ML24346A174

LLC - Response to SDAA Audit Question Number A-4.3-29

ML24346A174
Person / Time
Site:	05200050
Issue date:	12/11/2024
From:	NuScale
To:	Office of Nuclear Reactor Regulation
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Text

Response to SDAA Audit Question Question Number: A-4.3-29 Receipt Date: 06/17/2024 Question:

FSAR Table 4.3-3 indicates that the power defect in end-of-cycle shutdown margin calculations is 6036 pcm. FSAR Section 4.3.2.3.3 states that the minimum and maximum power defect are shown in Figure 4.3-16. However, the maximum power defect in Figure 4.3-16 is less than 4000 pcm. Please clarify why one power defect in FSAR Table 4.3-3 exceeds the maximum power defect in Figure 4.3-16, including any additional conservatisms that are applied in the calculation of power defect for shutdown margin.

Response

FSAR Figure 4.3-16 is updated to align with the assumptions made for the results in FSAR Table 4.3-3.

FSAR Section 4.3.1.2 states that the Doppler coefficient and the moderator temperature coefficient together provide inherent reactivity control and satisfy GDC 11. Additionally, FSAR Section 4.3.2.3.3 notes the power coefficient is the sum of the moderator temperature, fuel temperature... Therefore, the power coefficient plot presented in FSAR Figure 4.3-17 is also used to satisfy compliance to GDC 11.

Markups of the affected changes, as described in the response, are provided below:

NuScale Nonproprietary NuScale Nonproprietary

NuScale Final Safety Analysis Report Nuclear Design NuScale US460 SDAA 4.3-24 Draft Revision 2 Audit Question A-4.3-29, Audit Question A-4.3-33, Audit Question A-XPC.LTR-14 Table 4.3-3: Reactivity Requirements for Control Rods BOC MOC EOC Control Rod Assembly Worth (pcm)

Total available CRA worth (a) 1495414920 1638116305 1706416946 Power dependent insertion limits (b) 510524 642666 769797 Worst rod stuck out (c) 63026223 58765802 67686679 Subtotal (a-b-c=d) 81428173 98639837 95279470 Reactivity Allowances and Uncertainties (pcm)

Power defect (e) 30553104 39023967 59486036 Uncertainty (g) 977608 1184704 1143412 Shutdown Margin Available (d-e-g) (pcm) 41104461 47775166 24363022

NuScale Final Safety Analysis Report Nuclear Design NuScale US460 SDAA 4.3-43 Draft Revision 2 Audit Question A-4.3-29, Audit Question A-4.3-33, Audit Question A-XPC.LTR-14 Figure 4.3-16: Maximum and Minimum Power Defect