ML25003A173
| ML25003A173 | |
| Person / Time | |
|---|---|
| Issue date: | 01/15/2025 |
| From: | NRC/NRR/DNRL/NRLB |
| To: | |
| References | |
| Download: ML25003A173 (1) | |
Text
Non-Proprietary Presentation to the ACRS Subcommittee Staff Review of NuScale SDAA Part 2, Chapter 16, Technical Specifications, and Part 4, US460 Generic Technical Specifications, Volume 1, Specifications, and Volume 2, Bases Revision 1 January 15th, 2025 (Open Session) 1
Non-Proprietary NuScale SDAA Part 2 Chapter 16 and Part 4 Review NuScale submitted Part 2 (FSAR), Chapter 16, Technical Specifications (TS), and Part 4, US460 Generic Technical Specifications (GTS), Revision 0, of the NuScale SDAA on December 29 and December 31, 2022, respectively, and Revision 1 on October 31, 2023 NRC regulatory audit of FSAR Chapter 16 and Part 4 was performed from March 2023 to August 2024, generating 68 audit issues All audit issues were resolved in the audit 52 audit issues resulted in NuScale submitting supplemental information to address questions raised during the audit No RAIs issued Staff completed review of FSAR Chapter 16 and Part 4 and issued an advanced safety evaluation to support today's ACRS Subcommittee meeting 2
Overview
Non-Proprietary NuScale SDAA Part 2 Chapter 16 and Part 4 Review Technical Reviewers
- Craig Harbuck, Lead Reviewer, NRR/DSS/STSB
- Steve Smith, NRR/DSS/STSB
- Clint Ashley, NRR/DSS/STSB
- Josh Wilson, NRR/DSS/STSB Project Managers
- Alina Schiller, PM, NRR/DNRL/NRLB
- Getachew Tesfaye, Lead PM, NRR/DNRL/NRLB 3
Contributors
Non-Proprietary NuScale SDAA Part 2 Chapter 16 and Part 4 Review Chapter 1.0 Use and Application Chapter 2.0 Safety Limits (SLs)
Chapter 3.0 Limiting Conditions for Operation (LCOs) and Surveillance Requirements (SRs)
Chapter 4.0 Design Features Chapter 5.0 Administrative Controls 4
Part 4, GTS Volume 1, Specifications Part 4, GTS Volume 2, Bases Chapter B 2.0 SLs Chapter B 3.0 LCOs and SRs Part 2, FSAR Chapter 16, TS Section 16.1 Technical Specifications TR-101310-NP, Revision 0, US460 Standard Design Approval Technical Specifications Development
Non-Proprietary NuScale SDAA Part 2 Chapter 16 and Part 4 Review DCA Module is shutdown (keff < 0.99)
All indicated reactor coolant temperatures < 420 °F (minimum temperature for criticality) 5 Significant Changes from DCA to SDA GTS Chapter 1 Definition of MODE 3 - Safe Shutdown SDA Module is shutdown (keff < 0.99)
All indicated reactor coolant temperatures < 345 °F (minimum temperature for criticality)
OR PASSIVELY COOLED Any indicated reactor coolant temperature may be 345 °F
Non-Proprietary NuScale SDAA Part 2 Chapter 16 and Part 4 Review Industry Technical Specification Task Force (TSTF) traveler 554, Rev. 1, approved on December 18, 2020 (ML20324A083) and incorporated into Revision 5 of NUREG-1431, Standard TS Westinghouse Plants, changed the definition - as shown:
LEAKAGE (except primary to secondary LEAKAGE) through a nonisolable fault in an RCS component body, pipe wall, or vessel wall. LEAKAGE past seals, packing, and gaskets is not pressure boundary LEAKAGE.
6 Significant Changes from DCA to SDA GTS Chapter 1 (contd)
Definition of Reactor Coolant System (RCS) pressure boundary LEAKAGE
Non-Proprietary NuScale SDAA Part 2 Chapter 16 and Part 4 Review DCA US600 Critical Heat Flux Ratio Correlation Safety Limit NSP2
[1.17]
NSP4
[1.21]
Extended Hench-Levy [1.06]
7 Significant Changes from DCA to SDA GTS Chapter 2 Reactor Core Safety Limits SDAA US460 Critical Heat Flux Ratio Correlation Safety Limit NSP4
[1.21]
NSPN-1
[1.15]
Pressurizer Pressure 2285 psia Pressurizer Pressure 2420 psia Reactor Coolant System Pressure Safety Limit Peak fuel centerline temperature { 4901 - (1.37E-3 x Burnup, MWD/MTU) } °F.
Non-Proprietary NuScale SDAA Part 2 Chapter 16 and Part 4 Review DCA LCOs Omitted in SDAA 3.3.5 Remote Shutdown Station Indication-only monitors in I&C equipment rooms No Type-A PAM variables 3.7.3 In-Containment Secondary Piping Leakage Leak-before-break (LBB) methods not used High energy pipe break exclusion criteria met (consistent with BTP 3-4) 8 Significant Changes from DCA to SDA GTS Chapter 3 LCO Subsection Omissions and Additions Additional LCOs in SDAA 3.5.4 Emergency Core Cooling System Supplemental Boron (ECCS ESB) 3.3.3 Function 1 ECCS hour post reactor trip actuation timer; SR 3.3.3.3 3.6.3 Containment Closure Mode 3 and Passively Cooled; Mode 4 before unseating of upper module assembly from lower containment vessel flange Maintain reactor coolant inventory to ensure adequate core cooling 3.6.4 Passive Autocatalytic Recombiner Meets 10 CFR 50.44(d)
Non-Proprietary NuScale SDAA Part 2 Chapter 16 and Part 4 Review DCA Revision 5 22.a High Containment Water Level 23.a Low RCS Pressure Three reactor vent valves (RVVs)
Two reactor recirculation valves (RRVs)
Inadvertent Actuation Block (IAB) on each valve delays valve opening on ECCS actuation signal until RPV-CNV pressure difference below unblock setting 9
Significant Changes from DCA to SDA GTS Chapter 3 Instrument Functions that Initiate ECCS SDAA Revision 2 (draft) 23.a Low RPV Riser Level (if above 500 °F) 24.a Low Low RPV Riser Level 25.h Low AC Voltage to EDAS Battery Chargers Two RVVs Two RRVs No IAB on RVVs; EDAS DC power ensures ECCS hold function until ECCS actuation signal or reactor trip occurs RRV opening delayed by IAB
Non-Proprietary NuScale SDAA Part 2 Chapter 16 and Part 4 Review DCA Revision 5 7.b High Pressurizer Pressure 13.b High Narrow Range (NR) RCS THOT 16.b High Main Steam Pressure 25.b Low AC Voltage to ELVS Battery Chargers 10 Significant Changes from DCA to SDA GTS Chapter 3 Instrument Functions that Initiate DHRS SDAA Revision 2 (draft) 7.b High Pressurizer Pressure 11.c Low Pressurizer Level 13.b High Narrow Range (NR) RCS THOT 17.b High Main Steam Pressure 22.c High NR Containment Pressure 25.c Low AC Voltage to EDAS Battery Chargers 26.c High Under-the-Bioshield Temperature Low Pressurizer Level Steam Generator Tube Failure High Under-the-Bioshield Temperature High-energy line breaks under the bioshield High NR Containment Pressure Loss of containment vacuum Feedwater System pipe break Inadvertent RVV opening
Non-Proprietary NuScale SDAA Part 2 Chapter 16 and Part 4 Review 3.1.9 Boron Dilution Control
- Added configuration constraints on the Module Heatup System (MHS) to ensure the MHS is never aligned to the CVCS injection line of more than one NuScale Power Module 3.3.1 MPS Instrumentation - accommodating control rod coupling and uncoupling
- Mode 3 Applicability of selected reactor trip and DWSI instrument functions
- when capable of withdrawal of more than one control rod assembly (CRA) 5.5.4 Steam Generator (SG) Program
- 72 effective full power month inspection interval for all SG tubes
- RCS pressure is on the outside of the SG tubes, so the tubes are susceptible primarily to collapse or buckling rather than burst
- Tube plugging criterion of 40 percent through-wall thickness is bracketed as part of COL Item 16.1-1 11 Significant Changes from DCA to SDA GTS Chapters 3 and 5 SDA GTS Improvements Over DCA GTS
Non-Proprietary NuScale SDAA Part 2 Chapter 16 and Part 4 Review NuScale US460 Standard Design GTS and Bases are acceptable because they comply with
- 10 CFR 50.34, Contents of Applications; Technical Information;
- 10 CFR 50.36, Technical Specifications; and
- 10 CFR 50.36a, Technical Specifications on Effluents from Nuclear Power Reactors.
12 Conclusion
Non-Proprietary Presentation to the ACRS Subcommittee Staff Review of NuScales Loss-of-Coolant Accident (LOCA)
Evaluation Model Topical Report (TR 0516-49422-P)
January 15th, 2025 (Open Session) 13
Non-Proprietary Technical Reviewers
- Dr. Shanlai Lu, Lead, NRR
- Dr. Sean Piela, NRR
- Dr. Dong Zheng, NRR
- Mr. Carl Thurston, NRR
- Mr. Ryan Nolan, NRR
- Dr. Syed Haider, NRR
- Dr. Joshua Kaizer, NRR Project Managers
- Getachew Tesfaye, Lead PM, NRR 14 Contributors NuScale LOCA Topical Report Review
Non-Proprietary NuScale LOCA Topical Report Review NuScale submitted Loss-of-Coolant Accident (LOCA) Evaluation Model Topical Report (TR 0516-49422-P), rev. 3, on January 5, 2023. The topical report was formally accepted for review on July 31, 2023 NRC conducted an audit of the topical report from March 2023 to August 31, 2024 57 audit issues were generated, resulting in supplemental information being submitted by NuScale For items not resolved during the audit, 4 RAIs were generated All audit items and RAIs are resolved closed Staff completed review of the LOCA Topical report and issued an advanced safety evaluation to support today's ACRS Subcommittee meeting 15 Overview
Non-Proprietary NRC staff completed the review of LOSS-OF-COOLANT ACCIDENT EVALUATION MODEL topical report. Subject to the closure of the open and confirmatory items noted in the draft SER, and, with eleven limitations and conditions identified, the NRC staff finds the following:
The proposed LOCA analysis methodology is acceptable for meeting the requirements of 10 CFR 50.46 and the associated portions of Appendix K* evaluated in this TR, for evaluation of the ECCS performance in the NuScale NPM-20 for design-basis LOCAs. The proposed LOCA EM is conservative to determine CHF and collapsed liquid level above the reactor core.
The proposed containment response analysis methodology is conservative and acceptable.
The proposed NRELAP5 computer code and the NPM-20 model are acceptable to evaluate the MCHFR for IORV and LOCA events.
- Note that certain portions of Appendix K require exemptions as specified by limitation/condition (post-CHF phenomena).
16 Conclusion NuScale LOCA Topical Report Review