Carolina Power and Light Company, H.B. Robinson Steam Electric Plant, Unit No. 2; Exemption, 44942-44946 [E5-4147]
Download as PDF
<![CDATA[
44942
Federal Register / Vol. 70, No. 149 / Thursday, August 4, 2005 / Notices
In accordance with 10 CFR 2.390 of
NRC’s ‘‘Rules of Practice,’’ final NRC
records and documents regarding this
proposed action are publically available
in the records component of NRC’s
Agencywide Documents Access and
Management System (ADAMS). The
request for exemption dated June 13,
2005, and July 20, 2005, was docketed
under 10 CFR Part 72, Docket No. 72–
60. These documents may be inspected
at NRC’s Public Electronic Reading
Room at https://www.nrc.gov/readingrm/adams.html. These documents may
also be viewed electronically on the
public computers located at the NRC’s
Public Document Room (PDR), O1F21,
One White Flint North, 11555 Rockville
Pike, Rockville, MD 20852. The PDR
reproduction contractor will copy
documents for a fee. Persons who do not
have access to ADAMS or who
encounter problems in accessing the
documents located in ADAMS, should
contact the NRC PDR Reference staff by
telephone at 1–800–397–4209 or (301)
415–4737, or by e-mail to pdr@nrc.gov.
Dated at Rockville, Maryland, this 29th day
of July, 2005.
For the Nuclear Regulatory Commission.
L. Raynard Wharton,
Project Manager, Spent Fuel Project Office,
Office of Nuclear Material Safety and
Safeguards.
[FR Doc. E5–4145 Filed 8–3–05; 8:45 am]
BILLING CODE 7590–01–P
NUCLEAR REGULATORY
COMMISSION
[Docket No. 50–261]
Carolina Power and Light Company,
H.B. Robinson Steam Electric Plant,
Unit No. 2; Exemption
1.0 Background
Carolina Power & Light Company
(CP&L or the licensee) is the holder of
Renewed Facility Operating License No.
DPR–23, which authorizes operation of
the H. B. Robinson Steam Electric Plant,
Unit No. 2 (HBRSEP2). The license
provides, among other things, that the
facility is subject to all rules,
regulations, and orders of the Nuclear
Regulatory Commission (NRC, the
Commission) now or hereafter in effect.
The facility consists of a pressurizedwater reactor located in Darlington
County, South Carolina.
2.0 Request/Action
By letter dated February 22, 2005, as
supplemented by letters dated May 10,
July 6, and July 14, 2005, the licensee
submitted a request for an exemption
from the requirements of Title 10 of the
VerDate jul<14>2003
16:23 Aug 03, 2005
Jkt 205001
Code of Federal Regulations (10 CFR)
Section 50.68(b)(1) during the spent fuel
pool (SFP) activities related to the
underwater handling, loading, and
unloading of the dry shielded canister
(DSC) NUHOMS –24PTH, as described
in proposed Amendment No. 8 to
Certificate of Compliance No. 1004
listed in 10 CFR 72.214 at HBRSEP2.
Section 50.68(b)(1) of 10 CFR sets
forth the following requirement that
must be met, in lieu of a monitoring
system capable of detecting criticality
events.
Plant procedures shall prohibit the
handling and storage at any one time of more
fuel assemblies than have been determined to
be safely subcritical under the most adverse
moderation conditions feasible by unborated
water.
The licensee is unable to satisfy the
above requirement for handling of the
Transnuclear (TN) NUHOMS–24PTH
DSC authorized by 10 CFR Part 72 at
HBRSEP2. Section 50.12(a) allows
licensees to apply for an exemption
from the requirements of 10 CFR Part 50
if the application of the regulation is not
necessary to achieve the underlying
purpose of the rule and special
conditions are met. The licensee stated
in the application that compliance with
10 CFR 50.68(b)(1) is not necessary for
handling the TN NUHOMS–24PTH
DSC system to achieve the underlying
purpose of the rule.
3.0 Discussion
Pursuant to 10 CFR 50.12, the
Commission may, upon application by
any interested person or upon its own
initiative, grant exemptions from the
requirements of 10 CFR Part 50 when (1)
the exemptions are authorized by law,
will not present an undue risk to public
health or safety, and are consistent with
the common defense and security; and
(2) when special circumstances are
present. Therefore, in determining the
acceptability of the licensee’s exemption
request, the staff has performed the
following regulatory, technical, and
legal evaluations to satisfy the
requirements of 10 CFR 50.12 for
granting the exemption.
3.1 Regulatory Evaluation
The HBRSEP2 Technical
Specifications (TS) currently permit the
licensee to store spent fuel assemblies in
high-density storage racks in its SFP. In
accordance with the provisions of 10
CFR 50.68(b)(4), the licensee takes
credit for soluble boron for criticality
control and ensures that the effective
multiplication factor (keff) of the SFP
does not exceed 0.95, if flooded with
borated water. Section 50.68(b)(4) of 10
CFR also requires that if credit is taken
PO 00000
Frm 00060
Fmt 4703
Sfmt 4703
for soluble boron, the keff must remain
below 1.0 (subcritical) if flooded with
unborated water. However, the licensee
is unable to satisfy the requirement to
maintain the keff below 1.0 (subcritical)
with unborated water, which is also the
requirement of 10 CFR 50.68(b)(1),
during cask handling operations in the
SFP. Therefore, the licensee’s request
for exemption from 10 CFR 50.68(b)(1)
proposes to permit the licensee to
perform spent fuel loading, unloading,
and handling operations related to dry
cask storage without being subcritical
under the most adverse moderation
conditions feasible by unborated water.
Title 10 of the Code of Federal
Regulations, Part 50, Appendix A,
‘‘General Design Criteria (GDC) for
Nuclear Power Plants,’’ provides a list of
the minimum design requirements for
nuclear power plants. According to GDC
62, ‘‘Prevention of criticality in fuel
storage and handling,’’ the licensee
must limit the potential for criticality in
the fuel handling and storage system by
physical systems or processes.
HBRSEP2 was licensed prior to the
issuance of the GDC listed in 10 CFR 50,
Appendix A; therefore, GDC 62 is not
directly applicable. However, HBRSEP2
has committed to a plant-specific
version of the 1967 draft GDC as
discussed in its Updated Final Safety
Analysis Report (FSAR), Section 3.1.2.
The comparable GDC is Criterion 66,
‘‘Prevention of Fuel Storage Criticality,’’
that states: ‘‘Criticality in the new and
spent fuel storage pits shall be
prevented by physical systems or
processes. Such means as geometrically
safe configurations shall be emphasized
over procedural controls.’’
Section 50.68 of 10 CFR Part 50,
‘‘Criticality accident requirements,’’
provides the NRC requirements for
maintaining subcritical conditions in
SFPs. Section 50.68 provides criticality
control requirements that, if satisfied,
ensure that an inadvertent criticality in
the SFP is an extremely unlikely event.
These requirements ensure that the
licensee has appropriately conservative
criticality margins during handling and
storage of spent fuel. Section 50.68(b)(1)
states, ‘‘Plant procedures shall prohibit
the handling and storage at any one time
of more fuel assemblies than have been
determined to be safely subcritical
under the most adverse moderation
conditions feasible by unborated water.’’
Specifically, 10 CFR 50.68(b)(1) ensures
that the licensee will maintain the pool
in a subcritical condition during
handling and storage operations without
crediting the soluble boron in the SFP
water.
The licensee is authorized under
general license to construct and operate
E:\FR\FM\04AUN1.SGM
04AUN1
Federal Register / Vol. 70, No. 149 / Thursday, August 4, 2005 / Notices
an Independent Spent Fuel Storage
Installation (ISFSI) at HBRSEP2. The
ISFSI permits the licensee to store spent
fuel assemblies in large concrete dry
storage casks. As part of its ISFSI
loading campaigns, the licensee
transfers spent fuel assemblies to a DSC
in the cask pit area of the SFP. The
licensee performed criticality analyses
of the DSC fully loaded with fuel having
the highest permissible reactivity and
determined that a soluble boron credit
was necessary to ensure that the DSC
would remain subcritical in the SFP.
Since the licensee is unable to satisfy
the requirement of 10 CFR 50.68(b)(1) to
ensure subcritical conditions during
handling and storage of spent fuel
assemblies in the pool with unborated
water, the licensee identified the need
for an exemption from the 10 CFR
50.68(b)(1) requirement to support DSC
loading, unloading, and handling
operations without being subcritical
under the most adverse moderation
conditions feasible by unborated water.
The NRC staff evaluated the
possibility of an inadvertent criticality
of the spent nuclear fuel at HBRSEP2
during DSC loading, unloading, and
handling. The NRC staff has established
a set of acceptance criteria that, if met,
satisfy the underlying intent of 10 CFR
50.68(b)(1). In lieu of complying with 10
CFR 50.68(b)(1), the staff determined
that an inadvertent criticality accident is
unlikely to occur if the licensee meets
the following five criteria:
1. The cask criticality analyses are
based on the following conservative
assumptions:
a. All fuel assemblies in the cask are
unirradiated and at the highest
permissible enrichment,
b. Only 75 percent of the Boron-10 in
the fixed poison panel inserts is
credited,
c. No credit is taken for fuel-related
burnable absorbers, and
d. The cask is assumed to be flooded
with moderator at the temperature and
density corresponding to optimum
moderation.
2. The licensee’s ISFSI TS require the
soluble boron concentration to be equal
to or greater than the level assumed in
the criticality analysis, and surveillance
requirements necessitate the periodic
verification of the concentration both
prior to and during loading and
unloading operations.
3. Radiation monitors, as required by
GDC 63, ‘‘Monitoring Fuel and Waste
Storage,’’ are provided in fuel storage
and handling areas to detect excessive
radiation levels and to initiate
appropriate safety actions.
4. The quantity of other forms of
special nuclear material, such as
VerDate jul<14>2003
16:23 Aug 03, 2005
Jkt 205001
sources, detectors, etc., to be stored in
the cask will not increase the effective
multiplication factor above the limit
calculated in the criticality analysis.
5. Sufficient time exists for plant
personnel to identify and terminate a
boron dilution event prior to achieving
a critical boron concentration in the
DSC. To demonstrate that it can safely
identify and terminate a boron dilution
event, the licensee must provide the
following:
a. A plant-specific criticality analysis
to identify the critical boron
concentration in the cask based on the
highest reactivity loading pattern.
b. A plant-specific boron dilution
analysis to identify all potential dilution
pathways, their flowrates, and the time
necessary to reach a critical boron
concentration.
c. A description of all alarms and
indications available to promptly alert
operators of a boron dilution event.
d. A description of plant controls that
will be implemented to minimize the
potential for a boron dilution event.
e. A summary of operator training and
procedures that will be used to ensure
that operators can quickly identify and
terminate a boron dilution event.
On March 23, 2005, the NRC issued
Regulatory Issue Summary (RIS) 2005–
05, ‘‘Regulatory Issues Regarding
Criticality Analyses for Spent Fuel Pools
and Independent Spent Fuel Storage
Installations.’’ In RIS 2005–05, the NRC
identified an acceptable methodology
for demonstrating compliance with the
10 CFR 50.68(b)(1) requirements during
cask loading, unloading, and handling
operations in pressurized-water reactor
SFPs. The NRC staff has determined that
implementation of this methodology by
licensees will eliminate the need to
grant future exemptions for cask storage
and handling evolutions. However,
since the licensee submitted its
exemption request prior to issuance of
the RIS and identification of an NRCacceptable methodology for compliance
with the regulations, the NRC staff has
determined that it is still appropriate to
consider the exemption request.
3.2 Technical Evaluation
In determining the acceptability of the
licensee’s exemption request, the staff
reviewed three aspects of the licensee’s
analyses: (1) criticality analyses
submitted to support the ISFSI license
application and its exemption request,
(2) boron dilution analysis, and (3) legal
basis for approving the exemption. For
each of the aspects, the staff evaluated
whether the licensee’s analyses and
methodologies provide reasonable
assurance that adequate safety margins
are developed and can be maintained in
PO 00000
Frm 00061
Fmt 4703
Sfmt 4703
44943
the HBRSEP2 SFP during loading of
spent fuel into canisters for dry cask
storage.
3.2.1 Criticality Analyses
For evaluation of the acceptability of
the licensee’s exemption request, the
NRC staff reviewed the criticality
analyses provided by the licensee in
support of its ISFSI license application.
First, the NRC staff reviewed the
methodology and assumptions used by
the licensee in its criticality analysis to
determine if Criterion 1 was satisfied.
The licensee stated that it took no credit
in the criticality analyses for burnup or
fuel-related burnable neutron absorbers.
The licensee also stated that all
assemblies were analyzed at the highest
permissible enrichment. Additionally,
the licensee stated that all criticality
analyses for a flooded DSC were
performed at temperatures and densities
of water corresponding to optimum
moderation conditions. Finally, the
licensee stated that it credited 90
percent of the Boron-10 content for the
fixed neutron absorber in the DSC.
NUREG–1536, ‘‘Standard Review Plan
for Dry Cask Storage System,’’ states that
‘‘[f]or a greater credit allowance [i.e.,
greater than 75 percent for fixed neutron
absorbers] special, comprehensive
fabrication tests capable of verifying the
presence and uniformity of the neutron
absorber are needed.’’ As part of an
amendment to the Part 72 license for the
Transnuclear NUHOMS–24PTH
design, the NRC staff reviewed and
accepted the results of additional data
supplied by the manufacturer that
demonstrated that a 90-percent credit
for the fixed neutron absorbers was
acceptable. These tests and
corresponding results are detailed in
Appendix P of the Standardized
NUHOMS FSAR. Therefore, for the
purposes of this exemption, the staff
finds a 90-percent credit acceptable on
the basis that it has previously been
reviewed and approved by the NRC.
Subsequently, based on its review of the
criticality analyses and the information
submitted in its exemption request, the
NRC staff finds that the licensee has
satisfied Criterion 1.
Second, the NRC staff reviewed the
proposed HBRSEP2 ISFSI TS. The
licensee’s criticality analyses credit
soluble boron for reactivity control
during DSC loading, unloading, and
handling operations. Since the boron
concentration is a key safety component
necessary for ensuring subcritical
conditions in the pool, the licensee
must have a conservative ISFSI TS
capable of ensuring that sufficient
soluble boron is present to perform its
safety function. The ISFSI TS applicable
E:\FR\FM\04AUN1.SGM
04AUN1
44944
Federal Register / Vol. 70, No. 149 / Thursday, August 4, 2005 / Notices
to the NUHOMS–24PTH DSC, and
attached to the Certificate of
Compliance No. 1004, contain the
requirements for the minimum soluble
boron concentration as a function of fuel
assembly class, DSC basket type, and
corresponding assembly average initial
enrichment values. In all cases, the
boron concentration required by the
ISFSI TS ensures that the keff will be
below 0.95 for the analyzed loading
configuration. Additionally, the
licensee’s ISFSI TS contain surveillance
requirements that assure it will verify
the boron concentration is above the
required level both prior to and during
DSC loading, unloading, and handling
operations. Based on its review of the
HBRSEP2 ISFSI TS, the NRC staff finds
that the licensee has satisfied Criterion
2.
Third, the NRC staff reviewed the
HBRSEP2 Updated FSAR and the
information provided by the licensee in
its exemption request to ensure that it
complies with GDC 63. GDC 63 requires
that licensees have radiation monitors
in fuel storage and associated handling
areas to detect conditions that may
result in a loss of residual heat removal
capability and excessive radiation levels
and initiate appropriate safety actions.
As previously described, HBRSEP2 was
licensed prior to the issuance of the
GDC listed in 10 CFR 50, Appendix A;
therefore, GDC 63 is not directly
applicable. However, HBRSEP2 has
committed to a plant-specific version of
the 1967 draft GDC as discussed in its
Updated FSAR, Section 3.1.2. The
comparable GDC is Criterion 18,
‘‘Monitoring Fuel and Waste Storage,’’
that states the following: ‘‘Monitoring
and alarm instrumentation shall be
provided for fuel and waste storage and
associated handling areas for conditions
that might result in loss of capability to
remove decay heat and detect excessive
radiation levels.’’ The NRC staff
reviewed the HBRSEP2 Updated FSAR,
plant-specific GDC, and exemption
request to determine whether the
licensee had provided sufficient
information to demonstrate compliance
with the intent of GDC 63. In its
exemption request, the licensee stated
that an area radiation monitor is located
in the area of the SFP. Additionally,
station procedures specify appropriate
safety actions upon a high radiation
alarm, including evacuation of local
personnel, determination of cause, and
determination of potential low water
level in the SFP. In addition, personnel
working in the area of the SFP wear
individual, gamma-sensitive, electronic
alarming dosimeters that provide an
audible alarm should the dose or dose
VerDate jul<14>2003
16:23 Aug 03, 2005
Jkt 205001
rate exceed pre-established setpoints.
Based on its review of the exemption
request, the HBRSEP2 Updated FSAR,
and the licensee’s plant-specific GDC,
the NRC staff finds that the licensee has
satisfied Criterion 3.
Finally, as part of the criticality
analysis review, the NRC staff evaluated
the storage of non-fuel-related material
in a DSC. The NRC staff evaluated the
potential to increase the reactivity of a
DSC by loading it with materials other
than spent nuclear fuel and fuel debris.
The approved contents for storage in the
NUHOMS–24PTH cask design are
listed in the HBRSEP2 ISFSI TS
Limiting Condition for Operation (LCO)
1.2.1 ‘‘Fuel Specifications.’’ This ISFSI
TS LCO restricts the contents of the DSC
to only fuels and non-fissile materials
irradiated at HBRSEP2. As such,
HBRSEP2 is prohibited from loading
other forms of special nuclear material,
such as sources, detectors, etc., in the
DSC. Therefore, the NRC staff
determined that the loading limitations
described in the HBRSEP2 ISFSI TS will
ensure that any authorized components
loaded in the DSCs will not result in a
reactivity increase. Based on its review
of the loading restrictions, the NRC staff
finds that the licensee has satisfied
Criterion 4.3.2.2.
Boron Dilution Analysis. Since the
licensee’s ISFSI application relies on
soluble boron to maintain subcritical
conditions within the DSCs during
loading, unloading, and handling
operations, the NRC staff reviewed the
licensee’s boron dilution analysis to
determine whether appropriate controls,
alarms, and procedures were available
to identify and terminate a boron
dilution accident prior to reaching a
critical boron concentration.
By letter dated October 25, 1996, the
NRC staff issued a safety evaluation on
licensing topical report WCAP–14416,
‘‘Westinghouse Spent Fuel Rack
Criticality Analysis Methodology.’’ This
safety evaluation specified that the
following issues be evaluated for
applications involving soluble boron
credit: the events that could cause boron
dilution, the time available to detect and
mitigate each dilution event, the
potential for incomplete boron mixing,
and the adequacy of the boron
concentration surveillance interval.
The criticality analyses performed for
the NUHOMS–24PTH DSC are
described in Section 6 of Appendix P of
the FSAR for the Standardized
NUHOMS Horizontal Modular Storage
System for Irradiated Nuclear Fuel. For
this boron dilution evaluation, the
licensee employed the same criticality
analysis methods, models, and
assumptions. These HBRSEP2 criticality
PO 00000
Frm 00062
Fmt 4703
Sfmt 4703
calculations are based on the KENO V.a
code. The calculations determined the
minimum soluble boron concentration
required to maintain subcriticality (keff
< 1.0) following a boron dilution event
in a NUHOMS–24PTH DSC loaded
with fuel assemblies that bound the
HBRSEP2 fuel designs (Westinghouse
15 x 15 fuel). Both intact and damaged
fuel over the range of soluble boron
concentrations permitted for various
enrichments and basket types were
evaluated. The results of these
calculations for the bounding case
indicate that subcriticality is maintained
with 73 percent or more of the
minimum boron concentration levels
required in the ISFSI TS for all basket
types as a function of initial enrichment.
Calculations were performed by the
licensee to determine the time required
to dilute the SFP such that the boron
concentration is reduced from the
NUHOMS TS (required boron
concentration for maintaining keff
< 0.95) to a just subcritical boron
concentration (keff < 1.0) for fuel loaded
into a NUHOMS–24PTH DSC.
The HBRSEP2 SFP is a large structure
filled with borated water that
completely covers the spent fuel
assemblies with more than 21 feet of
water above the top of the fuel racks and
the fuel cask. The cask lay down area is
not separated by any structure from the
remainder of the SFP. Thermal gradients
generated by stored fuel and operation
of the SFP cooling system will cause
significant mixing within the pool. The
licensee assumed that all unborated
water introduced from any uncontrolled
dilution source instantaneously mixes
with the water in the SFP (i.e., no
unborated water is lost prior to its
mixing with borated water). The
configuration of the pool and the mixing
of the coolant provide reasonable
assurance that this assumption is valid
for low to moderate dilution flow rates.
The volume of water in the SFP is
240,000 gallons. To reduce the boron
concentration by a factor of 0.73 from
the TS for keff ≤ 0.95 and approach a keff
of 1.0 requires the addition of 75,530
gallons of unborated water. Three
examples of potential dilution sources
were identified by the licensee: a 2-gpm
flowrate from small failures or
misaligned valves that could occur in
the normal soluble boron control system
or related systems, the failure of the 2inch demineralized water header, and
the maximum credible dilution event
involving the rupture of a fire protection
system header.
To demonstrate that sufficient time
exists for plant personnel to identify
and terminate a boron dilution event,
the licensee provided a description of
E:\FR\FM\04AUN1.SGM
04AUN1
Federal Register / Vol. 70, No. 149 / Thursday, August 4, 2005 / Notices
all alarms available to alert operators,
and plant procedures, administrative
controls, and training that will be
implemented in response to an alarm.
There is no automatic level control
system for the SFP; therefore, any large,
uncontrolled water addition would
cause the SFP to overflow. However, a
high level alarm in the control room
would alert personnel of a potential
boron dilution event when the water
level reaches the high level setpoint.
The highest uncontrolled dilution
flow rate was determined to be the fire
protection header on the SFP floor for
fire hose station 104. As stated in the
letter dated July 6, 2005, this fire
protection header will be isolated
during DSC loading and unloading to
preclude this as a source of
uncontrolled dilution to the SFP. The
licensee has revised DSC loading and
unloading procedures to include a
requirement to close the fire protection
system valve (FP–71) prior to placing
fuel in the DSC during loading and prior
to placing the loaded DSC back in the
SFP during unloading. This change has
resulted in the most limiting
uncontrolled dilution source being
identified as the assumed break of a 2inch demineralized water header, which
could cause a dilution flow of
approximately 103 gpm. No other single
source has been identified that would
exceed this dilution rate. Therefore, the
time to reach a critical boron
concentration, as provided by licensee,
is estimated to be 755 minutes.
In the case of the 103-gpm
demineralized water pipe rupture, there
would be no alarm from the
demineralized water system. However,
there would be available approximately
10 hours to isolate the leak once the SFP
high level alarm was received. This
analysis provides reasonable assurance
that dilution flows leading to pool
overflow would be detected and isolated
well before the critical boron
concentration could be reached from
credible dilution sources.
The licensee stated that plant
procedures do allow for continued
operation with the SFP high level alarm
illuminated. The licensee stated that
operating procedures had been revised
to specify that, if the SPF high level
alarm is illuminated and there is fuel in
the DSC in the SFP, then continuous
coverage to monitor the SFP water level
will be required. A local level indicator
is available in the SFP. The personnel
providing continuous coverage when
the SFP Hi Level Alarm is illuminated
or inoperable can use this indication to
detect possible dilution of the SFP. The
available time before criticality by
dilution is sufficient to allow
VerDate jul<14>2003
16:23 Aug 03, 2005
Jkt 205001
identification and termination of any
credible source of dilution.
When fuel is loaded in the DSC in the
SFP, boron analyses of the SFP water
are required at least once every 48 hours
per the TS. Small dilution flows may
not be readily identified by level
changes in the SFP due to operational
leakage through the pool liner and the
SFP cooling system. The licensee
determined that a dilution flow of 2
gpm would require approximately 26
days to dilute the boron concentration
of the SFP near to that calculated as the
critical boron concentration. Therefore,
the reduction in boron concentration
due to a dilution flowrate of 2 gpm
would be detected by the required boron
concentration surveillance well before a
significant dilution occurs.
To ensure that operators are capable
of identifying and terminating a boron
dilution event during DSC loading,
unloading, and handling operations,
operator training will be conducted.
This training will highlight the boron
concentration requirements for loading
the DSC, the potential for criticality
should boron concentration levels
decrease, and the need for timely
mitigating activities if a boron dilution
event occurs. Operators and other
personnel involved in the dry fuel
storage implementation will receive this
new training prior to loading of the first
DSC. Additionally, before each DSC
loading evolution, the crew involved in
performance of the work will receive a
pre-job briefing, where the need for
boron concentration control will be
discussed.
Based on the NRC staff’s review of the
licensee’s boron dilution analysis, the
NRC staff finds the licensee has
provided sufficient information to
demonstrate that an undetected and
uncorrected dilution from the TSrequired boron concentration to the
calculated critical boron concentration
is very unlikely. Based on its review of
the boron analysis and enhancements to
the operating procedures and operator
training program, the NRC staff finds the
licensee has satisfied Criterion 5.
Therefore, in conjunction with the
conservative assumptions used to
establish the TS-required boron
concentration and critical boron
concentration, the boron dilution
evaluation demonstrates that the
underlying intent of 10 CFR 50.68(b)(1)
is satisfied.
3.3
3.3.1
Legal Basis for the Exemption
Authorized by Law
This exemption results in changes to
the operation of the plant by allowing
the operation of the new dry fuel storage
PO 00000
Frm 00063
Fmt 4703
Sfmt 4703
44945
facility and loading of the NUHOMS–
24PTH DSC. As stated above, 10 CFR
50.12 allows the NRC to grant
exemptions from the requirements of 10
CFR Part 50. In addition, the granting of
the licensee’s exemption request will
not result in a violation of the Atomic
Energy Act of 1954, as amended, or the
intent of the Commission’s regulations.
Therefore, the exemption is authorized
by law.
3.3.2 No Undue Risk to Public Health
and Safety
The underlying purposes of 10 CFR
50.68(b)(1) is to ensure that adequate
controls are in place to ensure that the
handling and storage of fuel assemblies
is conducted in a manner such that the
fuel assemblies remain safely
subcritical. Based on the NRC staff’s
review of the licensee’s exemption
request, the licensee has demonstrated
that sufficient controls are in place to
provide reasonable assurance that there
is no undue risk to public health and
safety given conservative assumption in
the criticality analysis (criterion 1
above); surveillances periodically verify
the boron concentration before and
during loading and unloading (criterion
2 above); radiation monitoring
equipment is used to detect excessive
radiation and initiate appropriate
protective actions (criterion 3 above);
only fuel authorized by the ISFSI TS
will be loaded and stored in the ISFSI
(criterion 4 above); and boron dilution
events have been analyzed, and there
are sufficient monitoring capabilities
and time for the licensee to identify and
terminate a dilution event prior to
achieving a critical boron concentration
in the cask (criterion 5 above).
Therefore, the NRC staff concluded that
the underlying purpose of the rule has
been satisfied and that there is no undue
risk to public health and safety.
3.3.3 Consistent with Common
Defense and Security
This exemption results in changes to
the operation of the plant by allowing
the operation of the new dry fuel storage
facility and loading of the NUHOMS–
24PTH DSC. This change to the fuel
assembly storage and handling in the
plant does not affect the national
defense strategy because the national
defense is maintained by resources
(hardware or software or other) that are
outside the plant and that have no direct
relation to plant operation. In addition,
loading spent fuel into the NUHOMS–
24PTH DSC in the SFP does not affect
the ability of the licensee to defend the
plant against a terrorist attack.
Therefore, the common defense and
E:\FR\FM\04AUN1.SGM
04AUN1
44946
Federal Register / Vol. 70, No. 149 / Thursday, August 4, 2005 / Notices
security is not impacted by this
exemption request.
3.3.4 Special Circumstances
Pursuant to 10 CFR 50.12, ‘‘Specific
Exemption,’’ the NRC staff reviewed the
licensee’s exemption request to
determine if the legal basis for granting
an exemption had been satisfied. With
regards to the six special circumstances
listed in 10 CFR 50.12(a)(2), the NRC
staff finds that the licensee’s exemption
request satisfies 50.12(a)(2)(ii),
‘‘Application of the regulation in the
particular circumstances would not
serve the underlying purpose of the rule
or is not necessary to achieve the
underlying purpose of the rule.’’
Specifically, the NRC staff concludes
that since the licensee has satisfied the
five criteria in Section 3.1 of this
exemption, the application of the rule is
not necessary to achieve its underlying
purpose in this particular case.
3.4 Summary
Based upon the review of the
licensee’s exemption request to credit
soluble boron during DSC loading,
unloading, and handling in the
HBRSEP2 SFP, the NRC staff concludes
that pursuant to 10 CFR 50.12(a)(2) the
licensee’s exemption request is
acceptable. However, the NRC staff
places the following limitations/
conditions on the approval of this
exemption:
1. This exemption is limited to the
loading, unloading, and handling of the
DSC for only the TN NUHOMS–24PTH
at HBRSEP2.
2. This exemption is limited to the
loading, unloading, and handling in the
DSC at HBRSEP2 of Westinghouse 15 x
15 fuel assemblies that had maximum
initial, unirradiated U–235 enrichments
corresponding to the TS limitations in
LCO 1.2.1 for Amendment 8 to the
NUHOMS –24PTH cask design.
4.0 Conclusion
Accordingly, the Commission has
determined that, pursuant to 10 CFR
50.12(a), the exemption is authorized by
law, will not present an undue risk to
the public health and safety, and is
consistent with the common defense
and security. Also, special
circumstances are present. Therefore,
the Commission hereby grants CP&L an
exemption from the requirements of 10
CFR 50.68(b)(1) for the loading,
unloading, and handling of the
components of the Transnuclear
NUHOMS–24PTH dry cask storage
system at HBRSEP2. However, since the
licensee does not have an NRCapproved methodology for evaluating
changes to the analyses or systems
VerDate jul<14>2003
16:23 Aug 03, 2005
Jkt 205001
supporting this exemption request, the
NRC staff’s approval of the exemption is
restricted to those specific design and
operating conditions described in the
licensee’s February 22, 2005, exemption
request. The licensee may not apply the
10 CFR 50.59 process for evaluating
changes to specific exemptions. Any
changes to the design or operation of (1)
the dry cask storage system, (2) the
spent fuel pool, (3) the fuel assemblies
to be stored, (4) the boron dilution
analyses, or (5) supporting procedures
and controls, regardless of whether they
are approved under the general Part 72
license or perceived to be conservative,
will invalidate this exemption. Upon
invalidation of the exemption, the
licensee will be required to comply with
NRC regulations prior to future cask
loadings.
Pursuant to 10 CFR 51.32, the
Commission has determined that the
granting of this exemption will not have
a significant effect on the quality of the
human environment (70 FR 43462). This
exemption is effective upon issuance.
Dated at Rockville, Maryland, this 27th day
of July 2005.
For the Nuclear Regulatory Commission.
Ledyard B. Marsh,
Director, Division of Licensing Project
Management, Office of Nuclear Reactor
Regulation.
[FR Doc. E5–4147 Filed 8–3–05; 8:45 am]
BILLING CODE 7590–01–P
NUCLEAR REGULATORY
COMMISSION
[Docket Nos. 50–413 and 50–414]
Duke Energy Corporation, et al.;
Catawba Nuclear Station, Units 1 and
2; Notice of Consideration of Issuance
of Amendment to Renewed Facility
Operating Licenses, Proposed No
Significant Hazards Consideration
Determination, and Opportunity for a
Hearing
The U.S. Nuclear Regulatory
Commission (NRC or the Commission)
is considering issuance of amendments
to Renewed Facility Operating License
Nos. NPF–35 and NPF–52 issued to
Duke Energy Corporation (the licensee)
for operation of the Catawba Nuclear
Station, Units 1 and 2, located in York
County, South Carolina.
The proposed amendment would
revise the Technical Specification 3.7.9,
‘‘Standby Nuclear Service Water Pond
(SNSWP),’’ temperature limit from 91.5
°F to 95 °F.
Before issuance of the proposed
license amendment, the Commission
will have made findings required by the
PO 00000
Frm 00064
Fmt 4703
Sfmt 4703
Atomic Energy Act of 1954, as amended
(the Act), and the Commission’s
regulations.
The Commission has made a
proposed determination that the
amendment request involves no
significant hazards consideration. Under
the Commission’s regulations in Title 10
of the Code Of Federal Regulations (10
CFR), Section 50.92, this means that
operation of the facility in accordance
with the proposed amendment would
not (1) involve a significant increase in
the probability or consequences of an
accident previously evaluated; or (2)
create the possibility of a new or
different kind of accident from any
accident previously evaluated; or (3)
involve a significant reduction in a
margin of safety. As required by 10 CFR
50.91(a), the licensee has provided its
analysis of the issue of no significant
hazards consideration, which is
presented below:
1. Does operation of the facility in
accordance with the proposed amendment
involve a significant increase in the
probability or consequences of an accident
previously evaluated?
No.
This license amendment request proposes
a change to the SNSWP [Standby Nuclear
Service Water Pond] TS [Technical
Specification] requirement for maximum
temperature. The SNSWP is the safety related
ultimate heat sink utilized by the NSWS
[Nuclear Service Water System]. Neither the
NSWS nor the SNSWP is capable of initiating
an accident. Therefore, the probability of
initiation of any accident cannot be affected.
The technical evaluation provided in support
of this amendment request demonstrated that
with a maximum allowable SNSWP
temperature of 95 °F as specified in SR
3.7.9.2, the environmental qualification limit
for applicable safety related equipment is not
reached and the peak containment pressure
remains below the TS limit. This amendment
request does not involve any change to
previously analyzed dose analysis results.
The accident of interest from a dose
perspective is the Main Steam Line Break
Accident. The dose release path during this
accident is via steaming of the Reactor
Coolant System through the steam generator
power operated relief valves. The results of
this accident have been reviewed with the
revised SNSWP temperature limit and it has
been determined that the Reactor Coolant
System cooldown is terminated early enough
such that the dose analysis results are not
adversely impacted. Therefore, there is no
increase in any accident consequences.
2. Does operation of the facility in
accordance with the proposed amendment
create the possibility of a new or different
kind of accident from any accident
previously evaluated?
No.
This proposed amendment does not
involve addition, removal, or modification of
any plant system, structure, or component.
This change will not affect the operation of
E:\FR\FM\04AUN1.SGM
04AUN1
]]>Agencies
[Federal Register Volume 70, Number 149 (Thursday, August 4, 2005)]
[Notices]
[Pages 44942-44946]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E5-4147]
-----------------------------------------------------------------------
NUCLEAR REGULATORY COMMISSION
[Docket No. 50-261]
Carolina Power and Light Company, H.B. Robinson Steam Electric
Plant, Unit No. 2; Exemption
1.0 Background
Carolina Power & Light Company (CP&L or the licensee) is the holder
of Renewed Facility Operating License No. DPR-23, which authorizes
operation of the H. B. Robinson Steam Electric Plant, Unit No. 2
(HBRSEP2). The license provides, among other things, that the facility
is subject to all rules, regulations, and orders of the Nuclear
Regulatory Commission (NRC, the Commission) now or hereafter in effect.
The facility consists of a pressurized-water reactor located in
Darlington County, South Carolina.
2.0 Request/Action
By letter dated February 22, 2005, as supplemented by letters dated
May 10, July 6, and July 14, 2005, the licensee submitted a request for
an exemption from the requirements of Title 10 of the Code of Federal
Regulations (10 CFR) Section 50.68(b)(1) during the spent fuel pool
(SFP) activities related to the underwater handling, loading, and
unloading of the dry shielded canister (DSC) NUHOMS[supreg] -24PTH, as
described in proposed Amendment No. 8 to Certificate of Compliance No.
1004 listed in 10 CFR 72.214 at HBRSEP2.
Section 50.68(b)(1) of 10 CFR sets forth the following requirement
that must be met, in lieu of a monitoring system capable of detecting
criticality events.
Plant procedures shall prohibit the handling and storage at any
one time of more fuel assemblies than have been determined to be
safely subcritical under the most adverse moderation conditions
feasible by unborated water.
The licensee is unable to satisfy the above requirement for
handling of the Transnuclear (TN) NUHOMS[supreg]-24PTH DSC authorized
by 10 CFR Part 72 at HBRSEP2. Section 50.12(a) allows licensees to
apply for an exemption from the requirements of 10 CFR Part 50 if the
application of the regulation is not necessary to achieve the
underlying purpose of the rule and special conditions are met. The
licensee stated in the application that compliance with 10 CFR
50.68(b)(1) is not necessary for handling the TN NUHOMS[supreg]-24PTH
DSC system to achieve the underlying purpose of the rule.
3.0 Discussion
Pursuant to 10 CFR 50.12, the Commission may, upon application by
any interested person or upon its own initiative, grant exemptions from
the requirements of 10 CFR Part 50 when (1) the exemptions are
authorized by law, will not present an undue risk to public health or
safety, and are consistent with the common defense and security; and
(2) when special circumstances are present. Therefore, in determining
the acceptability of the licensee's exemption request, the staff has
performed the following regulatory, technical, and legal evaluations to
satisfy the requirements of 10 CFR 50.12 for granting the exemption.
3.1 Regulatory Evaluation
The HBRSEP2 Technical Specifications (TS) currently permit the
licensee to store spent fuel assemblies in high-density storage racks
in its SFP. In accordance with the provisions of 10 CFR 50.68(b)(4),
the licensee takes credit for soluble boron for criticality control and
ensures that the effective multiplication factor (keff) of
the SFP does not exceed 0.95, if flooded with borated water. Section
50.68(b)(4) of 10 CFR also requires that if credit is taken for soluble
boron, the keff must remain below 1.0 (subcritical) if
flooded with unborated water. However, the licensee is unable to
satisfy the requirement to maintain the keff below 1.0
(subcritical) with unborated water, which is also the requirement of 10
CFR 50.68(b)(1), during cask handling operations in the SFP. Therefore,
the licensee's request for exemption from 10 CFR 50.68(b)(1) proposes
to permit the licensee to perform spent fuel loading, unloading, and
handling operations related to dry cask storage without being
subcritical under the most adverse moderation conditions feasible by
unborated water.
Title 10 of the Code of Federal Regulations, Part 50, Appendix A,
``General Design Criteria (GDC) for Nuclear Power Plants,'' provides a
list of the minimum design requirements for nuclear power plants.
According to GDC 62, ``Prevention of criticality in fuel storage and
handling,'' the licensee must limit the potential for criticality in
the fuel handling and storage system by physical systems or processes.
HBRSEP2 was licensed prior to the issuance of the GDC listed in 10 CFR
50, Appendix A; therefore, GDC 62 is not directly applicable. However,
HBRSEP2 has committed to a plant-specific version of the 1967 draft GDC
as discussed in its Updated Final Safety Analysis Report (FSAR),
Section 3.1.2. The comparable GDC is Criterion 66, ``Prevention of Fuel
Storage Criticality,'' that states: ``Criticality in the new and spent
fuel storage pits shall be prevented by physical systems or processes.
Such means as geometrically safe configurations shall be emphasized
over procedural controls.''
Section 50.68 of 10 CFR Part 50, ``Criticality accident
requirements,'' provides the NRC requirements for maintaining
subcritical conditions in SFPs. Section 50.68 provides criticality
control requirements that, if satisfied, ensure that an inadvertent
criticality in the SFP is an extremely unlikely event. These
requirements ensure that the licensee has appropriately conservative
criticality margins during handling and storage of spent fuel. Section
50.68(b)(1) states, ``Plant procedures shall prohibit the handling and
storage at any one time of more fuel assemblies than have been
determined to be safely subcritical under the most adverse moderation
conditions feasible by unborated water.'' Specifically, 10 CFR
50.68(b)(1) ensures that the licensee will maintain the pool in a
subcritical condition during handling and storage operations without
crediting the soluble boron in the SFP water.
The licensee is authorized under general license to construct and
operate
[[Page 44943]]
an Independent Spent Fuel Storage Installation (ISFSI) at HBRSEP2. The
ISFSI permits the licensee to store spent fuel assemblies in large
concrete dry storage casks. As part of its ISFSI loading campaigns, the
licensee transfers spent fuel assemblies to a DSC in the cask pit area
of the SFP. The licensee performed criticality analyses of the DSC
fully loaded with fuel having the highest permissible reactivity and
determined that a soluble boron credit was necessary to ensure that the
DSC would remain subcritical in the SFP. Since the licensee is unable
to satisfy the requirement of 10 CFR 50.68(b)(1) to ensure subcritical
conditions during handling and storage of spent fuel assemblies in the
pool with unborated water, the licensee identified the need for an
exemption from the 10 CFR 50.68(b)(1) requirement to support DSC
loading, unloading, and handling operations without being subcritical
under the most adverse moderation conditions feasible by unborated
water.
The NRC staff evaluated the possibility of an inadvertent
criticality of the spent nuclear fuel at HBRSEP2 during DSC loading,
unloading, and handling. The NRC staff has established a set of
acceptance criteria that, if met, satisfy the underlying intent of 10
CFR 50.68(b)(1). In lieu of complying with 10 CFR 50.68(b)(1), the
staff determined that an inadvertent criticality accident is unlikely
to occur if the licensee meets the following five criteria:
1. The cask criticality analyses are based on the following
conservative assumptions:
a. All fuel assemblies in the cask are unirradiated and at the
highest permissible enrichment,
b. Only 75 percent of the Boron-10 in the fixed poison panel
inserts is credited,
c. No credit is taken for fuel-related burnable absorbers, and
d. The cask is assumed to be flooded with moderator at the
temperature and density corresponding to optimum moderation.
2. The licensee's ISFSI TS require the soluble boron concentration
to be equal to or greater than the level assumed in the criticality
analysis, and surveillance requirements necessitate the periodic
verification of the concentration both prior to and during loading and
unloading operations.
3. Radiation monitors, as required by GDC 63, ``Monitoring Fuel and
Waste Storage,'' are provided in fuel storage and handling areas to
detect excessive radiation levels and to initiate appropriate safety
actions.
4. The quantity of other forms of special nuclear material, such as
sources, detectors, etc., to be stored in the cask will not increase
the effective multiplication factor above the limit calculated in the
criticality analysis.
5. Sufficient time exists for plant personnel to identify and
terminate a boron dilution event prior to achieving a critical boron
concentration in the DSC. To demonstrate that it can safely identify
and terminate a boron dilution event, the licensee must provide the
following:
a. A plant-specific criticality analysis to identify the critical
boron concentration in the cask based on the highest reactivity loading
pattern.
b. A plant-specific boron dilution analysis to identify all
potential dilution pathways, their flowrates, and the time necessary to
reach a critical boron concentration.
c. A description of all alarms and indications available to
promptly alert operators of a boron dilution event.
d. A description of plant controls that will be implemented to
minimize the potential for a boron dilution event.
e. A summary of operator training and procedures that will be used
to ensure that operators can quickly identify and terminate a boron
dilution event.
On March 23, 2005, the NRC issued Regulatory Issue Summary (RIS)
2005-05, ``Regulatory Issues Regarding Criticality Analyses for Spent
Fuel Pools and Independent Spent Fuel Storage Installations.'' In RIS
2005-05, the NRC identified an acceptable methodology for demonstrating
compliance with the 10 CFR 50.68(b)(1) requirements during cask
loading, unloading, and handling operations in pressurized-water
reactor SFPs. The NRC staff has determined that implementation of this
methodology by licensees will eliminate the need to grant future
exemptions for cask storage and handling evolutions. However, since the
licensee submitted its exemption request prior to issuance of the RIS
and identification of an NRC-acceptable methodology for compliance with
the regulations, the NRC staff has determined that it is still
appropriate to consider the exemption request.
3.2 Technical Evaluation
In determining the acceptability of the licensee's exemption
request, the staff reviewed three aspects of the licensee's analyses:
(1) criticality analyses submitted to support the ISFSI license
application and its exemption request, (2) boron dilution analysis, and
(3) legal basis for approving the exemption. For each of the aspects,
the staff evaluated whether the licensee's analyses and methodologies
provide reasonable assurance that adequate safety margins are developed
and can be maintained in the HBRSEP2 SFP during loading of spent fuel
into canisters for dry cask storage.
3.2.1 Criticality Analyses
For evaluation of the acceptability of the licensee's exemption
request, the NRC staff reviewed the criticality analyses provided by
the licensee in support of its ISFSI license application. First, the
NRC staff reviewed the methodology and assumptions used by the licensee
in its criticality analysis to determine if Criterion 1 was satisfied.
The licensee stated that it took no credit in the criticality analyses
for burnup or fuel-related burnable neutron absorbers. The licensee
also stated that all assemblies were analyzed at the highest
permissible enrichment. Additionally, the licensee stated that all
criticality analyses for a flooded DSC were performed at temperatures
and densities of water corresponding to optimum moderation conditions.
Finally, the licensee stated that it credited 90 percent of the Boron-
10 content for the fixed neutron absorber in the DSC. NUREG-1536,
``Standard Review Plan for Dry Cask Storage System,'' states that
``[f]or a greater credit allowance [i.e., greater than 75 percent for
fixed neutron absorbers] special, comprehensive fabrication tests
capable of verifying the presence and uniformity of the neutron
absorber are needed.'' As part of an amendment to the Part 72 license
for the Transnuclear NUHOMS[supreg]-24PTH design, the NRC staff
reviewed and accepted the results of additional data supplied by the
manufacturer that demonstrated that a 90-percent credit for the fixed
neutron absorbers was acceptable. These tests and corresponding results
are detailed in Appendix P of the Standardized NUHOMS[supreg] FSAR.
Therefore, for the purposes of this exemption, the staff finds a 90-
percent credit acceptable on the basis that it has previously been
reviewed and approved by the NRC. Subsequently, based on its review of
the criticality analyses and the information submitted in its exemption
request, the NRC staff finds that the licensee has satisfied Criterion
1.
Second, the NRC staff reviewed the proposed HBRSEP2 ISFSI TS. The
licensee's criticality analyses credit soluble boron for reactivity
control during DSC loading, unloading, and handling operations. Since
the boron concentration is a key safety component necessary for
ensuring subcritical conditions in the pool, the licensee must have a
conservative ISFSI TS capable of ensuring that sufficient soluble boron
is present to perform its safety function. The ISFSI TS applicable
[[Page 44944]]
to the NUHOMS[supreg]-24PTH DSC, and attached to the Certificate of
Compliance No. 1004, contain the requirements for the minimum soluble
boron concentration as a function of fuel assembly class, DSC basket
type, and corresponding assembly average initial enrichment values. In
all cases, the boron concentration required by the ISFSI TS ensures
that the keff will be below 0.95 for the analyzed loading
configuration. Additionally, the licensee's ISFSI TS contain
surveillance requirements that assure it will verify the boron
concentration is above the required level both prior to and during DSC
loading, unloading, and handling operations. Based on its review of the
HBRSEP2 ISFSI TS, the NRC staff finds that the licensee has satisfied
Criterion 2.
Third, the NRC staff reviewed the HBRSEP2 Updated FSAR and the
information provided by the licensee in its exemption request to ensure
that it complies with GDC 63. GDC 63 requires that licensees have
radiation monitors in fuel storage and associated handling areas to
detect conditions that may result in a loss of residual heat removal
capability and excessive radiation levels and initiate appropriate
safety actions. As previously described, HBRSEP2 was licensed prior to
the issuance of the GDC listed in 10 CFR 50, Appendix A; therefore, GDC
63 is not directly applicable. However, HBRSEP2 has committed to a
plant-specific version of the 1967 draft GDC as discussed in its
Updated FSAR, Section 3.1.2. The comparable GDC is Criterion 18,
``Monitoring Fuel and Waste Storage,'' that states the following:
``Monitoring and alarm instrumentation shall be provided for fuel and
waste storage and associated handling areas for conditions that might
result in loss of capability to remove decay heat and detect excessive
radiation levels.'' The NRC staff reviewed the HBRSEP2 Updated FSAR,
plant-specific GDC, and exemption request to determine whether the
licensee had provided sufficient information to demonstrate compliance
with the intent of GDC 63. In its exemption request, the licensee
stated that an area radiation monitor is located in the area of the
SFP. Additionally, station procedures specify appropriate safety
actions upon a high radiation alarm, including evacuation of local
personnel, determination of cause, and determination of potential low
water level in the SFP. In addition, personnel working in the area of
the SFP wear individual, gamma-sensitive, electronic alarming
dosimeters that provide an audible alarm should the dose or dose rate
exceed pre-established setpoints. Based on its review of the exemption
request, the HBRSEP2 Updated FSAR, and the licensee's plant-specific
GDC, the NRC staff finds that the licensee has satisfied Criterion 3.
Finally, as part of the criticality analysis review, the NRC staff
evaluated the storage of non-fuel-related material in a DSC. The NRC
staff evaluated the potential to increase the reactivity of a DSC by
loading it with materials other than spent nuclear fuel and fuel
debris. The approved contents for storage in the NUHOMS[supreg]-24PTH
cask design are listed in the HBRSEP2 ISFSI TS Limiting Condition for
Operation (LCO) 1.2.1 ``Fuel Specifications.'' This ISFSI TS LCO
restricts the contents of the DSC to only fuels and non-fissile
materials irradiated at HBRSEP2. As such, HBRSEP2 is prohibited from
loading other forms of special nuclear material, such as sources,
detectors, etc., in the DSC. Therefore, the NRC staff determined that
the loading limitations described in the HBRSEP2 ISFSI TS will ensure
that any authorized components loaded in the DSCs will not result in a
reactivity increase. Based on its review of the loading restrictions,
the NRC staff finds that the licensee has satisfied Criterion 4.3.2.2.
Boron Dilution Analysis. Since the licensee's ISFSI application
relies on soluble boron to maintain subcritical conditions within the
DSCs during loading, unloading, and handling operations, the NRC staff
reviewed the licensee's boron dilution analysis to determine whether
appropriate controls, alarms, and procedures were available to identify
and terminate a boron dilution accident prior to reaching a critical
boron concentration.
By letter dated October 25, 1996, the NRC staff issued a safety
evaluation on licensing topical report WCAP-14416, ``Westinghouse Spent
Fuel Rack Criticality Analysis Methodology.'' This safety evaluation
specified that the following issues be evaluated for applications
involving soluble boron credit: the events that could cause boron
dilution, the time available to detect and mitigate each dilution
event, the potential for incomplete boron mixing, and the adequacy of
the boron concentration surveillance interval.
The criticality analyses performed for the NUHOMS[supreg]-24PTH DSC
are described in Section 6 of Appendix P of the FSAR for the
Standardized NUHOMS[supreg] Horizontal Modular Storage System for
Irradiated Nuclear Fuel. For this boron dilution evaluation, the
licensee employed the same criticality analysis methods, models, and
assumptions. These HBRSEP2 criticality calculations are based on the
KENO V.a code. The calculations determined the minimum soluble boron
concentration required to maintain subcriticality (keff <
1.0) following a boron dilution event in a NUHOMS[supreg]-24PTH DSC
loaded with fuel assemblies that bound the HBRSEP2 fuel designs
(Westinghouse 15 x 15 fuel). Both intact and damaged fuel over the
range of soluble boron concentrations permitted for various enrichments
and basket types were evaluated. The results of these calculations for
the bounding case indicate that subcriticality is maintained with 73
percent or more of the minimum boron concentration levels required in
the ISFSI TS for all basket types as a function of initial enrichment.
Calculations were performed by the licensee to determine the time
required to dilute the SFP such that the boron concentration is reduced
from the NUHOMS[supreg] TS (required boron concentration for
maintaining keff < 0.95) to a just subcritical boron
concentration (keff < 1.0) for fuel loaded into a
NUHOMS[supreg]-24PTH DSC.
The HBRSEP2 SFP is a large structure filled with borated water that
completely covers the spent fuel assemblies with more than 21 feet of
water above the top of the fuel racks and the fuel cask. The cask lay
down area is not separated by any structure from the remainder of the
SFP. Thermal gradients generated by stored fuel and operation of the
SFP cooling system will cause significant mixing within the pool. The
licensee assumed that all unborated water introduced from any
uncontrolled dilution source instantaneously mixes with the water in
the SFP (i.e., no unborated water is lost prior to its mixing with
borated water). The configuration of the pool and the mixing of the
coolant provide reasonable assurance that this assumption is valid for
low to moderate dilution flow rates.
The volume of water in the SFP is 240,000 gallons. To reduce the
boron concentration by a factor of 0.73 from the TS for keff
<= 0.95 and approach a keff of 1.0 requires the addition of
75,530 gallons of unborated water. Three examples of potential dilution
sources were identified by the licensee: a 2-gpm flowrate from small
failures or misaligned valves that could occur in the normal soluble
boron control system or related systems, the failure of the 2-inch
demineralized water header, and the maximum credible dilution event
involving the rupture of a fire protection system header.
To demonstrate that sufficient time exists for plant personnel to
identify and terminate a boron dilution event, the licensee provided a
description of
[[Page 44945]]
all alarms available to alert operators, and plant procedures,
administrative controls, and training that will be implemented in
response to an alarm. There is no automatic level control system for
the SFP; therefore, any large, uncontrolled water addition would cause
the SFP to overflow. However, a high level alarm in the control room
would alert personnel of a potential boron dilution event when the
water level reaches the high level setpoint.
The highest uncontrolled dilution flow rate was determined to be
the fire protection header on the SFP floor for fire hose station 104.
As stated in the letter dated July 6, 2005, this fire protection header
will be isolated during DSC loading and unloading to preclude this as a
source of uncontrolled dilution to the SFP. The licensee has revised
DSC loading and unloading procedures to include a requirement to close
the fire protection system valve (FP-71) prior to placing fuel in the
DSC during loading and prior to placing the loaded DSC back in the SFP
during unloading. This change has resulted in the most limiting
uncontrolled dilution source being identified as the assumed break of a
2-inch demineralized water header, which could cause a dilution flow of
approximately 103 gpm. No other single source has been identified that
would exceed this dilution rate. Therefore, the time to reach a
critical boron concentration, as provided by licensee, is estimated to
be 755 minutes.
In the case of the 103-gpm demineralized water pipe rupture, there
would be no alarm from the demineralized water system. However, there
would be available approximately 10 hours to isolate the leak once the
SFP high level alarm was received. This analysis provides reasonable
assurance that dilution flows leading to pool overflow would be
detected and isolated well before the critical boron concentration
could be reached from credible dilution sources.
The licensee stated that plant procedures do allow for continued
operation with the SFP high level alarm illuminated. The licensee
stated that operating procedures had been revised to specify that, if
the SPF high level alarm is illuminated and there is fuel in the DSC in
the SFP, then continuous coverage to monitor the SFP water level will
be required. A local level indicator is available in the SFP. The
personnel providing continuous coverage when the SFP Hi Level Alarm is
illuminated or inoperable can use this indication to detect possible
dilution of the SFP. The available time before criticality by dilution
is sufficient to allow identification and termination of any credible
source of dilution.
When fuel is loaded in the DSC in the SFP, boron analyses of the
SFP water are required at least once every 48 hours per the TS. Small
dilution flows may not be readily identified by level changes in the
SFP due to operational leakage through the pool liner and the SFP
cooling system. The licensee determined that a dilution flow of 2 gpm
would require approximately 26 days to dilute the boron concentration
of the SFP near to that calculated as the critical boron concentration.
Therefore, the reduction in boron concentration due to a dilution
flowrate of 2 gpm would be detected by the required boron concentration
surveillance well before a significant dilution occurs.
To ensure that operators are capable of identifying and terminating
a boron dilution event during DSC loading, unloading, and handling
operations, operator training will be conducted. This training will
highlight the boron concentration requirements for loading the DSC, the
potential for criticality should boron concentration levels decrease,
and the need for timely mitigating activities if a boron dilution event
occurs. Operators and other personnel involved in the dry fuel storage
implementation will receive this new training prior to loading of the
first DSC. Additionally, before each DSC loading evolution, the crew
involved in performance of the work will receive a pre-job briefing,
where the need for boron concentration control will be discussed.
Based on the NRC staff's review of the licensee's boron dilution
analysis, the NRC staff finds the licensee has provided sufficient
information to demonstrate that an undetected and uncorrected dilution
from the TS-required boron concentration to the calculated critical
boron concentration is very unlikely. Based on its review of the boron
analysis and enhancements to the operating procedures and operator
training program, the NRC staff finds the licensee has satisfied
Criterion 5.
Therefore, in conjunction with the conservative assumptions used to
establish the TS-required boron concentration and critical boron
concentration, the boron dilution evaluation demonstrates that the
underlying intent of 10 CFR 50.68(b)(1) is satisfied.
3.3 Legal Basis for the Exemption
3.3.1 Authorized by Law
This exemption results in changes to the operation of the plant by
allowing the operation of the new dry fuel storage facility and loading
of the NUHOMS[supreg]-24PTH DSC. As stated above, 10 CFR 50.12 allows
the NRC to grant exemptions from the requirements of 10 CFR Part 50. In
addition, the granting of the licensee's exemption request will not
result in a violation of the Atomic Energy Act of 1954, as amended, or
the intent of the Commission's regulations. Therefore, the exemption is
authorized by law.
3.3.2 No Undue Risk to Public Health and Safety
The underlying purposes of 10 CFR 50.68(b)(1) is to ensure that
adequate controls are in place to ensure that the handling and storage
of fuel assemblies is conducted in a manner such that the fuel
assemblies remain safely subcritical. Based on the NRC staff's review
of the licensee's exemption request, the licensee has demonstrated that
sufficient controls are in place to provide reasonable assurance that
there is no undue risk to public health and safety given conservative
assumption in the criticality analysis (criterion 1 above);
surveillances periodically verify the boron concentration before and
during loading and unloading (criterion 2 above); radiation monitoring
equipment is used to detect excessive radiation and initiate
appropriate protective actions (criterion 3 above); only fuel
authorized by the ISFSI TS will be loaded and stored in the ISFSI
(criterion 4 above); and boron dilution events have been analyzed, and
there are sufficient monitoring capabilities and time for the licensee
to identify and terminate a dilution event prior to achieving a
critical boron concentration in the cask (criterion 5 above).
Therefore, the NRC staff concluded that the underlying purpose of the
rule has been satisfied and that there is no undue risk to public
health and safety.
3.3.3 Consistent with Common Defense and Security
This exemption results in changes to the operation of the plant by
allowing the operation of the new dry fuel storage facility and loading
of the NUHOMS[supreg]-24PTH DSC. This change to the fuel assembly
storage and handling in the plant does not affect the national defense
strategy because the national defense is maintained by resources
(hardware or software or other) that are outside the plant and that
have no direct relation to plant operation. In addition, loading spent
fuel into the NUHOMS[supreg]-24PTH DSC in the SFP does not affect the
ability of the licensee to defend the plant against a terrorist attack.
Therefore, the common defense and
[[Page 44946]]
security is not impacted by this exemption request.
3.3.4 Special Circumstances
Pursuant to 10 CFR 50.12, ``Specific Exemption,'' the NRC staff
reviewed the licensee's exemption request to determine if the legal
basis for granting an exemption had been satisfied. With regards to the
six special circumstances listed in 10 CFR 50.12(a)(2), the NRC staff
finds that the licensee's exemption request satisfies 50.12(a)(2)(ii),
``Application of the regulation in the particular circumstances would
not serve the underlying purpose of the rule or is not necessary to
achieve the underlying purpose of the rule.'' Specifically, the NRC
staff concludes that since the licensee has satisfied the five criteria
in Section 3.1 of this exemption, the application of the rule is not
necessary to achieve its underlying purpose in this particular case.
3.4 Summary
Based upon the review of the licensee's exemption request to credit
soluble boron during DSC loading, unloading, and handling in the
HBRSEP2 SFP, the NRC staff concludes that pursuant to 10 CFR
50.12(a)(2) the licensee's exemption request is acceptable. However,
the NRC staff places the following limitations/conditions on the
approval of this exemption:
1. This exemption is limited to the loading, unloading, and
handling of the DSC for only the TN NUHOMS[supreg]-24PTH at HBRSEP2.
2. This exemption is limited to the loading, unloading, and
handling in the DSC at HBRSEP2 of Westinghouse 15 x 15 fuel assemblies
that had maximum initial, unirradiated U-235 enrichments corresponding
to the TS limitations in LCO 1.2.1 for Amendment 8 to the
NUHOMS[supreg] -24PTH cask design.
4.0 Conclusion
Accordingly, the Commission has determined that, pursuant to 10 CFR
50.12(a), the exemption is authorized by law, will not present an undue
risk to the public health and safety, and is consistent with the common
defense and security. Also, special circumstances are present.
Therefore, the Commission hereby grants CP&L an exemption from the
requirements of 10 CFR 50.68(b)(1) for the loading, unloading, and
handling of the components of the Transnuclear NUHOMS[supreg]-24PTH dry
cask storage system at HBRSEP2. However, since the licensee does not
have an NRC-approved methodology for evaluating changes to the analyses
or systems supporting this exemption request, the NRC staff's approval
of the exemption is restricted to those specific design and operating
conditions described in the licensee's February 22, 2005, exemption
request. The licensee may not apply the 10 CFR 50.59 process for
evaluating changes to specific exemptions. Any changes to the design or
operation of (1) the dry cask storage system, (2) the spent fuel pool,
(3) the fuel assemblies to be stored, (4) the boron dilution analyses,
or (5) supporting procedures and controls, regardless of whether they
are approved under the general Part 72 license or perceived to be
conservative, will invalidate this exemption. Upon invalidation of the
exemption, the licensee will be required to comply with NRC regulations
prior to future cask loadings.
Pursuant to 10 CFR 51.32, the Commission has determined that the
granting of this exemption will not have a significant effect on the
quality of the human environment (70 FR 43462). This exemption is
effective upon issuance.
Dated at Rockville, Maryland, this 27th day of July 2005.
For the Nuclear Regulatory Commission.
Ledyard B. Marsh,
Director, Division of Licensing Project Management, Office of Nuclear
Reactor Regulation.
[FR Doc. E5-4147 Filed 8-3-05; 8:45 am]
BILLING CODE 7590-01-P
