shield. The source of water was
noted as leakage through the seal between the drywell and the refueling
cavity. The IN supplement noted that the stainless steel liners in the
refueling cavity and equipment pool developed cracks along the
perimeter of the liner plates where they were welded to embedded
channels. The IN supplement also noted that ultrasonic testing (UT)
discovered minor corrosion in the cylindrical portion of the drywell,
and significant corrosion in the sand-bed region of the shell.
Discussion
Generic Letter (GL) 87-05, ``Request for Additional Information-
Assessment of Licensee Measures to Mitigate And/Or Identify Potential
Degradation of Mark I Drywells,'' requested additional information
regarding licensee actions to mitigate and/or identify potential
degradation of boiling water reactor Mark I drywells. As a result, a
number of licensees performed UT of their carbon steel drywell shells
adjacent to the sand-bed region. In addition, many licensees
established leakage monitoring programs for drain lines to identify
leakage that may have resulted from refueling or spillage of water into
the gap between the drywell and the surrounding concrete. UT performed
as a result of GL 87-05 provided a set of data points to determine the
drywell shell thickness that could be compared to the nominal
fabrication thickness and the minimum thickness required to withstand
the postulated loads. These UT measurements taken during the 1987-1988
time frame fall approximately near the mid-point of the current 40-year
operating license period for most plants with Mark I steel
containments.
The drywell shell is a passive, long-lived structure within the
scope of license renewal that is subject to aging degradation. Pursuant
to 10 CFR 54.21, the applicant must demonstrate that the effects of
aging will be adequately managed so that the intended function will be
maintained consistent with the current licensing basis for the period
of extended operation. On the basis of license renewal application
reviews and industry operating experience, the NRC staff determined
that a plant-specific aging management program (AMP) is needed to
address the potential loss of material due to corrosion in the
inaccessible areas of the Mark I steel containment drywell shell for
the period of extended operation.
Recommended Action
In addressing Line Item II.B1.1-2 of NUREG-1801, Volume 2, Revision
1, applicants for license renewal for plants with a Mark I steel
containment should perform an aging management review of the
inaccessible areas of its containment drywell shell and provide a
plant-specific aging management program that addresses the potential
loss of material due to corrosion for the period of extended operation.
In conducting the aging management review and developing the plant-
specific aging management program for the drywell shell, the applicant
should consider the following recommended actions based upon plant
design and operating experience:
(1) Develop a corrosion rate that can be reasonably inferred from
past UT examinations or establish a corrosion rate using representative
samples in similar operating conditions, materials, and environments.
If degradation has occurred, provide a technical basis using the
developed or established corrosion rate to demonstrate that the drywell
shell will have sufficient wall thickness to perform its intended
function through the period of extended operation.
(2) Demonstrate that UT measurements performed in response to GL
87-05 did not show degradation inconsistent with the developed or
established corrosion rate.
(3) Where degradation has been identified in the accessible areas
of the drywell, provide an evaluation that addresses the condition of
the inaccessible areas for similar conditions, that is, the applicant
should evaluate the acceptability of inaccessible areas when conditions
exist in the adjacent accessible areas that could indicate the presence
of or could result in degradation to such inaccessible areas.
(4) To assure that there are no circumstances that would result in
degradation of the drywell, demonstrate
[[Page 67925]]
that moisture levels associated with accelerated corrosion rates do not
exist in the exterior portion of the drywell shell, for example: (1)
The sand pocket area drains and/or the refueling seal drains are
monitored periodically; (2) the top of the sand pocket area is sealed
to exclude water accumulation in the sand pocket area; and/or alarms
are used to monitor regions for moisture/leakage.
(5) If moisture has been detected or suspected \1\ in the
inaccessible area on the exterior of the drywell shell or the source of
moisture cannot be determined subsequent to root cause analyses:
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\1\ The term ``suspected'' refers to surface areas likely to
experience accelerated degradation and aging as described in IWE-
1241(a) of Section XI of the ASME Code. Specifically, typical
locations are those areas exposed to standing water, repeated
wetting and drying, persistent leakage, and those with geometries
that permit water accumulation, condensation, and microbiological
attack.
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(a) Include in the scope of license renewal any components that are
identified as a source of moisture, if applicable, such as the
refueling seal or cracks in the stainless steel liners of the refueling
cavity pool walls, and perform an aging management review.
(b) Identify surface areas requiring examination by implementing
augmented inspections for the period of extended operation in
accordance with the American Society of Mechanical Engineers (ASME)
Section XI IWE-1240 as identified in Table IWE-2500-1, Examination
Category E-C.
(c) Use examination methods, that are in accordance with ASME
Section XI IWE-2500, which specifies:
(i) surface areas accessible from both sides shall be visually
examined using a VT-1 visual examination method,
(ii) surface areas accessible from one side only shall be examined
for wall thinning using an ultrasonic thickness measurement method,
(iii) when ultrasonic thickness measurements are performed, one
foot square grids shall be used, unless justified otherwise, and
(iv) ultrasonic measurements shall be used to determine the minimum
wall thickness within each grid. The location of the minimum wall
thickness shall be marked such that periodic reexamination of that
location can be performed.
(d) Demonstrate through use of augmented inspections performed in
accordance with ASME Section XI IWE that corrosion is not occurring, or
that corrosion is progressing so slowly that the age-related
degradation will not jeopardize the intended function of the drywell
shell through the period of extended operation.
(6) If the intended function of the drywell shell cannot be
demonstrated for the period of extended operation (i.e., wall thickness
is less than the minimum required thickness), identify actions that
will be taken as part of the aging management program to ensure that
the integrity of the drywell shell will be maintained through the
period of extended operation.
[FR Doc. E6-19838 Filed 11-22-06; 8:45 am]
BILLING CODE 7590-01-P
