ML25293A454
| ML25293A454 | |
| Person / Time | |
|---|---|
| Site: | Kemmerer File:TerraPower icon.png |
| Issue date: | 10/20/2025 |
| From: | Reed Anzalone, Steve Jones, Radel T Advisory Committee on Reactor Safeguards, NRC/NRR/DANU |
| To: | |
| References | |
| Download: ML25293A454 (1) | |
Text
NRC Review of Kemmerer Unit 1 Construction Permit Application Radionuclide Retention in Fuel Handling Systems Steven Jones, Tracy Radel, and Reed Anzalone NRR/DANU/UTB2&3 ACRS Subcommittee Meeting October 22-23, 2025
Topics
- Overview
- Safety-Significant Functions
- Design Standards and Hazard Protection
- Fuel Handling Licensing Basis Event Groups
- Fuel Handling Accidents
- Excess Sodium/Water Reactions
- Loss of Cooling
- Events without Release
- Sample Analysis
- EVHM Fuel Handling Accident 2
Fuel Handling System Overview
- Ex-Vessel Fuel Handling System (FHE):
- Core assembly (includes fuel) receipt and preconditioning
- Transfer to and safe ex-vessel storage in a sodium environment (i.e., cooling, criticality prevention, confinement, shielding, purification, and protection from external and internal hazards)
- Transfer to and from reactor vessel
- Removal of test/demonstration pins and preparation for transport/analysis
- Preparation for transfer to a water environment for long-term storage (remove fuel from sodium-filled core assembly pot (CAP))
3 PSAR Figure 7.3.2-1: Ex-Vessel Handling Machine Primary Components
Fuel Handling System Overview (Cont)
- In-Vessel Fuel Handling System (FHI):
- Moving core assemblies between planned core, in-vessel storage, and fuel transfer lift (FTL) locations within the reactor vessel sodium pool
- Elevating or lowering core assemblies in the FTL for transfer to or from the EVHM
- Pool Fuel Handling System (FHP):
- Removal of residual sodium by steam oxidation (or placement of failed fuel in storage canister) in pool immersion cell (PIC) and lowering into pool water environment
- Maintain safe pool storage (i.e., cooling, criticality prevention, confinement, shielding, purification, and protection from external and internal hazards) 4 Figure 7.3.3-1 FHI General Arrangement within Reactor Vessel
Radionuclide Retention Functions
- Ex-Vessel Storage Tank (EVST) - (SR) - DL3-RR4
- Ex-Vessel Handling Machine (EVHM) and Bottom-Loading Transfer Cask (BLTC) - (SR) - DL3-RR3/3a and DL3-RR5/5a
- Isolated
- Transfer barrier, which adds fueling floor valve (FFV) and vessel (with adapter for RV and EVST)
- Failed Fuel Canister (FFC) - (SR) - DL3-RR8
- FHI seal to RV Head - (SR) - DL3-RR1f
- *PIC - (NSRST) - DL2-RR2 - Importance and safety classification to be reassessed for OL Stage 5
Other Safety Significant Functions
- Heat Removal - Protection of Fuel Cladding Barrier
- EVST Passive Heat Removal - (SR) - DL3-HR7 - Redesigned during CPA review to include natural circulation air cooling
- PRC Passive Heat Removal - (SR) - DL3-HR9
- EVHM Passive Heat Removal - (SR) - DL3-HR6
- BLTC Passive Heat Removal - (SR) - DL3-HR8
- FHP Passive Heat Removal - (SR) - DL3-HR10 - Includes heat removal from spent fuel racks and PIC
- FFC Passive Heat Removal - (SR) - DL3-HR13
- Fuel Pool Emergency Makeup - (NSRST) - DL4-HR4 (Post 7 days)
- Reactivity Control - Prevention of Challenge to Cladding Barrier
- Criticality Prevention in EVST and Spent Fuel Pool - (SR) - Accomplished by Structural Support Function
- Criticality Prevention in New Assembly Preconditioning Station (NAPS) - NSRST as Preventive Control
- Support Functions (SR) and Temporary Support Functions (NSRST) 6
Design Standards and Hazard Protection
- EVST, including vessel, rotating carousel, and support structure
- EVHM and BLTC shielded cask assemblies
- FFC, FFV, and vessel adapters (RV and EVST)
- Pin removal cell sodium tank
- Temporary Support Function for EVHM and BLTC
- EVHM and BLTC transporters and hoists designed to ASME NOG-1
- NSRST with seismic qualification to retain function
- Hazard Protection
- Most Major components located in Fuel Handling Building Substructure
- EVHM and BLTC protection to be evaluated at OL stage 7
Fuel Handling Accidents Drop or Mechanical Damage
- NSRST Temporary Support Function /
Interlocks / Periodic Refueling Reduce Damage Frequency (PDC 2 & 4 - Hazards)
Transfer Barrier Function
- SR Barrier to Radionuclide Release (PDC 61 - Containment)
Rapid Release to Environment
- Source Term Limits Consequences 8
Excess Sodium/Water Reaction 9
Excess Sodium Present
Sodium/Water Prevention/Mitigation)
Transfer Barrier Function
FHB Filtered Release to Environment
- Applicant Re-evaluating ESWR Frequency, Consequence, and Barrier Configuration for OL Stage
Loss of Cooling (EVHM and BLTC) 10 Loss of Active Cooling
- NST Active Cooling Capacity Adequate for Early Fuel Transfer (PDC 61); Detection for Loss of Active Heat Removal (PDC 63)
Passive Cooling Function
- SR Passive Cooling Maintains Cladding Barrier with Adequate Decay (PDC 61)
Shielded Cask Assembly Barrier
- SR Containment Independent of Passive Cooling (PDC 61)
Events without Release
- EVST Loss of Cooling Event
- Active and Passive Cooling Systems with Large Heat Capacity (PDC 61)
- Design features to detect and prevent loss of cooling under accident conditions (PDC 61 and 63)
- Spent Fuel Pool (SFP) Loss of Cooling Event
- Active Cooling System, Passive Cooling, and Very Large Heat Capacity (PDC 61)
- Design features to detect loss of cooling, prevent loss of coolant under accident conditions, and provide makeup (PDC 61 and 63) 11
EVHM Fuel Handling Accident 12
Acronyms 13 ACRS - Advisory Committee on Reactor Safeguards ASME - American Society of Mechanical Engineers BLTC - Bottom Loading Transfer Cask CAP - Core Assembly Pot CATT - Core Assembly Transfer Tube CFR - Code of Federal Regulations DBE - Design Basis Event DID - Defense In Depth EAB - Exclusion Area Boundary ESWR - Excess Sodium/Water Reaction EVHM - Ex-Vessel Handling Machine EVST - Ex-Vessel Storage Tank F-C - Frequency-Consequence FFC - Failed Fuel Canister FFV - Fueling Floor Valve FHE - Ex-Vessel Fuel Handling System OL - Operating License PDC - Principal Design Criterion PIC - Pool Immersion Cell PRC - Pin Removal Cell PSF - PRA Safety Functions PSAR - Preliminary Safety Analysis Report RG - Regulatory Guide RSF - Required Safety Functions RV - Reactor Vessel SE - Safety Evaluation SFP - Spent Fuel Pool SR - Safety Related SSC - Structures, Systems, and Components TEDE - Total Effective Dose Equivalent USO - US SFR Owner FHI - In-Vessel Fuel Handling System FHP - Pool Fuel Handling System FTL - Fuel Transfer Lift KU1 - Kemmerer Unit 1 LDA - Lead Demonstration Assembly LTA - Lead Test Assembly NAPS - New Assembly Preconditioning Station NOG - Nuclear Overhead Gantry NRC - Nuclear Regulatory Commission NST - Non-safety-related with no Special Treatment NRR - Office of Nuclear Reactor Regulation NSRST - Non-safety-related with Special Treatment