GNRO-2018/00029, Supplement to Application for Technical Specification Change Regarding Risk-Informed Justification for the Relocation of Specific Surveillance Frequency Requirements to a Licensee Controlled Program (TSTF-425)

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Supplement to Application for Technical Specification Change Regarding Risk-Informed Justification for the Relocation of Specific Surveillance Frequency Requirements to a Licensee Controlled Program (TSTF-425)
ML18158A514
Person / Time
Site: Grand Gulf Entergy icon.png
Issue date: 06/07/2018
From: Emily Larson
Entergy Operations
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
EPID L-2018-LLA-0106, GNRO-2018/00029
Download: ML18158A514 (39)
v • d • e


Text

  • Enterpv e:=u . b.J Entergy Operations, Inc.

P.O. Box756 Port Gibson, Mississippi 39150 Tel 601-437-7500 Eric A. Larson Site Vice President Grand Gulf Nuclear Station 10 CFR 50.90 GNR0-2018/00029 June 7, 2018 ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Washington, D. C. 20555

SUBJECT:

Supplement to Application for Technical Specification Change Regarding Risk-Informed Justification for the Relocation of Specific Surveillance Frequency Requirements to a Licensee Controlled Program (TSTF-425)

Grand Gulf Nuclear Station, Unit 1 Docket No. 50-416 License No. NPF-29

REFERENCES:

. 1. Letter from E.A. Larson (Entergy) to Document Control Desk (NRC) dated April 12, 2018, "Application for Technical Specification Change Regarding Risk..;lnformed Justification for the Relocation of-Specific Surveillance Frequency Requirements to a Licensee Controlled Program (TSTF-425)" (NRC Agencywide Documents Access and Management System (ADAMS) Accession No. ML181028445)

2. Letter from L. M. Regner (NRC) to Vice President, Operations (Entergy) dated May 23, 2018, "Grand Gulf Nuclear Station, Unit 1 -

Supplemental Information Needed for Acceptance of Requested Ucensing Action HE: Adoption ofTechnical Specifications Task-Force (TSTF) Traveler TSTF-425, Revision 3 (EPI D L-2018-LLA-0106)"

(NRC ADAMS Accession No. ML18138A468)

Dear Sir or Madam:

By letter dated April 12, 2018 (Reference 1), Entergy Operations, Inc. (Entergy) requested a

  • license amendment to modify the Grand Gulf Nuclear *station, *Unit 1 technical specifications *by relocating specific surveillance frequencies to a licensee-controlled program with the--

implementation of Nuclear Energy 1Institute 04-10, "Risk-Informed Technical Specification Initiative 5b, Risk-Informed Method for Control of Surveillance Frequencies." By letter dated May 23, 2018, (Reference 2), the NRC provided a formal request for supplemental information to support acceptance of the TSTF-425 license amendment request.

This letter provides the requested supplemental information that includes the finding-level facts and observations (F&Os) from the 2015 full-scope industry probabilistic risk assessment peer review with the associated resolutions and conclusions. The supplement includes a description

GNR0-2018100029 Page 2 of 3 of whether each F&O is a maintenance update or an upgrade and how it meets the capability Category II of the American Society of Mechanical Engineers probabilistic risk assessment standard. The information provided herein does not change the intent or the justification for the requested license amendment (Reference 1) and does not alter the conclusion that the proposed license amendment does not involve a significant hazards consideration as published in Federal Register 74 FR 32000 dated July 6, 2009.

No new regulatory commitments are made in this submittal.

In accordance with 10 CFR 50.91, "Notice for public comment; State consultation," a copy of this application, with attachments, is being provided to designated State of Mississippi Official.

If you should have any questions regarding this submittal, please contact Douglas A. Neve, Manager, Regulatory Assurance, at 601.437.2103.

I declare under penalty of perjury that the foregoing is true and correct. Executed on th day of June 2018.

Sincerely, Eric A. Larson EAURN/gwe

Attachment:

Supplemental Information Supporting License Amendment Request to*

Relocate Specific Surveillance Frequency Requirements cc: with Attachment Ms. Lisa Regner U.S. Nuclear Regulatory Commission Mail Stop OWFN 8 81 Rockville, MD 20852-2738 Mr. Siva Lingam U.S. Nuclear Regulatory Commission Mail Stop OWFN 8 81 Rockville, MD 20852-2738 Dr. Mary Currier, M.D., M.P.H State Health Officer Mississippi Department of Health P.O. 8ox-1700 Jackson, MS 39215-1700 Email: mary.currier@msdh.ms.gov

GNR0-2018/00029 Page 3 of 3 cc: without Attachment Mr. Kriss Kennedy Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 1600 East Lamar Boulevard Arlington, TX 76011-4511 NRC Resident Inspector Grand Gulf Nuclear Station Port Gibson, MS 39150

\

ATTACHMENT to -G-NR0..;20t8/00029 Supplemental Information Supporting License Amendment Request to Relocate Specific Surveillance Frequency Requirements

Attachment GNRO 2018/00029 Page 1 of 2

1. Summary Description By letter dated April 12, 2018 (Reference 1), Entergy Operations, Inc. (Entergy) requested a license amendment to modify the Grand Gulf Nuclear Station, Unit.1 (GGNS) technical specifications by relocating specific surveillance frequencies to a licensee-controlled program with the implementation of Nuclear Energy Institute 04-10, "Risk-Informed

. Technical Specification Initiative Sb, Risk-Informed Method for Control of Surveillance Frequencies.". By letter dated May 23, 2018, (Reference 2), the NRC provided a formal request for supplemental information to support acceptance of.the Technical Specifications Task Force (TSTF) traveler TSTF-425 license amendment request (LAR).

2. NRC Staff Request for Supplemental Information In the letter dated May 23, 2018 (Reference 2), the NRC staff states:

In the letter dated May 3, 2017, the NRC staff states, in part, that "in order for the NRC to consider the F&Os closed so that they need not be provided in submissions of future risk-informed licensing applications, the licensee should adhere to the guidance in Appendix X in its entirety. Following the guidance in Appendix X will reinforce the NRC staffs confidence in the F&O closure process and potentially obviate the need for a more in-depth review."

The NRC observed GGNS's process for review and closure of F&Os on August 23-25, 2017, at Jackson, MS. The observations were limited to the onsite review; however, as stated in the Appendix X guidance, the onsite review and associated "consensus process, as described in the body of this document, should be followed during which the full team present on the day of the associated consensus session considers and reaches consensus on adequacy of closure of each finding." The guidance in Appendix X permits remote reviews (i.e., via web and teleconference connection to the onsite team), but only for a limited number of findings. The guidance in Appendix X also permits evaluating and crediting post onsite closure work by the licensee but then requires a re-review of the licensee resolution and associated documentation and separate consensus session. As detailed in the observation report (ADAMS Accession No. ML17356A055), the NRC observers could not conclude that the licensee fully adhered to the endorsed guidance in conducting the F&O closure audit.

Therefore, as specified in the letter dated May 3, 2017, in order for the NRC to review

  • the technical adequacy of GGNS PRA with regard to Risk..:lnformed Technical Specification Initiative Sb, the LAR must be supplemented by the F&Os and associated resolutions and conclusion [emphasis added], or the LAR must be supplemented by the following information demonstrating that the licensee adhered to the guidance in Appendix X in its entirety ...

Entergy Supplemental Information:

Entergy herein provides the requested listing of the 39 finding-level facts and observations (F&Os) from the 2015 full-scope industry probabilistic risk assessment peer review that were closed by an independent assessment conducted August 23-31, 2017. The listing includes the resolutions and conclusions of the F&Os. In addition, the listing documents the written

Attachment GNRO 2018/00029 Page 2 of 2 basis for each F&O to validate whether the F&O constituted a PRA upgrade, maintenance update, or other; and documents the results from the independent assessment team review of the supporting requirements to ensure that Capability Category II of the American Society ofMechariical-Engineers probabilistic risk assessment standard was met for the F&Os.

3.

References:

1. Letter from E.A. Larson (Entergy) to Document Control Desk (NRC) dated April 12, 2018, "Application for Technical Specification Change Regarding Risk-Informed Justification for the Relocation of Specific Surveillance Erequency Requirements to a

'Licensee Controlled Program {TSTF-425)" {NRC Agencywide Documents Access and Management System (ADAMS) Accession No. ML181028445)

2. Letter from L. M. Regner (NRC) to Vice President, Operations (Entergy) dated May 23, 2018, "Grand Gulf Nuclear Station, Unit 1 -Supplemental Information Needed for Acceptance of Requested Licensing Action RE: Adoption of Technical Specifications Task Force (TSTF) Traveler TSTF-425, Revision 3 (EPID L-2018-LLA-0106)" (NRC ADAMS Accession No. ML18138A468)

List of Finding Facts and Observations (F&Os) on the GGNS Internal Events PRA Model *

(32 Pages)

List of ,Finding Facts and Observations {F&Os) on the GGNS Internal Events PRA Model 1-3 QU-04 This was not addressed A comparison to similar (all Resolved, QU-04: Cat Maintenance This finding was as a comparison of Mark 111/BWR-6) plants was Closed 2-3 MET update. Added closed and therefore results to similar plants added to the Summary Report per documentation does has no impact on was not conducted. associated with the Rev 4 independent not impact the surveillance test Possible Resolution PRA model. Causes for assessment methodologies used interval (STI) change significant differences in of finding or change the PRA evaluations performed Provide a comparison results between the plants closure. scope or capability. in accordance with similar to the comparison were identified. It is a comparison of the surveillance provided for some of the results from the frequency control other technical elements.

analysis. program (SFCP).

1-4 QU-F2 The documentation does A detailed discussion of the Resolved, QU-F2: Cat Maintenance This finding was QU-F3 not describe significant significant accident Closed 1-3 MET update. Added closed and therefore accident sequences in sequences for both CDF and per documentation does has no impact on STI sufficient detail. LERF was added to the Model BWROG not impact the change evaluations Possible Resolution Integration and Quantification peer review methodologies or performed in Report for the internal events QU-F3: Cat change the PRA accordance with the Describe the accident model 2-3 MET scope or capability. SFCP.

sequences in detail Similarly, a detailed per It is a discussion of discussion of the significant independent results from the accident sequences for both assessment analysis.

CDF and LERF was added to of finding the Internal Flood Report for closure.

the flood scenarios.

1-6 QU-F2 The documentation does A detailed discussion of the Resolved, QU-F2: Cat Maintenance This finding was not describe significant significant accident Closed 1-3 MET update. Added closed and therefore accident sequences in sequences for both CDF and per documentation does has no impact on STI sufficient detail. A LERF was added to the Model BWROG not impact the change evaluations sensitivity study on Integration and Quantification peer review methodologies used performed in LOOP recovery may be Report for the internal events or change the PRA accordance with the appropriate as the base model scope or capability. SFCP.

case. Similarly, a detailed It is a discussion of The key sequences use discussion of the significant results from the a battery lifetime of 4 accident sequences for both analysis.

hours. Appears division II CDF and LERF was added to The sensitivity study battery lifetime is 1O the Internal Flood Report. used the same underlying Page 1 of 32

hours. During the Peer Review, a methodology.

Possible Resolution sensitivity study on the loss of The battery lifetimes offsite power (LOOP) initiators used in the analysis Refine analyses and was performed, and based on are division-specific.

upgrade documentation.

the sensitivity study, the Recovery Rule files were changed from using the normal weather recovery probabilities to using the average weather recovery probabilities.

As documented in the LOOP timing analysis, RCIC operation is limited by suppression pool heat-up and/or Division I battery depletion while RCS depressurization is limited by Division II battery depletion.

The time assumed for power recovery prior to RCIC loss is 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> (based on minimum design battery life), and the time assumed for power recovery prior to loss of RCS depressurization capability is 1O hours (based on calculated battery depletion time without load shed).

1-7 QU-F6 A quantitative definition The quantitative definition of Resolved, QU-F6: Cat Maintenance This finding was of significant is not "significant" was added to the Closed 1-3 MET update. Although the closed and therefore provided. GGNS PRA Summary Report. per definition of has no impact on STI independent significant was not change evaluations assessment included in the performed in Possible Resolution of finding GGNS accordance with the Address closure documentation, the SFCP. ~

evaluation of the results was based on the definition of significant provided Page 2 of 32

in the Standard.

Added documentation does not impact the methodologies used or change the PRA scope or capability.

1-8 QU-A2 RSC 14-15 (PRA The quantitative definition of Resolved, QU-A2: Cat Maintenance This finding was Summary Report) "significant" was added to the Closed 1-3 MET update. Although the closed and therefore provides results. Fault GGNS PRA Summary Report, per definition of has no impact on STI tree linking is used. and the GGNS PRA independent significant was not change evaluations Significant is not defined Uncertainty and Sensitivity assessment included in the performed in but sequences are rank Report. These reports also of finding GGNS accordance with the ordered and provide a identify the risk significant closure documentation, the SFCP.

high percentage of the accident sequences based on evaluation of the CDF results. this definition. results was based on

[There are errors in the The Initiating Events Report the definition of initiating event was updated to ensure that it significant provided frequencies, wrong specified which column of in the Standard.

version of database was values should be used in the Added used, such that a new CAFTA .RR file, and the .RR documentation does quantification is needed. file used for quantification was not impact the updated to ensure it contains methodologies or In addition, there are change the PRA conservatisms in the values from the correct column. scope or capability.

significant accident sequences which should As documented in the LOOP The initiating event be addressed. Primarily timing analysis, RCIC issue was a in the DC lifetime for operation is limited by translation error division II which could suppression pool heat-up when the values impact the top two and/or Division I battery were transferred sequences and several depletion while RCS from the IE notebook others.] depressurization is limited by to the RR file. The Division II battery depletion. underlying Possible Resolution methodology to The time assumed for power Correct the model input calculate the recovery prior to RCIC loss is and re-quantify. initiating event 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> (based on minimum Page 3 of 32

design battery life), and the values and for time assumed for power quantification were recovery prior to loss of RCS not affected by

_depressurization capability is correcting the values 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> (based on calculated The battery lifetimes battery depletion time without used in the analysis load shed). are division-specific.

1-12 LE-E4 The LERF is quantified The updated quantification of Resolved, LE-E4: Cat Maintenance This finding was using the same general the Internal Events PRA and Closed 1-3 MET update. A review of closed and therefore process as the CDF and the Internal Flood PRA both per the LERF model has no impact on STI is documented in the au now show convergence for BWROG identified an error in change evaluations notebook. The review of both the pre-recovery and the peer review the LERF model performed in the LE quantification post-recovery cases. where a gate that accordance with the against the requirements The revised quantitative was supposed to be SFCP.

of Tables 2-2.7-2(a), (b) uncertainty analysis yields a an AND gate was and (c) is essentially mean value of CDF that is inadvertently identical to the CDF greater than the mean value modeled as an OR reviews documented of LERF. gate. With this error under the au High Level corrected, Requirement. Direct convergence was linking of the Level 1 obtained, and the sequences with the CET LERF was calculated provides assurance that to be a decade lower all system dependencies than CDF, as are captured, etc. expected.

A LERF truncation Correction of the sensitivity was modeling error to performed, but does not achieve convergence meet the criterion did not impact the identified in the au methodologies used notebook. However, the or change the PRA truncation was as low as scope or capability.

could be achieved, and the lack of convergence does not significantly affect the results.

Also when uncertainty is considered LERF mean value is calculated to Page 4 of 32

exceed mean CDF value.

This is not possible.

Possible Resolution Consider the reasons and address.

1-13 IFPP-A5 Walkdowns are Correction made to the Resolved, IFPP-A5: Maintenance This finding was documented in RSC 13- equipment location mapping Closed Cat 1-3 update. The DC closed and therefore 20 Internal Flooding (OC215 replaced OC125) in MET per equipment was has no impact on STI Walk down the flooding analysis software BWROG incorrectly mapped change evaluations Documentation. In (TIFA) and FRANX database. Peer to room OC 125 rather performed in general, this information Room OC215 has no flood Review than OC215. accordance with the was found to sources, so no new scenarios Correction of the SFCP.

substantiate the flood were introduced by the mapping error did not zone definition correction of this mapping. result in new discussions in Section scenarios and did not 4.0 of RSC 13-37, impact the Revision O (Internal methodology used or Flooding Analysis). change the PRA Flooding scenarios scope or capability.

associated with Control Building area OC125, which contribute to approximately 5% CDF may be overly conservative. Based on discussions with GG PRA consultants, these scenarios were dominant due to the presence of DC equipment in this room, as documented in the GG equipment database. However, this critical equipment is not Page 5 of 32

located in this area.

Possible Resolution Reevaluate the subject scenarios and equipment locations.

2-1 IE-C15 The mean values The Initiating Events Report Resolved, IE-C15: Cat Maintenance This finding was provided in the IE was updated to ensure that it Closed 1-3 MET update. This was a closed and therefore Notebook were not used specified which column of per translation error has no impact on STI in the quantification of values should be used in the independent when the values change evaluations the PRA results. The CAFTA .RR file, and the .RR assessment were transferred performed in values from Table 9 in file used for quantification was of finding from the IE notebook accordance with the the IE Notebook were not updated to ensure it contains closure to the RR file. The SFCP.

correctly used in the the values from the correct underlying CAFTAmodel. column. methodology to calculate the Possible Resolution initiating event Update the CAFTA values and for database to reflect the quantification were updated initiating event not affected by analysis mean value correcting the values, frequencies. nor was there a change to the PRA scope or capability.

Page 6 of 32

3-1 IE-C12 Table 6 of the initiating Based on a review of the Resolved, IE-C4: Cat Maintenance This finding was IE-C4 events report shows data Plant-specific Data Analysis Closed 1-3 MET update. The issue closed and therefore used for Bayesian and Initiating Events Reports, per associated with % T2 has no impact on STI updating of plant specific there was a typo in the Prior BWROG was a typo, for which change evaluations initiating events. In some Frequency Mean value for Peer the resolution did not performed in cases it appears that the %T2 (LOCHS) and Review impact the accordance with the plant experience would corresponding spreadsheet. IE-C12: Cat methodology or SFCP.

imply a substantially The value should be 1.12E-1 1-3 MET change the PRA higher frequency than instead of 1.12E-2. The per scope or capability.

the prior data. For values were updated in the BWROG The issue associated example for %T2 the Initiating Events Report, the Peer with %TSTT1 was prior is 1.12E-2 /yr associated spreadsheet, and Review inclusion of non-whereas the plant the CAFTA. RR file. applicable data when specific experience is The analysis for %TSTT1 evaluating the IE

-0.3/yr. Also for incorrectly included the Loss frequency for

%TSTT1 the prior is of Switchyard Power Lines in*

  • transformer ST11.

8.80E-3 /yr whereas the both the LOOP and the The underlying plant experience is %TSTT1 IE frequencies, methodology or the

-0.13/yr. These rather than the LOOP PRA scope or differences are large frequency only. Correction of capability were not enough that the prior the analysis reduced the changed, but the may not be appropriate frequency for %TSTT1 to be classification of the for Bayesian updating. comparable to the generic events was corrected Some explanation of this estimate. The current value is to apply only to the difference is warranted 9.19E-3/yr. LOOP frequency.

especially with regard to the Bayesian process.

Also since the experience timeframe covers a period of much earlier GGNS operation, it is possible that more recent data is better because of plant fixes.

Possible Resolution Provide justification for this deviance or consider alternate methods for calculating the IE frequencies.

Page 7 of 32

3-2 IE-C15 Table 9 of the Initiating The Initiating Events Report Resolved, IE-C2: Cat Maintenance This finding was Events Notebook was updated to ensure that it Closed 1-3 MET update. This was a closed and therefore IE-C2 includes a summary of specified which column of per translation error has no impact on STI the Initiating Events values should be used in the BWROG when the values change evaluations Frequencies derived CAFTA .RR file, and the .RR Peer were transferred performed in from the updated IE file used for quantification was Review from the notebook to accordance with the analysis. The Frequency updated to ensure it contains IE-C15: Cat the RR file. The SFCP.

/

per reactor year (the the values from the correct 1-3 MET underlying fourth column from the column. per methodology to left) shows the final independent calculate the updated number that assessment initiating event should be used for of finding values or for quantification. However, closure quantification were the IE frequencies used not affected by for quantification have correcting the values, come from other columns nor was there a that do not represent the change to the PRA most recent data. scope or capability.

Possible Resolution Correct this transposition error.

4~4 HR-F1 There are multiple A review of the HFEs in the Resolved, HR-F1: Cat Maintenance This finding was human failure events GGNS model of record (MOR) Closed 1-2 MET update. The closed and therefore (HFEs) for performing was performed to identify per methodology used has no impact on STI the same action, only on those for performing the same BWROG for the calculation of change evaluations a different piece of action on different pieces of Peer the HEP values, and performed in equipment. For example, equipment within the same Review the PRA scope or accordance with the there are three different system. A total of 16 capability, are not SFCP.

HFEs for failing to start individual HFEs were replaced impacted by this The pending standby air compressors. with 6 common HFEs for the change. documentation update If an operator fails to actions. The common HFEs to the System start a compressor, they have the same value of the Analysis Report to likely fail to start any/ individual HFEs they replaced, reflect the new HFE compressor, not just one which is effectively a names also has no in particular. There dependency of 1.0, instead of impact on STI change should be only one assigning a dependency of evaluations.

failure for the operator to 1.0 during the dependency start a compressor that analysis.

fails the action for all air These changes were made in compressors. Otherwise Page 8 of 32

there are failed and the Rev 4a MOR, HRA unfailed actions in the Report, Quantification Report, model to start the and Summary Report. The compressor. affected System Analysis Possible Resolution Report Appendices will be updated per a Model Change Group similar operator Request (MCR).

actions into one action.

4-5 HR-F2 The timing of cues is not Time delays were added into Resolved, HR-F2: Maintenance This finding was HR-H2 explicitly documented in the HRA Calculator, and the Closed Cat2 MET update. The HRA closed and therefore the HRA calculator. The dependency analysis was per Calculator is used for has no impact on STI time delay to the cue is updated using the new independent the calculation of the change evaluations set to zero in every information. assessment human error performed in instance. The time delay of finding __ probabilities (HEPs). accordance with the is an important step closure Inclusion of the SFCP.

because it can limit the timing of cues does HR-H2: Cat amount of time in the not impact the 1-3 MET scenario to recover from calculated HEP but per the action. The only could impact the BWROG timing listed in the time "order" of the HFEs Peer window is the median in the dependency Review response and execution analysis. The time. Operator recovery methodology used is based on the for the dependency remaining time available, analysis, and the but without the time scope and capability delay to the cue of the PRA are not included, more time is changed by including allowed to recover than the timing of cues.

is actually available. The inclusion of the Possible Resolution cues helps to ensure correct ordering of Use the identified delay the HFEs in a times in the HRA combination during calculator to accurately the dependency reflect the timing of the analysis.

actions in the scenario Page 9 of 32

and recovery actions.

4-6 HR-F2 Scenario timeframes are As documented in the Resolved, HR-F2: Cat Maintenance This finding was included in the evaluation Success Criteria Report, new Closed 2 MET per update. The closed and therefore HR-G4 of the HFE. However, MAAP thermal/hydraulic independent methodology used by has no impact on STI there are no references analyses were done after the assessment the HRA Calculator change evaluations to where the scenario extended power uprate to of finding to calculate HEPs, performed in timeframes are support the Rev. 4 PRA closure and the PRA scope accordance with the calculated. There was update. HR-G4: Cat and capability were SFCP.

some indication that Scenario time frames were 2 MET per not impacted by MAAP had been used in reviewed and addressed by BWROG documenting the the past to develop the adding the delay times for the Peer updated bases for scenarios, but nothing HEP cues. The bases for the Review the HFE time frames.

could be found to support HFE timing were updated the times used. Following based on the new MAAP plant uprate a scaling analyses and documented in evaluation of the the timing notes in the HRA increased power was Calculator database and in a performed to revise the detailed table on HFE timing scenario times. in the HRA Report.

Additional MAAP cases were performed following the uprate, but these have not been incorporated into the HFE analysis.

Possible Resolution Determine the reference for each scenario timeframe and document the link between the HFE Page 10 of 32

and the reference.

4-7 HR-G2 All operator actions The updated HRA evaluation Resolved, HR-G2: Cat Maintenance This finding was include an estimation of no longer sets the execution Closed 1-3 MET update. For HFEs closed and therefore the failure in cognition. probability to zero and instead per where no execution has no impact on STI However, a number of is based on the maximum BWROG contribution was change evaluations operator actions had the combined value for the Peer included, the performed in execution failure CBDTH/HCR approach. Review execution actions accordance with the probability set to zero were added using SFCP.

stating that the action is the same methods memorized and practiced as for all other HFEs.

routinely. These actions The underlying HRA are in the first few methodology, and minutes following an the PRA scope and initiating event and capability were not based on the time impacted by adding available may have high additional detail for HEPs. some of the HF Es.

Possible Resolution Include execution failure probabilities for all operator actions.

4-10 HR-H3 The independent Time delays were added into Resolved, HR-H3: Cat Maintenance This finding was HR-G7 evaluation of HFEs did the HRA Calculator, and the Closed 1-3 MET update. The HRA closed and therefore not include any delay dependency analysis was per Calculator is used for has no impact on STI time to the cue. This updated using the new BWROG the calculation of the change evaluations carried forward into the information. Peer HEPs. Inclusion of performed in dependency analysis In addition, the most Review the timing of cues accordance with the where all HFEs were significant HFE combinations HR-G7: Cat and consideration of SFCP.

evaluated to have the were reviewed as part of the 1-3 MET intervening same delay time of zero. dependency analysis for per successes does not This paired events that separation of events and independent impact the calculated should be separated in intervening successes. When assessment HEP but could the accident sequence identified, the default of finding impact the "order" of by hours together dependency was adjusted in closure the HFEs in the resulting in dependent the HRA Calculator software. dependency combinations that should analysis. The not exist or have a lower methodology used dependency. With all of for the dependency Page 11 of 32

the actions having the analysis, and the same delay time, scope and capability complete dependence of the PRA are not was calculated resulting changed by including in much higher

  • the timing of cues dependent failure and consideration of probabilities than actually intervening exist. The HRA calculator successes.

software has overrides available to offset delay times or reduce dependence, but these were not used. There also does not appear to be any evaluation of intervening successes which would remove the dependence between actions.

Possible Resolution Perform the dependency analysis using accurate delay times. Include review for intervening successes.

4-13 DA-C3 A number of component Additional plant-specific data Resolved, DA-C3: Cat Maintenance This finding was types were excluded was obtained for various Closed 1-3 MET update. Using closed and therefore from the evaluation valves and air compressors per Bayesian updating to has no impact on STI including motor operated which were previously not independent evaluate reliability change evaluations valves, air operated included in the PRA. The new assessment data for additional performed in valves, and temperature data includes number and of finding component types did accordance with the switches in PSA-GGNS- type of failures, demand data, closure' not result in a SFCP.

01-DA-01. These and exposure data per change in component types were component and type code, methodology or in not reviewed for plant and this data was analyzed the scope or specific failures to consistent with the capability of the determine if Bayesian established data analysis PRA.

updating of the generic Bayesian update failure data should be methodology. The new data was compiled into the Page 12 of 32

performed. spreadsheets used for the Possible Resolution data analysis, and all changes and additions were Include evaluation of documented in the Plant-these component types Specific Data and CCF and subtypes so that Report.

plant specific data can be evaluated for inclusion to the generic failure rates.

4-14 DA-C3 The failures removed The bases for failure inclusion Resolved, DA-C3: Cat Maintenance This finding was from consideration do not and exclusion are established Closed 1-3 MET update. closed and therefore have adequate in the Plant-Specific Data and per Enhancement of the has no impact on STI justification for CCF Report, where it is now independent documentation to change evaluations disregarding previous documented that all failures assessment describe the bases performed in plant failures. Many included in the PRA must of finding for excluding some accordance with the failures were removed in have occurred during the time closure equipment failure SFCP.

previous model revisions, frame for the PRA update data does not impact but there is no (September 1, 2006 through the methodology documentation as to why August 31, 2012) and must used or change the the failures were no meet the definition of a PRA PRA scope or longer applicable. functional failure. capability.

Possible Resolution Develop bases for failure inclusion and exclusion and document the failures using th~ bases.

4-15 DA-C13 One discrepancy was The unavailability data for the Resolved, DA-C13: Maintenance This finding was identified for battery 125V DC battery chargers Closed Cat 2-3 update. Update of closed and therefore charger unavailability. In was updated as documented MET per unavailability data for has no impact on STI the notebook in the Plant-Specific Data and BWROG several components change evaluations unavailability was CCF Report. All unavailability Peer to be consistent with performed in calculated for the L51 data was reviewed for similar Review plant operating accordance with the battery chargers based concerns, and data for the history does not SFCP.

on past history. following were also updated: involve a change in However, the reliability radial well pumps, air methodology or database had zero compressors, AC circuit change the PRA unavailability for each of breakers, and switchyards. scope or capability.

the battery chargers.

Possible Resolution Page 13 of 32

Update the model unavailabilities for 125V DC battery chargers.

4-17 DA-C14 Coincident unavailability A thorough review of previous Resolved, DA-C14: Maintenance This finding was was identified to occur in analyses and the current Closed Cat 1-3 update. closed and therefore the data analysis system notebooks determined MET per Enhancement of the has no impact on STI timeframe (PSA-GGNS- that the previously modeled independent documentation to change evaluations 01-DA-01 ). This coincident unavailabilities did assessment describe the plant performed in unavailability is not not meet the criteria for of finding practices and criteria accordance with the included in the model so inclusion. It was confirmed closure for modeling SFCP.

is therefore not included that no more than one safety- coincident in the final results. related system is scheduled to unavailability did not Possibl~ Resolution be in maintenance at any change the given time. The Plant-Specific methodology for Include coincident modeling Data and CCF Report was maintenance in the maintenance updated to document this model where analysis unavailability, or the review and information.

has determined it exists. PRA scope or capability.

4-19 DA~E1 There are numerous All data documentation was Resolved, DA-E1: Cat Maintenance This finding was conflicts between the two aggregated into a single Closed 1-3 MET update. closed and therefore data analysis notebooks Plant-Specific Data and CCF per Consolidation, has no impact on STI and the two common Report, which directly independent consistency update, change evaluations cause notebooks. This is incorporates the supporting assessment and enhancement of performed in likely due to a two-year calculation spreadsheets, and of finding documentation did accordance with the gap between publishing describes the formulas used closure not change the SFCP.

of the notebooks. in the spreadsheets. underlying data Information is not analysis consistent between methodologies or notebooks and even change the scope or within the same capability of the notebook. The final data PRA.

rollup notebook appears to be accurate, but its information is based off the plant specific notebook which has information that is out of date, not used, and Page 14 of 32

results in contradictory information to the data development notebook.

The same is true of the common cause notebooks.

Much of the plant specific data (run and demand estimates, maintenance unavailability data) was not found in the notebooks, but in spreadsheets provided separately. This information should be included in the notebook for ease in identification.

Possible Resolution Resolve conflicts between notebooks and include supplementary data into the notebooks.

5-4 SC-AS DC battery life is As documented in the LOOP Resolved, SC-AS: Cat Maintenance This finding was AS-87 presented as 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> in timing analysis, RCIC Closed 2-3 MET update. closed and therefore the SC notebook, but the operation is limited by per Enhancement of the has no impact on STI Div 11 battery was suppression pool heat-up BWROG documentation to change evaluations credited to 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> per (MAAP runs that credit RCIC peer review clarify the division- performed in the LOSP notebook. The under SBO conditions) and/or AS-87: Cat specific battery accordance with the documentation is not Division I battery depletion 1-3 MET depletion times used SFCP.

consistent, and it is not while RCS depressurization is per in the analysis does clear if an operator action limited by Division II battery BWROG not change the for load shedding is depletion. The time assumed Peer analysis required. for power recovery prior to Review methodologies are Possible Resolution RCIC loss is 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> (based used or change the on Div. I minimum design PRA scope or Determine realistic battery life), and the time capability.

battery life times with and assumed for power recovery without load shedding, prior to loss of RCS and model with any depressurization capability is necessary HEPs in the Page 15 of 32

PRA. 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> (based on Div. II calculated battery depletion time without load shed).

The DC Power system analysis documentation was updated to reference the division-specific battery lifetime from the LOSP analysis and revise the battery depletion assumption.

The Success Criteria Report was also updated to document the division-specific battery depletion times.

5-6 AS-87 AC power recoveries are The recovery factor typos Resolved, AS-87: Cat Maintenance This finding was developed on a cutset documented in the F&O were Closed 1-3 MET update. Correction closed and therefore level to account for corrected. A detailed review of per of typographical has no impact on STI timing in the LOSP the remaining AC power BWROG errors in recovery change evaluations notebook (report PSA- recovery rules found no Peer factors and update to performed in GGNS-01-IE-01 ). Spot additional issues. Review include more accordance with the checks of the Qrecover During the Peer Review, a appropriate offsite SFCP.

file compared to the sensitivity study on the loss of power recovery notebook identified the offsite power (LOOP) initiators factors for average following errors/ was performed, and based on weather and long-inconsistencies: the sensitivity study, the term scenarios does Recovery Rule files were not change the ZHE-OSP-DSGO-NW- changed from using the underlying used the "average" normal weather recovery methodology used to recovery of 6.56E-1 probabilities to using the calculate the average weather recovery recovery probabilities probabilities. or change the PRA ZHE-OSP-DLGO-NW - scope or capability.

was entered into the The timing for long term Qrecover file with a scenarios was addressed by a probability of 1.22E-2 sensitivity study documented instead of 1.22E-1. in the peer reviewed Quantification Report which Approximately 1O other has now been included in the events were spot base model.

checked and found to be Page 16 of 32

entered properly.

Additionally, the normal weather offsite power recovery data were applied to all the LOSP initiating events. The weighted average of the offsite power recovery probabilities did not include the severe weather portion in the weighting. This makes the application of the non-recovery probabilities non-conservative Finally, the GG PRA team self-identified that offsite power recoveries for failure of OHR sequences was overly conservative, more aligned with loss of makeup timing than loss of OHR timing. The GG team performed a sensitivity that significantly reduced COF and LERF.

Possible Resolution Review the entire list of offsite power recovery events to confirm they are entered into the Qrecovery file properly.

Apply normalized offsite power non-recovery probabilities that include the severe weather Page 17 of 32

component.

Re-evaluate the offsite power non-recovery probabilities for loss of OHR sequences to consider realistic probabilities.

5-7 AS-A7 The very small LOCA The %53 initiating event was Resolved, AS-A7: Cat Maintenance This finding was

(%53) was identified as added to the list of transient Closed 1-2 MET update. Clarification closed and therefore an initiating event in the events in the Accident per of the documentation has no impact on STI IE analysis. In Table 1 of Sequence Analysis Report BWROG on the treatment of change evaluations the AS notebook; it was because it can be mitigated by Peer very small LOCA performed in listed as being treated as the same equipment as a Review does not change the accordance with the a transient. However, no transient initiating event. This methodology for SFCP.

basis is given, and the is consistent with inclusion as identification and

%53 initiating event is a transient event in the PRA grouping of initiating not included in the model logic. events or change the CAFTAmodel. PRA scope or Possible Resolution capability.

Either provide a defendable basis for excluding the very small LOCA, or develop it for analysis.

5-8 AS-81 The small and medium The Success Criteria Report Resolved, AS-81: Cat Maintenance This finding was SC-83 LOCA A TWS scenarios was updated to document that Closed 1-3 MET update. closed and therefore do not appear to have any medium LOCA or large per Enhancement of the has no impact on STI considered the LOCA LOCA with failure of rod BWROG documentation on change evaluations effects on system insertion is assumed to lead to Peer the success criteria performed in success criteria, such as core damage. Review for LOCA A TWS accordance with the SLC. A small LOCA would not SC-83: Cat does not change the SFCP.

Large LOCA A TWSs impact the mechanical or 1-3 MET methodology to have not been addressed electrical reactor protection per define accident with either a valid system (RPS), or the ability to BWROG sequence qualitative argument or a manually scram, perform Peer progression. There is Page 18 of 32

quantitative evaluation. alternate rod insertion, or trip Review also no change to A success criteria basis the recirculation pumps. the PRA scope or could not be found for Therefore, the only system in capability.

using RCIC to question for a small LOCA depressurize to allow A TWS is standby liquid SDC in transients or control (SLC). Based on the ATWS. system design criteria for SLC, and in accordance with In transient sequences GDC 4, SLC is designed to with success of operate following a LOCA.

depressurization, SDC is Therefore, the leakage during credited to prevent core a small LOCA is not damage, which large enough to render SLC disagrees with the MAAP ineffective regardless of the calculation RSC-location of the leak.

CALMAP-2014-1202, which shows this sequence as core The Success Criteria Report damage. also documents that RCIC is Possible Resolution not credited as a method of depressurization in the Document the success transient or A TWS accident criteria for LOCA A TWS sequences. Decay heat events.

removal options with Document bases for use successful RCIC injection are of RCIC and SDC to limited to RHR in Suppression make a sequence a safe, Pool Cooling (SPC) Mode and stable end state. If this RHR in Containment Spray cannot be justified, (CS) Mode. Decay heat should be considered removal via RHR in Shutdown core damage. Cooling (SDC) Mode is not Remove credit for credited as a viable option depressurization/SDC to when RCIC is injecting for prevent core damage in inventory control.

transients. A new MAAP calculation was performed for a transient with depressurization in which LPCI and SPC alternate based on RPV level. The plant reaches a safe stable state after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Based on the Page 19 of 32

similarity of flow between the LPCI/SPC alignment and SOC, this case also provides a basis to credit SOC.

5-9 SC-81 GGNS assumes that SPMU is only required for Resolved, SC-81: Cat Maintenance This finding was SC-82 suppression pool large and medium LOCAsthat Closed 2 MET per update. closed and therefore makeup (SPMU) is experience failure of decay BWROG Enhancements to has no impact on STI required in combination heat removal. Peer documentation to change evaluations with containment venting For large LOCA, the ECCS Review clarify and provide performed in in order to avoid pumps are assumed to fail SC-82: Cat the analytical basis accordance with the cavitation of ECCS pump due to loss of NPSH if 2-3 MET for analysis SFCP.

suction in containment containment venting or per assumptions does heat-up sequences. containment failure occurs. BWROG not impact the The assumption that Peer methodology used to The above assumptions are venting fails the ECCS Review determine accident based on MAAP analysis pumps is conservative, sequence showing SP level drops to the which is noted in Topic 7 progression or SPMU limit shortly after the of Table 11 of the QU success criteria.

sequence mission time. The notebook.* There is also no ECCS pumps can pump change to the PRA Regarding SPMU saturated water if SP level scope or capability.

successfully facilitating remains above SPMU limit, pump operation, there is unless there is flashing of the no analytical basis for SP water, steam entrapment, this success criteria, but cavitation, or a pump trip instead is based upon when containment fails.

the expert judgment of However, injection of CST the modeler. While this volume will increase level in may be a reasonable the SP and the potential for assumption, it would be trip was eliminated in most of better to have an cases. The use of HPCS after analytical basis or at containment failure is now least carry th is item as addressed in the Accident an additional source of Sequence and Success "

modeling uncertainty. Criteria Reports.

Since these assumptions are a significant driver to Page 20 of 32

the CDF and LERF, consideration should be given to attempt to refine the assumption. At a minimum, sensitivity analyses should be performed to ensure the impact of these SC assumptions are fully understood for risk characterization.

Possible Resolution Since these assumptions are a significant driver to the CDF and LERF, consideration should be given to attempt to refine the assumptions. At a minimum, sensitivity analyses should be performed to ensure the impact of this SC assumption are fully understood for risk characterization.

5-10 LE-A2 The characteristics The LERF Report was Resolved, LE-A2: Cat Maintenance This finding was identified as important in updated to clearly define the Closed 1-3 MET update. closed and therefore LE-A 1 are documented high to low pressure transition per Enhancement of the has no impact on STI in Section 1 of the LE at 200 psig, based on MAAP BWROG documentation, change evaluations notebook (PSA-GGNS- analysis. peer review assumptions and performed in 01-LE). However, the LE bases for sequence accordance with the The updated report also notebook does not clarifies that only the pressure binning did not SFCP.

provide any bases for the at the time of RPV failure is changes the binning of sequences relevant for this binning methodology used (e.g., determination of criterion. This resulted in a for binning or result which sequences are change to the binning of small in a change to PRA high pressure and which LOCA sequences with scope or capability.

are low). Per the Grand successful depressurization Gulf PRA team, selection -prior to RPV failure to low was based on Page 21 of 32

information from MAAP pressure scenarios.

gathered from both success criteria and LE RF-specific assessments and the engineer's experience working on other BWR 6 designs.

This SR is considered met because the binning appears reasonable in most cases, but documentation of more definitive bases is needed. Some examples of sequences for which the high/low pressure binning are not obvious are:

P-009 {SORV, RCIC initially successful, but LPI fails and RX depressurization not questioned) is "Low" pressure, and all Small LOCAs {even with depressurization successful) are binned as high pressure.

Possible Resolution Document the bases for the binning of the characteristics.

Qualitative evaluation of many of the sequences is intuitive (e.g., large LOCAs are low pressure),* but some detail should be provided for the binning of less Page 22 of 32

obvious sequence characteristics.

Clearly identify the criterion for high vs. low pressure binning (200 psi).

5-12 LE-C10 There is no quantitative The quantitative definition of Resolved, LE-C3, LE- Maintenance This finding was LE-C12 definition of significant "significant accident Closed C10, LE- update. Update of closed and therefore LE-F2 accident progression progression" was added to the C12: Cat 2 the LERF model and has no impact on STI LE-C3 sequences. There are Model Integration and MET per results with the change evaluations LE-G3 SRs that require Quantification Report. independent updated igniter HEP performed in LE-G6 documenting the The new LERF MAAP assessment did not require a accordance with the quantitative definition, as Analysis Report documents of finding change in SFCP.

well as review of the the basis of the accident closure methodology or PRA significant severe sequence progression. LE-F2: Cat scope or capability, accident progression 1-3 MET but updated insights The Quantification Report was sequences for possible per were obtained.

updated to discuss the review credit for repairs and independent Additional review and and relative contributions of engineering analyses to assessment enhanced the LERF sequences, and the provide a more realistic of finding documentation of the Summary Report was updated analysis. An example of closure LERF results to provide a comparison of the lack of reviews for contributions, and initiating event and other LE-G3: Cat excess conservatism is documentation of relative contributions to LERF 2 MET per that the operator action definitions also did as well as a more detailed independent for turning on the H2 not affect comparison of the relative assessment igniters was set to 1.0 in methodology or PRA sequence contributions to of finding the analysis, yet is very scope or capability.

LERF. closure significant to the results.

LE-G6: Cat Possible Resolution The operator action to start 1-3 MET Define severe accident per the igniters was updated and progression sequence independent documented in the HRA and review the results to assessment Report. The updated HEP remove significant of finding was incorporated in the model conservatisms. closure during the rule-based Page 23 of 32

recovery process.

The model was -re-quantified and reviewed after changes were made. The igniter operator action identified in the Finding was the only significant conservatism that required refinement. Although the relative importance of hydrogen combustion was reduced, the updated LERF results continue to show that LERF is dominated by containment failures caused by loss of suppression pool cooling and failure of the hydrogen igniters.

5-13 LE-C1 The approach to the LE The LERF model reviewed by Resolved, LE-C1: Cat Maintenance This finding was LE-C2 analysis was the the BWROG Peer Review Closed 2 MET per update. As stated in closed and-therefore NUREG/CR-6595 team double-counted early BWROG the finding, the LERF has ho impact on STI analysis, with a more and late hydrogen events in peer review analysis and change evaluations detailed evaluation of the many of the cutsets which LE-C2: Cat quantification performed in loss of OHR sequences. resulted in overestimation of 2 MET per methodology used accordance with the Since the Level 1 and LE LERF. independent conforms to Cat 2. SFCP.

results are dominated by The LERF model was updated assessment Update of the LERF loss of OHR, this SR was to eliminate the double- of finding model and results to evaluated as met to counting, as verified by LERF closure address issues in the Category 11. However, cutset reviews. Level 1 and 2 PRA the following items are models, and the The Level 1 model/data

  • also noted from the peer updated igniter HEP issues identified in other review: dtd not require a F&Os were corrected as

- The Level 1 SR review change in described in those F&Os identified many items methodology or PRA listed above.

that will change the COF scope or capability, A new "Basis for Value" but updated insights risk results (incorrect IE column was added to the were obtained.

frequencies utilized, LERF basic events table in incorrect offsite power the LERF Analysis Report to recoveries applied, etc.).

explain the bases for the

- The LE results are values used.

Page 24 of 32

dominated by Updates to the igniter HEPs containment failure at were performed in the HRA vessel breach, but the and the values were added to majority of this fraction is the HRA and LERF Analysis hydrogen-related failures Reports.

of containment. The HEP The model was re-quantified for turning on igniters and reviewed after the above was set to 1.0; the peer changes were made. Although review team set it to 0.1 the relative importance of in the LERF cutset file hydrogen combustion was (1 E-10/yr truncation), reduced, the updated LERF and the LERF dropped results continue to show that from 5.81 E-6/yr to 1.74E- LERF is dominated by 6/yr. containment failures caused Because of the peer by loss of suppression pool review team's uncertainty cooling and failure of the in how the risk profile will hydrogen igniters.

change with the identified errors, a finding is developed to ensure the LE analysis is re-examined. If the LE risk profile changes significantly, then some conservative assessments may require more detailed analysis.

Possible Resolution After updating the Level 1 and igniter operation action probability, consider if a more detailed approach to LE is necessary.

5-14 LE-C2 No credit is given to The LERF Analysis Report Resolved, LE-C2: Cat Maintenance This finding was LE-C4 operator actions in the was updated to document the Closed 2 MET per update. Enhanced closed and therefore LE-E1 LE analysis. There is no review of procedures that had independent documentation of the has no impact on STI documentation of a previously been performed to assessment process used to change evaluations Page 25 of 32

review of Grand Gulf identify the operator actions of finding identify and model performed in procedures for severe that would be used to respond closure operator actions for accordance with the accident responses by to the LERF sequence in LE-C4: Cat LERF sequences did SFCP.

operations. There is a progress. As part of this 2 MET per not change the HEP identified for turning review, the systems that could BWROG methodology used on hydrogen igniters, but be used by the operators to peer review for the LERF it is set to 1.0 in the respond to the scenario had analysis or HRA, or LE-E1: Cat model. been identified and modeled the PRA scope or 1-3 MET Possible Resolution appropriately. The LERF- capability. Nor did per related operator actions were the update of the Document a review of BWROG evaluated as part of the HEP to actuate the GG procedures for peer review Human Reliability Analysis. igniters.

potential operator actions to reduce the LERF. Updates to the igniter HEPs were performed in.the HRA and the values were added to the HRA and LERF Analysis Reports.

5-16 LE-03 Per the containment The evaluation of containment Resolved, LE-03: Cat Maintenance This finding was capacity report (GGNS failure in the updated Success Closed 2 MET per update. Additional closed and therefore 92-0034), the failure Criteria Report considers the independent evaluation of has no impact on STI location with the lowest location of the containment assessment containment failure change evaluations mean pressure is the failure. The specific locations of finding locations did not performed in basemat (65 psid). The considered were based on the closure change the accordance with the containment failure same design basis

  • methodology used SFCP.

location was not Containment performance for the LERF

  • considered in the LE calculation used to identify the analysis, or the PRA analysis (all basemat as the weakest point. scope or capability.

overpressurization was The LERF analysis does not The lack of credit for considered a large credit any fission product a decontamination release, after the 0.5 scrubbing based on factor for releases scrubbing credit for the Containment Failure location has no numerical Auxiliary Building). since no approve,c;I impact on LERF.

Since basemat failures methodology for crediting could potentially result in scrubbing due to Containment underground releases to failure location currently allow significant exists.

scrubbing, the approach There is some probability that taken is conservative. the containment failure could It is noted that other be located such that it impacts Page 26 of 32

containment failure HPCS operation and the locations have mean probability of this occurrence failure pressures that are was developed in the not much higher than the Calculation of Split Fraction basemat failures, but for GGNS ECCS Equipment some credit could be Given Containment Failure.

given to reduce the Additional GOTHIC room LERF. heatup analyses were run to

[Basis: SR LE-03 evaluate the environment that Category II states when would be present in the HPCS containment failure and LPCS rooms following a

  • location affects the Containment failure at a LERF, define failure location other than at the location using a realistic base mat.

assessment.]

Possible Resolution Evaluate the potential for containment failures to result in underground releases to potentially remove conservatism from the LERF.

5-18 LE-C1 The GG LE analysis The new LERF MAAP Resolved, LE-C1: Cat Maintenance *This finding was LE-E3 does not provide a Analysis Report defines Closed 2 MET per update. Enhanced closed and therefore quantitative definition of 'Large' and 'Early' releases, BWROG documentation of has no impact on STI

'Large' releases, and documents the results of the peer review "large" and "early change evaluations does not document the LERF MAAP analyses versus LE-E3: Cat release definitions performed in evaluation of sequences the defined criteria, and 2 MET per did not change the accordance with the as resulting in a 'Early' summarizes the MAAP runs independent methodology used SFCP.

release. Discussions that contribute to LERF. assessment for the LERF with the GG PRA team of finding analysis, or the PRA identified that the 'Early' closure scope or capability.

evaluations were based on comparison of MAAP-predicted containment failure time for the dominant sequence (loss of OHR) with the time of declaration of a general Page 27 of 32

emergency. This is acceptable, but the evaluation needs to be documented.

[Basis: The LERF contributors from the CSET are all evaluated and carried through the accident progression analysis to the CSET end states. The end states categorization of LERF or not LERF is not documented, but appears to be reasonable.]

Possible Resolution Document a definition of

'Large' releases, and document the evaluation of sequences as resulting in a 'Early' release. The evaluation of 'Large' was qualitative, but appears reasonable (e.g., ISLOCA, Containment Isolation, Containment rupture),

but needs to be documented, and the bases should be tied to a quantitative definition of

'Large.'

5-20 LE-F1 The Quantification The Quantification Report was Resolved, LE-F1, LE- Maintenance This finding was LE-F2 notebook (PSA-GGNS- updated to discuss the relative Closed G3: Cat 2-3 update. Enhanced closed and therefore LE-G3 QU-01) presents the total contributions of the LERF MET per documentation of the has no impact on STI LERF, the top 100 LERF sequences, and the Summary independent LERF results change evaluations cutsets, and some LERF Report was updated to assessment contributions did not performed in importance analyses. provide a comparison of of finding change the accordance with the There is no presentation initiating event and other methodology used Page 28 of 32

of the relative relative contributions to LERF closure for the LERF SFCP.

contribution to LERF as well as a more detailed LE-F2: Cat analysis or from various contributors comparison of the relative 1-3 MET quantification, or the other than the sequence contributions to per PRA scope or im~ortance analysis. LERF. independent capability.

Possible Resolution assessment Document the relative of finding contribution to LERF closure from plant damage states and significant LERF contributors from Table 2-2.8-3.

5-22 LE-GS Limitations in the The Limitations of the LERF Resolved, LE-GS: Cat Maintenance This finding was analysis have not been analysis were added to the Closed 1-3 MET update. Enhanced closed and therefore identified. The LE LERF Analysis Report. per documentation of the has no impact on STI analysis should be independent LERF analysis change evaluations examined to identify how assessment limitations did not performed in any simplifying of finding change the accordance with the assumptions can impact closure methodology used SFCP.

applications. for the LERF Possible Resolution analysis, or the PRA scope or capability.

Examine the LE analysis to identify how any simplifying assumptions can impact applications.

7-1 IFPP-83 There is no apparent The uncertainty associated Resolved, IFEV-83, Maintenance This finding was IFS0-83 documentation of an with internal flood plant Closed IFPP-83, update. Enhanced closed and therefore uncertainty analysis for partitioning; internal flood IFQU-83, documentation of the has no impact on STI IFSN-83 any of the following: sources; flood-induced IFSN-83, uncertainty change evaluations IFEV-83 internal flood plant initiating events; accident IFS0-83: associated with the performed in IFQU-83 partitioning; internal flood sequences and quantification Cat 1-3 IF analysis did not accordance with the sources; flood-induced were added to Internal MET per change the SFCP.

initiating events; accident Flooding Analysis Report. The independent methodology used sequences and discussion addresses both assessment for the IF analysis, or quantification aleatory and epistemic of finding the PRA scope or Possible Resolution (modeling) uncertainty. closure capability.

Document the uncertainties in Page 29 of 32

accordance with the standard 7-2 IFSN-A12 The EDG building is The Internal Flooding Analysis Resolved, IFSN-A12 Maintenance This finding was screened from further Report was updated to Closed IFSN-A13, update. Enhanced closed and therefore IFSN-A13 has no impact on STI analysis based upon .a provide a more robust basis IFSO-A3: documentation of the IFSO-A3 for screening of the EDG Cat 1-3 EDG building change evaluations statement in FSAR that "pipe cracks are not building, based on the inability MET per screening from the IF performed in postulated inside the of a flood within the EDG BWROG analysis did not accordance with the diesel generator . building to result in a reactor peer review change the SFCP.

building;" trip since offsite power would methodology used not be affected. for the IF flood area Possible Resolution screening, or the Consider spray scenarios PRA scope or for the diesel generator capability.

buildings.

7-4 IFEV-A3 The flood induced Review of the internal flooding Resolved, IFEV-A3: Maintenance This finding was initiating event defaults to (IF) FRANX database Closed Cat 1-2 update. Enhanced closed and therefore loss of power conversion revealed that pipe breaks MET per documentation of the has no impact on STI system plant initiator (T- associated with a loss of a BWROG IF initiating event change evaluations

2) is conservatiye. system that results in a Peer grouping did not performed in reactor trip (e.g., plant service Review change the accordance with the Possible Resolution water, circulating water) are methodology used SFCP.

Run sensitivities to for the IF actually grouped with the simple turbine trip for internal events initiator quantification, or the comparison to loss of associated with that failed PRA scope or power conversion system. Only IF initiators that capability.

system. do not result in a loss of a system that causes a plant trip are grouped with the loss of power conversion system initiating event. This is much more detailed than suggested by the peer review team.

The Internal Flooding Analysis Report was updated to better describe the grouping of Page 30 of 32

initiating events and document the detailed grouping in an appendix.

7-5 IFQU-A1 It is not evident that The internal flooding model is Resolved, IFQU-A1: Maintenance This finding was accident sequences were integrated with the internal Closed Cat 1-3 update. Enhanced closed and therefore performed and events model, and the internal MET per documentation of the has no impact on STI documented. There is flood accident sequences are BWROG IF accident change evaluations little evidence contained quantified using the same Peer sequences did not performed iri in RSC-CALKNX-2015- methodology as the internal Review change the accordance with the 0803 events accident sequences. methodology used SFCP.

Possible Resolution The Internal Flooding Analysis for the internal Report was updated to events or IF Perform and document sequence quantification in document the IF accident sequences (formerly included quantification, or the accordance with H LR PRA scope or IFQU-A1 in the PRA Summary Report).

capability.

7-7 IFQU-A1 In Table 1, reference to Table 1 (IF "roadmap" for the Resolved, IFQU-A1, Maintenance This finding was IFQU-A2 Section 14.0 seems ASME/ANS PRA Closed IFQU-A2, update. Corrections closed and therefore incorrect. requirements) was revised to IFQU-A4: to the IF "roadmap" has no impact on STI IFQU-A3 Cat 1-3 for the ASME/ANS change evaluations Possible Resolution reference the correct sections IFQU-A4 and/or other reports as MET per PRA requirements, performed in Revise Table 1 as BWROG and enhanced accordance with the IFQU-A7 necessary.

appropriate Peer documentation of the SFCP.

IFQU-A10 The updated quantification of

[IFQU-A7 Basis: it is not Review IF quantification, IFQU-B1 the Internal Events PRA and evident that the IFQU-A3: convergence and the Internal Flood PRA both IFQU-B2 requirements of 2-2. 7 Cat 1-2 results did not now show convergence for were satisfied. For both the pre-recovery and the MET per change the example, no evidence of BWROG methodology used post-recovery cases.

convergence Peer for the IF determination or A review of the Internal Flood Review quantification, or the uncertainty analysis.] (IF) analysis was performed PRA scope or and documented in the IFQU-A7,

[IFQU-B2 Basis: While capability.

Internal Flooding Analysis IFQU-A10 Page 31 of 32

most are documentation Report. This review included IFQU-81,

~lements satisfied, the is cutset reviews for the IF, a IFQU-82:

no evidence to support d, review and discussion of the Cat 1-3 results of the IF analysis significant IF accident MET per consistent with HLR-QU- sequences, a review and independent D] discussion of the significant IF assessment cutsets, and identification of of finding the top IF basic events, HFEs, closure Maintenance events, CCF events, and initiating events based on Fussell-Vesely and RAW.

7-8 IFQU-A10 Although it is apparent A review of the Internal Flood Resolved, IFQU-A10: Maintenance This finding was that quantification of the (IF) LERF analysis was Closed Cat 1-3 update. Enhanced closed and therefore flooding model was performed and documented in MET per documentation of the has no impact on STI performed as the Internal Flooding Analysis independent IF LERF results did change evaluations documented in RSC- Report. This review included assessment not change the performed in CALKNX-2015-0803, it is cutset reviews for the IF of finding methodology used accordance with the not evident that the LERF, a review and closure for the IF LERF SFCP.

LERF analysis was discussion of the significant IF quantification, or the reviewed and LERF accident sequences, a PRA scope or documented. review and discussion of the capability.

Possible Resolution significant IF LERF cutsets, and identification of the top IF Document the LERF LERF basic events, HFEs, analysis in accordance Maintenance events, CCF with IFQU-A10 events, and initiating events based on Fussell-Vesely and RAW.

Page 32 of 32

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