ML25023A095
| ML25023A095 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 01/23/2025 |
| From: | Southern Nuclear Operating Co |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| L-2024-LRM-0139 | |
| Download: ML25023A095 (1) | |
Text
February 6, 2025 Vogtle Units 1 & 2 Pre-Submittal Meeting: Alternative Source Term License Amendment Request (RG 1.183 Revision 1)
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2 Overview
- Purpose
- Submittal Scope
- License Amendment Request (LAR) Overview
- Preliminary Dose Analyses Summary
- LAR Table of Contents
- Requested Review Schedule
- Comments and Discussion
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3 Purpose Communicate to the staff Southern Nuclear Companys (SNC) intent to submit for approval, implementation of the Alternative Source Term Methodology (RG - 1.183 Revision 1) for Vogtle 1&2.
Discuss the following:
- An overview of the VEGP Units 1 and 2 AST LAR contents
- SNC schedule for LAR submittal
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4 Submittal Scope
- SNC will submit for NRC approval descriptions of the full complement of dose consequence analyses specified by RG 1.183 Revision 1
- Vogtle 1 & 2 adoption of Revision 0 of RG 1.183 approved by NRC in 2023
- Adopting RG 1.183 Revision 1 is necessary to support strategic objectives (e.g. higher burn-up)
- Associated Technical Specification Bases and FSAR markups (no Tech Spec changes)
- RADTRAD 3.10 input and output files for all events to assist in NRC review (non-docketed reviewer aid)
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5 License Amendment Request Overview-AST Technical Evaluations
- Technical Evaluations for AST:
- Atmospheric Dispersion Factors
>> Meteorological data used is same as in the approved analyses of record
>> Same onsite release-receptor pairs that were approved for initial AST IAW RG 1.183 R0
- Core Inventory and Isotopes Considered
>> Updated core inventory corresponding to 68 GWD/MTU; bounds 62 GWD/MTU core inventory
>> Evaluation and selection of dose-significant isotopes for RG 1.183 Rev. 1 source term
- Transient fission gas release for non-LOCAs
>> Rod ejection TFGR using Rev. 1 method and bounding enthalpy rise
>> No TFGR for other non-LOCAs
- Maximum Hypothetical Accident Loss of Coolant Accident (MHA LOCA)
>> Sump pH re-evaluated with no credit for bases formed from the release of Cs
>> Adjusted NUREG/CR-6189 10th percentile correlations for natural deposition in containment
>> Containment spray duration credit extended from 2 to 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />; same DF limits apply
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6 License Amendment Request Overview-AST Technical Evaluations
- Technical Evaluations for AST:
- Fuel Handling Accident (FHA)
>> RG 1.183 Rev. 1 App B, 2-phase release method
>> Decay time reduced from 70 hours8.101852e-4 days <br />0.0194 hours <br />1.157407e-4 weeks <br />2.6635e-5 months <br /> to 60 hours6.944444e-4 days <br />0.0167 hours <br />9.920635e-5 weeks <br />2.283e-5 months <br />
- Control Rod Ejection Accident (CREA)
>> Use of updated core inventory with Table 4 gap fractions plus bounding TFGR
- Locked Rotor Accident (LRA)
>> Use of updated core inventory and Table 4 gap fractions
- Main Steam Line Break Accident (MSLB)
>> Minimal changes from RG 1.183 Rev. 0 analysis (no fuel failure)
- Steam Generator Tube Rupture Accident (SGTR)
>> Minimal changes from RG 1.183 Rev. 0 analysis (no fuel failure)
- Environmental Qualification
>> Evaluated consistent with the RG 1.183 Rev. 0 submittal
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7 License Amendment Request Overview (contd)
- Key analysis specific descriptions / inputs included in enclosure attachments:
- Control Room Emergency Filtration System (CREFS) Modeling Specifics
>> No changes in CREFS modeling from Rev. 0 submittal (including unfiltered in-leakage)
- Analysis Specific Inputs
>> Activity releases
>> X/Q values
>> RCS / SG masses and volumes (where applicable)
>> Primary to secondary flows, atmospheric flows, leak rates, etc. (where applicable)
- RG-1.183 Rev. 1 Conformance Tables
- Addresses all positions in RG 1.183 Rev. 1 (incl DID and safety margins) like Rev. 0 submittal
- No exceptions or deviations; no retention of Rev. 0 elements
- Input Comparison Tables
- Rev. 0 submittal values, Rev. 1 submittal values, no change or change with comments
- Changes from Rev. 0 submittal to CLB will be described with comments
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8 Preliminary Dose Analyses Summary REM (TEDE)
Accident EAB LPZ CR Acceptance Criteria (EAB/LPZ/CR)
MHA LOCA 4.4 7.1 3.0 25/25/5 FHA 0.4 0.3 1.5 6.3/6.3/5 CREA*
3.7 4.5 1.9 6.3/6.3/5 LRA
<0.1
<0.1 0.3 2.5/2.5/5 MSLB Concurrent 0.3 0.2 0.3 2.5/2.5/5 MSLB Pre-accident 0.3 0.1 0.2 25/25/5 SGTR Concurrent 1.1 0.6 0.5 2.5/2.5/5 SGTR Pre-accident 1.8 1.0 1.3 25/25/5
- Containment release limiting for offsite. Secondary release limiting for CR.
All doses demonstrate margin to limits
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9 Preliminary Dose Analyses Summary Accident Discussion MHA LOCA Limiting analysis for dose (EAB/LPZ/CR)
- 1. Utilizes Rev. 1 App B guidance for two phase release
- 2. No credit for filtration, containment hatch closures, or elevated Plant Vent CREA
- 1. Containment release limiting for offsite
- 2. Secondary release limiting for onsite
- 3. Transient fission gas release added to steady state gap release LRA Not a significant contributor to dose MSLB No fuel failure; not a significant contributor to dose SGTR No fuel failure
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10 LAR Table of Contents Enclosure 1.0 Summary Description 2.0 Detailed Description 3.0 Technical Evaluation 4.0 Regulatory Evaluation 5.0 Environmental Consideration 6.0 References
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11 LAR Table of Contents Attachments
- 1. FSAR Markups
- 2. TS Bases Markups
- 3. RG 1.183 Rev. 1 Conformance Tables
- 5. Fuel Handling Accident (FHA)
- 6. Main Steam Line Break (MSLB)
- 7. Steam Generator Tube Rupture (SGTR)
- 8. Control Rod Ejection Accident (CREA)
- 9. Locked Rotor Accident (LRA)
- 10. Input Values Comparison Tables
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12 Submittal and Requested Review Schedule SNC Submit LAR May 2025 NRC Acceptance
& Review (Requested) May 2025 - June 2026 LAR Approval June 2026
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13 Comments and Discussion
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