ML20273A237

Request for Additional Information Review of License Amendment Request to Revise Technical Specifications to Adopt Risk-Informed Completion Times

ML20273A237
Person / Time
Site:	Nine Mile Point
Issue date:	09/28/2020
From:	Marshall M Plant Licensing Branch 1
To:	James Danna Exelon Generation Co, Exelon Nuclear
Marhsall M, NRR/DORL/LPL, 415-2871
References
EPID L-2019-LLA-0234
Download: ML20273A237 (2)

Text

From: Marshall, Michael To: [Licensee] Ron Reynolds (Exelon)

Cc: Danna, James

Subject:

NINE MILE POINT NUCLEAR STATION, UNIT 2 - REQUEST FOR ADDITIONAL INFORMATION RE: REVIEW OF LICENSE AMENDMENT REQUEST TO REVISE TECHNICAL SPECIFICATIONS TO ADOPT RISK-INFORMED COMPLETION TIMES (EPID L-2019-LLA-0234)

Date: Monday, September 28, 2020 3:09:00 PM Hello Ron:

B letter dated October 31, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19304B653), as supplemented by letters dated December 12, 2019, and August 28, 2020 (ADAMS Accession Nos. ML19346F427 and ML20241A044, respectively), Exelon Generation Company, LLC (Exelon, the licensee) requested that the U.S. Nuclear Regulatory Commission (NRC) amend the Appendix A, Technical Specifications, of Renewed Facility Operating License No. NPF-69 for Nine Mile Point Nuclear Station, Unit 2. Exelons proposed license amendment request (LAR) would revise technical specification requirements to permit the use of risk-informed completion times for actions to be taken when limiting conditions for operation are not met. The proposed changes are based on Technical Specifications Task Force Traveler, TSTF-505, Revision 2, Provide Risk Informed Extended Completion Times - RITSTF Initiative 4b, dated July 2, 2018 (ADAMS Accession No. ML18269A041).

The U.S. Nuclear Regulatory Commission staff has reviewed the information provided in the LAR and has determined that additional information is needed to complete its review.

The request for additional information was discussed with you on September 25, 2020, and it was agreed that your response would be provided within 30 days of the date of this email.

The RAI listed below is in addition to RAIs 1 to 5 and RAIs 6 to 25 sent to you in emails dated July 30, 2020 and September 2, 2020 (ADAMS Accession Nos. ML20213A935 and ML20246G636).

RAI 26

Section 2.3.1, Item 7, of Nuclear Energy Institute (NEI) 06-09, Revision 0-A (ADAMS Accession No. ML12286A322), states, The impact of other external events risks shall be addressed in the RRMTS [Risk-Managed Technical Specifications] program, and explains that one method to do this is by performing a reasonable bounding analysis and applying it along with the internal events risk contribution in calculating the configuration risk and the associated RICT [riskinformed completion time] RICT. The NRC staffs safety evaluation for NEI 06-09 (ADAMS Accession No. ML071200238) states, Where PRA [probabilistic risk assessment] models are not available, conservative or bounding analyses may be performed to quantify the risk impact and support the calculation of the RICT.

LAR Enclosure 4, Section 3, states that to determine a bounding seismic core damage frequency, the peak ground acceleration hazard curve for the 50th percentile high confidence of low probability of failure (HCLPF) value of 0.42g was used from its individual plant evaluation of external events (IPEEE) seismic margins analysis (SMA). (Note: The SMA HCLPF value of 0.5g is the 84th percentile value). The IPEEE HCLPF value of 0.42g was used rather than the HCLPF value of 0.23g in Table C-2 of Results of Safety/Risk Assessment of Generic Issue 199 (GI-199), Implications of Updated Probabilistic Seismic

Hazard Estimates in Central and Eastern United States on Existing Plants (ADAMS Accession No. ML100270582). The LAR states that related sensitivity studies were performed on the impact to risk of changing the ground motion frequencies and seismic hazard intervals. The LAR does not describe those sensitivity studies results or how insights from those studies were used. The exception to this is that sensitivity study results are presented in LAR Table E4-4 to justify the defined seismic hazard interval for the highest seismic bin, the %G8 interval (i.e., seismic hazard internal > 1.5g).

a) Explain why the IPEEE HCLPF value of 0.42g was used rather than the HCLPF value of 0.23g in GI-199 and why it is acceptable for this application.

b) Describe the cited sensitivity studies and results.

c) Explain how insights from the sensitivity studies were used to select to a bounding ground motion and to define the seismic hazard intervals.

Best Regards, Michael L. Marshall, Jr.

Senior Project Manager Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation 301-415-2871 Docket No.05-410