ML24346A322

LLC - Response to SDAA Audit Question Number A-19.1-63

ML24346A322
Person / Time
Site:	05200050
Issue date:	12/11/2024
From:	NuScale
To:	Office of Nuclear Reactor Regulation
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Download: ML24346A322 (1)

Text

Response to SDAA Audit Question Question Number: A-19.1-63 Receipt Date: 04/22/2024 Question:

DCA FSER Section 19.1.4.7.2, Quantification and Results, provided a conclusion that was based, in part, on the response to RAI 8926. Specifically, the DCA FSER states:

Additionally, in a letter dated May 21, 2018 (ADAMS Accession No. ML18141A883), the applicant stated that the CNV is pressurized during module transport. The intent of pressurizing the CNV is to limit the exchange of water when the CNV flange is opened. The pressurization is set such that an inflow of water that could submerge components near the top of the CNV is prevented by the presence of the gas bubble; and an outflow of water that could lower the water level enough to release noncondensable gases into the refueling pool does not occur.

It is unclear to the staff if the containment vessel is pressurized during module transport for the SDAA and, if so, if the pressurization is such that the conclusions reached in the DCA FSER remain valid for the SDAA.

NuScale is requested to:

1.

Describe if the containment vessel is pressurized during module transport. If so, describe if the pressurization is set such that an inflow of water that could submerge components near the top of the containment vessel is prevented by the presence of the gas bubble; and an outflow of water that could lower the water level enough to release noncondensable gases into the refueling pool does not occur.

2.

If the containment vessel is either (1) not pressurized during module transport or (2) pressurized and the pressurization is set such that the release of noncondensable gases into the refueling pool can occur, describe the impact of this design change on the results of the module drop analysis for the SDAA.

NuScale Nonproprietary NuScale Nonproprietary

Response

1. ((2(a),(c) At this water level, there is no risk of releasing noncondensable gas into the refueling pool, but the pressurizer heater terminal could become submerged. Submerging the pressurizer heater terminal is acceptable because it is qualified for submergence.

2. The reduced internal pressure at the time of a postulated NPM drop for the SDAA design does not significantly affect the consequences of the event. Section 3.2.3 of ER-126919, Dropped Module Consequence Analysis, which is available in the SDAA Audit Section 19.1-19.3 eRR, evaluates the impact of design changes from the US600 design on the source term characteristics of the limiting NPM drop sequence (Case 5 in ER-126919). In summary, ((

}}2(a),(c) No changes to the SDAA are necessary. NuScale Nonproprietary NuScale Nonproprietary}}