ML24281A020

LLC, Response to NRC Request for Additional Information No. 023 (RAI-10177 R1) on the NuScale Standard Design Approval Application

ML24281A020
Person / Time
Site:	05200050
Issue date:	10/07/2024
From:	Shaver M NuScale
To:	Office of Nuclear Reactor Regulation, Document Control Desk
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ML24281A019	List: ML24281A020
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RAIO-174777
Download: ML24281A020 (1)

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RAIO-174777 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360.0500 Fax 541.207.3928 www.nuscalepower.com October 07, 2024 Docket No.52-050 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852-2738

SUBJECT:

NuScale Power, LLC Response to NRC Request for Additional Information No. 023 (RAI-10177 R1) on the NuScale Standard Design Approval Application

REFERENCE:

1. NRC Letter to NuScale, Request for Additional Information No. 023 (RAI-10177 R1), dated March 29, 2024 The purpose of this letter is to provide the NuScale Power, LLC (NuScale) response to the referenced NRC Request for Additional Information (RAI).

The enclosure to this letter contains the NuScale response to the following RAI question from NRC RAI-10177 R1:

3.6.2-2 is the proprietary version of the NuScale Response to NRC RAI No. 023 (RAI-10177 R1, Question 3.6.2-2). NuScale requests that the proprietary version be withheld from public disclosure in accordance with the requirements of 10 CFR § 2.390. The enclosed affidavit (Enclosure 3) supports this request. Enclosure 1 has also been determined to contain Export Controlled Information. This information must be protected from disclosure per the requirement of 10 CFR § 810. Enclosure 2 is the nonproprietary version of the NuScale response.

This letter makes no regulatory commitments and no revisions to any existing regulatory commitments.

If you have any questions, please contact Elisa Fairbanks at 541-452-7872 or at efairbanks@nuscalepower.com.

I declare under penalty of perjury that the foregoing is true and correct. Executed on October 07, 2024.

Sincerely, Mark W. Shaver Director, Regulatory Affairs NuScale Power, LLC

RAIO-174777 Page 2 of 2 10/07/2024 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360.0500 Fax 541.207.3928 www.nuscalepower.com Distribution:

Mahmoud Jardaneh, Chief New Reactor Licensing Branch, NRC Getachew Tesfaye, Senior Project Manager, NRC Prosanta Chowdhury, Senior Project Manager, NRC

NuScale Response to NRC Request for Additional Information RAI-10177 R1, Question 3.6.2-2, proprietary : NuScale Response to NRC Request for Additional Information RAI-10177 R1, Question 3.6.2-2, nonproprietary : Affidavit of Mark W. Shaver, AF-174778

RAIO-174777 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360.0500 Fax 541.207.3928 www.nuscalepower.com NuScale Response to NRC Request for Additional Information RAI-10177 R1, Question 3.6.2-2, proprietary

RAIO-174777 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360.0500 Fax 541.207.3928 www.nuscalepower.com NuScale Response to NRC Request for Additional Information RAI-10177 R1, Question 3.6.2-2, nonproprietary

Response to Request for Additional Information Docket: 052000050 RAI No.: 10177 Date of RAI Issue: 04/12/2024 NRC Question No.: 3.6.2-2 Regulatory Basis

• 10 CFR 50.55a Codes and standards requires that Class 1, 2, and 3 piping systems be designed to ASME Section III criteria.

• 10 CFR Part 50 Appendix-A, GDC 4, Environmental and dynamic effects design bases, states that structures, systems, and components shall be appropriately protected against dynamic effects, including the effects of missiles, pipe whipping, and discharging fluids, that may result from equipment failures and from events and conditions outside the nuclear power unit. However, dynamic effects associated with postulated pipe ruptures in nuclear power units may be excluded from the design basis when analyses reviewed and approved by the Commission demonstrate that the probability of fluid system piping rupture is extremely low under conditions consistent with the design basis for the piping.

• 10 CFR 50.46, Acceptance criteria for emergency core cooling systems (ECCS) for light-water nuclear power reactors, describes, in part, that emergency core cooling systems cooling performance must be calculated in accordance with an acceptable evaluation model and must be calculated for a number of postulated loss-of-coolant accidents of different sizes, locations, and other properties sufficient to provide assurance that the most severe postulated loss-of-coolant accidents are calculated.

Issue SRP Branch Technical Position (BTP) 3-4, Postulated Rupture Locations in Fluid System Piping Inside and Outside Containment, provides guidance on postulated break locations and piping system design considerations.

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In the Standard Design Approval (SDA) Pipe Rupture Hazards Analysis Technical Report (TR-121507-P), it is noted that containment system piping, which includes injection, discharge, Pressurizer (PZR) spray piping, and degasification piping, is classified as break exclusion and is required to meet applicable stress criteria of BTP 3-4 B.1.(ii). The containment system piping includes safety related ASME BPV Code Section III class 1 welded connections that constitute the reactor coolant pressure boundary. These welded containment penetration locations are important not only from 10 CFR part 50 Appendix A GDC 4, but are also extremely critical from 10 CFR Part 50.46 considerations.

Loss of fluid due to breaks in the welds at Containment Vessel (CNV) to CNV nozzle safe end, CNV nozzle safe end to Containment Isolation Valve (CIV) weld, or CIV outboard weld in the containment penetration area of Chemical and Volume Control System (CVCS) injection and discharge piping welded connections, Pressurizer (PZR) spray piping, and degasification line welded connections can result in significant consequences. Gross failure of welds at these locations would result in a LOCA that would challenge fuel integrity with concurrent containment bypass.

Breaks in these locations would also result in dynamic effects. BTP3-4 points out that subject to certain limitations, GDC 4 allows that dynamic effects associated with postulated pipe ruptures be excluded from the design basis when analyses reviewed and approved by the NRC demonstrate that the probability of fluid system piping rupture is extremely low under design-basis conditions. This can be satisfied, in part, by confirming that stress and cumulative usage factors (CUF) margins meet at least the BTP3-4 criteria using acceptable analysis methods, having appropriate augmented measures in materials, fabrication, and preservice and inservice inspections (PSI and ISI). The information provided in the application does not provide the staff sufficient information to make a regulatory finding. Specifically, a summary of the analyses and additional measures described above have not been provided as part of the application.

If breaks at these connections are not assumed to satisfy 10 CFR 50.46, then appropriate justification must be provided. The decrease in defense-in-depth due to not postulating losses of coolant accidents at these locations can be compensated, in part, by a high confidence in the structural integrity of the welded connections such that the probability of fluid system piping rupture is extremely low under design basis conditions are reviewed and approved by the NRC.

This can be satisfied, in part, by confirming that stress and cumulative usage factors (CUF) margins meet at least the BTP3-4 criteria using acceptable analysis methods, having appropriate augmented measures in materials, fabrication, and preservice and inservice inspections assuring the robustness of design.

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Postponing completion of the preliminary analyses based on the current design until the ITAAC phase does not provide adequate assurance demonstrating the robustness of the design and margins for these welded connections. The staff does not consider regulatory commitments to complete the design evaluation and meet the BTP3-4 Break Exclusion area requirements and ASME BPV Code acceptance criteria through an ITAAC as an appropriate resolution for these highly safety significant weld connections due to the far-reaching implications from 10 CFR Appendix A, GDC 4, and 10 CFR 50.46 perspectives.

Information Requested Provide a summary of preliminary stress analysis results (stresses and CUF values as applicable) for welded joints, including all welds between the CNV vessel nozzle to CIV outboard weld in the containment penetration area for the CVCS injection and discharge lines, PZR spray piping, and degasification lines, to demonstrate the robustness of the design and margins in the results. Describe additional measures that will be implemented for PSI and ISI beyond the ASME Section III and Section XI requirements for these locations. Include a markup of the FSAR, as appropriate, with the summary of significant assumptions, analysis results, and any measures taken to ensure the probability of fluid system piping rupture is extremely low under design-basis conditions.

NuScale Response:

Executive Summary:

In this response, NuScale provides a summary of the preliminary or representative stress analysis results for the weld locations depicted in Figure 1. This response also includes a description of the break exclusion zone treatment for these welds and their applicability to Branch Technical Position (BTP) 3-4 as summarized in Table 1.

In addition to preliminary stress analysis results, the staff requested descriptions of additional preservice inspections (PSI) and inservice inspections (ISI) beyond the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC)Section III and Section XI requirements for welds. This response includes a description of the augmented inspections performed on the welds of interest in addition to the PSI and ISI requirements of ASME BPVC Section III and Section XI.

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Table 2 includes the preliminary stress results for the pipe to containment isolation valve welds, as depicted in Figure 1 at location A. Table 2 includes the results for the chemical and volume control system (CVCS) injection line, CVCS discharge line, pressurizer spray line, and reactor pressure vessel (RPV) high point degasification line. Table 2 includes both the analysis results for these welds and the limits of BTP 3-4 B.1.(ii).(d) and (e) to demonstrate compliance with the BTP stress requirements. Table 2 also includes the margin for the analyzed locations to demonstrate the robustness of the design.

Tables 3 through 5 include the preliminary stress results for the pressurizer spray and the RPV high point degasification lines welds, as depicted in Figure 1 at locations C and D. Table 3 includes both the cumulative usage factor results for these welds and the limits of BTP 3-4 B.1.(ii).(b) to demonstrate compliance with the BTP stress requirements. Table 4 includes the primary plus secondary stress range results, which are compared to the criteria in ASME BPVC Section III, Subsection NB, Appendices, Subsubarticle XIII-3420. For locations in Table 4 that exceed the limits in XIII-3420, Table 5 includes primary plus secondary stress range results without thermal bending, which are compared to the criteria in ASME BPVC Section III, Subsection NB, Appendices, Subsubarticle XIII-3450. The margin results for the analyzed locations demonstrate the robustness of the design.

Scope of the Analysis and Description of Weld Locations:

The welds depicted in Figure 1 are on the four CVCS lines located between the containment vessel (CNV) nozzle up to and including the containment isolation valve (CIV) outboard weld.

Figure 1 depicts a typical CVCS line containment penetration with the specific welds identified for the information requested.

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Figure 1: Typical Chemical and Volume Control System Line Containment Penetration and Weld Identification Both the US600 and US460 designs comply with General Design Criterion (GDC) 54, providing "isolation and containment capabilities... which reflect the importance to safety of isolating these piping systems." Both the US600 and US460 designs locate the two containment isolation valves in each CVCS line outside of containment, pursuant to design-specific Principal Design Criterion 55 (Exemption justified in SDAA Part 7, Exemptions and Departures, Section 9.2).

The design applies Design-Specific Review Standard (DSRS) Section 6.2.4, Containment Isolation System, acceptance criterion 4 to these lines to meet the purpose of GDC 55 by ensuring adequate containment isolation reliability. The DSRS 6.2.4 acceptance criterion 4 NuScale Nonproprietary NuScale Nonproprietary

relies on compliance with SRP Section 3.6.2 to preclude a breach of piping integrity between the containment and CIVs, which in turn relies on BTP 3-4 for postulated pipe rupture locations.

Table 1 provides information relevant to the application of break exclusion zone (BEZ) requirements (i.e., BTP 3-4 B.1.(ii)) for the welds depicted in Figure 1. As indicated in Table 1, the welds identified at Figure 1 locations A, B, and C, are within the BEZ, and are evaluated against all seven criteria of BTP 3-4 B.1.(ii). While the vessel welds identified at location D (Figure 1) are outside the scope of BTP 3-4 B.1.(ii), NuScale performed preliminary stress analyses to demonstrate the welds meet the specified criteria with margin as shown in Table 3.

The US460 jurisdictional boundaries between the CVCS lines and CNV changed such that the welds at location C (safe-end to the containment isolation test fixture (CITF)) are within the jurisdiction of the piping system, rather than the CNV. NuScale includes the impacted pages of TR-121507-P, Pipe Rupture Hazards Analysis, corresponding to this design change with this response.

Analysis results for the welds at location A in Figure 1 are compared to the limits of BTP 3-4 B.1.(ii).(d) and (e) in Table 2, demonstrating compliance with the BTP stress requirements.

Analyzed locations have margin to ensure weld integrity during operation.

Welds shown in Figure 1 comply with the remaining BTP 3-4 B.1.(ii) criteria, including the ISI criteria of BTP 3-4 B.1.(ii)(7). Although the welds at location D (Figure 1) are not within the jurisdiction of the piping system, and therefore not subject to BTP 3-4, SDAA Section 3.6.2, Determination of Rupture Locations and Dynamic Effects Associated with the Postulated Rupture of Piping, requires volumetric ISI examination of these welds. The attached mark-up provides updates to Section 3.6.2 to reference ISI for Class 1 welds in Section 5.2.4, Reactor Coolant Pressure Boundary Inservice Inspection and Testing, and to clarify that all welds greater than NPS 1 (i.e., not only the NPS 2 welds) receive volumetric examination. Compliance with BTP 3-4 B.1.(ii)(7) is also discussed in TR-121507-P, Section A.1. Weld sizes NPS 4 or larger require volumetric exams at every inspection interval in accordance with ASME Section III and Section XI, pursuant to 10 CFR 50.55a. NuScales response to Audit Question A-5.2.4.1-1 describes detailed ISI requirements for welds at Figure 1 locations B, C and D. The weld at location D in Figure 1 receives volumetric examination as an augmented inspection as described in SDAA Section 3.6.2. Where augmented volumetric ISI is specified for these lines, the commensurate PSI in accordance with ASME BPVC,Section XI is also specified in the applicable ASME design specifications to provide a baseline examination.

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NuScale incorporates FSAR changes to SDAA Sections 5.2.4 and 6.6, Inservice Inspection and Testing of Class 2 and 3 Systems and Components, to clarify PSI requirements.

Representative Preliminary Stress Analysis Results:

NuScale performed a detailed quantitative analysis of the pressurizer spray line and RPV high point degasification line connections on the exterior of the CNV head. The scope of the calculation also qualitatively assessed the remaining CVCS connections on the exterior of the CNV. This ASME stress evaluation utilizes thermal and structural finite element analysis and provides primary plus secondary stress range and cumulative usage factor results for weld location C (Figure 1) in the pressurizer spray and RPV high point degasification lines. This analysis considers loads prescribed by the ASME design specification and addresses the applicable ASME Code rules with assumptions for aspects of the design and loading conditions.

Cumulative usage factor results for the weld at location C (Figure 1) are compared to the limits of BTP 3-4 B.1.(ii).(b) in Table 3 demonstrating compliance with the BTP stress requirements.

The cumulative usage factor of 0.4 is an NRC-accepted modification to the BTP 3-4 criteria when considering the effects of environmentally assisted fatigue. Table 4 summarizes primary plus secondary stress range results for the weld at location C (Figure 1), which are compared to the criteria in ASME BPVC Section III Subsection NB and Appendices, Subsubarticles XIII-3420. The analyzed locations have sufficient margin to ensure weld integrity during operation.

The qualitative evaluation demonstrates that the pressurizer spray line results are representative of the injection and discharge lines. The applicable mechanical piping extension loads are greater for the pressurizer spray nozzle compared to both the injection and discharge nozzle locations. The outboard safe ends on the pressurizer spray, injection, and discharge nozzles have identical geometries. Locations utilize equal loads for the specified safe shutdown earthquake (SSE). The nozzle location differences in critical transients defined (maximum stress range pairs contributing to 95% of the cumulative fatigue usage) are negligible and do not change the conclusions on primary plus secondary stress and cumulative fatigue usage.

CITF to CIV Weld Connection Representative Analysis:

Preliminary ASME stress evaluations for the welds at B (Figure 1) between the CITF and the CIV are not available. Stress analysis results provided above for the welds at A (Figure 1) in the

((2(a),(c) CIV to piping weld (Tables 1 and 2) and at C (Figure 1) in the ((

}}2(a),(c) safe end to CITF weld (Table 3) demonstrate significant margin at these locations, which experience the same transients, utilize similar materials, and are less NuScale Nonproprietary NuScale Nonproprietary

than 20 inches away from the weld at B (Figure 1). The detailed design of this connection includes selection of appropriate dimensions to satisfy stress and fatigue criteria. Safe End at Nozzle Weld Connection Summary: Although the welds located at D (Figure 1) are outside the scope of BTP 3-4 B.1.(ii) per TR-121507-P, Pipe Rupture Hazards Analysis, Appendix A, NuScale included these locations on the pressurizer spray and degasification lines in the preliminary ASME stress analysis described above. Table 3 reports the cumulative usage factor results for location D (Figure 1) and compares them to the break exclusion zone criteria. The increased wall thickness at location D (Figure 1) provides increased margin compared to location C (Figure 1) ( (( }}2(a),(c) ). Table 4 includes the primary plus secondary stress range results for location D (Figure 1), which are compared to the criteria in ASME BPVC Section III, Subsection NB, Appendices, Subsubarticle XIII-3420. For locations in Table 4 that exceed the limits in XIII-3420, Table 5 includes primary plus secondary stress range results without thermal bending, which are compared to the criteria in ASME BPVC Section III, Subsection NB, Appendices, Subsubarticle XIII-3450. The results demonstrate that the welds located at the safe end to nozzle also have margin to ensure weld integrity during operation. NuScale Nonproprietary NuScale Nonproprietary

Table 1: Application of Break Exclusion Zone Requirements ID ASME Component Type ASME Class (Subsection) Located in Containment Penetration Area per definition in BTP 3-4 B.1.ii (portions of piping from containment wall to and including the inboard or outboard isolation valves) Included in NuScales Break Exclusion Zone (i.e., BTP 3-4 B.1.ii. conforming areas even if not located in the containment penetration area as defined to the left. Break Excluded in US460 SDAA Chapter 15 Analysis? Analysis Results Provided in the US600 DCA A Piping Class 3 (ND) No, this weld is beyond the CIV. Yes, NuScale extended the BEZ to include this weld No, analyzed in Section 15.6.2 Results provided in RAI 8836, NRC Question No. 03.06.02-2. B Piping Class 1 (NB) Yes, this weld is in the jurisdiction of the piping system and is between the CNV and CIV. Yes Yes This weld did not exist. There was no CITF in the US600 design. C Piping Class 1 (NB) Yes, this weld is in the jurisdiction of the piping system and is between the CNV and CIV. Yes Yes Results provided in RAI 8836, NRC Question No. 03.0 6.02-2, although the weld was to the CIV rather than the CITF. D Vessel Class 1 (NB) No, this weld is a vessel weld. No, however NuScale has applied the ISI requirements of BTP 3-4 B.1.ii.(7) Yes Analysis results were not provided in RAI 8836, NRC Question No. 03.06.02-2. However, the entire analysis was provided later as part of a larger NRC audit on ASME stress and fatigue (see NRC Agencywide Document Access and Management System (ADAMS) Accession No. ML19340A971). NuScale Nonproprietary NuScale Nonproprietary

Table 2: Preliminary Stress Results for Welds at Location A (Pipe to Containment Isolation Valve) Line BTP 3-4 Criteria ASME Equation Calculation Result [psi] BTP 3-4 Stress Limit(1) [psi] Margin(2) [%] Injection BTP 3-4 B.1.(ii).(d), Level A/B (9a) + (10a) (( }}2(a),(c) (( }}2(a),(c) (( }}2(a),(c) BTP 3-4 B.1.(ii).(e), Break (9a) (( }}2(a),(c) (( }}2(a),(c) (( }}2(a),(c) Discharge BTP 3-4 B.1.(ii).(d), Level A/B (9a) + (10a) (( }}2(a),(c) (( }}2(a),(c) (( }}2(a),(c) BTP 3-4 B.1.(ii).(e), Break (9a) (( }}2(a),(c) (( }}2(a),(c) (( }}2(a),(c) Pressurizer Spray BTP 3-4 B.1.(ii).(d), Level A/B (9a) + (10a) (( }}2(a),(c) (( }}2(a),(c) (( }}2(a),(c) BTP 3-4 B.1.(ii).(e), Break (9a) (( }}2(a),(c) (( }}2(a),(c) (( }}2(a),(c) RPV High Point Degasification BTP 3-4 B.1.(ii).(d), Level A/B (9a) + (10a) (( }}2(a),(c) (( }}2(a),(c) (( }}2(a),(c) BTP 3-4 B.1.(ii).(e), Break (9a) (( }}2(a),(c) (( }}2(a),(c) (( }}2(a),(c) Notes: (1) The BTP 3-4 stress range limits are conservatively 80 percent of the allowable ASME Section III limits. (2) The Margin demonstrates the robustness of the design by comparing the quantitative analysis results for the maximum stress range against the limits of BTP 3-4. NuScale Nonproprietary NuScale Nonproprietary

Table 3: Preliminary Fatigue CUF Results for Welds at Locations C and D (Figure 1) for the Pressurizer Spray and High Point Degasification Lines Line Location (Figure 1) Criteria Calculation Result Criteria Allowable(3) Margin(4) [%] Pressurizer Spray C Uen, CUF(1) (( }}2(a),(c) (( }}2(a),(c) (( }}2(a),(c) D Uen, CUF(1) (( }}2(a),(c) (( }}2(a),(c) (( }}2(a),(c) RPV High Point Degasification C U, CUF(2) (( }}2(a),(c) (( }}2(a),(c) (( }}2(a),(c) D U, CUF(2) (( }}2(a),(c) (( }}2(a),(c) (( }}2(a),(c) Notes: (1) The cumulative usage factor, Uen, includes environmentally assisted fatigue effects. (2) The cumulative usage factor, U, is evaluated without environmentally assisted fatigue effects. (3) Criteria Allowable represents the more conservative limits of BTP 3-4 (e.g., fatigue usage of 0.1 for BTP 3-4 compared to fatigue usage of 1.0 for ASME Section III). (4) Margin demonstrates the robustness of the design by comparing the quantitative analysis results for cumulative usage factor against the limits of BTP 3-4. NuScale Nonproprietary NuScale Nonproprietary

Table 4: (( }}2(a),(c),ECI NuScale Nonproprietary NuScale Nonproprietary

Table 5: (( }}2(a),(c),ECI NuScale Nonproprietary NuScale Nonproprietary

NuScale Final Safety Analysis Report Protection against Dynamic Effects Associated with Postulated Rupture of Piping NuScale US460 SDAA 3.6-9 Draft Revision 2 There is a minimum number of circumferential and no longitudinal welds in these lines in the containment penetration area. The length of the piping is the minimum practicable. There are no pipe anchors or restraints that require welding directly to the outer surface of the piping. Guard pipes are not used. RAI 3.6.2-2 The piping welds are included in the ISI program as described in Section 5.2, Integrity of Reactor Coolant Boundary, for Class 1 welds and Section 6.6, Inservice Inspection and Testing of Class 2 and 3 Systems and Components, for Class 2 and 3 welds., and the NPS 2 weldsWelds larger than NPS 1, including and inboard of those of the pipe to outer nozzle welds of the CIVs, are 100 percent volumetrically inspected, in addition to surface inspections as required by the ASME Boiler and Pressure Vessel Code Section XI. RAI 3.6.2-2 The in-service inspection criteria of BTP 3-4 B.1.(ii)(7) are also applied to non-piping welds between valves, vessel safe-ends, and vessel nozzles that are located between the containment wall and break exclusion areas. Outboard of the containment isolation valves, the CVCS NPS 2, RCS discharge, RCS injection, PZR spray supply, and high point degasification lines are ASME Class 3 lines to the next valve outboard of the CIV. The line transitions to ASME B31.1 outboard of the additional valve. At the first spool piece breakaway flange, the four lines become part of the CVCS. Piping under the bioshield, outboard of the containment penetration area including the refueling pipe spools, is designed to comply with BTP 3-4 Rev. 3 Paragraph B.1.(iii) to preclude breaks at intermediate locations by limiting stresses calculated by the sum of equations (9) and (10) in NC/ND-3653 of Section III of the ASME Boiler and Pressure Vessel Code to not exceed 0.8 times the sum of the stress limits given in NC/ ND-3653. Final stress analysis is performed concurrent with fabrication of the first NPM. Based on designing to meet the criteria from BTP 3-4, no breaks in the NPM bay outside the CNV (under the bioshield) are postulated. However, nonmechanistic breaks in MSS and FWS lines in the containment penetration area and leakage cracks are considered. Decay Heat Removal System Lines The DHRS is a closed loop system outside of the CNV that is entirely associated with a single NPM. Each NPM has two independent DHRS trains. Each train is associated with an independent steam generator (SG). The only active components in the DHRS are the DHRS actuation valves. The DHRS also relies on the MSS and FWS containment isolation valves to provide a closed loop system when it is activated. The DHRS is used to respond to transients including HELB outside containment. It is not used for normal

NuScale Final Safety Analysis Report Integrity of Reactor Coolant Boundary NuScale US460 SDAA 5.2-23 Draft Revision 2 Evaluation of examination results for Class 1 components is in accordance with IWA-3000 and IWB-3000 of Reference 5.2-9. Repair of unacceptable indications conforms to the requirements of IWA-4000 of Reference 5.2-9. Criteria for establishing need for repair or replacement are in accordance with IWB-3000 of Reference 5.2-9. System leakage tests, followed by a VT-2 examination for the RPV Class 1 pressure retaining boundary, conform to the requirements specified in Reference 5.2-9, Table IWB-2500-1 (B-P) and Articles IWA-5000 and IWB-5000. Leakage monitoring continuously occurs from the Class 1 boundary into the CNV. This constitutes a VT-2 exam in accordance with Section XI IWA-5241 (c). Section 5.2.5, RCPB Leakage Detection contains further details. The body-to-bonnet seals on the ECCS trip/reset actuator valve form a portion of the RCPB and require testing to RCS operating pressure before going into operation. Because this valve is located in the reactor pool, there is no means to perform the required ASME BPVC Section XI, Table IWB-2500-1 (B-P), VT-2 examination during the system pressure test. Therefore, a seal test is performed and meets the requirements of Reference 5.2-9, Table IWB-2500-1 (B-P). RAI 3.6.2-2 The exterior nozzle-to-safe end welds and safe end-to-containment isolation test fixture (CITF)piping welds associated with the PZR spray lines, RPV high point degasification line, and CVCS injection and discharge lines require surface and volumetric examination. The nozzle-to-safe end welds examination conform to the guidance in IWB-2500-1 Category B-F and safe end-to-CITFpiping welds examination conform to the guidance in IWB-2500-1 Category B-J. RAI 3.6.2-2 The ASME Class 1 boundary valves (i.e., CIVs) are outside of the NPM. The reduced inspection requirements for the small primary system pipe welds associated with smaller than four inch nominal pipe size piping are not applied to the welds between the CITFscontainment and the CIVs because a break at one of these weld locations would result in an RCPB leak outside the containment. Therefore, ASME Class 1 welds between the CITFscontainment and the CIVs undergo a volumetric examination in addition to the Code required surface examination each interval in accordance with the requirements of Reference 5.2-9, Subarticle IWB-2500. Flanges on the RPV have dual O-rings with a leak port tube between the O-rings to allow for leakage testing. Leakage testing is performed following installation of the O-rings each time they are removed to ensure the seals are seated as designed. 5.2.4.2 Preservice Inspection and Testing Program RAI 3.6.2-2 Preservice examinations required by the design specification and preservice documentation are in accordance with Reference 5.2-8, Paragraph NB-5281.

NuScale Final Safety Analysis Report Integrity of Reactor Coolant Boundary NuScale US460 SDAA 5.2-24 Draft Revision 2 Volumetric and surface examinations conform to ASME BPVC Section III, Paragraph NB-5282. Components described in ASME BPVC Section III, Paragraph NB-5283, are exempt from preservice examination. Consistent with Branch Technical Position 3-4, welds greater than NPS 1 in the PZR spray, RPV high point degasification line, CVCS injection, and CVCS discharge included within the break exclusion zone require a volumetric examination in addition to the required surface examination. Surfaces of the RPV are suitable for examinations and conform to the applicable requirements of ASME BPVC Sections III and XI. For welds requiring an ultrasonic preservice examination, the surface finish meets the requirements of Reference 5.2-8, Subsubparagraph NB-4424.2(a). Preservice examinations for ASME Code Class 1 pressure boundary and attachment welds conform with Reference 5.2-8, Paragraph NB-5280 and Reference 5.2-9, Subarticle IWB-2200. These preservice examinations include essentially 100 percent of the pressure boundary welds. Preservice eddy current examinations for the SG tubing are in accordance with the applicable requirements of the EPRI Steam Generator Management Program guidelines (Reference 5.2-7) and Reference 5.2-9. COL Item 5.2-4: An applicant that references the NuScale Power Plant US460 standard design will develop site-specific preservice examination, inservice inspection, and inservice testing program plans in accordance with Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code and the American Society of Mechanical Engineers Operations and Maintenance Code, and will establish implementation milestones. If applicable, an applicant that references the NuScale Power Plant US460 standard design will identify the implementation milestone for the augmented inservice inspection program. The applicant will identify the applicable edition of the American Society of Mechanical Engineers Code utilized in the program plans consistent with the requirements of 10 CFR 50.55a. 5.2.5 Reactor Coolant Pressure Boundary Leakage Detection The RCS of each NPM does not employ traditional light water reactor components with designed leakage rates, such as through pump seals or valve stem shafts. The RCS leakage detection system withstands the effects of seismic events and other natural phenomena without losing the capability to perform its intended safety functions, thus meeting GDC 2. The RCPB leakage detection system detects leakage after an earthquake for an early indication of degradation so that corrective action can be taken before such degradation becomes severe enough to result in a leak rate greater than the capability of the makeup system to replenish the coolant loss. For each NPM, distinguishing between RCS identified and unidentified leakage inside the containment is not practicable with the installed instrumentation. Leakage into containment may originate from sources other than from the RCPB (e.g., leakage from reactor component cooling water). Expected leakage occurs from the RCS to

NuScale Final Safety Analysis Report Inservice Inspection and Testing of Class 2 and 3 Systems and Components NuScale US460 SDAA 6.6-3 Draft Revision 2 connections, and other fittings remain disconnected unless they have an extended tangent length adjacent to the weld to permit weld examination. In accordance with ASME BPVC Section XI, Article IWA-1500(d), there is space for examinations alternative to those specified, in the event that there are structural defects or modifications requiring alternative examinations. In accordance with ASME BPVC Section XI, Article IWA-1500(e), there is space for necessary operations associated with repair or replacement activities. Piping and pipe support locations, insulation, hangers, and stops do not interfere with the inspection equipment and personnel. Where this cannot be done, the components are removable. The Nuscale Power Plant ensures accessibility of welds and other areas requiring periodic inspection. Reinforcing pads, supports, piping, and equipment do not obstruct welds. Removable insulating materials above the containment vessel provide accessibility for ISI. Areas requiring inspection and servicing of valves provide working platforms. Temporary or permanent working platforms, walkways, scaffolding, and ladders facilitate access to piping and component welds. The components and welds requiring ISI allow for the application of the required ISI methods. Such design features include sufficient clearances for personnel and equipment, maximized examination surface distances, access, favorable materials, weld-joint simplicity, elimination of geometrical interferences, and proper weld surface preparation. Some ASME BPVC Class 2 and 3 components are in modules fabricated offsite and shipped to the site. The modules design and engineering provides access for preservice inspections, ISI, and maintenance activities. 6.6.3 Examination Techniques and Procedures The ISI examination techniques include visual, surface, and volumetric examination methods. The examination procedures describe the examination equipment, inspection techniques, operator qualifications, calibration standards, flaw evaluation methods, and records. The techniques and procedures meet the requirements of ASME BPVC Section XI, Articles IWA-2000, IWC-2000 and IWD-2000. Preservice inspection and subsequent ISI use equivalent equipment and techniques. RAI 3.6.2-2 Preservice inspections occur once, in accordance with ASME BPVC, Section XI, Article IWC-2000 and Article IWD-2000. Main steam and feedwater nozzle-to-safe end welds and safe end-to-piping welds, and the outboard side CIV to piping welds for the PZR spray, RPV high point degasification, CVC injection, and CVC discharge lines, are included within the break exclusion zone. Consistent with Branch Technical Position 3-4, break exclusion zone welds require a volumetric examination in addition to requirements of ASME BPVC, Section XI.

Pipe Rupture Hazards Analysis TR-121507-NP Draft Revision 1 © Copyright 2024 by NuScale Power, LLC A-5 RAI 3.6.2-2 Figure A-2 Containment pPenetration aAreas - cContainment sSystem

RAIO-174777 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360.0500 Fax 541.207.3928 www.nuscalepower.com Affidavit of Mark W. Shaver, AF-174778

AF-174778 Page 1 of 2

NuScale Power, LLC AFFIDAVIT of Mark W. Shaver I, Mark W. Shaver, state as follows: (1) I am the Director of Regulatory Affairs of NuScale Power, LLC (NuScale), and as such, I have been specifically delegated the function of reviewing the information described in this Affidavit that NuScale seeks to have withheld from public disclosure, and am authorized to apply for its withholding on behalf of NuScale. (2) I am knowledgeable of the criteria and procedures used by NuScale in designating information as a trade secret, privileged, or as confidential commercial or financial information. This request to withhold information from public disclosure is driven by one or more of the following: (a) The information requested to be withheld reveals distinguishing aspects of a process (or component, structure, tool, method, etc.) whose use by NuScale competitors, without a license from NuScale, would constitute a competitive economic disadvantage to NuScale. (b) The information requested to be withheld consists of supporting data, including test data, relative to a process (or component, structure, tool, method, etc.), and the application of the data secures a competitive economic advantage, as described more fully in paragraph 3 of this Affidavit. (c) Use by a competitor of the information requested to be withheld would reduce the competitors expenditure of resources, or improve its competitive position, in the design, manufacture, shipment, installation, assurance of quality, or licensing of a similar product. (d) The information requested to be withheld reveals cost or price information, production capabilities, budget levels, or commercial strategies of NuScale. (e) The information requested to be withheld consists of patentable ideas. (3) Public disclosure of the information sought to be withheld is likely to cause substantial harm to NuScales competitive position and foreclose or reduce the availability of profit-making opportunities. The accompanying Request for Additional Information response reveals distinguishing aspects about the response by which NuScale develops its NuScale Power, LLC Response to NRC Request for Additional Information (RAI No. 10177 R1, Question 3.6.2-2) on the NuScale Standard Design Approval Application. NuScale has performed significant research and evaluation to develop a basis for this response and has invested significant resources, including the expenditure of a considerable sum of money. The precise financial value of the information is difficult to quantify, but it is a key element of the design basis for a NuScale plant and, therefore, has substantial value to NuScale. If the information were disclosed to the public, NuScales competitors would have access to the information without purchasing the right to use it or having been required to undertake a similar expenditure of resources. Such disclosure would constitute a misappropriation of NuScales intellectual property, and would deprive NuScale of the opportunity to exercise its competitive advantage to seek an adequate return on its investment. (4) The information sought to be withheld is in the enclosed response to NRC Request for Additional Information RAI 10177 R1, Question 3.6.2-2. The enclosure contains the designation Proprietary at the top of each page containing proprietary information. The information considered by NuScale to be proprietary is identified within double braces, (( }} in the document.

AF-174778 Page 2 of 2 (5) The basis for proposing that the information be withheld is that NuScale treats the information as a trade secret, privileged, or as confidential commercial or financial information. NuScale relies upon the exemption from disclosure set forth in the Freedom of Information Act (FOIA), 5 USC § 552(b)(4), as well as exemptions applicable to the NRC under 10 CFR §§ 2.390(a)(4) and 9.17(a)(4). (6) Pursuant to the provisions set forth in 10 CFR § 2.390(b)(4), the following is provided for consideration by the Commission in determining whether the information sought to be withheld from public disclosure should be withheld: (a) The information sought to be withheld is owned and has been held in confidence by NuScale. (b) The information is of a sort customarily held in confidence by NuScale and, to the best of my knowledge and belief, consistently has been held in confidence by NuScale. The procedure for approval of external release of such information typically requires review by the staff manager, project manager, chief technology officer or other equivalent authority, or the manager of the cognizant marketing function (or his delegate), for technical content, competitive effect, and determination of the accuracy of the proprietary designation. Disclosures outside NuScale are limited to regulatory bodies, customers and potential customers and their agents, suppliers, licensees, and others with a legitimate need for the information, and then only in accordance with appropriate regulatory provisions or contractual agreements to maintain confidentiality. (c) The information is being transmitted to and received by the NRC in confidence. (d) No public disclosure of the information has been made, and it is not available in public sources. All disclosures to third parties, including any required transmittals to NRC, have been made, or must be made, pursuant to regulatory provisions or contractual agreements that provide for maintenance of the information in confidence. (e) Public disclosure of the information is likely to cause substantial harm to the competitive position of NuScale, taking into account the value of the information to NuScale, the amount of effort and money expended by NuScale in developing the information, and the difficulty others would have in acquiring or duplicating the information. The information sought to be withheld is part of NuScales technology that provides NuScale with a competitive advantage over other firms in the industry. NuScale has invested significant human and financial capital in developing this technology and NuScale believes it would be difficult for others to duplicate the technology without access to the information sought to be withheld. I declare under penalty of perjury that the foregoing is true and correct. Executed on October 07, 2024. Mark W. Shaver}}