NL-19-1532, Units 1 and 2 - Response to Requests for Additional Information Regarding Application to Adopt 10 CFR 50.69, Risk-Informed Categorization and Treatment of Structures. Systems and Components for Nuclear Power Reactors

Units 1 and 2 - Response to Requests for Additional Information Regarding Application to Adopt 10 CFR 50.69, Risk-Informed Categorization and Treatment of Structures. Systems and Components for Nuclear Power Reactors

ML19352F705
Person / Time
Site:	Hatch
Issue date:	12/18/2019
From:	Gayheart C Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-19-1532
Download: ML19352F705 (8)

Text

~ Southern Nuclear Cheryl A. Gayheart Regulatory Affairs Director 3535 Colonnade Parkway Binningham, AL 35243 205 992 53 16 DEC 1 8 2019 cagayhea t southemco.com Docket Nos.: 50-321 NL-19-1532 50-366 U. S. Nuclear Regulatory Commission ATTN : Document Control Desk Washington , D. C. 20555-0001 Edwin I. Hatch Nuclear Plant- Units 1 and 2 Response to Requests for Additional Information Regarding Application to Adopt 10 CFR 50 .69, "Risk-Informed Categorization and Treatment of Structures. Systems and Components for Nuclear Power Reactors" Ladies and Gentlemen:

By letter dated June 7, 2018 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML18158A583), Southern Nuclear Operating Company (SNC) submitted a license amendment request (LAR) for Edwin I. Hatch Nuclear Plant (HNP)

Units 1 and 2 to adopt Title 10 of Code of Federal Regulations (CFR) 50.69 , "Risk-informed categorization and treatment of structu res , systems and components for nuclear power reactors ."

By email correspondence dated April17 , 2019 , the Nuclear Regulatory Commission (NRC) staff requested additional information to complete its review. By letter dated July 16, 2019, SNC provided responses to the NRC requests , except for requests RAI 03 and RAI 12. Enclosure 1 provides the SNC response to the remaining NRC requests .

As discussed in the March 2019 NRC LAR audit, and as further discussed in the responses , not all plant modifications listed in Attachment 1 of the June 7, 2018 LAR are required in order to meet the acceptance criteria of RG 1.174 Rev. 3. As such , the proposed facil ity operating license (FOL) condition is being revised accordingly. The revised FOL condition is provided in Enclosure 2.

In its July 16, 2019 letter, SNC stated the expectation that the focused scope peer review scheduled in July 2019 would resolve the probabilistic risk assessment (PRA) finding level Facts and Observations (F&Os) 1- 15 and 4-5. These F&Os were resolved , and no new finding level F&Os were issued.

The conclusions of the No Significant Hazards Consideration and Environmental Consideration contained in the original LAR have been reviewed and are unaffected by this response .

This letter contains no NRC commitments . If you have any questions , please contact Jamie Coleman at 205.992.6611 .

U.S. Nuclear Regulatory Commission NL-19-1532 Page 2 I declare under penalty of perjury that the foregoing is true and correct . Executed on the lf?'M day of December 2019.

Respectfully submitted, Director, Re ulatory Affairs Southern Nuclear Operating Company CAG/RMJ Enclosures : 1. Response to NRC RAI 03 and RAI 12

2. Revised FOL Condition cc: Regional Administrator, Region II NRR Project Manager - Hatch Senior Resident Inspector- Hatch Director, Environmental Protection Division - State of Georgia RType : CHA02.004

Response to Request for Addition Information Regarding Application to Adopt 10 CFR 50.69, "Risk-Informed Categorization and Treatment of Structures. Systems and Components for Nuclear Power Reactors" Enclosure 1 Response to NRC RAI 03 and RAI 12

Enclosure 1 to NL-19-1532 Response to NRC RAI 03 and RAI 12 RAt 03 (APLA) - Hatch FPRA under Review for Adoption to NFPA-805 Paragraphs 50.69(c)(1)(i) and (ii) of 10 CFR require a licensee 's PRA be of sufficient quality and level of detail to support the system, structures, and components (SSCs) categorization process, and that all aspects of the integrated, systematic process used to characterize sse importance must reasonably reflect the current plant configuration and operating practices, and applicable plant and industry operational experience.

Section 3 of the 10 CFR 50. 69 LAR states that a LAR was submitted requesting transition to the National Fire Protection Association (NFPA) 805 Performance-Based Standard for Fire Protection (ADAMS Accession No. ML18096A955). Attachment 1 of the 10 CFR 50.69 LAR lists several plant modifications that are credited in the FPRA risk estimates for the NFPA 805 LAR to meet the risk acceptance guidance of RG 1.174, Revision 3 (ADAMS Accession No. ML17317A256). AttachmentS of the NFPA 805 LAR lists several implementation items (such

. as updating of the fire response procedures) that are also credited in the FPRA to meet the risk acceptance guidelines discussed in RG 1. 174, Revision 3.

Because there is a potential for additional FPRA model changes to resolve requests for additional information (RAts) associated with the staff determination of acceptability of the FPRA for approval of the Hatch adoption of NFPA 805 LAR that is currently under NRC staff review, address the following:

a) Confirm that all the NFPA 805 plant modifications, implementation items, and FPRA model changes necessary to resolve questions associated with the NFPA -805 LAR review are complete, or alternatively, propose a mechanism to ensure that all these items are complete prior to the implementation of the 10 CFR 50.69 categorization process. This mechanism should also provide an explicit description of changes that will be made to the PRA model(s) and/or documentation to resolve the identified issues. An example would be a table of listed implementation items referenced in a license condition.

SNC Response The FPRA model changes necessary to resolve questions associated with the NFPA 805 LAR review have been incorporated. As discussed in the March 2019 NRC LAR audit, not all plant modifications listed in Attachment 1 are required in order to meet the acceptance criteria of RG 1.174 Rev. 3. It is SNC 's expectation that following startup from the Unit 1 refueling outage scheduled to commence February 2020, all required modifications to meet the acceptance criteria of RG 1.174 Rev. 3 will be complete. Accordingly , SNC is revising the facility operating license condition proposed in the LAR to instead require that the PRA risk is within the RG 1.174 Rev . 3 core damage frequency (CDF) and large early release frequency (LERF) acceptance criteria prior to implementing the 10 CFR 50.69 categorization process .

b) Alternatively to item (a) above, address the following:

i. Provide detailed justification that the NFPA 805 modifications, implementations items and FPRA model changes necessary to resolve questions associated with the NFPA-805 LAR review have no impact the PRA models (i.e., lEPRA, FPRA and SPRA) used for the 10 CFR 50. 69 application.

E1-1 to NL-19-1532 Response to NRC RAI 03 and RAI 12 SNC Response Not applicable ; see response to RAI 03(a) .

ii. If any plant modifications, implementations items or FPRA model changes necessary to resolve questions associated with the NFPA-805 LAR review are determined to impact the PRA models (i.e ., lEPRA, FPRA and SPRA) and documentation, address the following:

1. Provide explicit description for how they will be addressed in the PRA models that will be used for the 10CFR 50.69 categorization.

SNC Response Not applicable ; see response to RAI 03(a) .

2. Confirm the status of the plant modifications and how the PRA models will reflect the as-built and as-operated plant at the time of implementation of the 10 CFR 50. 69 process.

SNC Response Not applicable ; see response to RAI 03(a) .

3. Provide detailed description and justification for any alternative PRA modeling that is not subject to the NRC staff review for the NFPA-805 application or the 10 CFR 50.69 application (e .g., subsequent removal of credit for modifications) .

SNC Response Not applicable; see response to RAI 03(a) .

iii. Provide any updated Core Damage Frequency (CDF) and Large Early Release Frequency (LERF) estimates resulting from removal of credit for the NFPA -805 modifications and/or implementation items to confirm that the acceptance criteria for total CDF and LERF values provided in RG 1. 174, Revision 3 (ADAMS Accession No. ML17317A256) remain met.

SNC Response Not applicable ; see response to RAI 03(a) .

RAI12 (APLA) - Implementation Items 10 CFR 50.69(b)(2)(ii) requires that a licensee 's application contain a description of the measures taken to assure that the quality and level of detail of the systematic processes that evaluates the plant for internal and external events during normal operation, low power, and shutdown are adequate for the categorization of SSCs.

E1-2 to NL-19-1532 Response to NRC RAI 03 and RAI 12 If the responses to any of the 50.69 RAJ 01 through RAJ 11 above or the responses to any of the requests for additional information related to the NFPA-805 application require any follow-up actions prior to implementation of the 10 CFR 50.69 categorization process, provide a list of those actions and any PRA modeling changes, including any items that will not be completed prior to issuing the amendment, but must be completed prior to implementing the 10 CFR 50.69 categorization process.

Propose a mechanism that ensures these activities and changes will be completed and appropriately reviewed and any issues resolved prior to implementing the 10 CFR 50.69 categorization process. An example would be a table of listed implementation items referenced in a license condition.

As an alternative to providing an implementation item for an F&O, demonstrate that the F&O(s) will have no adverse impact and/or insignificant impact on the 10 CFR 50.69 categorization process.

SNC Response As discussed in the response to RAI 03, SNC's expectation is that all required modifications necessary to achieve CDF and LERF values within the RG 1.17 4 Revision 3 acceptance criteria will be complete following startup from the Unit 1 refueling outage scheduled to commence February 2020. In addition, as discussed in the response to RAI 03, the proposed facility operating license condition is revised to require the as-built, as-operated plant following installation of the required modifications and implementation items to meet the risk acceptance guidelines found in Regulatory Guide (RG) 1.174 Revision 3 prior to 10 CFR 50 .69 implementation . There are no open finding level F&Os affecting 50.69 categorization results .

The two internal events finding level F&Os that are still open have no effect on 50.69 categorization results .

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Response to Request for Addition Information Regarding Application to Adopt 10 CFR 50.69, "Risk-Informed Categorization and Treatment of Structures. Systems and Components for Nuclear Power Reactors" Enclosure 2 Revised FOL Condition to NL 1532 Revised FOL Condition Facility Operating License Condition Insert:

Southern Nuclear Operating Company is approved to implement 10 CFR 50. 69 using the processes for categorization of Risk-Informed Safety Class (RISC)- 1, RISC-2, RISC-3, and RISC-4 structures, systems, and components (SSCs) specified in the renewed license amendment dated DATE.

Prior NRC approval, under 10 CFR 50.90, is required for a change to the categorization process specified above (e.g., change from a seismic margins approach to a seismic probabilistic risk assessment approach).

Prior to implementation, Southern Nuclear Operating Company shall update the PRA models to reflect the as-built, as-operated plant following installation of the required modifications, implementation items, and the as-built installation details required to meet the risk acceptance guidelines found in Regulatory Guide (RG) 1. 174 Revision 3. If, prior to the issuance of renewed license amendment dated DATE , the risk estimates from the updated PRA models do not meet the risk acceptance guidelines found in RG 1. 174 Revision 3, measures will be taken to reduce the risk. Measures may include approaches such as plant modifications or analytical updates to the PRA model. If any of the measures taken include the use of an upgrade that have not been Peer Reviewed for use in the Hatch PRA models, a focused scope Peer Review will be conducted.

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