ML20161A390

Request for Supporting Information for the Sequoyah SPRA Audit Review - Follow-up to Plant Response Question 5

ML20161A390
Person / Time
Site:	Sequoyah
Issue date:	04/09/2020
From:	Stephen Philpott NRC/NRR/DORL/LPMB
To:	Thompson R Tennessee Valley Authority
Philpott S
References
EPID L-2019-JLD-0013
Download: ML20161A390 (2)

Text

From: Philpott, Stephen To: Thompson, Russell R Cc: Valentin-Olmeda, Milton

Subject:

Follow-up to Plant Response Question 5 - Sequoyah SPRA Audit Review Date: Thursday, April 09, 2020 12:07:00 PM Good morning Russell, The staff has been reviewing the responses to the audit review questions that you posted in the e-Portal. At this point, I dont think we have any further fragility-related questions. With regard to the response to Question 5 (Plant Response), the reviewers would like to get a little further understanding of a couple points. We would like to set up a follow-up call to discuss the response a bit further. Below is a more detailed description of the points the staff would like to discuss.

Could you please review the discussion points below and let me know when your appropriate staff might be available for a call?

Question 5.1 - Topic #16 - Review of Plant Modifications and Licensee Actions PRA, Accounting for NEI 12-13 (SPID Section 6.7)

Based on the results in the Sequoyah SPRA submittal, it appears that SEIS_-0-30-5, HAMARV, and HACIV may provide non-trivial risk reduction. The response to Question #5 provides information about the licensees rationale for the lack of cost-justified plant improvements that would eliminate or significantly reduce the risk of one or more of the failures resulting in a reduction in seismic LERF of 1E-06 per year for either unit for each of the above-mentioned seismic failures. The staff would like to better understand the response to Question #5 given the potential for risk reduction from the individual seismic failures identified above.

Therefore, the staff would like a discussion to clarify the following topics from the response to Question #5:

a. The approach used to identify potential plant modifications and any plant modifications that were considered, but not discussed in the response to Question

1. 5.

b. Quantitative results (i.e., change in SCDF, SLERF, and importance measures) for the sensitivity study where the median capacity of the fragility group SEIS_0-30-5 (Relay Chatter - 480V/6.9V SD BD GE HEA Breakers) was increased to 1.65g.

As always, feel free to reach out to me if you have any questions or would like to discuss further.

Thank you, Steve

301-415-2365