ML19365A046

Audit Documents Needed for the Robinson SPRA Review

ML19365A046
Person / Time
Site:	Robinson
Issue date:	12/18/2019
From:	Milton Valentin-Olmeda NRC/NRR/DORL/LPMB
To:	Grzeck L Duke Energy Progress
Valentin-Olmeda M
References
Download: ML19365A046 (2)

Text

From: Valentin-Olmeda, Milton To: Grzeck, Lee Cc: Philpott, Stephen

Subject:

Audit documents needed for the Robinson SPRA Review Date: Wednesday, December 18, 2019 5:15:00 PM Greetings Lee, Based on the initial review of the H.B. Robinson Nuclear Plant, Unit 2, (RNP) seismic probabilistic risk assessment (SPRA) submittal (ADAMS Accession No. ML19346E204), please make the following information available in the electronic portal for staff audit (reference numbers from Section 7 of the report are included for clarity):

1. SPRA Peer Review Reports (Full-Scope and Focused-Scope; References [7] and [86])

2. Station Calculation for the Robinson PRA System Notebook (Reference [66])

3. Station Calculation for the SPRA Model Notebook (Reference [77])

4. Station Calculation for the SPRA Quantification Notebook (Reference [13])

5. Station Calculation for the SPRA Uncertainty and Sensitivity (Reference [70])

6. Station Calculation for the RNP PRA Model Peer Review Resolution (Reference [71])

7. Station Calculation for Seismic fragility of Pounding Between Class III Turbine Bldg. and Reactor Aux. Bldg. by Nonlinear Analysis (Reference [68])

8. Internal Events PRA Peer Review Report (Full-Scope, Focused-Scope, and Close-Out, as applicable)

9. Confirmation that the licensees SPRA model incorporates the latest resolutions to all IEPRA peer review finding level F&Os (open as well as closed). Provide justification that the exclusion of those resolutions from the SPRA as well as dispositions of open findings does not significantly change the corresponding results.

10. Summary of the refinements made to the SPRA (e.g., to fragility analysis and plant response representation) to achieve realism in the determination of risk from seismic events. Include a discussion of any areas of refinement that remain to be addressed.

11. For the liquefaction-induced dominant risk contributors in Table 5.4-2 and 5.5-2 of the report:

(a) Clarify whether the failure probabilities were modeled below the lowest corresponding PGA values in those tables and a justification if they were not modeled. If such failures were modeled, provide the probability of failure from liquefaction for the relevant dominant risk contributors in Table 5.4-2 and 5.5-2 below the lowest PGA level in those tables (except for SF-DAM-LIQ); and (b) Clarify whether uncertainty on liquefaction-induced failure probabilities

in Table 5.4-2 and 5.5-2 of the report were used. Provide the uncertainty values used or justify not using uncertainties for liquefaction-induced failures.

12. The percentage contribution of each risk contributor in Table 5.4-2 and 5.5-2 of the report for each seismic bin (i.e., contribution as a function of each bin).

13. Clarify whether the cutset values provided in Tables 5.4-1 and 5.5-1 represent the final quantified values for the cutsets (i.e., the final refined quantification as opposed to the cutset determination quantification). If not, provide the information in Tables 5.4-1 and 5.5-1 from the final refined quantification.

The rationale for items 8 and 9 is to determine the acceptability of the base internal event PRA model.

Please let me know if you have any questions regarding this request.

Respectfully, Milton Valentín, PM Beyond Design Basis Management (Fukushima)

US NRC NRR/DORL/LPMB Milton.Valentin@nrc.gov 301-415-2864