ML24348A075

Response to NuScale Topical Report Audit Question Number A-NonLOCA.LTR-58

ML24348A075
Person / Time
Site:	05200050
Issue date:	12/13/2024
From:	NuScale
To:	Office of Nuclear Reactor Regulation
Shared Package
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Download: ML24348A075 (1)

Text

Response to NuScale Topical Report Audit Question Question Number: A-NonLOCA.LTR-58 Receipt Date: 06/28/2024 Question:

The staff notes that the basis for PZR Pressure Control PZR spray in Table 7-7 and Table 7-19 of Version 3 of the TR states: (( 2(a),(c) These bases are removed from Table 7-7 and Table 7-19 of Revision 4 of the TR. Please clarify if the statement in Version 3 of the TR remains true for the NRELAP5 code. If it is true, please revise the basis for PZR Pressure Control PZR spray in Table 7-7 and Table 7-19 of the TR to the same language as approved in Revision 3 (( }} 2(a),(c) Provide proposed markup to the TR.

Response

TR-0516-49416-P-A, Revision 3, Non-Loss-of-Coolant Accident Analysis Methodology, Section 4.3.5 includes an extensive discussion of the effect of pressure on critical heat flux (CHF). Generally, there is a negative trend in CHF versus pressure (CHF is more limiting as pressure decreases) that changes to a positive trend at low pressures. These trends are consistent with CHF test data. (( }}2(a),(c) NuScale Nonproprietary NuScale Nonproprietary

For this reason, the discussion in Tables 7-7, 7-14, and 7-19 of TR-0516-49416-P-A, Revision 3, identifies that (( }}2(a),(c) The Standard Design Approval Application (SDAA) for the US460 design uses NPM-20. The NPM-20 has a higher power, higher normal operating pressure, and higher flow than the NPM-160 of the DCA. (( }}2(a),(c) The sensitivity study results supporting this trend are shown in EC-117453, Revision 2, Steady-State Subchannel Analysis, by comparison of Tables 4-1 and 4-2. (( }}2(a),(c) EC-117453 was previously provided in the electronic reading room (eRR) with the response to audit question A-5.4.5-1. Additionally, sensitivities in EC-103521, Revision 3, VIPRE-01 Sensitivity Analysis for the Core-250B design, Section 4.6 and Figure 4-19 demonstrate that (( }}2(a),(c) EC-103521 was previously provided in the eRR for the Statistical Subchannel Audit. (( }}2(a),(c) Therefore, TR-0516-49416-P, Revision 4, is accurate for NPM-20. With the above background, NuScale provides the following response to the NRC request. The NRC request is identified by the indented, italicized text, with the NuScale response identified by the non-indented, non-italicized text. Please clarify if the statement in Version 3 of the TR remains true for the NRELAP5 code. The statement in Sections 4.3.5 and Tables 7-7, 7-14, and 7-19 of TR-0516-49416-P-A, Revision 3, are accurate for the NPM-160 design (( }}2(a),(c) NuScale Nonproprietary NuScale Nonproprietary

If it is true, please revise the basis for PZR Pressure Control PZR spray in Table 7-7 and Table 7-19of the TR to the same language as approved in Revision 3... The statements in Sections 4.3.5 and Tables 7-7, 7-14, and 7-19 of TR-0516-49416-P-A, Revision 3, are (( }}2(a),(c) revised in Revision 4. No further modification to Revision 4 is required. (( }}2(a),(c) (( }}2(a),(c) No changes to the SDAA are necessary. NuScale Nonproprietary NuScale Nonproprietary}}