ML23291A050
| ML23291A050 | |
| Person / Time | |
|---|---|
| Site: | 99902078 |
| Issue date: | 10/18/2023 |
| From: | NRC |
| To: | NRC/NRR/DNRL/NRLB |
| References | |
| Download: ML23291A050 (5) | |
Text
From:
Getachew Tesfaye Sent:
Wednesday, October 18, 2023 7:27 AM To:
Request for Additional Information Cc:
Taylor Lamb (She/Her); Mahmoud Jardaneh; Griffith, Thomas; Osborn, Jim; NuScale-SDA-720RAIsPEm Resource
Subject:
NuScale SDAA Section 9.1.2 - Request for Additional Information No. 004 (RAI-10085-R1)
Attachments:
SECTION 9.1.2 RAI-10085-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. ML222339A066).
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:
12 Mail Envelope Properties (BY5PR09MB5682896B9931554281A9552C8CD5A)
Subject:
NuScale SDAA Section 9.1.2 - Request for Additional Information No. 004 (RAI-10085-R1)
Sent Date:
10/18/2023 7:27:15 AM Received Date:
10/18/2023 7:27:20 AM From:
Getachew Tesfaye Created By:
Getachew.Tesfaye@nrc.gov Recipients:
"Taylor Lamb (She/Her)" <Taylor.Lamb@nrc.gov>
Tracking Status: None "Mahmoud Jardaneh" <Mahmoud.Jardaneh@nrc.gov>
Tracking Status: None "Griffith, Thomas" <tgriffith@nuscalepower.com>
Tracking Status: None "Osborn, Jim" <josborn@nuscalepower.com>
Tracking Status: None "NuScale-SDA-720RAIsPEm Resource"
<NuScale-SDA-720RAIsPEm.Resource@usnrc.onmicrosoft.com>
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 585 10/18/2023 7:27:20 AM SECTION 9.1.2 RAI-10085-R1-FINAL.pdf 156978 Options Priority:
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1 REQUEST FOR ADDITIONAL INFORMATION No. 004 (RAI-10085-R1)
BY THE OFFICE OF NUCLEAR REACTOR REGULATION NUSCALE STANDARD DESIGN APPROVAL APPLICATION DOCKET NO. 05200050 CHAPTER 9, AUXILIARY SYSTEMS SECTION 9.1.2, NEW AND SPENT FUEL STORAGE ISSUE DATE: 10/18/2023
Background
By letter dated December 15, 2022, NuScale Power, LLC (NuScale or the applicant),
submitted Part 2, Final Safety Analysis Report, (FSAR), Chapter 9, Auxiliary Systems, Revision 0, Agencywide Documents Access and Management System Accession No. ML22364A281of the NuScale Standard Design Approval Application (SDAA) for its US460 standard plant design. The applicant submitted US460 plant SDAA in accordance with 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 on the New and Spent Fuel Storage provided in Chapter 9 of the SDAA and determined that additional information is required to complete its review.
Question 9.1.2-1.1 Regulatory Basis GDC 61 requires that the fuel storage system be designed for adequate safety under anticipated operating and accident conditions. The system must be designed with (1) the capability for appropriate periodic inspection and testing of components important to safety, (2) suitable shielding for radiation protection, (3) appropriate containment, confinement, and filtering capability, (4) residual heat removal that reflects the safety importance of decay heat and other residual heat removal, and (5) the capability to prevent a significant reduction in fuel storage coolant inventory under accident conditions.
Issue As indicated in SECY-96-128 - Policy and Key Technical Issues Pertaining to the Westinghouse AP600 Standardized Passive Reactor Design, it is the staffs position that the site be capable of sustaining all design basis events with onsite equipment and supplies for the long term. After 7 days, replenishment of consumables such as diesel fuel oil from offsite suppliers can be credited. The equipment required after 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> need not be in automatic standby response mode but must be readily available for connection and be protected from natural phenomena including seismic events (per GDC 2).
In the SDAA design, the spent fuel pool and the ultimate heat sink form a combined body of water, when the water level is above the weir. In Section 9.1.2.1 the SDAA indicates that Section 9.1.3 describes the design of the systems for pool water cooling, purification, inventory control, and for pool leakage detection. Section 9.1.3 indicates that, as described in Section 9.2.5, the large quantity of water in the UHS provides a supply of water that takes weeks to evaporate to the level of the top of the weir wall.
2 The staff evaluated SDAA Section 9.2.5 and found that the UHS (which includes the SFP) does not require makeup for at least 30 days, but this analysis is based on nominal temperature and level. The application included a discussion of how the design addresses the first 72 hrs (at the most limiting conditions) with safety related equipment.
The SDAA does not address adequate cooling for the first 7 days, based on the most limiting conditions (TS limits), crediting onsite equipment.
The discussion of adequate cooling included in the SDAA represent the licensing basis of the design and should clearly identify the assumptions of the analysis.
Requested Information Based on its review of Chapter 9, the staff has determined that additional information is needed to satisfy the requirements of GDC 61. The staff requests that NuScale update Chapter 9 of the SDAA to include a discussion of adequate SFP cooling for the first 7 days, based on the most limiting conditions (TS limits).
Question 9.1.2-1.2 Regulatory Basis GDC 2 requires that nuclear power plant SSCs important to safety be designed to withstand the effects of such natural phenomena as earthquake, tornado, hurricane, flood, tsunami, and seiche without loss of capability to perform their safety functions. The design of these SSCs also must reflect appropriate combinations of the effects of accidents and natural phenomena.
GDC 61 requires that the fuel storage system be designed for adequate safety under anticipated operating and accident conditions. The system must be designed with (1) the capability for appropriate periodic inspection and testing of components important to safety, (2) suitable shielding for radiation protection, (3) appropriate containment, confinement, and filtering capability, (4) residual heat removal that reflects the safety importance of decay heat and other residual heat removal, and (5) the capability to prevent a significant reduction in fuel storage coolant inventory under accident conditions.
Issue NUREG 0800, Standard Review Plan, 9.1.2 New and Spent Fuel Storage indicates that prevention of significant reduction in spent fuel pool coolant inventory under accident conditions is by elimination of pool penetrations below coolant levels necessary for shielding and by anti-syphon devices and check valves on piping that could be a source of coolant draining; furthermore, gates and weirs should separate the spent fuel storage pool from adjacent fuel-handling areas.
SDAA Section 9.2.5 states that the pools that comprise the UHS are open to each other with a weir wall partially separating the SFP from the refueling pool area. The dry dock area is not considered in this volume; the dry dock gate is assumed closed and no credit is taken for the water volume. Section 9.1.2.2.1 identifies that the dry dock gate is design to Seismic Category II requirements, and that SDAA Section 9.1.3 addresses a failure of the dry dock gate due to an SSE. SDAA Section 9.1.3.3.5 states:
3 The dry dock gate, classified as Seismic Category II, is not ensured to function following a safe shutdown earthquake. An empty dry dock at the time of an accident and a safe shutdown earthquake is assumed to cause the gate to fail and open. For this condition, water in the UHS pools reenters the dry dock until an equalization level is reached and the UHS pool water level remains above the minimum pool level for cooling and shielding the SFAs.
Section 9.2.5 states that during an SSE, the failure of the dry dock gate with an empty dry dock results in lowering the water level in the UHS pools by approximately 8 feet.
In Audit Question 9.1.2-1 the staff identified that the applicants discussion of the gate failure did not address the impact of this level drop on the minimum required water level.
In its response to the audit question, the applicant indicated that the Seismic Category II dry dock gate is design to maintain structural integrity and water seal during SSE conditions and that a failure of the gates is considered to be a beyond design basis event.
The staff finds that the gate description in several sections of the SDAA is not consistent with the statements provided in the response to Audit Question 9.1.2-1.
Requested Information Based on its review of Chapter 9, the staff has determined that additional information is needed to satisfy the requirements of GDC 2 and 61. The staff requests that NuScale update all applicable sections of the SDAA to clearly indicate the design parameters of the dry dock gate and any impact (if applicable) on the minimum UHS water level.