ML25293A459
| ML25293A459 | |
| Person / Time | |
|---|---|
| Site: | Kemmerer File:TerraPower icon.png |
| Issue date: | 10/20/2025 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| Download: ML25293A459 (1) | |
Text
NRC Review of Kemmerer Unit 1 Construction Permit Application ACRS Subcommittee Meeting October 22-23, 2025
NRC Opening Remarks Joshua Borromeo, Branch Chief, NRR/DANU/UAL1 2
Agenda October 21, 2025
- Review of items from previous meeting
- Control of heat generation October 22, 2025
- Safety-significant SSC design requirements
- Control of heat removal
- Radionuclide retention October 23, 2025
- Radionuclide retention (fuel handling SSCs)
- Cross-cutting systems
- R&D items 3
Review of Items from Previous Meeting Reed Anzalone, Senior Nuclear Engineer, NRR/DANU/UTB2 4
Questions from previous meeting
- Questions related to specific SSCs will be discussed in relevant slides over the course of the meeting
- Example: Fuel and core design slides will discuss relevant core parameters
- This presentation will review subjects related to PRA and LMP 5
PRA supports LMP and Issuance of a Construction Permit
- The CP PRA is acceptable for supporting the preliminary KU1 safety analysis using the LMP process at the CP stage.
6
Accidents considered under LMP
- AOOs, DBEs, and BDBEs are identified solely based on the LBE frequency, which is derived from PRA event sequence frequencies
- DBAs are developed based on limiting DBEs and AOOs/BDBEs whose uncertainty bands lie in the DBE region, but have no frequency
- One additional DBA was analyzed to ensure seismic reactivity insertions were appropriately captured at the CP
- USO identified OQEs for consideration in integrated risk assessment and evaluation of cliff edge effects 7
Example: DHP-LOOP Family 8
DHP-LOOP-BL DHP-LOOP-1 DHP-LOOP-2 DHP-LOOP-3 DHP-LOOP-4 LOOP with non-passive IAC LOOP with passive IAC LOOP with RAC LOOP with scram motor drive-in LOOP with AST 1.00E-07 1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00 DHP-LOOP Family Non-passive IAC fails Passive IAC fails Gravity scram fails, motor drive-in succeeds Scram signal fails, AST succeeds, gravity scram succeeds AOO DBE BDBE
Example: RFH-FDPI Family 9
Role of major accident under LMP
- 10 CFR 50.34(a)(1)(ii)(D) requires evaluation of a fission product release from the core into containment and states [s]pecial attention must be directed to plant design features intended to mitigate the radiological consequences of accidents.
- Requirement to select a bounding event was to address the concern that safety analysis did not explicitly consider all potential failures and hazards
- LMP directly addresses the underlying purpose of the major accident by comprehensively evaluating events that could result in releases and the impacts of preventive and mitigative SSCs but identification of a major accident is required by regulation
- Selected a bounding in-vessel DBA to meet requirements of 10 CFR 50.34(a)(1)(ii)(D) and for consistency with historical major accident analyses which use conservative assumptions 10
How this meeting relates to last meeting
- Last meeting covered implementation of the LMP process from LBE identification through SSC safety classification, the supporting safety analyses, and the DID adequacy evaluation
- This meeting will cover
- Characterization of design basis hazard levels (DBHLs)
- Design requirements and special treatments applied based on safety classification, risk significance, and DBHLs
- Detailed information on the design of SSCs with a focus on how that design supports performance of safety functions and conformance with PDCs
- SSCs grouped based on which FSF they primarily support 11
Acronyms 12 10 CFR - Title 10 of the Code of Federal Regulations ACRS - Advisory Committee on Reactor Safeguards AOO - Anticipated Operational Occurrence AST - Alternative Shunt Trip BDBE - Beyond Design Basis Event CP - Construction Permit DANU - Division of Advanced Reactors and Non-Power Production and Utilization Facilities DBA - Design Basis Accident DBE - Design Basis Event DBHL - Design Basis Hazard Level PDC - Principal Design Criteria PIC - Pool Immersion Cell PRA - Probabilistic Risk Assessment QHO - Quantitative Health Objective RAC - Reactor Air Cooling System RG - Regulatory Guide R&D - Research and Development SSC - Structures, Systems, and Components TEDE - Total Effective Dose Equivalent UAL1 - Advanced Reactor Licensing Branch 1 UTB2 - Advanced Reactor Technical Branch 2 YR - Year EAB - Exclusion Area Boundary EPA - Environmental Protection Agency F-C - Frequency-Consequence FSF - Fundamental Safety Function IAC - Intermediate Air Cooling System KU1 - Kemmerer Unit 1 LBE - Licensing Basis Event LMP - Licensing Modernization Project LOOP - Loss of Offsite Power NRC - Nuclear Regulatory Commission NRR - Office of Nuclear Reactor Regulation PAG - Protective Action Guide