ML18194A914

Supplemental Response to Request for Additional Information 3.a for License Amendment Request to Adopt 10 CFR 50.69 Risk-Informed Categorization and Treatment of Structures, Systems, and Components

ML18194A914
Person / Time
Site:	Palo Verde
Issue date:	07/13/2018
From:	Lacal M Arizona Public Service Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
102-07751-MLL/PJH
Download: ML18194A914 (2)

Text

10 CFR 50.69 10 CFR 50.90 MARIA L. LACAL Senior Vice President Nuclear Regulatory and Oversight Palo Verde Nuclear Generating Station 102-07751-MLL/PJH P.O. Box 52034 July 13, 2018 Phoenix, AZ 85072 Mail Station 7605 Tel 623.393.6491 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Reference:

Arizona Public Service Company (APS) Letter 102-07690, APS Response to Request for Additional Information for License Amendment Request to Adopt 10 CFR 50.69 Risk-Informed Categorization and Treatment of Structures, Systems, and Components, dated May 9, 2018, ADAMS No. ML18129A448

Subject:

Palo Verde Nuclear Generating Station Units 1, 2, and 3 Docket Nos. STN 50-528, 50-529, and 50-530 APS Supplemental Response to Request for Additional Information 3.a for License Amendment Request to Adopt 10 CFR 50.69 Risk-Informed Categorization and Treatment of Structures, Systems, and Components On July 19, 2017, APS submitted a license amendment request (LAR) to adopt Title 10 of the Code of Federal Regulations (10 CFR) Section 50.69, Risk-Informed Categorization and Treatment Of Structures, Systems, and Components for Nuclear Power Reactors. During the week of February 20, 2018, the NRC staff conducted an audit at the Palo Verde Nuclear Generating Station (PVNGS) to gain an understanding of the risk-informed categorization process and to review the probabilistic risk assessment model that will be used by APS for this risk-informed LAR. The NRC staff determined that additional information was required to complete their review. The APS responses to the Request for Additional Information (RAI) were provided in the enclosure to the referenced letter.

Subsequently, the NRC staff requested a clarification call with APS that was held on June 29, 2018. During the call the NRC reviewer noted that the specific source of the internal events model utilized for development of the seismic PRA (SPRA) was not specifically described in the response to RAI 3.a.

Additionally, it was not clear to the NRC reviewer that future upgrades of the internal events PRA (IEPRA) would be carried forward into the SPRA. APS discussed the process by which the IEPRA is the foundation for the PRA hazard models, and that revisions to the IEPRA will be propagated into the A member of the STARS Alliance Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek

102-07751-MLL/PJH ATTN: Document Control Desk U.S. Nuclear Regulatory Commission APS Supplemental Response to RAI 3.a for LAR to Adopt 10 CFR 50.69 Page 2 hazard models. The basis and process discussed during the clarification call is provided below as supplemental information to the RAI 3.a response.

Supplemental Information for Response 3.a As per Westinghouse calculation note CN-RAM-12-015, Revision 1, Palo Verde Seismic Probabilistic Risk Assessment - Model Development, the SPRA was developed from the fire PRA model version documented in Westinghouse calculation note CN-RAM 011, Revision 0, Fire Risk Model for Palo Verde Nuclear Generating Station, which was based on the foundation of the IEPRA model version documented in Westinghouse calculation note CN-RAM 019, Revision 1, Validation of Probabilistic Risk Assessment Model Conversion for Palo Verde Nuclear Generating Station. This IEPRA model (and each subsequent version) is the foundation upon which the other hazard PRA models are maintained and quantified. The IEPRA is the backbone of the integrated One-Top Multi-Hazard model under development as discussed in APS Response to RAI 22.

APS has reviewed the information supporting a finding of no significant hazards consideration that was provided to the NRC. The information provided in this response does not affect the basis for concluding that the proposed license amendment does not involve a significant hazards consideration under the standards set forth in 10 CFR 50.92.

No new commitments are being made to the NRC by this letter.

Should you need further information regarding this letter, please contact Michael DiLorenzo, Nuclear Regulatory Affairs, at (623) 393-3495.

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

Executed on July 13, 2018 (Date)

Sincerely, Lacal, Maria Digitally signed by Lacal, Maria L(Z06149)

DN: cn=Lacal, Maria L(Z06149)

L(Z06149) Date: 2018.07.13 10:13:51

-07'00' MLL/PJH/sa cc: K. M. Kennedy NRC Region IV Regional Administrator M. D. Orenak NRC NRR Project Manager for PVNGS C. A. Peabody NRC Senior Resident Inspector for PVNGS