ML24198A035
| ML24198A035 | |
| Person / Time | |
|---|---|
| Site: | 99902078 |
| Issue date: | 07/16/2024 |
| From: | NRC |
| To: | NRC/NRR/DNRL/NRLB |
| References | |
| Download: ML24198A035 (5) | |
Text
From:
Getachew Tesfaye Sent:
Tuesday, July 16, 2024 9:34 AM To:
Request for Additional Information Cc:
Stacy Joseph; Mahmoud -MJ-Jardaneh; Griffith, Thomas; Lockwood, Chelsea; Osborn, Jim; NuScale-SDA-720RAIsPEm Resource
Subject:
NuScale SDAA Section 5.4.1.6.1 - Request for Additional Information No. 027 (RAI-10189-R1)
Attachments:
SECTION 5.4.1.6.1 - RAI-10189-R1-FINAL.pdf Attached please find NRC staffs request for additional information (RAI) concerning the review of NuScale Standard Design Approval Application for its US460 standard plant design (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23306A033).
Please submit your technically correct and complete response by the agreed upon date to the NRC Document Control Desk.
If you have any questions, please do not hesitate to contact me.
Thank you, Getachew Tesfaye (He/Him)
Senior Project Manager NRC/NRR/DNRL/NRLB 301-415-8013
Hearing Identifier:
NuScale_SDA720_RAI_Public Email Number:
37 Mail Envelope Properties (BY5PR09MB568262F87FD59053F7AA52258CA22)
Subject:
NuScale SDAA Section 5.4.1.6.1 - Request for Additional Information No. 027 (RAI-10189-R1)
Sent Date:
7/16/2024 9:33:33 AM Received Date:
7/16/2024 9:33:37 AM From:
Getachew Tesfaye Created By:
Getachew.Tesfaye@nrc.gov Recipients:
"Stacy Joseph" <stacy.joseph@nrc.gov>
Tracking Status: None "Mahmoud -MJ-Jardaneh" <Mahmoud.Jardaneh@nrc.gov>
Tracking Status: None "Griffith, Thomas" <tgriffith@nuscalepower.com>
Tracking Status: None "Lockwood, Chelsea" <clockwood@nuscalepower.com>
Tracking Status: None "Osborn, Jim" <josborn@nuscalepower.com>
Tracking Status: None "NuScale-SDA-720RAIsPEm Resource" <NuScale-SDA-720RAIsPEm.Resource@nrc.gov>
Tracking Status: None "Request for Additional Information" <RAI@nuscalepower.com>
Tracking Status: None Post Office:
BY5PR09MB5682.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 584 7/16/2024 9:33:37 AM SECTION 5.4.1.6.1 - RAI-10189-R1-FINAL.pdf 189346 Options Priority:
Normal Return Notification:
No Reply Requested:
No Sensitivity:
Normal Expiration Date:
1 REQUEST FOR ADDITIONAL INFORMATION No. 027 (RAI-10189-R1)
BY THE OFFICE OF NUCLEAR REACTOR REGULATION NUSCALE STANDARD DESIGN APPROVAL APPLICATION DOCKET NO.
05200050 CHAPTER 5, REACTOR COOLANT SYSTEM AND CONNECTING SYSTEMS SECTION 5.4.1.6.1, DEGRADATION ASSESSMENT ISSUE DATE: 07/16/2024
=
Background===
By letter dated October 31, 2023, NuScale Power, LLC (NuScale or the applicant) submitted Part 2, Final Safety Analysis Report (FSAR), Revision 1, Chapter 5, Reactor Coolant System and Connecting Systems (Agencywide Documents Access and Management System Accession No. ML23304A338) and Chapter 16, Technical Specifications (ML23304A368), of the NuScale Standard Design Approval Application (SDAA) for its US460 standard plant design.
The applicant submitted the US460 plant SDAA in accordance with the requirements of Title 10 Code of Federal Regulations (10 CFR) Part 52, Licenses, Certifications, and Approvals for Nuclear Power Plants, Subpart E, Standard Design Approvals. The NRC staff has reviewed the information in Chapters 5 and 16 of the SDAA and has determined that additional information is required to complete its review.
Question 5.4.1.6.1-1 Regulatory Basis Appendix A of 10 CFR Part 50, General Design Criteria 32, Inspection of the reactor coolant pressure boundary, requires, in part, that the designs of all components that are part of the reactor coolant pressure boundary permit periodic inspection and testing of critical areas and features to assess their structural and leak tight integrity.
10 CFR 50.36, Technical Specifications, requires, in part, limiting conditions for operation and administrative controls for maintaining integrity of a fission product barrier.
10 CFR 50.55a, Codes and Standards, requires that throughout the service life of a PWR, Class 1 components must meet the requirements, except design and access provisions and PSI requirements, in Section XI, to the extent practical.
10 CFR 50.65, Requirements for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants, requires that licensees monitor the performance or condition of SSCs against goals to provide reasonable assurance that such SSCs are capable of fulfilling their intended functions.
Issue Section 16.1.1, Introduction to Technical Specifications, of the Standard Design Approval Application (SDAA) states, These revised GTS [Generic Technical Specifications] were developed consistent with the Improved Standard Technical Specification (ISTS) format and content typified in NUREG-1431 Standard Technical Specifications - Westinghouse Plants, Volume 1, Specifications, and Volume 2, Bases, Revision 5, dated September 2021
2 (ML21259A155 and ML21259A159, respectively), and NUREG-1432, [Standard Technical Specifications - Combustion Engineering Plants, Volume 1, Specifications, and Volume 2, Bases,] Revision 5, dated September 2021 (ML21258A421 and ML21258A424, respectively).
The ISTS include a plugging criterion in Section 5.5.8, Steam Generator (SG) Program, as part of maintaining structural and leakage integrity of the SG tubes in accordance with the ASME Code (10 CFR 50.55a). The criterion is defined in terms of a percentage of the nominal tube wall thickness and requires that tubes found by inservice inspection to contain flaws with a depth equal to or exceeding the plugging criterion must be plugged (or repaired if a licensee has an NRC-approved alternate repair criteria).
For the Design Certification Application (DCA), NuScale proposed a plugging criterion value of 40 percent of the nominal tube wall thickness, based on design factors considered to be bounding, and determined using a finite element analysis (FEA) in accordance with Regulatory Guide (RG) 1.121, Bases for Plugging Degraded PWR Steam Generator Tubes (ML003739366). In addition, the 40 percent plugging criterion was bracketed in the DCA GTS to ensure plant-specific factors would be addressed by Combined License (COL) applicants.
For the SDAA, NuScale proposed a value of 40 percent of nominal tube wall thickness as a tube plugging criterion in the GTS and Sections 5.4.1.4 and 5.4.1.6.1 of the Final Safety Analysis Report (FSAR); however this value is not bracketed in the GTS. During the SDA audit, NuScale stated that the 40 percent plugging criterion is intended to apply to all plants referencing the SDAA, providing only general qualitative statements for considering this value, lacking adequate justification. NuScale did not address the staffs questions about whether the FEA used to justify the value of 40 percent in the NuScale DCA had been updated for SDAA design changes, i.e.,
whether any other analyses have been performed to support the value of 40 percent, or how the updated analysis or any other analyses considered applicable loads, degradation mechanisms, degradation growth, nondestructive examination uncertainty, and tube ovality.
NuScale stated that the FEA performed for the US600 in the DCA has not been revised to reflect the US460 design in the SDAA. NuScale also stated that the geometry and tube material are the same as for the US600 but acknowledged that the different operating conditions for the US460 may affect the plugging criterion. However, because the SDAA proposes a different design for SG tube supports, the staff disagreed with NuScale that the geometry to be considered in the plugging criterion determination has not changed. In response, NuScale proposed using a bracketed value of [40%] in the GTS and deleting the value from FSAR Sections 5.4.1.4 and 5.4.1.6.1.
The staff considers NuScales proposal to be inadequate to make a finding on the plugging criterion. The staff acknowledges the benefit of bracketing the value, designating it as COL information that must be finalized by each COL applicant referencing the US460 SDAA.
Therefore, consistent with DSRS Chapter 16, the staff needs additional information as specified below to make a finding that the value proposed in the SDAA reasonably agrees with the expected operational capability of the plant.
3 Information Requested