ML24215A017

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LLC, Response to Sdaa Audit Question Number A-3.4.2-10
ML24215A017
Person / Time
Site: 05200050
Issue date: 08/02/2024
From:
NuScale
To:
Office of Nuclear Reactor Regulation
Shared Package
ML24215A000 List: ... further results
References
LO-169995
Download: ML24215A017 (1)
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Response to SDAA Audit Question Question Number: A-3.4.2-10 Receipt Date: 08/14/2023 Question:

Follow-on from A-3.4.2-5: The applicant stated that the SDAA design eliminated the personnel tunnel between the RXB and CRB, therefore the applicant concluded that DCA COL item 3.4-7 is not applicable. However, the staff reviewed the report EC-112976, Differential settlement analysis of the double building model, and finds that tunnels exist between the RXB and RWB.

The staff further searched the NuScale FSAR and identified 3 underground safety-related tunnels described in Sections 3.6.1.1.5 and 3.8.5.1. Therefore, the applicants response is not acceptable, and DCA COL item 3.4-7 should be applicable to the SDAA.

Response

The US600 design certification application (DCA) COL Item 3.4-7 was applicable to the personnel tunnel. The purpose of the COL Item was to prevent groundwater and foreign material intrusion into the expansion gap between the end of the tunnel and the buildings.

The tunnels identified in the standard design approval application (SDAA) of the US460 design, Section 3.8.5.1 are not personnel tunnels nor safety-related. The tunnel identified in SDAA Section 3.6.1.1.5 refers to the safety-related underground duct bank shown in Figure 3-3 of TR-121507-P, Revision 0, Pipe Rupture Hazards Analysis. ((2(a),(c) Although the DCA COL Item 3.4-7 is not applicable to the duct bank, waterproofing and damp proofing are addressed by SDAA COL Item 3.4-4. SDAA Section 3.6 is revised to address the safety-related underground duct bank and COL Item 3.4-4 is revised to include the duct bank connection to the Reactor Building. An updated Change Package has been generated to address the call held on 9/20/2023. Markups of the affected changes, as described in the response, are provided below: NuScale Nonproprietary NuScale Nonproprietary

NuScale Final Safety Analysis Report Interfaces with Standard Design NuScale US460 SDAA 1.8-3 Draft Revision 2 COL Item 3.4-2: An applicant that references the NuScale Power Plant US460 standard design will develop the on-site program addressing the key points of flood mitigation. The key points to this program include the procedures for mitigating internal flooding events; the equipment list of structures, systems, and components subject to flood protection in each plant area; and providing assurance that the program reliably mitigates flooding to the identified structures, systems, and components. 3.4 COL Item 3.4-3: An applicant that references the NuScale Power Plant US460 standard design will develop an inspection and maintenance program to ensure that each water-tight door, penetration seal, or other degradable measure remains capable of performing its intended function. 3.4 Audit Question A-3.4.2-10 COL Item 3.4-4: An applicant that references the NuScale Power Plant US460 standard design will determine the extent of waterproofing and damp proofing needed for the underground portion of the Reactor Building, including the duct bank connection to the Reactor Building based on site-specific conditions. Additionally, the applicant will provide the specified design life for waterstops, waterproofing, damp proofing, and watertight seals. If the design life is less than the operating life of the plant, the applicant will describe how continued protection will be ensured. 3.4 COL Item 3.4-5: An applicant that references the NuScale Power Plant US460 standard design will confirm that nearby structures exposed to external flooding will not collapse and adversely affect the Reactor Building or Seismic Category I portion of the Control Building. 3.4 COL Item 3.5-1: An applicant that references the NuScale Power Plant US460 standard design will demonstrate the site-specific turbine missile parameters are bounded by the standard design analysis, or provide a missile analysis using the site-specific turbine generator parameters to demonstrate that barriers adequately protect essential structures, systems, and components from turbine missiles. Parameters to verify are: limiting turbine missile spectrum (rotor and blade material properties); turbine rotor design, geometry and number of blades; final design of the Reactor Building exterior wall; and location of the turbines with respect to the Reactor Building and Control Building. 3.5 COL Item 3.5-2: An applicant that references the NuScale Power Plant US460 standard design will confirm the design-basis automobile missile parameters for the reference plant of velocity and maximum altitude of impact will not be exceeded as a result of extreme wind conditions that may occur in the vicinity of the site. 3.5 COL Item 3.5-3: An applicant that references the NuScale Power Plant US460 standard design will evaluate site-specific hazards due to external events, such as turbine failures that can occur at nearby or co-located facilities, which may produce more energetic missiles than the design-basis missiles defined in Section 3.5.1. 3.5 COL Item 3.6-1: An applicant that references the NuScale Power Plant US460 standard design will perform the pipe rupture hazards analysis (including dynamic and environmental effects) of the high-and moderate-energy lines outside the reactor pool bay in the Reactor Building (RXB). This analysis includes an evaluation of multi-module impacts in common pipe galleries, and evaluations regarding subcompartment pressurization. The as-built Pipe Rupture Hazards Analysis (PRHA) will show that the analysis of RXB piping bounds the possible effects of ruptures for the routings of lines outside of the RXB, or will perform the PRHA of the high-and moderate-energy lines outside the buildings. 3.6 COL Item 3.7-1: An applicant that references the NuScale Power Plant US460 standard design will describe the site-specific safe shutdown earthquake. 3.7 Table 1.8-1: Combined License Information Items (Continued) Item No. Description of COL Information Item Section

NuScale Final Safety Analysis Report Water Level (Flood) Design NuScale US460 SDAA 3.4-4 Draft Revision 2 buildings. There are no large tanks or water sources near entrances to the RXB and CRB. The site is graded to transport water away from these buildings. Therefore, failure of equipment outside the CRB and RXB cannot cause internal flooding. 3.4.1.5 Site Specific Analysis COL Item 3.4-1: An applicant that references the NuScale Power Plant US460 standard design will confirm the final location of structures, systems, and components subject to flood protection. The final routing of piping, and site-specific tanks or water source tanks are placed in locations that would not cause flooding to the Reactor Building or Control Building. COL Item 3.4-2: An applicant that references the NuScale Power Plant US460 standard design will develop the on-site program addressing the key points of flood mitigation. The key points to this program include the procedures for mitigating internal flooding events; the equipment list of structures, systems, and components subject to flood protection in each plant area; and providing assurance that the program reliably mitigates flooding to the identified structures, systems, and components. COL Item 3.4-3: An applicant that references the NuScale Power Plant US460 standard design will develop an inspection and maintenance program to ensure that each water-tight door, penetration seal, or other degradable measure remains capable of performing its intended function. 3.4.2 Flood Protection from External Sources Portions of the RXB and CRB are Seismic Category I. The RW-IIa portions of the Radioactive Waste Building do not contain equipment subject to flood protection. There are no other safety-related structures in the design. 3.4.2.1 Probable Maximum Flood The design is a "Dry Site" as defined in Regulatory Guide 1.102, "Flood Protection for Nuclear Power Plants." Seismic Category I structures are protected from external floods and groundwater. Table 2.0-1 provides site parameter probable maximum flood and maximum groundwater elevations. The yard is graded to slope away from these buildings. The design does not use a permanent dewatering system. Audit Question A-3.4.2-10 COL Item 3.4-4: An applicant that references the NuScale Power Plant US460 standard design will determine the extent of waterproofing and damp proofing needed for the underground portion of the Reactor Building, including the duct bank connection to the Reactor Building based on site-specific conditions. Additionally, the applicant will provide the specified design life for waterstops,

NuScale Final Safety Analysis Report Protection against Dynamic Effects Associated with Postulated Rupture of Piping NuScale US460 SDAA 3.6-3 Draft Revision 2 and the RCS injection line. These high-energy ECCS lines are excluded from consideration as they are smaller than NPS 1. 3.6.1.1.2 Outside the Containment Vessel (Under the Bioshield) The high-energy lines and the moderate-energy lines (RCCWS, CFDS, and the containment evacuation system (CES)) continue outside containment to the NPM disconnect flange (Table 3.6-1). The DHRS steam line connects to the MSS line outside containment, immediately upstream of the MSS containment isolation valve, and leads to the DHRS condenser and then to the DHRS condensate return lines. Although not normally in use, this system is pressurized during NPM operation. 3.6.1.1.3 In the Reactor Building (Outside the Bioshield) Within the RXB but outside the area under the bioshield, the high-energy lines with piping larger than NPS 1 include the MSS, FWS, MHS, and CVCS lines. The high-energy MSS and FWS lines exit the module bay through the north and south reactor pool walls, cross a mechanical equipment area (pipe gallery), and exit the RXB. Once they exit the area under the bioshield, the high-energy CVCS lines run vertically downward in a pipe chase to the CVCS heat exchanger rooms and associated CVCS rooms. Moderate-energy lines are routed throughout the RXB. 3.6.1.1.4 In the Control Building There are no high-energy lines in the CRB, with the exception of the piping associated with the high pressure breathing air storage bottles in the control room habitability system. 3.6.1.1.5 Onsite (outside the Reactor Building and Control Building) Outside of the RXB and CRB there are three high-energy lines: MSS, FWS, and extraction steam, and multiple moderate-energy lines. Audit Question A-3.4.2-10 Outside the RXB and CRB, the only essential or other protected SSC are located in the safety-related underground duct bankunderground safety-related tunnels, where they are separated from HELB effects. 3.6.1.2 Identification of Essential Structures, Systems, and Components Essential SSC are primarily associated with the NPM, either inside the CNV or mounted on the top of the CNV head. Essential SSC in the design are a subset of}}

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