[Federal Register Volume 71, Number 69 (Tuesday, April 11, 2006)]
[Notices]
[Pages 18380-18390]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-5216]
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NUCLEAR REGULATORY COMMISSION
Notice of Opportunity To Comment on Model Safety Evaluation on
Technical Specification Improvement Regarding Revision to the
Completion Time in STS 3.6.6A, ``Containment Spray and Cooling
Systems'' for Combustion Engineering Pressurized Water Reactors Using
the Consolidated Line Item Improvement Process
AGENCY: Nuclear Regulatory Commission.
ACTION: Request for comment.
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SUMMARY: Notice is hereby given that the staff of the U.S. Nuclear
Regulatory Commission (NRC) has prepared a model license amendment
request (LAR), model safety evaluation (SE), and model proposed no
significant hazards consideration (NSHC) determination related to
changes to the completion times (CT) in Standard Technical
Specification (STS) 3.6.6A, ``Containment Spray and Cooling Systems.''
The proposed changes would revise STS 3.6.6A by extending the CT for
one containment spray system (CSS) train inoperable from 72 hours to
seven days, and add a Condition describing required Actions and CT when
one CSS and one containment cooling system (CCS) are inoperable. These
changes are based on analyses provided in a joint applications report
submitted by the Combustion Engineering Owner's Group (CEOG). The CEOG
participants in the Technical Specifications Task Force (TSTF) proposed
this change to the STS in Change Traveler No. TSTF-409, Revision 2.
The purpose of these models is to permit the NRC to efficiently
process amendments to incorporate these changes into plant-specific STS
for Combustion Engineering pressurized water reactors (PWRs). Licensees
of nuclear power reactors to which the models apply can request
amendments conforming to the models. In such a
[[Page 18381]]
request, a licensee should confirm the applicability of the SE and NSHC
determination to its plant, and provide the expected supplemental
information requested in the model LAR. The NRC staff is requesting
comments on the model LAR, model SE and NSHC determination before
announcing their availability for referencing in license amendment
applications.
DATES: The comment period expires 30 days from the date of this
publication. Comments received after this date will be considered if it
is practical to do so, but the Commission is able to ensure
consideration only for comments received on or before this date.
ADDRESSES: Comments may be submitted either electronically or via U.S.
mail.
Submit written comments to: Chief, Rules and Directives Branch,
Division of Administrative Services, Office of Administration, Mail
Stop: T-6 D59, U.S. Nuclear Regulatory Commission, Washington, DC
20555-0001.
Hand deliver comments to 11545 Rockville Pike, Rockville, Maryland,
between 7:45 a.m. and 4:15 p.m. on Federal workdays.
Comments may be submitted by electronic mail to [email protected].
Copies of comments received may be examined at the NRC's Public
Document Room, located at One White Flint North, Public File Area O1-
F21, 11555 Rockville Pike (first floor), Rockville, Maryland.
FOR FURTHER INFORMATION CONTACT: Eric Thomas, Mail Stop: O-12H2,
Division of Inspection and Regional Support, Office of Nuclear Reactor
Regulation, U.S. Nuclear Regulatory Commission, Washington, DC 20555-
0001, telephone (301) 415-6772.
SUPPLEMENTARY INFORMATION:
Background
Regulatory Issue Summary 2000-06, ``Consolidated Line Item
Improvement Process [CLIIP] for Adopting Standard Technical
Specifications Changes for Power Reactors,'' was issued on March 20,
2000. The CLIIP is intended to improve the efficiency and transparency
of NRC licensing processes. This is accomplished by processing proposed
changes to the STS in a manner that supports subsequent license
amendment applications. The CLIIP includes an opportunity for the
public to comment on proposed changes to the STS following a
preliminary assessment by the NRC staff and finding that the change
will likely be offered for adoption by licensees. This notice is
soliciting comment on a proposed change to the STS that changes the CSS
CTs for the Combustion Engineering reactor STS, NUREG-1432, Revision 3.
The CLIIP directs the NRC staff to evaluate any comments received for a
proposed change to the STS and to either reconsider the change or
proceed with announcing the availability of the change for proposed
adoption by licensees. Those licensees opting to apply for the subject
change to TSs are responsible for reviewing the staff's evaluation,
referencing the applicable technical justifications, and providing any
necessary plant-specific information. Following the public comment
period, the model SE will be finalized, and posted on the NRC webpage.
The model SE is accompanied by a model LAR. The model LAR shows
licensees the expected level of detail that needs to be included in
order to adopt TSTF-409, Rev. 2, as well as guidelines for staff
review. The NRC will establish an internal review plan that designates
the appropriate staff and approximate timelines to review plant-
specific LARs that reference TSTF-409. Each amendment application made
in response to the notice of availability will be processed and noticed
in accordance with applicable NRC rules and procedures.
This notice involves an increase in the allowed CTs to restore an
inoperable CSS on Combustion Engineering PWRs. By letter dated November
10, 2003, the CEOG proposed this change for incorporation into the STS
as TSTF-409, Revision 2. This change is based on the NRC staff-approved
generic analyses contained in the CE NPSD-1045-A, ``Joint Applications
Report: Modification to the Containment Spray System, and Low Pressure
Safety Injection System Technical Specifications,'' dated March 2000,
as approved by NRC in a SE dated December 21, 1999, accessible
electronically from the Agencywide Documents Access and Management
System's (ADAMS) Public Electronic Reading Room on the Internet (ADAMS
Accession No. ML993620241) at the NRC Web site http://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 Reference staff by telephone at 1-
800-397-4209, 301-415-4737, or by e-mail to [email protected].
Applicability
This proposed change to revise the Technical Specification (TS) CT
for one inoperable CSS is applicable to Combustion Engineering PWRs.
To efficiently process the incoming license amendment applications,
the NRC staff requests that each licensee applying for the changes
addressed by TSTF-409, Revision 2, use the CLIIP to submit a LAR that
adheres to the following model. Any deviations from the model LAR
should be explained in the licensee's submittal. When applying,
licensees should ensure they address the eight conditions and one
regulatory commitment listed in the model LAR and model SE.
The CLIIP does not prevent licensees from requesting an alternative
approach or proposing the changes without providing the information
described in the eight model LAR conditions, or making the requested
commitment. Variations from the approach recommended in this notice
may, however, require additional review by the NRC staff and may
increase the time and resources needed for the review. Significant
variations from the approach, or inclusion of additional changes to the
license, will result in staff rejection of the submittal. Instead,
licensees desiring significant variations and/or additional changes
should submit a LAR that does not claim to adopt TSTF-409.
Public Notices
This notice requests comments from interested members of the public
within 30 days of the date of this publication. Following the NRC
staff's evaluation of comments received as a result of this notice, the
NRC staff may reconsider the proposed change or may proceed with
announcing the availability of the change in a subsequent notice
(possibly with some changes to the model LAR, model SE or model NSHC
determination as a result of public comments). If the NRC staff
announces the availability of the change, licensees wishing to adopt
the change will submit a LAR in accordance with applicable rules and
other regulatory requirements. The NRC staff will, in turn, issue a
notice of consideration of issuance of amendment to facility operating
license(s) for each LAR, a proposed NSHC determination, and an
opportunity for a hearing. A notice of issuance of an amendment to
operating license(s) will also be issued to announce the revised
requirements for each plant that applies for and receives the requested
change.
Dated at Rockville, Maryland this 29th day of March 2006.
[[Page 18382]]
For the Nuclear Regulatory Commission.
Thomas H. Boyce,
Branch Chief, Technical Specifications Branch, Division of Inspection
and Regional Support, Office of Nuclear Reactor Regulation.
For inclusion on the technical specification Web page. The
following example of a License Amendment Request (LAR) was prepared by
the NRC staff to facilitate the adoption of Technical Specifications
Task Force (TSTF) Traveler TSTF-409, Revision 2, ``Containment Spray
System Completion Time Extension (CE NPSD-1045-A).'' The model provides
the expected level of detail and content for a LAR to adopt TSTF-409,
Revision 2. Licensees remain responsible for ensuring that their plant-
specific LAR fulfills their administrative requirements as well as NRC
regulations.
U.S. Nuclear Regulatory Commission, Document Control Desk,
Washington, DC 20555.
SUBJECT: Plant Name Application for Technical Specification Improvement
to Extend the Completion Time for Containment Spray System
Inoperability in Accordance With TSTF-409, Revision 2.
Dear Sir or Madam:
In accordance with the provisions of Section 50.90 of Title 10 of
the Code of Federal Regulations (10 CFR), [LICENSEE] is submitting a
request for an amendment to the technical specifications (TS) for
[PLANT NAME, UNIT NOS.].
The proposed changes would revise TS 3.6.6A, ``Containment Spray
and Cooling Systems,'' by extending from 72 hours to seven days the
completion time (CT) to restore an inoperable containment spray system
(CSS). In addition, a Condition would be added to the TS to allow one
CSS and one containment cooling system (CCS) to be inoperable for a
period of 72 hours.
The changes are consistent with NRC-approved Industry Technical
Specification Task Force (TSTF) Standard Technical Specification Change
Traveler, TSTF-409, Revision 2, ``Containment Spray System Completion
Time Extension (CE NPSD-1045-A).''
Enclosure 1 provides a description and assessment of the proposed
changes and confirmation of applicability. Enclosure 2 provides the
existing TS pages marked-up to show the proposed changes. Enclosure 3
provides the existing TS Bases pages marked-up to reflect the proposed
changes (for information only). Final TS Bases will be provided in a
future update to the Updated Final Safety Analysis Report (UFSAR) in
accordance with the Bases Control Program. Attachments 1 through 8
provide the discussions of [LICENSEE'S] evaluations and supporting
information with regard to the conditions stipulated in Section 4.2.1
of Enclosure 1.
[LICENSEE] requests approval of the proposed license amendment by
[DATE], with the amendment being implemented [BY DATE OR WITHIN X
DAYS]. In accordance with 10 CFR 50.91, a copy of this application,
with enclosures, is being provided to the designated [STATE] Official.
I declare under penalty of perjury under the laws of the United
States of America that I am authorized by [LICENSEE] to make this
request and that the foregoing is true and correct. [Note that request
may be notarized in lieu of using this oath or affirmation statement].
If you should have any questions regarding this submittal, please
contact [ ].
Sincerely,
Name, Title
Enclosures:
1. Description and Assessment of Proposed Changes
2. Proposed Technical Specification Changes
3. Proposed Technical Specification Bases Changes (if applicable)
Attachments:
1. Licensee's supporting information for condition 1
2. Licensee's supporting information for condition 2
3. Licensee's supporting information for condition 3
4. Licensee's supporting information for condition 4
5. Licensee's supporting information for condition 5
6. Licensee's supporting information for condition 6
7. Licensee's supporting information for condition 7
8. Licensee's supporting information for condition 8
cc: NRR Project Manager
Regional Office
Resident Inspector
State Contact
ITSB Branch Chief
1.0 Description
This letter is a request to amend Operating License(s) [LICENSE
NUMBER(S)] for [PLANT/UNIT NAME(S)].
The proposed changes would revise Technical Specification (TS)
3.6.6A, ``Containment Spray and Cooling Systems,'' by extending from 72
hours to seven days the completion time (CT) to restore an inoperable
containment spray system (CSS) train to operable status, and would add
a Condition describing the required action and CT when one CSS and one
containment cooling system (CCS) are inoperable.
The changes are consistent with NRC approved Industry Owner's Group
Technical Specification Task Force (TSTF) Standard Technical
Specification Change Traveler TSTF-409, Revision 2 (Rev. 2),
``Containment Spray System Completion Time Extension (CE NPSD-1045-
A).'' TSTF-409, Rev. 2 was approved by the NRC on [DATE].
2.0 Proposed Change
Specifically, the proposed revision extends the CT (or allowed
outage time) that one CSS train is permitted to remain inoperable from
72 hours to seven days based on Reference 1, as accepted by, and
subject to the limitations specified in, Reference 2. TSTF-409, Rev. 2
states that the longer CT will enhance overall plant safety by avoiding
potential unscheduled plant shutdowns and allowing greater availability
of safety significant components during shutdown. In addition, the
TSTF-409, Rev. 2 states that this extension provides for increased
flexibility in scheduling and performing maintenance and surveillance
activities in order to enhance plant safety and operational flexibility
during lower modes of operation.
The revision also adds a condition statement to allow one CSS train
and one CCS train to be inoperable for up to 72 hours. Since the
Combustion Engineering Owners Group (CEOG) joint applications report
did not evaluate the concurrent inoperabilities of one CSS train and
one CCS train, the CT for this condition was limited to 72 hours.
[LICENSEE] also proposes to make changes to the supporting TS
Bases. Changes to the Bases include supporting information justifying
the addition of the Condition statement for one CSS train and one CCS
train inoperable. The Bases changes also include a reviewer's note that
requires [LICENSEE] to adopt Reference 1 and meet the requirements of
References 1 and 2 prior to utilizing the 7-day CT for one inoperable
CSS. Finally, a reference to Reference 1 is added to the Bases.
In summary, [LICENSEE] proposes to extend the CT for one inoperable
CSS from 72 hours to 7 days based on Reference 1, and add a Condition
statement to allow one CSS train and one CCS to be inoperable for up to
72 hours.
[[Page 18383]]
3.0 Background
The function of the containment heat removal systems under accident
conditions is to remove heat from the containment atmosphere, thus
maintaining the containment pressure and temperature at acceptably low
levels. The systems also serve to limit offsite radiation levels by
reducing the pressure differential between the containment atmosphere
and the external environment, thereby decreasing the driving force for
fission product leakage across the containment. The two containment
heat removal systems are the CCS and the CSS. The CCS fan coolers are
designed to operate during both normal plant operations and under loss-
of-coolant accident (LOCA) or main steam line break (MSLB) conditions.
The CSS is designed to operate during accident conditions only.
The heat removal capacity of the CCS and CSS is sufficient to keep
the containment temperature and pressure below design conditions for
any size break, up to and including a double-ended break of the largest
reactor coolant pipe. The systems are also designed to mitigate the
consequences of any size break, up to and including a double-ended
break of a main steam line. The CCS and CSS continue to reduce
containment pressure and temperature and maintain them at acceptable
levels post-accident.
The CCS and CSS at [PLANT NAME] each consist of [Substitute plant-
specific configuration if it differs from the following description]
two redundant loops and are designed such that a single failure does
not degrade their ability to provide the required heat removal
capability. Two of four containment fan coolers and one CSS loop are
powered from one safety-related bus. The other two containment fan
coolers and CSS loop are powered from another independent safety-
related bus. The loss of one bus does not affect the ability of the
containment heat removal systems to maintain containment temperature
and pressure below the design values in a post-accident mode.
The [PLANT NAME] CSS consists of [Substitute plant-specific
configuration if it differs from the following description] two
independent and redundant loops each containing a spray pump, shutdown
heat exchanger, piping, valves, spray headers, and spray nozzles. It
has two modes of operation, which are:
1. The injection mode, during which the system sprays borated water
from the refueling water tank (RWT) into the containment, and
2. The recirculation mode, which is automatically initiated by the
recirculation actuation signal (RAS) after low level is reached in the
RWT. During this mode of operation, the safety injection system (SIS)
sump provides suction for the spray pumps.
Containment spray is automatically initiated by the containment
spray actuation signal coincident with the safety injection actuation
signal and high containment pressure signal. If required, the operator
can manually activate the system from the main control room.
Each CSS pump, together with a CCS loop, provides the flow
necessary to remove the heat generated inside the containment following
a LOCA or MSLB. Upon system activation, the pumps are started and the
borated water flows into the containment spray headers. When low level
is reached in the RWT, sufficient water has been transferred to the
containment to allow for the recirculation mode of operation. Spray
pump suction is automatically realigned to the SIS sump upon a RAS.
During the recirculation mode, the spray water is cooled by the
shutdown heat exchangers prior to discharge into the containment. The
shutdown heat exchangers are cooled by the component cooling water
system. Post-LOCA pH control is provided by [Substitute plant-specific
configuration if it differs from the following description] trisodium
phosphate dodecahydrate, which is stored in stainless steel baskets
located in the containment near the SIS sump intake.
The longer CT for an inoperable CSS train will enhance overall
plant safety by avoiding potential unscheduled plant shutdowns and
allowing greater availability of safety significant components during
shutdown. In addition, this extension provides for increased
flexibility in scheduling and performing maintenance and surveillance
activities in order to enhance plant safety and operational flexibility
during lower modes of operation.
4.0 Technical Analysis
[LICENSEE] has reviewed References 1 and 2, as well as TSTF-409,
Rev. 2, and the model SE published on [DATE] ([ ] FR [ ]) as part of
the CLIIP Notice for Comment. [LICENSEE] has applied the methodology in
Reference 1 to develop the proposed TS changes. [LICENSEE] has also
concluded that the justifications presented in TSTF-409, Rev. 2 and the
model SE prepared by the NRC staff are applicable to [PLANT NAME], and
justify this amendment for the incorporation of changes to the [PLANT
NAME] TS.
In determining the suitability and safety impact of its adoption of
TSTF-409, Rev. 2, [LICENSEE] analyzed the effect of increasing the CT
for one CSS train to remain out of service using both traditional
engineering considerations and probabilistic risk assessment (PRA)
methods.
4.1 Traditional (Deterministic) Engineering Analysis
The functions and operation of the CSS and CCS were described in
Section 3.0 of this application. Based on a review of the design-basis
requirements for the CSS, [LICENSEE] concluded that the loss of one CSS
train is well within the design-basis analyses. This conclusion is
based on the fact that each CSS pump, together with a CCS loop,
provides the flow necessary to remove the heat generated inside the
containment following a LOCA or MSLB. Therefore, the combination of one
CSS pump and one CCS loop can carry out the design functions of
maintaining the containment pressure and temperature at acceptably low
levels following a design-basis accident (DBA), and limiting offsite
radiation levels by reducing the pressure differential between the
containment atmosphere and the external environment, thereby decreasing
the driving force for fission product leakage across the containment.
The plant status with both CSS trains inoperable is covered by TS
3.6.6A, ACTION G., which states:
[With] two containment spray trains inoperable or any
combination of three or more [CSS/CCS] trains inoperable, LCO
[Limiting Condition for Operation] 3.0.3 shall be entered
immediately.
ACTION G addresses the condition in which two CSS trains are
inoperable and requires restoration of at least one CSS train to
OPERABLE status within 1 hour or the plant be placed in HOT SHUTDOWN in
6 hours and COLD SHUTDOWN within the following 30 hours, with COLD
SHUTDOWN being the acceptable end state. These requirements are
consistent with similar requirements elsewhere in the TS and therefore
are acceptable.
The plant status with one CSS train and one CCS train inoperable is
covered by TS 3.6.6A, ACTION D, which states:
[With] one containment spray and one containment cooling train
inoperable, restore containment spray train to OPERABLE status
within 72 hours, or restore containment cooling train to OPERABLE
status within 72 hours.
[[Page 18384]]
ACTION D ensures that the iodine removal capabilities of the CSS
are available, along with 100 percent of the heat removal needs after
an accident. The supporting analyses performed in CE NPSD-1045-A did
not evaluate the concurrent inoperabilities of one CSS train and one
CCS train, therefore, the current CT of 72 hours is retained in
Condition D. The 72 hour Completion Time was developed taking into
account the redundant heat removal capabilities afforded by
combinations of the CSS and CCS, the iodine removal function of the
CSS, and the low probability of a DBA occurring during this period.
4.2 Probabilistic Risk Assessment Evaluation
[LICENSEE] evaluated the proposed CT extension for the CSS using
Reference 4. This is the same methodology that the NRC staff used in
Reference 2. The Principles of Risk-Informed Integrated Decisionmaking
listed in Reference 4 are as follows:
Principle I: The proposed CT change meets the current regulation
Principle II: The proposed CT change is consistent with the defense-in-
depth philosophy
Principle III: The proposed CT change maintains sufficient safety
margin
Principle IV: The CT risk (Incremental Conditional Core Damage
Probability [ICCDP], and Incremental Conditional Large Early Release
Probability [ICLERP]) is small
Principle V: Commitment to monitor the impact of the proposed CT change
In Reference 2, the NRC staff found, and [LICENSEE] agrees, that in
risk-informed TS CT applications, Principle I is met, since regulations
do not require specific CTs, but, rather, require ``remedial actions''
when an LCO cannot be met. Additionally, in its analysis of Principle
III, the NRC staff found, and [LICENSEE] agrees, that the proposed CT
extension maintains sufficient safety margins. For [PLANT NAME], the
loss of one CSS train is well within the plant's design basis.
In Reference 2, the NRC staff determined that the intent of
Principles II, IV, and V would be met by a three-tiered approach to
evaluate the plant-specific risk impact associated with the proposed TS
changes, consistent with the requirements of Reference 4. The first
tier evaluates the plant-specific PRA model and the impact of the
proposed CT extension on plant operational risk. The second tier
addresses the need to preclude potentially high risk configurations by
identifying the need for any additional constraints or compensatory
actions that, if implemented, would avoid or reduce the probability of
a risk-significant configuration during the time when one CSS train is
out of service. The third tier evaluates [LICENSEE'S] proposed
Configuration Risk Management Program (CRMP) to ensure that the
applicable plant configuration will be appropriately assessed from a
risk perspective before entering into or during the proposed CT.
In addition, the NRC staff determined in Reference 2 that the risk
analysis methodology and approach used by the CEOG to estimate the risk
impact of increasing the CT were reasonable. For most plants that
participated in the joint application report, the NRC staff found that
the risk impact was shown to be consistent with the acceptance
guidelines for change in core damage frequency ([Delta]CDF), change in
large early release frequency ([Delta]LERF), incremental conditional
core damage probability (ICCDP), and incremental conditional large
early release probability (ICLERP) specified in References 3 and 4 and
Chapters 19.0 and 16.1 of Reference 5. However, not all Combustion
Engineering (CE) plants participated in the joint application report,
and the estimated risk impacts for some plants exceeded the Reference 3
and/or Reference 4 acceptance guidelines, which would require
additional justifications and/or compensatory measures to be provided
for these plants to be determined to have acceptable risk impacts.
In addition, the NRC staff found that the Tier 2 and Tier 3
evaluations, as described in Reference 4, could not be approved
generically since they were not complete, which would require that each
individual plant-specific license amendment seeking adoption of TSTF-
409, Rev. 2 would need to include an assessment with respect to the
Tier 2 and Tier 3 principles of Reference 4.
4.2.1 Conditions and Supporting Information
The following conditions are provided to support adoption of TSTF-
409, Rev. 2 by [PLANT NAME]. Responses to the conditions are contained
in Attachments 1 through 8 to this application: [NOTE: Licensees who
cannot meet the Expectations and Acceptance Criteria listed in these
conditions should not submit an application to adopt TSTF-409, Rev. 2
under the CLIIP.]
1. As shown in Attachment 1, the plant-specific Tier 1 information
associated with extending the CSS CT meets the acceptance guidelines of
References 3 and 4 associated with [Delta]CDF, [Delta]LERF, ICCDP, and
ICLERP.
[EXPECTATIONS/ACCEPTANCE CRITERIA: The licensee's submittal must
provide the [Delta]CDF, [Delta]LERF, ICCDP, and ICLERP values related
to the CSS extended CT and confirm that they meet the associated
acceptance guidelines of References 3 and 4 as no more than a small
risk increase (i.e., are in Region II or III of the acceptance
guidelines figures). If a zero maintenance PRA model is used (as
opposed to an average/nominal maintenance PRA model) in performing
these calculations, then the licensee must make a commitment that no
other maintenance will be performed during the extended CSS CT and
describe how this commitment will be implemented.]
2. As shown in Attachment 2, the technical adequacy (quality) of
[PLANT NAME'S] plant-specific PRA is acceptable for this application in
accordance with the guidance provided in Reference 3. Specifically, the
supporting information addresses the following areas:
a. Justification that the plant-specific PRA reflects the as-built,
as-operated plant.
b. Discussion of plant-specific PRA updates and upgrades since the
individual plant examination (IPE) and individual plant examination of
external events (IPEEE).
c. Discussion of plant-specific PRA peer reviews and/or self-
assessments performed, their overall conclusions, any facts and
observations (F&Os) applicable to this application, and the licensee
evaluation and resolution (e.g., by implementing model changes and/or
sensitivity studies) of these F&Os to demonstrate the conclusions of
the plant-specific analyses for this application are not adversely
impacted (i.e., continued acceptability of the proposed extension of
the CSS CT).
d. Description of the licensee's plant-specific PRA configuration
control (quality assurance) program and associated procedures.
e. Overall determination of the adequacy of the plant-specific PRA
with respect to this application.
[EXPECTATION: The licensee's submittal must describe the scope of
the plant-specific PRA and must justify its technical adequacy
(quality) for this application in accordance with the guidance provided
in Reference 3. Specifically, the supporting information must address
each area in sufficient detail as shown in the following ACCEPTANCE
CRITERIA:
a. The licensee must provide a justification that confirms that the
plant-specific PRA reflects the as-built, as-operated plant. This
should include a description of the licensee's data and
[[Page 18385]]
model update process, and the frequency of these activities. The
licensee should also describe how the plant/corporate PRA staff are
involved in (and/or made aware of) plant and operational/procedural
modifications.
b. The licensee must provide a summary description of the plant-
specific PRA updates and upgrades since the IPE and IPEEE.
c. The licensee must discuss their plant-specific PRA peer reviews
and/or any self-assessments performed (especially noting those
conducted per the Nuclear Energy Institute (NEI) industry peer review
guidelines, American Society of Mechanical Engineers (ASME) (PRA
Standard, and Regulatory Guide (RG) 1.201), their overall conclusions,
any F&Os applicable to this application, and the licensee's evaluation
and resolution (e.g., by implementing model changes and/or sensitivity
studies) of these F&Os to demonstrate the conclusions of the plant-
specific analyses for this application are not adversely impacted
(i.e., continued acceptability of the proposed extension of the CSS
CT).
d. The licensee must describe their plant-specific PRA
configuration control (quality assurance) program and associated
procedures.
e. The licensee must make an overall determination of the adequacy
of their plant-specific PRA, confirming it is adequate with respect to
this application.]
3. Attachment 3 provides supporting information verifying that the
plant risk impact associated with external events (e.g., fires,
seismic, tornados, high winds, etc.) does not adversely impact the
conclusions of the plant-specific analyses for this application.
[EXPECTATIONS: The licensee's submittal must discuss the plant
risks associated with external events and specifically identify
(quantitatively and qualitatively, as appropriate) the impact of CSS CT
extension on the risks associated with external events.
If the licensee has performed updated analyses of an external event
since the staff review and acceptance of their IPEEE, the licensee must
describe the significant changes involved in their updated analyses and
the impact of these changes on plant risk associated with this external
event.
For external events in which the licensee used a screening approach
in their IPEEE to screen the external event from further consideration,
the licensee must specifically identify these external events and
provide confirmation that the screening took no credit for CSS
availability/reliability (e.g., fire conditional core damage
probability (CCDP) models/calculations did not include CSS failure
rates or unavailabilities) and confirm that the screening is still
appropriate, especially considering plant/procedural modifications
since the screening analyses were performed.
If, however, an external event was screened from consideration and
part of the screening took credit for the availability/reliability of
the CSS, or if plant/procedural modifications have occurred such that
the external event would no longer be screened out, then the licensee
must provide an analysis of the existing condition which also considers
the change in impact due to the requested CT extension.
ACCEPTANCE CRITERIA: For external events for which the licensee has
a PRA, the licensee must provide the risk values (i.e., CDF and LERF)
associated with the specifically analyzed external events and the
change in risk (i.e., [Delta]CDF, [Delta]LERF, ICCDP, and ICLERP)
associated with the CSS CT extension. The licensee must also provide
the total risk and total change in risk due to all PRA-analyzed
contributors (combining internal events, internal flooding, external
events, and shutdown PRA results) and this total contribution must meet
References 3 and 4 acceptance guidelines for the NRC staff to conclude
the quantified risk associated with the extension request is
acceptable.
For external events for which the licensee does not have a PRA (and
it is not screened out as above), but rather relies on a non-PRA method
(e.g., seismic margins analysis (SMA) or fire-induced vulnerability
evaluation (FIVE)), to determine if the plant risk is acceptable, the
licensee must confirm that there were and still are no vulnerabilities
or outliers associated with these external events, or identify any
vulnerabilities or outliers that were identified in their documented
analyses (most likely in their IPEEE) and confirm that all of these
vulnerabilities or outliers have been resolved and, as needed, the
appropriate plant/procedural modifications have been implemented as
described in their documented analyses.]
4. Supporting information is provided in Attachment 4, consistent
with the evaluation summary and conclusions (Sections 7 and 8) provided
in Reference 2, that discusses implementation of procedures that
prohibit entry into an extended CSS CT for scheduled maintenance
purposes if external event conditions or warnings (e.g., severe weather
warnings for ice, tornados, high winds, etc.) are in effect.
[LICENSEE'S] discussion confirms that [PLANT NAME'S] procedures include
compensatory measures and normal plant practices that help avoid
potentially high risk configurations during the proposed extension of
the CSS CT. This supporting information must also address the Tier 2
aspects of Reference 4.
[EXPECTATIONS: The licensee's submittal must discuss (including
licensee commitments related to) implementation of procedures that
prohibit entry into an extended CSS CT for scheduled maintenance
purposes if external event conditions or warnings are in effect. If the
licensee does not want to implement this prohibition for specific
severe weather conditions or warnings, the licensee must explicitly
identify these event conditions/warnings and provide a justification
for not including them.
The licensee must also confirm that their procedures include
compensatory measures and normal plant practices that help avoid
potentially high risk configurations during the proposed extension of
the CSS CT. This supporting information must also address the Tier 2
aspects of Reference 4. The Tier 2 evaluation is meant to be an early
evaluation (at the license submittal stage) to identify and preclude
potentially high-risk plant configurations that could result if
equipment, in addition to that associated with the proposed license
amendment, is taken out of service simultaneously, or if other risk-
significant operational factors, such as concurrent system or equipment
testing, are also involved.
ACCEPTANCE CRITERIA: The Tier 2 evaluation needs to identify, as
part of the licensee's submittal, potentially high-risk plant
configurations that need to be precluded and identify how this is
implemented (i.e., typically these aspects result in licensees
establishing compensatory measures/commitments to ensure these
configurations are precluded). If, in conducting the evaluation, the
licensee identifies no high-risk plant configurations, then the
licensee needs to explicitly state this fact.]
5. Attachment 5 provides supporting information, consistent with
the evaluation summary and conclusions (Sections 7 and 8) provided in
Reference 2, that describes the plant-specific risk-informed CRMP to
assess the risk associated with the removal of equipment from service
during the extended CSS CT. In this description, [LICENSEE] confirms
that the program provides the necessary assurances that appropriate
assessments of plant risk configurations are sufficient to support
[[Page 18386]]
the proposed CSS CT extension request. This supporting information also
addresses the Tier 3 aspects of Reference 4.
[EXPECTATIONS/ACCEPTANCE CRITERIA: The licensee's submittal must
describe their CRMP, including how it reflects the current plant PRA
model (specifically identifying any deviations and simplifications in
the CRMP model from the plant-specific PRA model) and how the CRMP is
updated to remain consistent with the plant-specific PRA.
The licensee's submittal must also describe how the CRMP provides
the necessary assurances that appropriate assessments of plant risk
configurations are sufficient to support the proposed CT extension
request for the CSS.
Finally, the licensee's submittal must address the Tier 3 aspects
of Reference 4, including the description of the CRMP, and must confirm
that their CRMP meets all aspects of Section 2.3.7 of Reference 4,
specifically describing how their CRMP meets each of the four Key
Components identified in this Section. The Tier 3 evaluation ensures
that the CRMP is adequate when maintenance is about to commence, as
opposed to the early (submittal stage) evaluation performed for Tier
2.]
6. Attachment 6 provides supporting information, consistent with
the evaluation summary (Section 7) provided in Reference 2, confirming
that the licensee's CRMP will not allow ``at power'' maintenance of the
CSS and shutdown cooling system (SDCS) at the same time since the SDCS
may be credited as a backup to CSS in supporting the containment spray
function. Similarly, supporting information is provided confirming that
the licensee's CRMP will ensure there is at least one CSS pump operable
when maintenance of the CSS is performed in the lower modes of
operation since CSS pumps are a backup to the SDCS pumps.
[EXPECTATION: The licensee's submittal must describe the
relationship/interfaces between the CSS and SDCS.
ACCEPTANCE CRITERIA: If the SDCS can be used as a backup to the
CSS, then the licensee must confirm that ``at power'' maintenance of
the CSS and SDCS will not be allowed at the same time and describe how
this is controlled (e.g., specifically identified in the CRMP as a
configuration that is not allowed). If the SDCS cannot be used (and is
not credited) as a backup to CSS, then the licensee needs to explicitly
state this fact.
If CSS pumps can be used as a backup to the SDCS pumps, then the
licensee must confirm that at least one CSS pump is required to be
operable when maintenance of the CSS is performed in lower modes of
operation and must describe how this is controlled. If CSS pumps cannot
be used (and are not credited) as a backup to SDCS pumps in lower modes
of operation, then the licensee needs to explicitly state this fact.]
7. Attachment 7 provides supporting information confirming that the
licensee's CRMP assessing Reference 3 and 4 risk acceptance guideline
metrics, including [Delta]CDF, [Delta]LERF, ICCDP, and ICLERP,
continues to be met for the CSS extended CT.
[EXPECTATIONS/ACCEPTANCE CRITERIA: The licensee must confirm that
their CRMP quantitative model calculates [Delta]CDF, [Delta]LERF,
ICCDP, and ICLERP and that their CRMP quantitative model explicitly
models the CSS or has been modified to include the CSS, which will be
used whenever CSS components are made unavailable.
The licensee also must describe how their CRMP ensures Reference 3
and 4 acceptance guidelines continue to be met during implementation
and must describe the actions that are taken if the above calculated
metrics exceed the associated Reference 3 and 4 acceptance guidelines
during CRMP implementation (i.e., plant-specific Tier 3/Maintenance
Rule results exceed acceptance guidelines).]
8. Attachment 8 provides information addressing how plant-specific
systems, structures and components (SSC) reliability and availability
are monitored and assessed at the plant under the Maintenance Rule
(i.e. 10 CFR 50.65) to confirm that performance continues to be
consistent with the analyses used to justify the extended CT and that
the risk-informed decision remains valid through implementation.
[EXPECTATIONS/ACCEPTANCE CRITERIA: The licensee must describe how
plant-specific SSC reliability and availability are monitored and
assessed at the plant under the Maintenance Rule (i.e., 10 CFR 50.65)
to confirm that performance continues to be consistent with the
analyses used to justify the extended CT. In providing this
description, the licensee should also indicate how they periodically
assess previous risk-informed licensing action decisions to ensure that
these decisions remain valid (i.e., continue to meet the Reference 3
and Reference 4 acceptance guidelines) for the current plant operations
and plant-specific PRA and what actions they take if a previously-
approved risk-informed licensing action decision is determined to no
longer meet these acceptance guidelines.]
4.2.2 Regulatory Commitment
The Reference 4 Tier 3 program ensures that, while the plant is
following the TS ACTIONS associated with an extended CT for restoring
an inoperable CSS to operable status, additional activities will not be
performed that could further degrade the capabilities of the plant to
respond to a condition that the inoperable CSS is designed to mitigate
and, as a result, increase plant risk beyond that determined by the
Reference 1 analyses. [LICENSEE's] implementation of Reference 4 Tier 3
guidelines generally implies the assessment of risk with respect to
CDF. However, the proposed CSS extended CT impacts accident sequences
that can be mitigated following core damage and, consequently, impacts
LERF as well as CDF. Therefore, [LICENSEE] has enhanced its CRMP,
[OPTIONAL: as implemented under 10 CFR 50.65(a)(4), the Maintenance
Rule,] to include a LERF methodology and assessment.
5.0 Regulatory Analysis
5.1 No Significant Hazards Consideration
[LICENSEE] has reviewed the proposed no significant hazards
consideration determination published in the Federal Register on [DATE]
([ ] FR [ ]) as part of the CLIIP. [LICENSEE] has concluded that the
proposed determination presented in the notice is applicable to [PLANT
NAME] and the determination is hereby incorporated by reference to
satisfy the requirements of 10 CFR 50.91(a).
5.2 Applicable Regulatory Requirements/Criteria
Based on its answers to the Section 4.2.1 questions provided in
Attachments 1 through 8 to this application [LICENSEE] determines that
the information provided in this application is consistent with
Reference 2. This determination is based on the following:
1. The traditional engineering evaluation reveals that the loss of
one CSS train is well within [PLANT NAME's] design basis analyses.
2. By meeting the conditions identified in Section 4.2.1,
[LICENSEE] believes that its PRA model is acceptable for this
application and also concludes that there is minimal impact of the CT
extensions for the CSS system on plant operational risk (Tier 1
evaluation).
3. By meeting the conditions identified in Section 4.2.1,
[LICENSEE] will ensure that its implementation will identify
potentially high risk configurations and the need for any
[[Page 18387]]
additional constraints or compensatory actions that, if implemented,
would avoid or reduce the probability of a risk-significant
configuration (Tier 2 evaluation).
4. By meeting the conditions identified in Section 4.2.1, [PLANT
NAME] will ensure that its risk-informed CRMP will satisfactorily
assess the risk associated with the removal of equipment from service
during the proposed CSS CT (Tier 3 evaluation) and the CRMP and plant
risk will be managed by plant procedures.
In conclusion, based on the considerations discussed above, (1)
there is reasonable assurance that the health and safety of the public
will not be endangered by operation in the proposed manner, (2) such
activities will be conducted in compliance with the Commission's
regulations, and (3) the issuance of the amendment will not be inimical
to the common defense and security or to the health and safety of the
public.
6.0 Environmental Consideration
[LICENSEE] has reviewed the environmental evaluation included in
the model safety evaluation as part of the CLIIP. [LICENSEE] concluded
that the staff's findings presented in the evaluation are applicable to
[PLANT NAME] and the evaluation is hereby incorporated by reference for
this application.
7.0 References
[Licensee should include an applicable list of references,
including but not limited to]
1. Joint Applications Report: Modification to the Containment
Spray System, and Low Pressure Safety Injection System Technical, CE
Owners Group, CE NPSD-1045, March 2000.
2. Safety Evaluation by the Office of Nuclear Reactor Regulation
Related to CE Owners Group CE NPSD-1045, ``Joint Application Report,
Modification to the Containment Spray System, and the Low Pressure
Safety Injection System Technical Specifications, December 21, 1999.
3. USNRC Regulatory Guide 1.174, ``An Approach for Using
Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-
Specific Changes to the Licensing Basis,'' Revision 1, November
2002.
4. USNRC Regulatory Guide 1.177, ``An Approach for Plant-
Specific, Risk-Informed Decisionmaking: Technical Specifications,''
August 1998.
5. NUREG-0800, ``Standard Review Plan for the Review of Safety
Analysis Reports for Nuclear Power Plants,'' June 1996.
Proposed Technical Specification Changes (Mark-Up)--Enclosure 2
Changes To TS Bases--Enclosure 3
Condition (1) [Licensee's] Evaluation and Supporting Information--
Attachment 1
Condition (2) [Licensee's] Evaluation and Supporting Information--
Attachment 2
Condition (3) [Licensee's] Evaluation and Supporting Information--
Attachment 3
Condition (4) [Licensee's] Evaluation and Supporting Information--
Attachment 4
Condition (5) [Licensee's] Evaluation and Supporting Information--
Attachment 5
Condition (6) [Licensee's] Evaluation and Supporting Information--
Attachment 6
Condition (7) [Licensee's] Evaluation and Supporting Information--
Attachment 7
Condition (8) [Licensee's] Evaluation and Supporting Information--
Attachment 8
Model Safety Evaluation
U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor
Regulation
Consolidated Line Item Improvement; Technical Specification Task Force
TSTF-409, Revision 2; ``Containment Spray System Completion Time
Extension''
1.0 Introduction
By letter to the Nuclear Regulatory Commission (NRC, Commission)
dated [DATE] (Agencywide Documents Access and Management System (ADAMS)
Accession Number MLXXXXXXXXX), [LICENSEE] (the licensee) requested
changes to the Technical Specifications (TSs) for [PLANT NAME]. The
proposed changes would revise TS 3.6.6A, ``Containment Spray and
Cooling Systems,'' by extending from 72 hours to seven days the
completion time (CT) to restore an inoperable containment spray system
(CSS) train to operable status, and would add a Condition describing
the required action and CT when one CSS and one containment cooling
system (CCS) are inoperable.
The changes are based on Technical Specification Task Force (TSTF)
Change Traveler, TSTF-409, Revision 2 (Rev. 2), ``Containment Spray
System Completion Time Extension (CE NPSD-1045-A)'' and associated TS
Bases. TSTF-409, Rev. 2, submitted to the NRC by the TSTF in a letter
dated November 10, 2003 (ADAMS Accession Number ML033280006), was
approved by the NRC on [DATE] and published in the Federal Register on
[DATE] ([] FR [ ]).
TSTF-409, Rev. 2 is based on Combustion Engineering Owner's Group
(CEOG) Joint Application Report CE NPSD-1045-A, ``Joint Applications
Report for Modifications to the Containment Spray System Technical
Specifications,'' dated March 2000 (Reference 1), as accepted by, and
subject to the limitations specified in, the associated NRC safety
evaluation (SE), dated December 21, 1999 (ADAMS Accession Number
ML993620241) (Reference 2).
In TSTF-409, Rev. 2, the CEOG states that the longer CT for
restoring an inoperable CSS train to operable status will enhance
overall plant safety by avoiding potential unscheduled plant shutdowns
and allowing greater availability of safety significant components
during shutdown. In addition the CEOG states that this extension
provides for increased flexibility in scheduling and performing
maintenance and surveillance activities in order to enhance plant
safety and operational flexibility during lower modes of operation.
2.0 Regulatory Evaluation
Since the mid-1980's, the NRC has been reviewing and granting
improvements to TS that are based, at least in part, on probabilistic
risk assessment (PRA) insights. In its final policy statement on TS
improvements dated July 22, 1993 (58 FR 39132), the NRC stated that it:
* * * expects that licensees, in preparing their Technical
Specification related submittals, will utilize any plant-specific
PSA [probabilistic safety assessment] \1\ or risk survey and any
available literature on risk insights and PSAs * * *. Similarly, the
NRC staff will also employ risk insights and PSAs in evaluating
Technical Specifications related submittals. Further, as a part of
the Commission's ongoing program of improving Technical
Specifications, it will continue to consider methods to make better
use of risk and reliability information for defining future generic
Technical Specification requirements.
---------------------------------------------------------------------------
\1\ PSA and PRA are used interchangeably herein.
The NRC reiterated this point when it issued the revision to 10 CFR
50.36, ``Technical Specifications,'' in July 1995. In August 1995, the
NRC adopted a final policy statement on the use of PRA methods in
nuclear regulatory activities that encouraged greater use of PRA to
improve safety decision-making and regulatory efficiency. The PRA
policy statement included the following points:
1. The use of PRA technology should be increased in all regulatory
matters to the extent supported by the state-of-the-art in PRA methods
and data, and in a manner that complements the NRC's deterministic
approach and supports the
[[Page 18388]]
NRC's traditional defense-in-depth philosophy.
2. PRA and associated analyses (e.g., sensitivity studies,
uncertainty analyses, and importance measures) should be used in
regulatory matters, where practical within the bounds of the state-of-
the-art, to reduce unnecessary conservatism associated with current
regulatory requirements.
3. PRA evaluations in support of regulatory decisions should be as
realistic as practicable and appropriate supporting data should be
publicly available for review.
In March 1998, the CEOG submitted a joint applications report for
the NRC staff's review entitled, ``Joint Applications Report for
Modifications to the Containment Spray System and Low Pressure Safety
System Technical Specifications.'' The NRC review accepting this joint
applications report for referencing in license applications for
Combustion Engineering (CE) plants, including appropriate exclusions,
conditions, and limitations, is documented in Reference 2. The final,
NRC-approved joint applications report, (Reference 1) is dated March
2000.
3.0 Technical Evaluation
The NRC staff evaluated the licensee's proposed amendment to extend
the TS CT for one CSS train out of service from 72 hours to seven days
using insights derived from traditional engineering considerations and
the use of PRA methods to determine the safety impact of extending the
CT.
3.1 Traditional Engineering Evaluation
The function of the containment heat removal systems under accident
conditions is to remove heat from the containment atmosphere, thus
maintaining the containment pressure and temperature at acceptably low
levels. The systems also serve to limit offsite radiation levels by
reducing the pressure differential between the containment atmosphere
and the external environment, thereby decreasing the driving force for
fission product leakage across the containment. The two containment
heat removal systems are the CCS and CSS. The CCS fan coolers are
designed to operate during both normal plant operations and under loss-
of-coolant accident (LOCA) or main steam line break (MSLB) conditions.
The CSS is designed to operate during accident conditions only.
The heat removal capacity of the CCS and CSS is sufficient to keep
the containment temperature and pressure below design conditions for
any size break, up to and including a double-ended break of the largest
reactor coolant pipe. The systems are also designed to mitigate the
consequences of any size break, up to and including a double-ended
break of a main steam line. The CCS and CSS continue to reduce
containment pressure and temperature and maintain them at acceptable
levels post-accident.
The CCS and CSS at [PLANT NAME] each consist of [Substitute plant-
specific configuration if it differs from the following description]
two redundant loops and are designed such that a single failure does
not degrade their ability to provide the required heat removal
capability. Two of four containment fan coolers and one CSS loop are
powered from one safety-related bus. The other two containment fan
coolers and CSS loop are powered from another independent safety
related bus. The loss of one bus does not affect the ability of the
containment heat removal systems to maintain containment temperature
and pressure below the design values in a post-accident mode.
The [PLANT NAME] CSS consists of [Substitute plant-specific
configuration if it differs from the following description] two
independent and redundant loops each containing a spray pump, shutdown
heat exchanger, piping, valves, spray headers, and spray nozzles. It
has two modes of operation, which are:
1. The injection mode, during which the system sprays borated water
from the refueling water tank (RWT) into the containment, and
2. The recirculation mode, which is automatically initiated by the
recirculation actuation signal (RAS) after low level is reached in the
RWT. During this mode of operation, the safety injection system (SIS)
sump provides suction for the spray pumps.
Containment spray is automatically initiated by the containment
spray actuation signal coincident with the safety injection actuation
signal and high containment pressure signal. If required, the operator
can manually activate the system from the main control room.
Each CSS pump, together with a CCS loop, provides the flow
necessary to remove the heat generated inside the containment following
a LOCA or MSLB. Upon system activation, the pumps are started, and
borated water flows into the containment spray headers. When low level
is reached in the RWT, sufficient water has been transferred to the
containment to allow for the recirculation mode of operation. Spray
pump suction is automatically realigned to the SIS sump upon a RAS.
During the recirculation mode, the spray water is cooled by the
shutdown heat exchangers prior to discharge into the containment. The
shutdown heat exchangers are cooled by the component cooling water
system. Post-LOCA pH control is provided by [Substitute plant-specific
configuration if it differs from the following description] trisodium
phosphate dodecahydrate, which is stored in stainless steel baskets
located in the containment near the SIS sump intake.
Based on a review of the design-basis requirements for the CSS, the
NRC staff concluded that the loss of one CSS train is well within the
design-basis analyses. The plant status with both CSS trains inoperable
is covered by TS 3.6.6A, ACTION G., which states:
[With] two containment spray trains inoperable or any
combination of three or more [CSS/CCS] trains inoperable, LCO
[Limiting Condition for Operation] 3.0.3 shall be entered
immediately.
ACTION G addresses the condition in which two CSS trains are
inoperable and requires restoration of at least one CSS train to
operable status within 1 hour or the plant be placed in hot shutdown in
6 hours and cold shutdown within the following 30 hours, with cold
shutdown being the acceptable end state. These requirements are
consistent with similar requirements elsewhere in the TS and,
therefore, are acceptable.
The plant status with one CSS train and one CCS train inoperable is
covered by TS 3.6.6A, action D, which states:
[With] one containment spray and one containment cooling train
inoperable, restore containment spray train to operable status
within 72 hours, or restore containment cooling train to operable
status within 72 hours.
ACTION D ensures that the iodine removal capabilities of the CSS
are available, along with 100 percent of the heat removal needs after
an accident. The supporting analyses performed in Reference 1 did not
evaluate the concurrent inoperabilities of one CSS train and one CCS
train. Therefore, the current CT of 72 hours is retained in Condition
D. The 72-hour CT was developed taking into account the redundant heat
removal capabilities afforded by combinations of the CSS and CCS, the
iodine removal function of the CSS, and the low probability of a DBA
occurring during this period.
3.2 Probabilistic Risk Assessment Evaluation
The proposed extension of the CSS CT from 72 hours to seven days
affects plant risk by impacting:
[[Page 18389]]
1. Accident sequences that can be prevented from leading to core
damage.
2. Accident sequences that can be mitigated following core damage.
The CSS therefore affects both core damage frequency (CDF) and
large early release frequency (LERF). This is because the CSS performs
the critical function of controlling containment temperature and
pressure to cool the reactor coolant system (RCS) inventory that is
spilled in the sump as a result of a LOCA (core damage prevention role)
and preventing the release of radionuclides subsequent to a core damage
event (core damage and radionuclide release mitigation role).
[The following paragraph will contain plant-specific information
based on the plant's ability to use the shutdown cooling system (SDCS)
as a backup to the CSS. The licensee should provide a plant-specific
system configuration description based on whether its SDCS can be used
as a backup to the CSS pump.]
The proposed CT extension also impacts the long-term cooling
function that can be provided by the SDCS following a small-break LOCA,
steam generator tube rupture (SGTR), or MSLB. If entry into the
extended CT is caused by a CSS pump outage, the plants with the ability
to use the SDCS as a backup to the CSS pump can still preserve the
spray function of the affected train. If, however, a SDCS heat
exchanger is removed from service, then both the CSS and SDCS
capability of the affected train would be lost unless cross-connect
capability with another unaffected system (e.g., service water) is
possible. However, this cross-connect capability should not be credited
unless it is proceduralized.
The NRC staff used a three-tiered approach to evaluate the plant-
specific risk impact associated with the proposed TS changes. The first
tier evaluates the plant-specific PRA model and the impact of the
proposed CT extension on plant operational risk. The second tier
addresses the need to preclude potentially high risk configurations by
identifying the need for any additional constraints or compensatory
actions that, if implemented, would avoid or reduce the probability of
a risk-significant configuration during the time when one CSS train is
out of service. The third tier evaluates the licensee's proposed
Configuration Risk Management Program (CRMP) to ensure that the
applicable plant configuration will be appropriately assessed from a
risk perspective before entering into, or during, the proposed CT.
In Reference 2, the NRC staff found that the risk analysis
methodology and approach used by the CEOG to estimate the risk impact
were reasonable. In its SE, the NRC staff also stated that, for most
plants that participated in the joint application report, the risk
impact can be shown to be consistent with the acceptance guidelines for
change in CDF ([Delta]CDF), change in LERF ([Delta]LERF), incremental
conditional core damage probability (ICCDP), and incremental large
early release frequency (ICLERP) specified in Regulatory Guide (RG)
1.174 (Reference 3) and RG 1.177 (Reference 4) and the associated
Standard Review Plan (SRP) Chapters 19.0 and 16.1 of NUREG-0800
(Reference 5). However, not all CE plants participated in the joint
application report, and the estimated risk impacts for some plants
exceeded the Reference 3 and/or Reference 4 acceptance guidelines,
which would require additional justifications and/or compensatory
measures to be provided for these plants to be determined to have
acceptable risk impacts.
In Reference 2, the NRC staff also found that the Tier 2 and Tier 3
evaluations, as described in Reference 4, could not be approved
generically since they were not complete, which would require that each
individual plant-specific license amendment seeking approval through
TSTF-409, Rev. 2 would need to include an assessment with respect to
the Tier 2 and Tier 3 principles of Reference 4.
Based on the above discussion, the NRC staff identified conditions
that must be addressed in the licensee's plant-specific application
requesting adoption of TSTF-409, Revision 2. In its application dated
[DATE], [LICENSEE] provided supporting information for each of the
conditions which met the NRC staff's expectations and acceptance
criteria [with the following exceptions: list any exceptions to the
conditions stated in the model LAR].
3.2.1 Commitment
The Reference 4 Tier 3 program ensures that, while the plant is
following the TS ACTIONS associated with an extended CT for restoring
an inoperable CSS to operable status, additional activities will not be
performed that could further degrade the capabilities of the plant to
respond to a condition that the inoperable CSS is designed to mitigate
and, as a result, increase plant risk beyond that determined by the
Reference 1 analyses. A licensee's implementation of Reference 4 Tier 3
guidelines generally implies the assessment of risk with respect to
CDF. However, the proposed CSS extended CT impacts accident sequences
that can be mitigated following core damage and, consequently, LERF as
well as CDF. Therefore, [LICENSEE] enhanced its CRMP [optional: as
implemented under 10 CFR 50.65(a)(4), the Maintenance Rule,] to include
a LERF methodology and assessment.
3.3 Summary
Having met the conditions identified in the model license amendment
request (LAR), the NRC staff finds that the licensee's plant-specific
LAR is consistent with the previous NRC staff approval of Reference 1,
as documented in the Reference 2 and TSTF-409, Rev. 2, and thus is
acceptable. This determination is based on the following:
1. The traditional engineering evaluation reveals that the loss of
one CSS train is well within the design-basis analyses.
2. Based on the licensee meeting the conditions identified in the
model LAR, the NRC staff finds that there is minimal impact of the CT
extensions for the CSS system on plant operational risk (Tier 1
evaluation).
3. Meeting the conditions identified in the model LAR will ensure
that the licensee's implementation will identify potentially high risk
configurations and the need for any additional constraints or
compensatory actions that, if implemented, would avoid or reduce the
probability of a risk-significant configuration (Tier 2 evaluation).
4. Meeting the conditions identified in the model LAR will ensure
that the risk-informed CRMP proposed by the licensee will
satisfactorily assess the risk associated with the removal of equipment
from service during the proposed CSS CT (Tier 3 evaluation) and the
CRMP and plant risk will be managed by plant procedures.
4.0 Regulatory Commitment
The licensee's letter dated [DATE], contained the following
regulatory commitment: [state the licensee's commitment and ensure that
it satisfies the commitment in section 3.2.1 of this SE].
The NRC staff finds that reasonable controls for the implementation
and for subsequent evaluation of proposed changes pertaining to the
above regulatory commitment are best provided by the licensee's
administrative controls process, including its commitment management
program. The above regulatory commitment does not warrant the creation
of a license condition (item requiring prior NRC approval of subsequent
changes).
[[Page 18390]]
5.0 State Consultation
In accordance with the Commission's regulations, the [STATE] State
official was notified of the proposed issuance of the amendment[s]. The
State official had [CHOOSE ONE: (1) No comments, OR (2) the following
comments--with subsequent disposition by the staff].
6.0 Environmental Consideration
The amendment changes a requirement with respect to the
installation or use of a facility component located within the
restricted area as defined in 10 CFR Part 20. The NRC staff has
determined that the amendment involves no significant increase in the
amounts, and no significant change in the types, of any effluents that
may be released offsite, and that there is no significant increase in
individual or cumulative occupational radiation exposure. The
Commission has previously issued a proposed finding that the amendment
involves no significant hazards consideration, and there has been no
public comment on such finding [(XX FR XXXXX, dated Month DD, YYYY)].
Accordingly, the amendment meets the eligibility criteria for
categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10
CFR 51.22(b), no environmental impact statement or environmental
assessment need be prepared in connection with the issuance of the
amendment
7.0 Conclusion
The Commission has concluded, based on the considerations discussed
above, that (1) there is reasonable assurance that the health and
safety of the public will not be endangered by operation in the
proposed manner, (2) such activities will be conducted in compliance
with the Commission's regulations, and (3) the issuance of the
amendment will not be inimical to the common defense and security or to
the health and safety of the public.
8.0 References
1. Joint Applications Report: Modification to the Containment Spray
System, and Low Pressure Safety Injection System Technical, CE
Owners Group, CE NPSD-1045, March 2000.
2. SE by the Office of Nuclear Reactor Regulation Related to CE
Owners Group CE-NPSD-1045, ``Joint Application Report, Modification
to the Containment Spray System, and the Low Pressure Safety
Injection System Technical Specifications,'' December 21, 1999.
3. U.S. NRC RG 1.174, ``An Approach for Using Probabilistic Risk
Assessment in Risk-Informed Decisions on Plant-Specific Changes to
the Licensing Basis,'' Revision 1, November 2002.
4. U.S. NRC RG 1.177, ``An Approach for Plant-Specific, Risk-
Informed Decisionmaking: Technical Specifications,'' August 1998.
5. NUREG-0800, ``Standard Review Plan for the Review of Safety
Analysis Reports for Nuclear Power Plants,'' June 1996.
Model No Significant Hazards Consideration
Description of Amendment Request: The proposed amendment would
revise the technical specifications to extend the completion time (CT)
from 72 hours to seven days to restore an inoperable containment spray
system (CSS) train to operable status, and add a Condition describing
the required Actions and CT when one CSS and one containment cooling
system (CCS) are inoperable.
Basis for proposed no significant hazards consideration
determination: As required by 10 CFR 50.91(a), an analysis of the issue
of no significant hazards consideration is presented below:
1. Does the proposed change involve a significant increase in the
probability or consequences of an accident previously evaluated?
Response: No.
The proposed change extends from 72 hours to 7 days the CT for
restoring an inoperable CSS train to operable status. Being in an
ACTION is not an initiator of any accident previously evaluated.
Consequently, the probability of an accident previously evaluated is
not significantly increased. The consequences of an accident while
relying on ACTIONS during the extended CT are no different than the
consequences of an accident while relying on the ACTION during the
existing 72-hour CT. Therefore, the consequences of an accident
previously evaluated are not significantly increased by this change.
Therefore, this change does not involve a significant increase in the
probability or consequences of an accident previously evaluated.
2. Does the change create the possibility of a new or different
kind of accident from any accident previously evaluated?
Response: No.
The proposed change extends from 72 hours to 7 days the CT for
restoring an inoperable CSS train to operable status. The proposed
change does not involve a physical alteration of the plant (no new or
different type of equipment will be installed) or a change in the
methods governing normal plant operation. Thus, this change does not
create the possibility of a new or different kind of accident from any
accident previously evaluated.
3. Does the proposed change involve a significant reduction in a
margin of safety?
Response: No.
The proposed change extends from 72 hours to 7 days the CT for
restoring an inoperable CSS train to operable status. [LICENSEE]
performed risk-based evaluations using its plant-specific probabilistic
risk assessment (PRA) model in order to determine the effect of this
change on plant risk. The PRA evaluations were based on the conditions
stipulated in NRC staff safety evaluations approving both Joint
Applications Report CE NPSD-1045-A, ``Joint Applications Report,
Modifications to the Containment Spray System and The Low Pressure
Safety Injection System Technical Specifications,'' and Technical
Specification Task Force Change Traveler, TSTF-409, Revision 2,
``Containment Spray System Completion Time Extension (CE NPSD-1045-
A).'' The results of these plant-specific evaluations determined that
the effect of the proposed change on plant risk is very small.
Therefore, this change does not involve a significant reduction in a
margin of safety.
Based on the above, the proposed change involves no significant
hazards consideration under the standards set forth in 10 CFR 50.92(c),
and accordingly, a finding of no significant hazards consideration is
justified.
For the Nuclear Regulatory Commission.
Project Manager,
Plant Licensing Branch, Division of Operating Reactor Licensing,
Office of Nuclear Reactor Regulation.
[FR Doc. E6-5216 Filed 4-10-06; 8:45 am]
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