ML18257A231

SPRA (Fukushima 50.54f) Audit Questions - 2nd Set

ML18257A231
Person / Time
Site:	North Anna
Issue date:	09/07/2018
From:	Milton Valentin-Olmeda Beyond-Design-Basis Management Branch
To:	Aitken D Dominion Energy Co
Valentin-Olmeda M, NRR/DLP, 415-2864
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ML18257A233 -Package	List: ML18257A223 ML18257A231
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From: Valentin-Olmeda, Milton To: "Diane Aitken"

Subject:

North Anna SPRA (Fukushima 50.54f) Audit Questions - 2nd set Date: Friday, September 07, 2018 3:25:00 PM

Diane, As a follow up to the first set of Fragility questions, please address the following:

1) The seismic PRA summary report identified the Fuel Oil Pump House and the Casing Cooling Pump Houses in the list of structures included in SEL. Please explain why the information on dynamic analysis and fragility evaluation of these structures were not presented in the report.

2) As a follow up of question 3 for Topic #6, after reviewing the proposed response in the ePortal, the NRC staff was not clear what the licensee meant with the scaling approach used in the reactor internals analysis to determine fragility parameters.

However, the response indicated that the scaling approach considered dynamic characteristic from the vendor analysis. In order to understand the similar scaling approach, provide an example where dynamic characteristics of the NSSS component vendor analysis were used to identify the capacity to demand ratio for the components. Of particular interest are the spectral shapes of the new GRMS in-structure response spectra and the vendor response spectra, for comparison.

We are open to discuss our questions if needed.

Respectfully, Milton Valentín, PM US NRC Division of Licensing Projects Beyond Design Basis Management (Fukushima)

Office of Nuclear Reactor Regulation Milton.Valentin@nrc.gov 301-415-2864