ML24215A038

LLC, Response to Sdaa Audit Question Number A-3.7.3-1

ML24215A038
Person / Time
Site:	05200050
Issue date:	08/02/2024
From:	NuScale
To:	Office of Nuclear Reactor Regulation
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Download: ML24215A038 (1)

Text

Response to SDAA Audit Question Question Number: A-3.7.3-1 Receipt Date: 07/10/2023 Question:

Figures 3.7.3-5 and 3.7.3-6 show the in-structure response spectra (ISRS) at the Bioshield in the X and Y directions, respectively.

(a) Clarify whether the ISRS presented are for the horizontal section or the vertical section of the Bioshield.

(b) Explain why Z direction ISRS are not provided.

Response

Item (a):

The US460 Standard Design Approval Application (SDAA) Figures 3.7.3-5 and 3.7.3-6 show the simplified in-structure response spectra (ISRS) curves used versus the exact ISRS curves for response spectrum analysis of the bioshield. The vertical and horizontal bioshield use the same ISRS curves. The ISRS curves shown in Figure 3.7.3-5 and Figure 3.7.3-6 represent both the horizontal and vertical bioshield. Those curves are not the bioshield response itself but the baywall response that is feeding the bioshield evaluation.

Item (b):

NuScale revises US460 SDAA Section 3.7.3 by adding new Figure 3.7.3-7 to show the Z direction ISRS as shown on the markup.

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

NuScale Nonproprietary NuScale Nonproprietary

NuScale Final Safety Analysis Report Seismic Design NuScale US460 SDAA 3.7-261 Draft Revision 2 COL Item 3.7-10: An applicant that references the NuScale Power Plant US460 standard design will determine the means and methods of lifting the bioshield. An applicant will demonstrate that bioshield components and connections can withstand the bioshield loads and appropriate load factors.

Reinforced Concrete Properties and Slab Capacity The concrete and reinforcement design values are from ACI 349 (Reference 3.7.3-3). The minimum concrete cover for cast-in-place members is based on ACI 349.

The horizontal slab capacity is determined based on ACI 318 (Reference 3.7.3-1) and the vertical tube frame is based on ANSI/AISC 360 (Reference 3.7.3-4). Individual equations in ACI 318 are used for determining out of plane moment and shear capacity.

Structural Steel Material Properties The vertical assembly of the bioshield is constructed from stainless steel tube members in the horizontal and vertical directions.

In-Structure Response Spectra Audit Question A-3.7.3-1 Descriptions of in-structure response spectra for multiple locations in the RXB are in Section 3.7.2. Locations at the top of the bay walls were selected to develop ISRS for the design of the bioshields. The enveloped ISRS with 4 percent damping are shown in Figure 3.7.3-5 andthrough Figure 3.7.3-6Figure 3.7.3-7. These figures envelop certified seismic design response spectra (CSDRS) curves and include effects of sensitivity analysis cases such as considering the effects of soil separation and different soil profiles. The figures also show the curves with the valleys removed that were used for the response spectrum analysis.

3.7.3.3.1.1 Evaluation The vertical framing analysis was completed with a linear finite element model consisting of BEAM188 element types and masses.

The vertical bioshield is supported by stainless steel structural members that reconnect to the bay walls. Connections are designed to allow for the vertical bioshield to be lifted and removed.

The horizontal bioshield is analyzed through two separate linear models.

In the first analysis, the loading is applied in the direction of gravity. In this model, boundary conditions were investigated and defined to conservatively capture stress in the slab with vertical restraints placed at the bottom of the slab. The second analysis captures load reversal effects with the slab restrained at its mid-plane like a simply supported beam.

NuScale Final Safety Analysis Report Seismic Design NuScale US460 SDAA 3.7-272 Draft Revision 2 Audit Question A-3.7.3-1 Figure 3.7.3-7: In-Structure Response Spectra at the Bioshield in Z-Direction for Bioshield Enveloped In-Structure Response Spectra Using 4 Percent Damping 0

0.5 1

1.5 2

2.5 3

0 20 40 60 80 100 120 Acceleration (g's)

Frequency (Hz)

ISRS Z-direction Exact Approximate