GO2-15-128, Response to Request for Additional Information Regarding License Amendment Request for Adopt Technical Specification Task Force (TSTF)-425, Revision 3

Response to Request for Additional Information Regarding License Amendment Request for Adopt Technical Specification Task Force (TSTF)-425, Revision 3

ML15260A570
Person / Time
Site:	Columbia
Issue date:	09/17/2015
From:	Schuetz R Energy Northwest
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GO2-15-128, TAC MF6042, TSTF-425, Rev. 3
Download: ML15260A570 (24)

Text

Robert E Schuetz Vice President, Operations P.O. Box 968, Mail Drop PE23 Richland, WA 99352-0968 Ph. 509-377-2425 F. 509-377-4674 reschuetz@energy-northwest.com GO2-15-128 September 17, 2015 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001

Subject:

COLUMBIA GENERATING STATION, DOCKET NO. 50-397 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPT TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3

References:

1. Letter, GO2-15-007, dated March 17, 2015, WG Hettel (Energy Northwest) to NRC, License Amendment Request for Adoption of Technical Specification Task Force Traveler (TSTF)-425, Revision 3

2. Email, dated August 12, 2015, Balwant Singal (NRC) to Lisa Williams (Energy Northwest), Request for Additional Information - License Amendment Request for Adoption of TSTF-425, Revision [3],

Columbia Generating Station - TAC No. MF6042

Dear Sir or Madam:

By Reference 1, Energy Northwest submitted for approval the License Amendment Request (LAR) to adopt TSTF-425, Revision 3.

Via Reference 2, the Nuclear Regulatory Commission (NRC) submitted Requests for Additional Information (RAIs) to Energy Northwest for response. Attachment 1 provides the requested information except RAI 3. A response to RAI 3 will be provided by October 31, 2015.

This letter and its attachment contain no regulatory commitments.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPT TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 2 of 2 If there are any questions or if additional information is needed, please contact Ms. L. L.

Williams, Licensing Supervisor, at 509-377-8148.

I declare under penalty of perjury that the foregoing is true and correct. Executed this

-1.fe_ day of ~ , 201 S'.

Respectfully, R. E. Schuetz Vice President, Operatio Attachments: As Stated.

cc: NRC Region IV Administrator NRC NRA Project Manager NRC Sr. Resident Inspector - 988C CD Sonoda - BPN1399 (email)

WA Horin - Winston & Strawn RR Cowley-WDOH (email)

EFSECutc.wa.gov-- EFSEC (email)

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 1 of 22 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION (RAI)

The NRC staffs Probabilistic Risk Assessment Licensing Branch (APLA) has completed its initial review of the licensees proposed technical specification changes for its

[Columbia Generating Station] CGS related to adoption of Technical Specification Task Force-425, Revision 3. Based on our review, the NRC staff has identified the following request for additional information for completing its review.

Request for Additional Information (RAI) for APLA:

NRC Request

1. The LAR mentions a number of peer reviews and a self-assessment:

A peer review had been performed in 2004.

A peer review had been performed in 2009 and a report issued in January 2010. Findings and Observations (F&Os) included those graded as capability category I (CCI) or not met.

A self-assessment had been performed.

A Fire Probabilistic Risk Assessment (PRA) peer review had been performed.

a. Please clarify which peer reviews (internal events PRA, Fire PRA, or other PRA) were full scope or focused scope, discuss the peer review guidance, standards, and regulatory guidance followed, and confirm the reviews were conducted consistent with applicable guidance and standards. Please clarify whether the internal events PRA was reviewed to the Addenda to American Society of Mechanical Engineers/American Nuclear Society (ASME/ANS) RA-S-2008 (i.e.,

ASME-ANS RA-Sa-2009). If reviews were not conducted consistent with applicable guidance and standards, please describe your plans to address any shortcomings in the review. With regard to the self-assessment, please describe when this was performed and the scope of the self-assessment, and whether it included a gap assessment between Regulatory Guide (RG) 1.200, Revision 1, An Approach for Determining the Technical Adequacy of a Probabilistic Risk Assessment Results for Risk-Informed Activities, (ADAMS Accession No. ML070240001) and RG 1.200, Revision 2 (ADAMS Accession No. ML090410014), for the internal events PRA. Please also provide additional information on the Fire PRA peer review describing when it was performed and what the peer review entailed.

b. Please provide the internal events PRA (including flooding) F&Os graded as CCI or not met and describe your disposition of these F&Os from the 2009 peer review and self assessment.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 2 of 22

c. If PRA models other than the internal events PRA model are used for detailed quantitative analysis versus for qualitative or bounding analyses, then please address the technical adequacy guidance of RG 1.200, Revision 2. If the LAR is requesting to use these PRA models as such, provide the F&Os graded as CCI or not met and describe your disposition of these F&Os from the peer reviews.

Energy Northwest Response:

1.a:

The following discussion clarifies which Columbia Generating Station (CGS) peer reviews (internal events PRA, fire PRA, and seismic PRA) were full scope or focused scope and discusses the peer review guidance, standards, and regulatory guidance followed. All reviews were conducted consistent with applicable guidance and standards.

Internal Events PRA In 2004 the CGS Revision 5.0 internal events PRA received a full scope peer review against the Capability Category II (CC-II) requirements of the ASME/ANS PRA Standard, ASME RA-Sa-2003, as clarified by Regulatory Guide (RG) 1.200 (DRAFT),

using the industry peer review process guidelines described in Nuclear Energy Institute (NEI) NEI-00-02, Revision A-3, Probabilistic Risk Assessment Peer Review Process Guidance.

In 2009, the CGS Revision 7.0 internal events PRA received a full scope peer review from the Boiling Water Reactor Owners Group (BWROG) against the ASME/ANS PRA Standard ASME/ANS RA-Sa-2009, as clarified by Regulatory Guide (RG) 1.200, Revision 2, using the industry peer review process guidelines in NEI-05-04, Revision 2, Process for Performing Follow-On PRA Peer Reviews Using the ASME PRA Standard.

CGS Fire PRA The fire PRA has not been upgraded to meet CC-II for the supporting requirements (SRs) of the combined ASME/ANS Standard, ASME/ANS RA-Sa-2009. There are no plans to perform a peer review of the current version of the fire PRA.

In 2004, the CGS Revision 1 fire PRA (FPRA) received a full scope peer review as part of the internal events peer review. At the time, the fire PRA peer review process had limited industry and regulatory guidance available. The following is an excerpt from the 2004 Peer Review report on the guidance used:

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 3 of 22 a technical checklist for conducting a FPRA Peer Review was developed based on the available references for use in the PRA Peer Review of the CGS Fire PRA.

In general, the objectives of the checklists are to provide a structured process to confirm:

1. Use of acceptable methodology in comparison with current state of the art and industry practices.

2. Appropriateness of methodology and analysis scope given intended application.

3. Analysis is free of obvious errors or misapplications

4. Acceptable level of detail to support the specific application under review -

S/G AOT Extension The Fire PRA Peer Review checklists were developed based in ERINs standard practices for FPRAs, the guidance provided in NEI 00-02, The [Electrical Power Research Institute] EPRI Fire PRA Implementation Guide, the industry responses to the NRC Generic RAIs, and Regulatory Guide (RG) 1.200. ERINs standard project approach for conducting a FPRA formed the basic framework and structure for the checklist. The NEI 00-02 document provided guidance for the depth of review while the RG 1.200 and EPRI documents provided specific issues for review. Based on this Information, the checklists are structured using six topical areas:

1. Fire Areas and Fire Compartments (FC)

2. Cable and Equipment Location Data (CE)

3. Developments of Fire Ignition Frequencies (FI)

4. FPRA Model Development - Plant Response (FM)

5. Fire Scenario Development (FS)

6. FPRA Model Quantification (MQ)

CGS Seismic PRA The CGS seismic PRA (SPRA) has not been peer reviewed. The SPRA has not been upgraded to meet CC-II for the supporting requirements of the combined ASME/ANS Standard, ASME/ANS RA-Sa-2009. There are no plans to perform a peer review of the current version of the seismic PRA.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 4 of 22 PRA Self-Assessment Process No gap assessment between RG 1.200 Revision 1 and Revision 2 has been performed on the CGS PRA. CGS Revision 7.0 internal events PRA received a full scope peer review from the BWR Owners Group against the ASME/ANS PRA Standard, ASME/ANS RA-Sa-2009, as clarified by Regulatory Guide 1.200, Revision 2, using the industry peer review process guidelines in NEI 05-04, Revision 2.

A Self-Assessment as described in the submittal refers to the process in which PRA modeling self-identified facts and observations (F&O) are entered into the CGS F&O database for inclusion in the next modeling update.

1.b:

The 2009 internal events peer review and self-assessment findings assigned to SRs that were graded as CC-I or not met are presented in Table 1. Dispositions of findings are provided in Table 2.

Table 1 F&Os for SRs Graded as CC-I or Not Met by the 2009 Peer Review and Self-Assessment SR 2009 Peer F&Os Review Assessment IE-C14 Not Met 1-10, 1-14 SY-A4 CC-I 2-14 SY-A14 Not Met 2-16, 2-17 SY-A24 Not Met 3-11 SY-B1 Not Met 6-10, 6-8, 6-9 SY-C2 Not Met 2-14, 2-16, 2-17 HR-D2 CC-I 1-23 HR-D3 CC-I 1-23 HR-D4 Not Met 1-23 HR-G3 CC-I 1-3 DA-D1 CC-I 3-1 LE-C7 Not Met 1-3, 1-33, 1-42, 1-43 LE-D4 Not Met 1-10, 1-14, 1-43 LE-G6 Not Met 2-18 IFPP-B3 Not Met 2-28 IFQU-A6 Not Met 1-3, SA-IF-E5a-1 MU-C1 Not Met 4-7

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 5 of 22 Table 2 Disposition of Findings from the 2009 Peer Review and Self-Assessment for Supporting Requirements Graded as CC-I or Not Met Finding Observations Recommendations Source Resolution F&O 1-10 High Pressure Core Spray (HPCS) notebook does not Consider the quarterly test of V-4 Peer Resolved: YES include the Surveillance Test for HPCS-V-4. Additionally, the in the ISLOCA analysis. Update Review SRs: screening for HPCS in the ISLOCA Section of the Initiating the HPCS notebook to include IST To resolve this finding, an ISLOCA assessment was Event Notebook (appendix E) does not account for the for HPCS valves, including V-4. performed for the HPCS system, including consideration of IE-C14 HPCS-V-23, HPCS-V24, and the inservice testing of possibility of ISLOCA during testing of this valve. A possible scenario is, prior to V-4 test, the injection Check Valve V-5 HPCS-V-4 and as discussed in the finding. Documentation LE-D4 has failed open, and once the test has completed, V-4 does of this assessment was added to Appendix E, ISLOCA not close and V-24 fails (may be CC). The result is ISLOCA Initiating Event Frequency, of the initiating events notebook.

to low pressure piping.

OSP-HPCS/IST-Q701 lists V-4 as being tested quarterly. V-23 is open during the test, given reactor is at pressure.

F&O 1-14 ISLOCA analysis applies a conditional probability of valve ISLOCA analysis should be revised Peer Resolved: YES closure from NSAC-154, but applies this to NUREG/CR- to remove NSAC-154 factors, and Review SRs: 6928 data. See IE notebook, Table E-1. Application of The apply factors based on the latest The ISLOCA event tree was modified to address this peer NSAC data does not appear appropriate when applied to valve failures in NUREG/CR-6928. review finding.

IE-C14 NUREG/CR-6928.

The ISLOCA analysis was revised to replace older valve LE-D4 failure data published by NSAC-154 with the latest valve The new valve failure data, such as check valve internal rupture, is not applicable to the older factors for valve re- failure data published in NUREG/CR-6928, wherever newer closes. For example, CV closes following pipe failure (0.01) data was available.

is based on older data, while the NUREG/CR-6928 data for check valve rupture would typically have screened failures A review of NUREG/CR-5124 revealed that the conditional probability of check valve closure (event tree node CV) is where the check valve stuck open (fails to close), but later applicable only to scenarios in which a testable check valve reclosed. ISLOCA is risk significant, and the factors affect multiple sequences. is held open due to reverse air flow to the controller. The 0.01 credit had minimal impact on the ISLOCA sequence cutsets, as the significant check valve failures are leakage and rupture. Therefore, event tree node CV was removed from the ISLOCA event tree.

Event tree node SML (small leak through the high/low pressure interface) is moved to an earlier position in the event tree, as leaks through the high/low pressure boundary are judged to be isolable (the 900-pound MOVs that are present at the boundaries are judged to be capable of closing against a leak). The model retains the assumption that MOVs would not likely close if a piping rupture and interface rupture were to occur, per

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 6 of 22 Table 2 Disposition of Findings from the 2009 Peer Review and Self-Assessment for Supporting Requirements Graded as CC-I or Not Met Finding Observations Recommendations Source Resolution NUREG/CR-5124 guidelines.

Also, the event tree node ISOVAV (early isolation of the ISLOCA) probability has been changed to a 0.1 based on documentation provided with the CGS SPAR model.

From the CGS SPAR model documentation:

Without doing detailed pressure capacity calculations and detailed modeling of the expected internal pressures and temperatures expected in the connected systems, it is impossible to predict the location of potential ruptures. Even with detailed calculations and modeling, precise rupture locations are impossible to identify. Nevertheless, some general observations can be made based on the GI-105 research. For most situations the RHR heat exchanger, and pump suction pipe are the components with the lowest pressure capacities. Generally, these components are positioned within the systems such that one or more valves are available to isolate a rupture, should an ISLOCA occur at these locations. However, it is possible that if the pressure isolation interface were to fail, that either the available valves would not successfully isolate the rupture, or the rupture could occur in a location that cannot be isolated. To account for these possibilities, a generic 10%

probability is assumed that if a rupture were to occur, it cannot be isolated.

This 10% probability for the rupture being non-isolable can be considered to be a reasonable estimate for a number of reasons. First, virtually every rupture location examined as part of the GI-105 research program was found to be potentially isolable. The pipe and other components (e.g.,

pump suction pipe and RHR heat exchangers) that are most susceptible to over-pressure induced rupture, are located deeper within the connected system such that a number of valves are typically available for isolating the rupture. Further, the typical failure mode postulated in the ISLOCA analysis for motor operated valves is spurious operation. The few actual instances of this observed in the

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 7 of 22 Table 2 Disposition of Findings from the 2009 Peer Review and Self-Assessment for Supporting Requirements Graded as CC-I or Not Met Finding Observations Recommendations Source Resolution operating experience were all recoverable from the control room. However, one factor that affects the ability to isolate the rupture is local accessibility. If a rupture were to occur, the resulting local environment would likely preclude access to the immediate vicinity. Therefore, if local access was necessary, and if the potential isolation valves were located close to the rupture then isolation would be unlikely. Again, the research performed to support resolution of GI-105 included an assessment of induced flooding and the resultant environment. That work concluded these effects would not significantly affect the ISLOCA risk. Therefore, the non-isolable ruptures are assumed to compose 10% of the potential ISLOCA ruptures.

The accident sequence notebook was updated to reflect all of these changes to the ISLOCA model.

F&O 1-23 The quantification of pre-initiating events using 3 surrogate Re-Analyze pre-initiating events for Peer Resolved: YES events to represent all pre-initiating events does not provide all significant HEPs, taking into Review SRs: an accurate assessment of each HEP, taking into account account the component specific Procedure-specific pre-initiator HEP calculations were plant specific or component specific attributes. Appendix A.4 testing, maintenance and developed for the top three pre-initiator human failure HR-D2 events when sorted by RAW and the top three pre-initiator for example, provides a "generic" assessment of operations attributes affecting the miscalibration with dependencies, without actually including HEP. Use of surrogate or generic human failure events when sorted by Fussell-Vesely based HR-D3 on the CGS Rev. 7.0 Level 1 PRA model results. This the specific attributes for the procedure affecting events it is analysis should be limited to non-HR-D4 applied. For pre-initiator failure to restore events, the use of significant events, with some resulted in a total of five pre-initiator human failure event for the surrogate event does not account for post-maintenance justification that the surrogate is which to perform procedure-specific HEP calculations.

testing, operations walkdowns, and when the system may representative or bounding for the (Note - Five are evaluated, rather than six, because the top be operated again. For pre-initiator miscalibration, the HEPs it is applied. pre-initiator human failure event when sorted by RAW was surrogate event does not represent the plant specific also the top pre-initiator action when sorted by F-V).

calibration procedures. In Appendix A.4, the following is Section 3.0a and Appendix A.0 were added to the HRA provided in the generic analysis "The results of these evaluations indicate that, depending on the methods used to Notebook to document the updated procedure specific pre-initiator HEP calculations.

verify the adequacy of the calibration and the assumptions used in the quantitative evaluation, there can be substantial The five revised pre-initiator HEPs were subsequently variation in the common cause miscalibration error incorporated into the final HRA Calculator file CGS 2008 probability." This statement is true, which is why plant- HRA.HRA specific attributes are needed for this analysis.

Numerous Pre-Initiating Events in all three categories are risk-significant, based on table E-2 of the QU notebook.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 8 of 22 Table 2 Disposition of Findings from the 2009 Peer Review and Self-Assessment for Supporting Requirements Graded as CC-I or Not Met Finding Observations Recommendations Source Resolution Comparison with other PRAs shows that variation between component/action specific HEPs is expected, and the range of differences from one component to the next can be several orders of magnitude. For mis-calibrations, for example, depending on whether the mis-calibration can be quickly recognized or whether there is a second check on the calibration can greatly affect the results. Variation in dependent failures and failure to restore is equally large within a PRA.

CGS provides discussion on this F&O suggesting the important pre-initiating events were represented by the "representative" actions, and the procedures for each action were similar. The following procedures were reviewed for this follow-up:

Representative Procedures:

SOP-CN-FILL (for CN-HUMNTK--1X3XX), ISP-LPCS/RHR-X301 (for LPSHUMNFIS-4XLL)

Significant HEP Procedures:

Calibration:

ISP-RCIC-Q901 (HEP: RCIHUMNPS13AX3LL), 10.27.86 (HEP: RCIHUMNPS--6X3LL)

Restoration:

OSP-SW/IST-Q702 (HEP: SWB-XHE-RE-RHRSW), OSP-SW/ISP-Q701 (HEP: SWA-XHE-RE-RHRSW), SOP-COLDWEATHER-OPS (HEP: SW-HUMNV218-X3LL), OSP-HPCS/IST-Q701 (HEP: HPC-XHE-RE-MAINT)

Based on a review and comparison of the representative procedures versus the procedures for significant HEPs, it is clear the procedures, associated critical steps, and verification steps are significantly different.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 9 of 22 Table 2 Disposition of Findings from the 2009 Peer Review and Self-Assessment for Supporting Requirements Graded as CC-I or Not Met Finding Observations Recommendations Source Resolution F&O 1-3 Analysis for HEPs apply low stress to post-accident Apply high stress factors per Table Peer Resolved: YES situations for almost all HEPs, even though the criteria in 17-1 of NUREG/CR-1278 to HEPs Review SRs: NUREG-/CR-1278 recommends High Stress especially where time pressure is present After reviewing the peer review F&Os, no changes to the when the time window is short. See HPSHUMN-SP-H3LL, during an accident situation. calculated post-initiator HEPs were judged necessary to HR-G3 address the post-initiator stress levels. Section 4.4 of the OP-SW-PMP, SLC-XHE-FO-LLVCT and others. Benchmarking against other PRAs performed by alternate vendors to HRA documentation has been enhanced to further justify LE-C7 Supplemental guidance was provided by CGS personnel as determine how the Stress Factors the position that the post-initiator stress levels are treated IFQU-A6 a result of this issue. The CGS argument included an from 1278 were applied can be appropriately in the CGS PRA.

argument that there was not extensive use of simulator useful for this issue.

training prior to the development of NUREG/CR-1278, and The use of high stress for the manipulation errors in the that this training affects the application of stress to simple post-initiator HEPs is performed on a case-by-case basis.

actions where training occurs. A second set of justification The blanket requirement that all manipulations in the plant was provided, with discussion that basically justified for the first hour of an event are high stress does not agree moderate or low stress would be appropriate, given enough with the intent of NUREG/CR-1278 nor common practice training for the operators. Review of this new guidance does within the industry as confirmed with the developers of the not provide sufficient justification for the revised application HRA Calculator and the Chairman of the EPRI committee of NUREG/Cr-1278 Guidance. Two points are important to on HRA. Results from the CGS inquiry of the industry and this finding: a) stress will affect actions occurring during an alternative vendors, the time consideration for the stress accident in comparison to non-accident actions making the factor for Internal Events PRA is NOT typically treated as actions less reliability, and b) Stress is based on an overall interpreted by the peer review team. HRA leaders in the sense of being pressured and/or threatened in some way industry do not agree with the position on time pressure with respect to what they are trying to accomplish. Training (less than 1 hr = high stress) associated with Finding 1-3.

can not fully remove the treat or pressure during an actual The Columbia upgrade project specifically used the most event. current methodology from EPRI (HRA Calculator) available.

The general consensus is there have been improvements Stress factors assumed to be nominal are also in the Level II in knowledge and methodology since NUREG/CR-1278 model and flooding model for short duration HEPs. was issued over 30 years ago that support execution error evaluations to be assessed considering current training NUREG/CR-1278 recommends applying optimum stress to regimes and the simple nature of such actions.

activities such as maintenance and calibration activities, reading an annunciator light, or scheduled readings in the control room. On the other hand, Page 17-7 states that 'In general, situations that impose time pressure on the performers are classified as heavy task load situations.' In almost all of the Post-Initiator HEPs where optimal stress is assumed, time is a factor with Core Damage occurring between 30 minutes and an hours. This time stress is typically modeled as high stress in HRA using NUREG/CR-1278.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 10 of 22 Table 2 Disposition of Findings from the 2009 Peer Review and Self-Assessment for Supporting Requirements Graded as CC-I or Not Met Finding Observations Recommendations Source Resolution Numerous HEPs where this is applied are risk-significant.

Discussions with CGS staff indicated that the low stress was applied to actions that are relatively simple. However, since this simple actions are already low if failure rate, the stress factor is still applicable in order to differentiate between a simple action performed as a routine action, and a simple action performed in order to avoid core damage. Nominal stress is also applied for level II actions, such as failure to provide injection after the control rods fail (10 minute window) just prior to core damage. The general rules for this as applied by CGS do not appear consistent with NUREG/CR-1278 or other PRAs reviewed for this issue.

F&O 1-33 HEPs are calculated using the HEP calculator, and are Add all missing HEPs from the Peer Resolved: YES realistically treated in most cases consistent to the Level II analysis into the HRA Review SRs: Applicable procedures. However, documentation on several section, including events set to 1.0. This finding was resolved by adding Level II human failure actions was not found in the HRA notebook: Additionally, provide basis for HEP events to the HRA Calculator and the summary Table 5.1-2 LE-C7 of the HRA Notebook. Also, as documented in Table C.4.7-L2-HUMN-RCVR-SYS equal to 0.9

1) L2-HUMN-MUPHNOWS (since it is risk-significant), 2 of the CGS Level 2 notebook, the basis for the screening including information on timing, HEP for L2-HUMN-RCVR-SYS is engineering judgement.

2) L2-HUMN-RCVR-SYS cues, procedures or other aspects Note this is just a sampling of the notebook, so others may causing little credit for the HEP.

also be missing.

L2-HUMN-MUPHNOWS is mentioned in Section C.16 of the LERF notebook, but not in the HRA notebook. Based on discussion with CGS, this HEP is set to 1.0 based on engineering judgment.

L2-HUMN-RCVR-SYS is listed as using the HRA calculator, but is set to 0.9 based on engineering judgment.

L2-HUMN-RCVR-SYS is risk-significant. Based on the Internal Events and Flooding HRA review, other HEPs are likely missing in the documentation (HRA notebook) that are credited in the analysis).

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 11 of 22 Table 2 Disposition of Findings from the 2009 Peer Review and Self-Assessment for Supporting Requirements Graded as CC-I or Not Met Finding Observations Recommendations Source Resolution F&O 1-42 HEP Dependency Analysis included in Appendix D of the Complete a dependency analysis Peer Resolved: YES HRA notebook does not included in the Level II Analysis. for Level II similar to the Level I Review SRs: Level II modeling includes new HEPs not in the Level I HRA. analysis in HRA appendix D. To resolve this peer review finding, a Level II HEP dependency analysis was performed and documented in LE-C7 LERF may be underestimated if dependent HEPs are not Section 5 and Appendix D of the HRA Notebook.

included along with the independent HEPs.

F&O 1-43 HRA events RHRHUMN-V--803XX and 903XX are included Either: a) Add a dependency Peer Resolved: YES in the ISLOCA analysis but do not include dependency analysis for these events, or b) Review SRs: considerations. See the top cutset in Appendix D, Provide justification for deletion of This peer review finding has been resolved. The RHR-V-8 dependency analysis. the cutset, and add the and RHR-V-9 have interlocks that prevent valve opening at LE-C7 normal RPV pressures above about 125 psig. Therefore combination to the mutually Based on discussion with CGS, the cutset with 2 operator exclusive event file. human failure events RHRHUMN-V--8O3XX and LE-D4 failures is not valid, since the valves are interlocked. RHRHUMN-V--9O3XX have been removed from the ISLOCA initiating event fault tree (that is, even in operators Since these are ISLOCA cutsets, and significant for both mistakenly select valve OPEN from the control board for CDF and LERF, dependency will be significant. either or both valves, the valves will not open).

F&O 2-14 Interviews with plant system engineers or operators have Perform and document the Peer Resolved: NO not been documented and cannot be verified by the peer interviews with the system Review SRs: review team. Original interviews were performed for the engineers and/or operators to F&O, 2-14, for SR SY-A4 remains open but Is in the original IPE. confirm that the systems analysis process being resolved to meet CC-II for SY-A4. Interviews SY-A4 correctly reflects the as-built, as- with the system engineers have been started with a focus System and operations change over time, and the system operated plant. It may be on confirming that the PRA systems analyses correctly SY-C2 engineers and operators should be consulted with regard to reasonable to develop a process reflect the asbuilt, asoperated plant, as well as to discuss the system models. that, following an initial interviews, recent operating history and any problems in system the confirmation the model operation. At the time of this transmittal, 6 out of 26, matches the as-built, as-operated interviews and reviews by System Engineering have been plant is confirmed through review fully completed. The interviews and reviews were or discussion with the system documented, and this documentation will be added to the engineers - typically through a system notebooks in the next PRA update. Discrepancies periodic review of the notebook identified by the system engineer interviews to date had no performed in accordance with plant impact on the PRA modeling, with the exception of one procedures. potential modeling conservatism for the reactor feedwater system model which does not have a risk-significant impact on the PRA results. Based upon the interviews and reviews conducted to date it is expected that there will be no risk significant findings. Resolution of this F&O will be provided by October 31, 2015 with the response to RAI 3.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 12 of 22 Table 2 Disposition of Findings from the 2009 Peer Review and Self-Assessment for Supporting Requirements Graded as CC-I or Not Met Finding Observations Recommendations Source Resolution F&O 2-16 Failure modes have been considered in development of the Consider adding documentation for Peer Resolved: YES system models adequately. However, the exclusion of both the inclusion and exclusion of Review SRs: some failure modes were not adequately documented. the failure modes with justification This peer review finding was resolved. A Tier 3 calculation Some failure modes could be important to system models. for components included the was prepared to ensure that failure modes have been SY-A14 considered in development of the system models A sample review of the system models show that the system boundary. Consider following failure modes may not have been fully adding more failure modes into the adequately, with evaluation for both the inclusion and SY-C2 investigated: system models if the exclusion exclusion of the failure modes for components within the requires additional quantitative system boundary, including justification. Failure modes (d) failure of a closed component to remain closed evaluations. were added or corrected in the system models and system especially for standby components where the failure would notebooks were updated based on this evaluation.

not be identified quickly - say months or greater).

(f) failure of an open component to remain open (see above)

(g) active component spurious operation (h) plugging of an active or passive component (i) leakage of an active or passive component (j) rupture of an active or passive component (k) internal leakage of a component (l) internal rupture of a component (m) failure to provide signal/operate (e.g., instrumentation)

(n) spurious signal/operation For example, in the [Residual Heat Removal] RHR system model, valves RHR-V54A/B could have a failure mode for fail to remain closed, which is not included in the model.

The exposure time on these valves would rely on the surveillance tests.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 13 of 22 Table 2 Disposition of Findings from the 2009 Peer Review and Self-Assessment for Supporting Requirements Graded as CC-I or Not Met Finding Observations Recommendations Source Resolution F&O 2-17 The following requirements associated with system Consider adding the Peer Resolved: YES modeling are determined to be not adequate: documentation associated with Review SRs: items (e), (l) and (q). Also consider This peer review finding was resolved by enhancing system (e) actual operational history (such as [Significant Operating enhancing the documentation for modeling documentation items associated with items (e),

S Y-A14 Experience Reports] SOERs) indicating any past problems (l), (q), (f) and (k). For item (e), significant operating the following two items:

in the system operation [not documented], experience has been collected, but this information has not SY-C2 (f) system success criteria and yet been incorporated into the system notebooks. This (l) the components and failure modes included in the model relationship to accident sequence information will be incorporated into the system notebooks and justification for any exclusion of components and failure models during future PRA update.

modes [also see F&O 2-16],

(k) assumptions or simplifications (e) actual operational history (such as SOERs) indicating (q) the sources of the above information (e.g., completed made in development of the any past problems in the system operation was collected, checklist from walkdowns, notes from discussions with plant system models (i.e., provide a and will be added to the system notebooks in a future PRA personnel) [also see F&O 2-14]. bulleted list of major assumptions update, in each system notebook).

The following should be enhanced: (f) documentation of system success criteria and relationship to accident sequence models was enhanced in (f) system success criteria and relationship to accident the system notebooks, sequence models (k) documentation of assumptions or simplifications made (k) assumptions or simplifications made in development of in development of the system models was enhanced in the the system models.

system notebooks, The inadequate documentation limits the review of the (l) the components and failure modes included in the model completeness of the system models.

and justification for any exclusion of components and failure modes, and (q) the sources of the above information (e.g., notes from discussions with plant personnel) were documented.

F&O 2-18 The quantitative definition used for significant accident Add the quantitative definition used Peer Resolved: YES progression sequence was not documented. for significant accident progression Review SR: sequence in the LE notebooks. This peer review finding was resolved. Section 6.3 of the Level 2 Notebook was enhanced to add the quantitative LE-G6 definition used for significant accident progression sequence.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 14 of 22 Table 2 Disposition of Findings from the 2009 Peer Review and Self-Assessment for Supporting Requirements Graded as CC-I or Not Met Finding Observations Recommendations Source Resolution F&O 2-28 Sources of model uncertainty and related assumptions for Investigate and document the Peer Resolved: YES flood plant partitioning were not documented in the flooding sources of model uncertainty and Review SR: notebooks. Neither do the Internal Flooding items included related assumptions for flood plant The PRA Quantification Notebook Table 5-3, documents in PSA-2-QU-0001 Tables 5-2 and 5-3. partitioning. Perform sensitivity uncertainties and related assumptions for the overall PRA, IFPP-B3 including uncertainties and related assumptions for flood studies if deemed necessary.

Sources of model uncertainty and related assumptions for plant partitioning. This information was added to the IF flood plant partitioning are not documented. notebooks for completeness.

Sensitivity studies, other than the standard set of sensitivities, i.e., CCFs set to 5th and 95th percentile and HEPs set to 5th and 95th percentile, are not directed for the base PRA model per the EPRI Uncertainties/Assumptions methodology, 1016737, and were not performed.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 15 of 22 Table 2 Disposition of Findings from the 2009 Peer Review and Self-Assessment for Supporting Requirements Graded as CC-I or Not Met Finding Observations Recommendations Source Resolution F&O 3-1 The process of developing plant-specific parameter data Consider using screening criteria Peer Resolved: YES updates based on plant-specific experience and generic more consistent with criteria used Review SRs: data is described in PSA-2-DA-0002, Bayesian Update of for important plant applications of This peer review finding has been resolved. Screening CGS PSA Data. the base PRA (e.g., Maintenance criteria consistent with important plant applications of the DA-D1 base PRA are now used, per RG 1.200, Rev. 2 (footnote Rule) to ensure that potentially risk The process is focused on significant basic events. significant failures reflect plant page 10: Significant basic event/contributor: The basic However, the process used to determine which events are experience. events (i.e., equipment unavailabilities and human failure significant and should be Bayesian updated appears to be events) that have a Fussell-Vesely (FV)importance greater faulted. A set of screening criteria based on risk than 0.005 or a risk-achievement worth greater than 2):

achievement worth, F-V, and Birnbaum importance measures is applied, but the criteria for determination of - The identification of plant-specific parameter data updates significant (i.e., per PSA-2-DA-0002, "RAW value of 3 is now uses a risk-achievement worth (RAW) value greater typically used in risk ranking initiatives to identify risk than 2 as one screening criterion, and important

- A FV of greater than 5E-3 is typically used in risk ranking components.") differs from those applied in risk-informed initiatives to identify risk-significant components. The applications (e.g., Maintenance Rule, where RAW of 2 and identification of plant-specific parameter data updates now F-V of 0.005 are normally used). In the DA screening, a uses a FV of 1E-4, because it was practical to do so.

RAW of 3 is used as the criterion, so it is possible that some significant basic events could be screened from consideration using the process in PSA-2-DA-0002 (i.e., in Table 4 there would be a lower value for the CDF change for which a failure would be a candidate for Bayesian updating).

Capability Category 2 for SR DA-D1 requires that realistic parameter estimates be calculated for all significant basic events. The process used to define which events are significant is not adequately objective and uses criteria that are inconsistent with selection criteria used for risk-informed applications (e.g., MR ), and may result in underestimating the set of significant events.

After discussion with CGS PRA personnel, they performed a sensitivity evaluation to estimate the impact of using more appropriate screening criteria. This exercise identified one additional component type (RV/SV) for which there were no EPIX failures.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 16 of 22 Table 2 Disposition of Findings from the 2009 Peer Review and Self-Assessment for Supporting Requirements Graded as CC-I or Not Met Finding Observations Recommendations Source Resolution F&O 3-11 The accident sequence model includes top event EAC, Provide a sound basis for the Peer Resolved: YES recovery of onsite AC power. The text of the AS notebook present-day validity of the repair Review SR: refers to Appendix D of that notebook for the onsite power probabilities, or remove the credit This peer review finding was resolved by enhancing recovery calculation. Appendix D is a portion of ERIN letter from the model. Appendix D of the accident sequence notebook to further SY-A24 support that the existing EDG non-recovery values based C1069805-3919 Completion of CGS PSA Model Modifications to Address PSA Certification Comments on SECY-93-190 are judged to be appropriate for CGS.

(P.O.00303454), August 3, 1999. titled Emergency AC Further, the Emergency AC Power recovery values from Power Recovery. That analysis uses as its basis a 1993 SECY-93-190 used in the CGS PRA were compared with regulatory analysis, SECY-93-190. There are 2 issues with this. First, the basis for the onsite AC power recovery is a more recent data from NUREG/CR-6890. The SECY 190 data produces non-recovery probabilities that are set of EDG repair data from before 1993, i.e., significantly higher relative to the NUREG/CR-6890 data. The following more than 16 years old, and originally based on relatively few data points. Second, this represents credit for repair of comparison is made:

failed equipment without checking against plant-specific Recovery Time (hr),SECY-93-190,NUREG/CR-6890 experience.

0.5, 0.89, 0.86 Credit should not be taken for repair of failed equipment, particularly EDGs, without sound plant-specific basis. 2, 0.86, 0.65 Significance may be increased if tied to the F&O on consequential LOOP. 3, 0.78, 0.56 4, 0.71, 0.48 6, 0.59, 0.37 10, 0.4, 0.24 15, 0.29, 0.14 24, 0.23, 0.24 The SECY-93-190 data provides higher non-recovery values for the entire range of EDG recovery times.

Although the NUREG/CR-6890 diesel non-recovery data development is more recent, there is one prominent concern about the NUREG/CR-6890 data for purposes of the Columbia PSA modeling. The NUREG/CR-6890 non-recovery values assume that the diesel generator that is most straightforward to repair will be chosen for recovery.

What is not clear from the NUREG/CR-6890 treatment is

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 17 of 22 Table 2 Disposition of Findings from the 2009 Peer Review and Self-Assessment for Supporting Requirements Graded as CC-I or Not Met Finding Observations Recommendations Source Resolution how the SPAR models address the possibility that the DG that is easiest to repair actually wont be restored because the associated SW pump or RHR pump is out of service.

The Columbia model assumes a 50-50 percent likelihood for recovery of DG-1 or DG-2, unless the SW or RHR pump on one of the diesel generators is out of service. Due to this potential conflict, the NUREG-6890 data was not used.

The SECY-93-190 data is judged to be the most applicable and realistic.

F&O 4-7 While consideration of pending model changes has occurred Consider revising SYS-4-34 or Peer Resolved: YES for important applications (e.g. DGAOT), there was no other procedure/instruction to Review SR: identified Columbia process that requires that pending address this issue. The peer review finding was resolved. A new Section 4.4 changes be considered for applications. was added to the model maintenance and update MU-C1 A industry model process for procedure, SYS-4-34, that documents the Columbia Having such a process is an explicit requirement of the performing Maintenance and process that requires pending model changes to be standard. Update is provided in the BWROG considered for applications. Also, a list of current document TP-09-012 Living PRA applications that require a consideration of pending model Configuration Control and Model changes in applications was added in SYS-4-34, Maintenance, however use of this Attachment 8.2.

process is not a requirement of the ASME Standard.

F&O 6-10 A variety of common cause basic events exist in the model Provide a basis for all CCF values, Peer Resolved: YES without documentation provided to substantiate their basis. including events set to 0.0, based Review SR: For example, Table 1 of PSA-2-DA-0004 lists 13 CCF on the CCF analysis process. This peer review finding has been resolved. The events with probabilities of zero related to relays, vacuum documentation of CCF events has been refined and SY-B1 breakers, and nitrogen bottles. Table 1 also lists two events improved. The bases for all CCF values are provided, that are termed CCF place keepers but not true CCF events. based on the CCF analysis process.

These are not further discussed. Table 1 lists CCF events with apparently generic values (1E-6), but no discussion or justification is provided to substantiate the value. Table 1 lists CCF events for 5 of 7 ADS valves and 5 of 11 SRVs, with values of 1.24E-6, but no discussion / justification is provided. Table 2 lists an event (CRDSV--24567C8LL) for "8 of 8", but uses the NRC data for "2 of 2" instead of the closer "6 of 6" value. Upon review, CGS noted that this event is not needed in the model and will be removed in the next update.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 18 of 22 Table 2 Disposition of Findings from the 2009 Peer Review and Self-Assessment for Supporting Requirements Graded as CC-I or Not Met Finding Observations Recommendations Source Resolution F&O 6-8 Several issues were identified in the review of CCF: Add CCF grouping methodology to Peer Resolved: YES PSA-2-DA-0004, and add formulae Review SR: 1) The process to develop common cause groups is not for the CCF basic event probability This peer review finding has been resolved. The process to documented in the CCF NB and therefore justification is not calculations. Add reference in the develop common cause groups is now documented in PSA-SY-B1 provided for the grouping scheme. Per CGS, selection of 2-DA-004. CGS employs staggered testing of redundant data notebook to NUREG/CR-CCF groups was performed following the guidance of 5485. Re-evaluated CCF values, trains modeled in the PRA. Therefore, CCF probabilities NUREG/CR-5485 based on similarities in service conditions, based on the revised methods. were recalculated using the CCF equations for staggered environment, design or manufacturer, and maintenance. testing, and these equations are documented in PSA-2-DA-NUREG/CR-5485 is not currently referenced in PSA-2-DA- 004, and the PRA was updated.

0004.

2) There are limited formulae documented in the CCF data package PSA-2-DA-0004. As a result, the bases for the calculations embedded in the spreadsheets are not fully documented. Discussions with CGS staff indicates the Alpha CCF calculations were performed incorrectly. Moreover, based on the formulae in NUREG/CR-5485, the CCF basic event probabilities may be slightly more conservative.

3) As a result of the above, CCF basic events are incorrectly calculated.

F&O 6-9 Per Section 2 of PSA-2-DA-0004, the common cause Redevelop CCF approach using Peer Resolved: YES calculations are based on a non-staggered testing scheme staggered approach where Review SR: based on the prior use of this scheme for the original PRA appropriate. This peer review finding has been resolved. CGS employs and the fact that current CGS test intervals / test information staggered testing of redundant trains modeled in the PRA.

SY-B1 Therefore, CCF probabilities were recalculated using the has not been developed for the current data update. PSA DA-0004 notes that the non-staggered approach is CCF equations for staggered testing, and these equations conservative. The staggered approach should be utilized are documented in PSA-2-DA-004, and the PRA was where appropriate to reflect plant practices. updated.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 19 of 22 Table 2 Disposition of Findings from the 2009 Peer Review and Self-Assessment for Supporting Requirements Graded as CC-I or Not Met Finding Observations Recommendations Source Resolution SA-IF- No documentation was found of how scenario-specific Review all HEPs for actions that Self- Resolved: YES E5a-1 impacts were addressed for operator actions taken in could be taken following an internal Assessme response to an internal flooding event. Supporting flood and address how they would nt This self-assessment finding has been resolved. The SR: requirement IFQU-A6 requires the following: be impacted by the flood. internal flooding HRA assesses scenario-specific impacts Document this review and modify on PSFs, including additional workload and stress, cue IFQU-A6 availability, effect of flood on mitigation, required response, the analysis accordingly.

timing, and recovery activities flooding-specific procedures For all human failure events in the internal flood scenarios, and training. These enhancements to the HRA are INCLUDE the following scenario-specific impacts on PSFs documented in the HRA Calculator and in the HRA for control room and ex-control room actions as appropriate Notebook.

to the HRA methodology being used:

(a) additional workload and stress (above that for similar sequences not caused by internal floods)

(b) cue availability (c) effect of flood on mitigation, required response, timing, and recovery activities (e.g., accessibility restrictions, possibility of physical harm)

(d) flooding-specific job aids and training (e.g., procedures, training exercises)

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 20 of 22 1.c:

No PRA models other than the internal events PRA will be used for detailed quantitative analysis.

NRC Request

2. The LAR indicates that PRA models other than the internal events PRA model may be used. Please confirm that these PRA models reflect the current plant configuration and operation. If this is not the case, please explain how the PRA models support the application, using Nuclear Energy Institute (NEI) 04-10, Revision 1, Risk-Informed Technical Specifications Initiative 5b, Risk-Informed method for Control of Surveillance Frequencies, April 2007 (ADAMS Accession No. ML071360456) guidance, and whether current plant configuration and operation is considered in their use.

Energy Northwest Response:

No PRA models other than the internal events PRA will be used for detailed quantitative analysis.

The qualitative assessment of fire risk and other external event risk will include a review of applicability to the current plant configuration and operation. For example, some STI change evaluations, per Step 10b qualitative reasoning and very low CDF and LERF results from the internal events analysis may be sufficient to support the STI change evaluation where Step 10b reads in part:

Alternative evaluations for the impact from external events and shutdown events are also deemed acceptable at this point. For example, if the CDF and LERF values have been demonstrated to be very small from an internal events perspective based on detailed analysis of the impact of the SSC being evaluated for the STI change, and if it is known that the CDF or LERF impact from external events (or shutdown events as applicable) is not specifically sensitive to the SSC being evaluated (by qualitative reasoning), then the detailed internal events evaluations and associated required sensitivity cases (as described in Step 14) can be used to bound the potential impact from external events and shutdown PRA model contributors.

Therefore, by following the NEI 04-10, Rev. 1 guidance, the evaluation of fire risk and other external events supporting this application will qualitatively reflect and consider the current plant configuration and operation.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 21 of 22 NRC Request

3. The impact of the open F&O for supporting requirement (SR) SY-A4 states that sensitivity analysis will be performed. It is not clear how a sensitivity analysis could be defined to address the lack of documented interviews that confirm that system analyses represent the as-built, as-operated plant. The TSTF-425 program considers capability category II for the internal events PRA model; therefore, please address this F&O to meet capability category II and provide the disposition of the F&O.

Energy Northwest Response:

Based on discussions with the Columbia NRC Project Manager, this RAI response will be submitted by October 31.

NRC Request

4. The peer review F&O on SR DA-C6 is related to meeting the data requirements for standby components (SR DA-C6) as well as for surveillance requirements (SR DA-C7). The F&O states: Estimates based on the surveillance tests and maintenance acts as described in DA-C6 and DA-C7 should be performed for significant components whose data are not tracked in the MSPI data. SR DA-C6 and SR DA-C7 include consideration of plant-specific data. Please explain the basis for concluding that the proposed sensitivity analyses, which are based on generic data, are considered bounding if these two SRs are graded at not met or capability category I. If use of plant-specific data consistent with SR DA-C6 and SR DA-C7 cannot be demonstrated to be bounding with respect to the proposed method to perform sensitivity analyses for relevant components, then please complete the work to meet SR DA-C6 and SR DA-C7 provide the disposition of the F&O.

Energy Northwest Response:

The 2009 peer review graded supporting requirements DA-C6 and DA-C7 as met for CC-II:

DA-C6 Assessment: MET for Capability Categories I-III DA-C7 Assessment: MET for Capability Categories I-III The SRs were met because the major components maintenance activities were based mainly on MSPI data. Finding 2-2 applies to non-MSPI components that were based on estimates.

RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON LICENSE AMENDMENT REQUEST FOR ADOPTION OF TECHNICAL SPECIFICATION TASK FORCE (TSTF)-425, REVISION 3 Page 22 of 22 A sensitivity study was performed by replacing the base data for these failure modes with generic data from NUREG/CR-6928. It was determined that the finding is unlikely to change the conclusions of risk-informed decisions.

Although Finding 2-2 is open, the SRs are graded at met for CC-II and the impact is unlikely to affect the results.

NRC Request

5. Do the failure probabilities of structures, systems, and components modeled in the CGS internal events PRA include a standby time-related contribution and a cyclic demand-related contribution? If not, please describe how standby time-related contribution is addressed for extended intervals.

Energy Northwest Response:

The failure probabilities of structures, systems, and components modeled in the CGS internal events PRA include either a standby time-related contribution or a demand-related contribution.

The standby time-related failures will be evaluated in accordance with NEI-04-10, Revision 1 by direct change in the test interval for those SSCs that include a standby periodically tested failure mode along with the appropriate adjustments to common cause failure events. For demand-related events an appropriate time-related failure contribution will be determined for each component that is uniquely impacted by the proposed STI change to obtain the maximum test-limited risk contribution.