ML22240A101
| ML22240A101 | |
| Person / Time | |
|---|---|
| Issue date: | 06/26/2015 |
| From: | NRC/NRR/DSS/STSB |
| To: | |
| Craig Harbuck NRR/DSS 301-415-3140 | |
| Shared Package | |
| ML22240A001 | List:
|
| References | |
| Download: ML22240A101 (25) | |
Text
GTST AP1000-O51-3.7.11, Rev. 1 Date report generated:
Friday, June 26, 2015 Page 1 Advanced Passive 1000 (AP1000)
Generic Technical Specification Traveler (GTST)
Title:
Changes Related to LCO 3.7.11, Spent Fuel Pool Boron Concentration I.
Technical Specifications Task Force (TSTF) Travelers, Approved Since Revision 2 of STS NUREG-1431, and Used to Develop this GTST TSTF Number and
Title:
TSTF-425-A, Rev 3, Relocate Surveillance Frequencies to Licensee Control - RITSTF Initiative 5b STS NUREGs Affected:
TSTF-425-A, Rev 3: NUREGs 1430, 1431, 1432, 1433, and 1434 NRC Approval Date:
TSTF-425-A, Rev. 3: 06-Jul-09 TSTF Classification:
TSTF-425-A, Rev 3: Technical Change
GTST AP1000-O51-3.7.11, Rev. 1 Date report generated:
Friday, June 26, 2015 Page 2 II.
Reference Combined License (RCOL) Standard Departures (Std. Dep.), RCOL COL Items, and RCOL Plant-Specific Technical Specifications (PTS) Changes Used to Develop this GTST RCOL Std. Dep. Number and
Title:
There are no Vogtle departures applicable to Specification 3.7.11.
RCOL COL Item Number and
Title:
There are no Vogtle COL items applicable to Specification 3.7.12.
RCOL PTS Change Number and
Title:
VEGP LAR DOC A003: References to various Chapters and Sections of the Final Safety Analysis Report (FSAR) are revised to include FSAR.
VEGP LAR DOC A105: TS 3.7.11 Applicability and Required Action A.2.2 are revised VEGP LAR DOC A109: TS 3.7.11 Applicability is revised VEGP LAR DOC L05:
TS LCO 3.0.8 is eliminated
GTST AP1000-O51-3.7.11, Rev. 1 Date report generated:
Friday, June 26, 2015 Page 3 III.
Comments on Relations Among TSTFs, RCOL Std. Dep., RCOL COL Items, and RCOL PTS Changes This section discusses the considered changes that are: (1) applicable to operating reactor designs, but not to the AP1000 design; (2) already incorporated in the GTS; or (3) superseded by another change.
TSTF-425-A deferred for future consideration.
GTST AP1000-O51-3.7.11, Rev. 1 Date report generated:
Friday, June 26, 2015 Page 4 IV.
Additional Changes Proposed as Part of this GTST (modifications proposed by NRC staff and/or clear editorial changes or deviations identified by preparer of GTST)
Minor corrections were made to correct grammatical errors in the bases.
APOG Recommended Changes to Improve the Bases Revise the second sentence of the Background section of the Bases to state:
... For storage of fuel in the spent fuel racks, the design basis for preventing criticality outside the reactor is that there is a 95% percent probability at a 95%
percent confidence level, without soluble boron, that the effective multiplication factor (keff) of the fuel assembly array will be less than 0.997, including uncertainties and tolerances....
This non-technical change provides improved clarity, consistency, and operator usability.
Throughout the Bases, references to Sections and Chapters of the FSAR do not include the FSAR clarifier. Since these Section and Chapter references are to an external document, it is appropriate to include the FSAR modifier. (DOC A003)
GTST AP1000-O51-3.7.11, Rev. 1 Date report generated:
Friday, June 26, 2015 Page 5 V.
Applicability Affected Generic Technical Specifications and Bases:
Section 3.7.11, Spent Fuel Storage Pool Boron Concentration Changes to the Generic Technical Specifications and Bases:
The GTS 3.7.11 LCO header, title and Specification statement are revised to provide consistent terminology for the Spent Fuel Pool system. (DOC A105)
The GTS 3.7.11 Applicability statement is revised and formatted. (DOC A105 and DOC A109)
The GTS 3.7.11 Action Note is revised to eliminate reference to AP1000 GTS LCO 3.0.8.
(DOC L05)
GTS 3.7.11 Condition A and associated Required Actions are revised to provide consistent terminology for the Spent Fuel Pool system. (DOC A105)
GTS SR 3.7.11.1 is revised to provide consistent terminology for the Spent Fuel Pool system.
(DOC A105)
The second sentence of the Background section of the Bases is revised to improve clarity, consistency, and operator usability. (APOG Comment)
The acronym FSAR is added to modify Section and Chapter in references to the FSAR throughout the Bases. (DOC A003) (APOG Comment)
GTST AP1000-O51-3.7.11, Rev. 1 Date report generated:
Friday, June 26, 2015 Page 6 VI.
Traveler Information Description of TSTF changes:
Not Applicable Rationale for TSTF changes:
Not Applicable Description of changes in RCOL Std. Dep., RCOL COL Item(s), and RCOL PTS Changes:
DOC A105 revises phrase Fuel Storage Pool Boron Concentration, to Spent Fuel Pool Boron Concentration throughout the GTS 3.7.11 LCO Specification and bases.
DOC A109 corrects the format of the Applicability statement.
DOC L05 removes reference to AP1000 GTS LCO 3.0.8, which is eliminated.
A more detailed description of each DOC can be found in Reference 2, VEGP TSU LAR, and the NRC staff safety evaluation can be found in Reference 3, VEGP LAR SER. The VEGP TSU LAR was modified in response to NRC staff RAIs in Reference 5 and the Southern Nuclear Operating Company RAI Response in Reference 6.
Rationale for changes in RCOL Std. Dep., RCOL COL Item(s), and RCOL PTS Changes:
DOC A105 provides consistent terminology with respect to the Spent Fuel Pool.
DOC A109 is consistent with the TS Writer's Guide (Reference 4).
DOC L05 notes that considerations of AP1000 GTS LCO 3.0.8 are adequately addressed within individual LCO referencing GTS LCO 3.0.8 or by TS 5.4.1.b to Monitor Safety System Shutdown Monitoring Trees parameters. AP1000 GTS LCO 3.0.8 is eliminated.
Description of additional changes proposed by NRC staff/preparer of GTST:
The second sentence of the Background section of the Bases is revised to state (APOG Comment):
... For storage of fuel in the spent fuel racks, the design basis for preventing criticality outside the reactor is that there is a 95% percent probability at a 95%
percent confidence level, without soluble boron, that the effective multiplication factor (keff) of the fuel assembly array will be less than 0.997, including uncertainties and tolerances....
The acronym FSAR is added to modify Section and Chapter in references to the FSAR throughout the Bases. (DOC A003) (APOG Comment)
GTST AP1000-O51-3.7.11, Rev. 1 Date report generated:
Friday, June 26, 2015 Page 7 Rationale for additional changes proposed by NRC staff/preparer of GTST:
These changes are to correct grammatical errors in the bases.
The non-technical changes to the Background section of the Bases provide improved clarity, consistency, and operator usability.
Since Bases references to FSAR Sections and Chapters are to an external document, it is appropriate to include the FSAR modifier.
GTST AP1000-O51-3.7.11, Rev. 1 Date report generated:
Friday, June 26, 2015 Page 8 VII. GTST Safety Evaluation Technical Analysis:
DOC L05 eliminates GTS LCO 3.0.8. In conjunction with the change to eliminate LCO 3.0.8, all Notes and references are no longer necessary and are administratively eliminated. The elimination of GTS LCO 3.0.8 is discussed in detail in GTS O01-LCO 3.0.
The remaining changes are editorial, clarifying, grammatical, or otherwise considered administrative. These changes do not affect the technical content, but improve the readability, implementation, and understanding of the requirements, and are therefore acceptable.
Having found that this GTSTs proposed changes to the GTS and Bases are acceptable, the NRC staff concludes that AP1000 STS Subsection 3.7.11 is an acceptable model Specification for the AP1000 standard reactor design.
References to Previous NRC Safety Evaluation Reports (SERs):
None
GTST AP1000-O51-3.7.11, Rev. 1 Date report generated:
Friday, June 26, 2015 Page 9 VIII. Review Information Evaluator Comments:
None Randy Belles Oak Ridge National Laboratory 865-574-0388 bellesrj@ornl.gov Review Information:
Availability for public review and comment on Revision 0 of this traveler approved by NRC staff on 5/19/2014.
APOG Comments (Ref. 7) and Resolutions:
- 1.
(Internal # 3) Throughout the Bases, references to Sections and Chapters of the FSAR do not include the FSAR clarifier. Since these Section and Chapter references are to an external document, it is appropriate (DOC A003) to include the FSAR modifier. This is resolved by adding the FSAR modifier as appropriate.
- 2.
(Internal # 6) The GTST sections often repeat VEGP LAR DOCs, which reference existing and current requirements. The inclusion in the GTST of references to existing and current, are not always valid in the context of the GTS. Each occurrence of existing and current should be revised to be clear and specific to GTS, MTS, or VEGP COL TS (or other), as appropriate. Noted ambiguities are corrected in the GTST body.
- 3.
(Internal # 7)Section VII, GTST Safety Evaluation, inconsistently completes the subsection References to Previous NRC Safety Evaluation Reports (SERs) by citing the associated SE for VEGP 3&4 COL Amendment 13. It is not clear whether there is a substantive intended difference when omitting the SE citation. This is resolved by removing the SE citation in Section VII of the GTST and ensuring that appropriate references to the consistent citation of this reference in Section X of the GTST are made.
- 4.
(Internal #13) Many GTSTs evaluated TSTF-425 with the following note: Risk-informed TS changes will be considered at a later time for application to the AP1000 STS.
The NRC approval of TSTF-425, and model safety evaluation provided in the CLIIP for TSTF-425, are generically applicable to any designs Technical Specifications. As such, the replacement of certain Frequencies with a Surveillance Frequency Control Program should be included in the GTST for AP1000 STS NUREG.
However, implementation in the AP1000 STS should not reflect optional (i.e., bracketed) material showing retention of fixed Surveillance Frequencies where relocation to a Surveillance Frequency Control Program is acceptable. Since each represented AP1000 Utility is committed to maintaining standardization, there is no rationale for an AP1000 STS that includes bracketed options.
GTST AP1000-O51-3.7.11, Rev. 1 Date report generated:
Friday, June 26, 2015 Page 10 Consistent with TSTF-425 criteria, replace applicable Surveillance Frequencies with In accordance with the Surveillance Frequency control Program and add that Program as new AP1000 STS Specification 5.5.15.
NRC Staff disagreed with implementing TSTF-425 in the initial version of the STS.
Although the APOG thinks the analysis supporting this traveler is general enough to be applicable to AP1000, staff thinks an AP1000-specific proposal from APOG is needed to identify any GTS SRs that should be excluded. Also, with the adoption of a Surveillance Frequency Control Program (SFCP) in the AP1000 STS, bracketed Frequencies, which provide a choice between the GTS Frequency and the SFCP Frequency, are needed because the NRC will use the AP1000 STS as a reference, and to be consistent with NUREG-1431, Rev. 4. APOG was requested to consider proposing an AP1000 version of TSTF-425 for a subsequent revision of the STS.
- 5.
(Internal # 440) In the Background section of the Bases, revise the second sentence as follows:
... For storage of fuel in the spent fuel racks, the design basis for preventing criticality outside the reactor is that there is a 95% percent probability at a 95% percent confidence level, without soluble boron, that the effective multiplication factor (keff) of the fuel assembly array will be less than 0.997, including uncertainties and tolerances....
This non-technical change provides improved clarity, consistency, and operator usability.
This is resolved by making the recommended change.
NRC Final Approval Date: June 26, 2015 NRC
Contact:
T. R. Tjader United States Nuclear Regulatory Commission 301-415-1187 Theodore.Tjader@nrc.gov
GTST AP1000-O51-3.7.11, Rev. 1 Date report generated:
Friday, June 26, 2015 Page 11 IX.
Evaluator Comments for Consideration in Finalizing Technical Specifications and Bases None
GTST AP1000-O51-3.7.11, Rev. 1 Date report generated:
Friday, June 26, 2015 Page 12 X.
References Used in GTST
- 1.
AP1000 DCD, Revision 19, Section 16, Technical Specifications, June 2011 (ML11171A500).
- 2.
Southern Nuclear Operating Company, Vogtle Electric Generating Plant, Units 3 and 4, Technical Specifications Upgrade License Amendment Request, February 24, 2011 (ML12065A057).
- 3.
NRC Safety Evaluation (SE) for Amendment No. 13 to Combined License (COL) No. NPF-91 for Vogtle Electric Generating Plant (VEGP) Unit 3, and Amendment No. 13 to COL No.
NPF-92 for VEGP Unit 4, September 9, 2013, ADAMS Package Accession No. ML13238A337, which contains:
ML13238A355 Cover Letter - Issuance of License Amendment No. 13 for Vogtle Units 3 and 4 (LAR 12-002).
ML13238A359 - Amendment No. 13 to COL No. NPF-91 ML13239A256 - Amendment No. 13 to COL No. NPF-92 ML13239A284 Enclosure 3 - Revised plant-specific TS pages (Attachment to Amendment No. 13)
ML13239A287 - Safety Evaluation (SE), and Attachment 1 - Acronyms ML13239A288 SE Attachment 2 - Table A - Administrative Changes ML13239A319 SE Attachment 3 - Table M - More Restrictive Changes ML13239A333 SE Attachment 4 - Table R - Relocated Specifications ML13239A331 SE Attachment 5 - Table D - Detail Removed Changes ML13239A316 SE Attachment 6 - Table L - Less Restrictive Changes The following documents were subsequently issued to correct an administrative error in :
ML13277A616 Letter - Correction To The Attachment (Replacement Pages) - Vogtle Electric Generating Plant Units 3 and 4-Issuance of Amendment Re:
Technical Specifications Upgrade (LAR 12-002) (TAC No. RP9402)
ML13277A637 - Revised plant-specific TS pages (Attachment to Amendment No. 13) (corrected)
- 4.
TSTF-GG-05-01, Writer's Guide for Plant-Specific Improved Technical Specifications, June 2005.
- 5.
RAI Letter No. 01 Related to License Amendment Request (LAR)12-002 for the Vogtle Electric Generating Plant Units 3 and 4 Combined Licenses, September 7, 2012 (ML12251A355).
- 6.
Southern Nuclear Operating Company, Vogtle Electric Generating Plant, Units 3 and 4, Response to Request for Additional Information Letter No. 01 Related to License Amendment Request LAR-12-002, ND-12-2015, October 04, 2012 (ML12286A363 and ML12286A360)
GTST AP1000-O51-3.7.11, Rev. 1 Date report generated:
Friday, June 26, 2015 Page 13
- 7.
APOG-2014-008, APOG (AP1000 Utilities) Comments on AP1000 Standardized Technical Specifications (STS) Generic Technical Specification Travelers (GTSTs), Docket ID NRC-2014-0147, September 22, 2014 (ML14265A493).
GTST AP1000-O51-3.7.11, Rev. 1 Date report generated:
Friday, June 26, 2015 Page 14 XI.
MARKUP of the Applicable GTS Subsection for Preparation of the STS NUREG The entire section of the Specifications and the Bases associated with this GTST is presented next.
Changes to the Specifications and Bases are denoted as follows: Deleted portions are marked in strikethrough red font, and inserted portions in bold blue font.
GTST AP1000-O51-3.7.11, Rev. 1 Spent Fuel Storage Pool Boron Concentration 3.7.11 AP1000 STS 3.7.11-1 Amendment 0Rev. 0 Revision 19 Date report generated:
Friday, June 26, 2015 Page 15 3.7 PLANT SYSTEMS 3.7.11 Spent Fuel Storage Pool Boron Concentration LCO 3.7.11 The spent fuel storage pool boron concentration shall be 2300 ppm.
APPLICABILITY:
When fuel assemblies are stored in the spent fuel storage pool and a spent fuel storage pool storage verification has not been performed since the last movement of fuel assemblies in the spent fuel storage pool.
ACTIONS
NOTE-----------------------------------------------------------
LCOs 3.0.3 is and 3.0.8 are not applicable.
CONDITION REQUIRED ACTION COMPLETION TIME A. Spent fuel Fuel storage pool boron concentration not within limit.
A.1 Suspend movement of fuel assemblies in the spent fuel storage pool.
AND Immediately A.2.1 Initiate action to restore spent fuel storage pool boron concentration to within limit.
OR Immediately A.2.1 Initiate action to perform a spent fuel storage pool storage verification.
Immediately
GTST AP1000-O51-3.7.11, Rev. 1 Spent Fuel Storage Pool Boron Concentration 3.7.11 AP1000 STS 3.7.11-2 Amendment 0Rev. 0 Revision 19 Date report generated:
Friday, June 26, 2015 Page 16 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.7.11.1 Verify the spent fuel storage pool boron concentration is within limit.
7 days
GTST AP1000-O51-3.7.11, Rev. 1 Spent Fuel Storage Pool Boron Concentration B 3.7.11 AP1000 STS B 3.7.11-1 Amendment 0Rev. 0 Revision 19 Date report generated:
Friday, June 26, 2015 Page 17 B 3.7 PLANT SYSTEMS B 3.7.11 Spent Fuel Storage Pool Boron Concentration BASES BACKGROUND The water in the spent fuel storage pool normally contains soluble boron, which would result in large subcriticality margins under actual operating conditions. For storage of fuel in the spent fuel racks, the design basis for preventing criticality outside the reactor is that there is a 95% percent probability at a 95 % percent confidence level, without soluble boron, that the effective multiplication factor (keff) of the fuel assembly array will be less than 0.997, including uncertainties and tolerances. The NRC guidelines specify a limiting keff of 1.0 for normal storage in the absence of soluble boron. Therefore, the design is based on the use of unborated water, which maintains a subcritical condition (Ref. 1). The double contingency principle discussed in ANSI N-16.1-1975 and the April 1978 NRC letter (Ref. 2) allows credit for soluble boron under other abnormal or accident conditions, since only a single independent accident need be considered at one time. For example, the only accident scenario that has a potential for more than negligible positive reactivity effect is an inadvertent misplacement of a new fuel assembly. This accident has the potential for exceeding the limiting reactivity, should there be a concurrent and independent accident condition resulting in the loss of all soluble poison. To mitigate these postulated criticality related accidents, boron is dissolved in the pool water. Safe operation with unborated water and no movement of assemblies may, therefore, be achieved by controlling the location of each assembly in accordance with LCO 3.7.12, Spent Fuel Pool Storage. Prior to movement of an assembly, it is necessary to perform SR 3.7.12.1.
APPLICABLE SAFETY ANALYSES Although credit for the soluble boron normally present in the spent fuel pool water is permitted under abnormal or accident conditions, most abnormal or accident conditions will not result in exceeding the limiting reactivity even in the absence of soluble boron. The effects on reactivity of credible abnormal and accident conditions due to temperature increase, assembly dropped on top of a rack, and misplacement/misloading of a fuel assembly have been analyzed. The reactivity effects of bulk spent fuel pool temperature increase (>140°F) and steaming from the pool water surface or intramodule water gap reductions between the firmly interconnected cell and module arrays due to a seismic event are bounded by the fuel mishandling/misloading reactivity increases and therefore assessed as negligible. The spent fuel pool keff storage limit of 0.95 is maintained during these events by a
GTST AP1000-O51-3.7.11, Rev. 1 Spent Fuel Storage Pool Boron Concentration B 3.7.11 AP1000 STS B 3.7.11-2 Amendment 0Rev. 0 Revision 19 Date report generated:
Friday, June 26, 2015 Page 18 BASES APPLICABLE SAFETY ANALYSES (continued) minimum boron concentration of greater than or equal to 800 ppm established by criticality analysis (Ref. 3). Compliance with the LCO minimum boron concentration limit of 2300 ppm ensures that the credited concentration is always available.
The concentration of dissolved boron in the spent fuel storage pool satisfies Criterion 2 of 10 CFR 50.36(c)(2)(ii).
LCO The spent fuel storage pool boron concentration is required to be 2300 ppm. The specified concentration of dissolved boron in the spent fuel storage pool preserves the assumptions used in the analyses of the potential critical accident scenarios as described in References 1 and 3.
This concentration of dissolved boron is the minimum required concentration for fuel assembly storage and movement within the spent fuel storage pool.
APPLICABILITY This LCO applies whenever fuel assemblies are stored in the spent fuel storage pool and a spent fuel storage pool storage verification has not been performed since the last movement of fuel assemblies in the spent fuel storage pool.
ACTIONS LCO 3.0.3 is applicable while in MODE 1, 2, 3, or 4. Since spent fuel pool cooling requirements apply in all MODES when fuel is stored in the spent fuel storage pool, the ACTIONS have been modified by the Note stating that LCO 3.0.3 is not applicable. Spent fuel pool boron concentration requirements are independent of reactor operations.
Entering LCO 3.0.3 while in MODE 1, 2, 3, or 4 would require the unit to be shutdown unnecessarily.
LCO 3.0.8 is applicable while in MODE 5 or 6. Since spent fuel pool cooling requirements apply in all MODES when fuel is stored in the spent fuel storage pool, the ACTIONS have been modified by a Note stating that LCO 3.0.8 is not applicable. Spent fuel pool boron concentration requirements are independent of shutdown reactor operations. Entering LCO 3.0.8 while in MODE 5 or 6 would require the optimization of plant safety, unnecessarily.
GTST AP1000-O51-3.7.11, Rev. 1 Spent Fuel Storage Pool Boron Concentration B 3.7.11 AP1000 STS B 3.7.11-3 Amendment 0Rev. 0 Revision 19 Date report generated:
Friday, June 26, 2015 Page 19 BASES ACTIONS (continued)
A.1, A.2.1, and A.2.2 When the concentration of boron in the spent fuel storage pool is less than required, immediate action must be taken to preclude the occurrence of an accident or to mitigate the consequences of an accident in progress. This is most efficiently achieved by immediately suspending the movement of fuel assemblies. The concentration of boron is restored simultaneously with suspending movement of fuel assemblies. An acceptable alternative is to verify by administrative means that the spent fuel storage pool storage verification has been performed since the last movement of fuel assemblies in the spent fuel storage pool. However, prior to resuming movement of fuel assemblies, the concentration of boron must be restored. This does not preclude movement of a fuel assembly to a safe position.
SURVEILLANCE REQUIREMENTS SR 3.7.11.1 This SR verifies that the concentration of boron in the spent fuel storage pool is within the required limit. As long as this SR is met, the analyzed accidents are fully addressed. The 7 day Frequency is appropriate because no major replenishment of pool water is expected to take place over such a short period of time.
REFERENCES
- 1. FSAR Sections 9.1.2, Spent Fuel Storage and 15.7.4, Fuel Handling Accident.
- 2. Double contingency principle of ANSI N16.1 1975, as specified in the April 14, 1978 NRC letter (Section 1.2) and implied in the proposed revision to Regulatory Guide 1.13 (Section 1.4, Appendix A).
- 3. APP GW GLR 029P, AP1000 Spent Fuel Storage Racks Criticality Analysis, Westinghouse Electric Company LLC (Westinghouse Proprietary).
GTST AP1000-O51-3.7.11, Rev. 1 Date report generated:
Friday, June 26, 2015 Page 20 XII. Applicable STS Subsection After Incorporation of this GTSTs Modifications The entire subsection of the Specifications and the Bases associated with this GTST, following incorporation of the modifications, is presented next.
GTST AP1000-O51-3.7.11, Rev. 1 Spent Fuel Pool Boron Concentration 3.7.11 AP1000 STS 3.7.11-1 Rev. 0 Date report generated:
Friday, June 26, 2015 Page 21 3.7 PLANT SYSTEMS 3.7.11 Spent Fuel Pool Boron Concentration LCO 3.7.11 The spent fuel pool boron concentration shall be 2300 ppm.
APPLICABILITY:
When fuel assemblies are stored in the spent fuel pool and a spent fuel pool storage verification has not been performed since the last movement of fuel assemblies in the spent fuel pool.
ACTIONS
NOTE-----------------------------------------------------------
LCO 3.0.3 is not applicable.
CONDITION REQUIRED ACTION COMPLETION TIME A. Spent fuel pool boron concentration not within limit.
A.1 Suspend movement of fuel assemblies in the spent fuel pool.
AND Immediately A.2.1 Initiate action to restore spent fuel pool boron concentration to within limit.
OR Immediately A.2.1 Initiate action to perform a spent fuel pool storage verification.
Immediately
GTST AP1000-O51-3.7.11, Rev. 1 Spent Fuel Pool Boron Concentration 3.7.11 AP1000 STS 3.7.11-2 Rev. 0 Date report generated:
Friday, June 26, 2015 Page 22 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.7.11.1 Verify the spent fuel pool boron concentration is within limit.
7 days
GTST AP1000-O51-3.7.11, Rev. 1 Spent Fuel Pool Boron Concentration B 3.7.11 AP1000 STS B 3.7.11-1 Rev. 0 Date report generated:
Friday, June 26, 2015 Page 23 B 3.7 PLANT SYSTEMS B 3.7.11 Spent Fuel Pool Boron Concentration BASES BACKGROUND The water in the spent fuel pool normally contains soluble boron, which would result in large subcriticality margins under actual operating conditions. For storage of fuel in the spent fuel racks, the design basis for preventing criticality outside the reactor is that there is a 95%
probability at a 95 % confidence level, without soluble boron, that the effective multiplication factor (keff) of the fuel assembly array will be less than 0.997, including uncertainties and tolerances. The NRC guidelines specify a limiting keff of 1.0 for normal storage in the absence of soluble boron. Therefore, the design is based on the use of unborated water, which maintains a subcritical condition (Ref. 1). The double contingency principle discussed in ANSI N-16.1-1975 and the April 1978 NRC letter (Ref. 2) allows credit for soluble boron under other abnormal or accident conditions, since only a single independent accident need be considered at one time. For example, the only accident scenario that has a potential for more than negligible positive reactivity effect is an inadvertent misplacement of a new fuel assembly. This accident has the potential for exceeding the limiting reactivity, should there be a concurrent and independent accident condition resulting in the loss of all soluble poison.
To mitigate these postulated criticality related accidents, boron is dissolved in the pool water. Safe operation with unborated water and no movement of assemblies may, therefore, be achieved by controlling the location of each assembly in accordance with LCO 3.7.12, Spent Fuel Pool Storage. Prior to movement of an assembly, it is necessary to perform SR 3.7.12.1.
APPLICABLE SAFETY ANALYSES Although credit for the soluble boron normally present in the spent fuel pool water is permitted under abnormal or accident conditions, most abnormal or accident conditions will not result in exceeding the limiting reactivity even in the absence of soluble boron. The effects on reactivity of credible abnormal and accident conditions due to temperature increase, assembly dropped on top of a rack, and misplacement/misloading of a fuel assembly have been analyzed. The reactivity effects of bulk spent fuel pool temperature increase (>140°F) and steaming from the pool water surface or intramodule water gap reductions between the firmly interconnected cell and module arrays due to a seismic event are bounded by the fuel mishandling/misloading reactivity increases and therefore assessed as negligible. The spent fuel pool keff storage limit of 0.95 is maintained during these events by a
GTST AP1000-O51-3.7.11, Rev. 1 Spent Fuel Pool Boron Concentration B 3.7.11 AP1000 STS B 3.7.11-2 Rev. 0 Date report generated:
Friday, June 26, 2015 Page 24 BASES APPLICABLE SAFETY ANALYSES (continued) minimum boron concentration of greater than or equal to 800 ppm established by criticality analysis (Ref. 3). Compliance with the LCO minimum boron concentration limit of 2300 ppm ensures that the credited concentration is always available.
The concentration of dissolved boron in the spent fuel pool satisfies Criterion 2 of 10 CFR 50.36(c)(2)(ii).
LCO The spent fuel pool boron concentration is required to be 2300 ppm.
The specified concentration of dissolved boron in the spent fuel pool preserves the assumptions used in the analyses of the potential critical accident scenarios as described in References 1 and 3. This concentration of dissolved boron is the minimum required concentration for fuel assembly storage and movement within the spent fuel pool.
APPLICABILITY This LCO applies whenever fuel assemblies are stored in the spent fuel pool and a spent fuel pool storage verification has not been performed since the last movement of fuel assemblies in the spent fuel pool.
ACTIONS LCO 3.0.3 is applicable while in MODE 1, 2, 3, or 4. Since spent fuel pool cooling requirements apply in all MODES when fuel is stored in the spent fuel pool, the ACTIONS have been modified by the Note stating that LCO 3.0.3 is not applicable. Spent fuel pool boron concentration requirements are independent of reactor operations. Entering LCO 3.0.3 while in MODE 1, 2, 3, or 4 would require the unit to be shutdown unnecessarily.
A.1, A.2.1, and A.2.2 When the concentration of boron in the spent fuel pool is less than required, immediate action must be taken to preclude the occurrence of an accident or to mitigate the consequences of an accident in progress.
This is most efficiently achieved by immediately suspending the movement of fuel assemblies. The concentration of boron is restored simultaneously with suspending movement of fuel assemblies. An acceptable alternative is to verify by administrative means that the spent fuel pool storage verification has been performed since the last movement of fuel assemblies in the spent fuel pool. However, prior to resuming movement of fuel assemblies, the concentration of boron must
GTST AP1000-O51-3.7.11, Rev. 1 Spent Fuel Pool Boron Concentration B 3.7.11 AP1000 STS B 3.7.11-3 Rev. 0 Date report generated:
Friday, June 26, 2015 Page 25 BASES ACTIONS (continued) be restored. This does not preclude movement of a fuel assembly to a safe position.
SURVEILLANCE REQUIREMENTS SR 3.7.11.1 This SR verifies that the concentration of boron in the spent fuel pool is within the required limit. As long as this SR is met, the analyzed accidents are fully addressed. The 7 day Frequency is appropriate because no major replenishment of pool water is expected to take place over such a short period of time.
REFERENCES
- 1. FSAR Sections 9.1.2, Spent Fuel Storage and 15.7.4, Fuel Handling Accident.
- 2. Double contingency principle of ANSI N16.1 1975, as specified in the April 14, 1978 NRC letter (Section 1.2) and implied in the proposed revision to Regulatory Guide 1.13 (Section 1.4, Appendix A).
- 3. APP GW GLR 029P, AP1000 Spent Fuel Storage Racks Criticality Analysis, Westinghouse Electric Company LLC (Westinghouse Proprietary).