ML19168A159
| ML19168A159 | |
| Person / Time | |
|---|---|
| Site: | FitzPatrick  |
| Issue date: | 06/17/2019 |
| From: | Exelon Generation Co |
| To: | Office of Nuclear Reactor Regulation |
| Parker C | |
| References | |
| Download: ML19168A159 (37) | |
Text
JAF BWR MSIV Leakage Optimization NRC Pre-Submittal Meeting June 20, 2019
Agenda
- Introductions
- Meeting Objectives
- Project Purpose / Background Information
- Scope of Technical Specification Changes
- Approach of the LAR Submittal
- Detailed Technical Review
- Overview of Licensing Schedule and Outage Needs
- Summary and Wrap-up 1
Introductions
Project Manager John Massari Project Technical Lead Shane Gardner Licensing Lead Christian Williams Site Technical Lead Katherine Leaveck 2
Meeting Objectives
- Present information to NRC to enable a clear understanding of the overall project and proposed site-specific License Amendment Request (LAR) submittal
- Technical Specification (TS) Changes
- Analysis Approach
- Full Scope Alternative Source Term (AST) Scope
- Obtain feedback from the NRC on the proposed LAR to ensure high quality submittal and minimize the need for future RAIs
- Mutual understanding of the proposed schedule and corresponding outage need date in order to ensure adequate NRC resource availability 3
Benchmark of U.S. Fleet 4
Project Purpose / Background Information Optimize AST LOCA analysis to increase MSIV local leak rate testing (LLRT) limits
- Reduce outage dose and increase safety
- Reduce MSIV maintenance costs
- Requesting approval to expand to full implementation
- Based on LOCA analysis only
- Supporting analyses and changes
- Drawdown analysis
- Standby Liquid Control evaluation and TS changes
- Definition of Dose Equivalent Iodine change
- SGT and CR filter efficiency TS changes
- Appendix J exemption to separate MSIV leakage from La 5
Approach of the LAR Submittal
- Evaluate the change impacts due to MSIV leakage rate change in accordance with Exelon configuration change process. Planned AST LOCA dose analysis requires prior NRC review:
- Existing RG 1.3 methodology replaced with RG 1.183 AST
- Provide information directly in support of the proposed Technical Specification Changes
- Approach to the full scope AST implementation technical evaluation
- AST LOCA analysis utilizing a revised core inventory for future implementation of an increased core average exposure (CAVEX)
- New drawdown analysis
- Post-LOCA pH analysis to address suppression pool pH
- Environmental Qualification evaluation for Standby Liquid Control (SLC) and deletion of Main Steam Leakage Collection (MSLC)
- New Control Room X/Q values for ground-level MSIV release
- Plant parameter input changes: MSIV Leakage, filter efficiencies.
6
Detailed Technical Review: Overview of LOCA Dose Analysis
- Current analysis based on RG 1.3
- Dose pathways
- Combined Containment & MSIV leakage (all leakage via stack)
- ESF leakage (all leakage via stack)
- Direct Shine
- Proposed analysis based on RG 1.183 & RIS 2006-04
- Dose pathways
- Containment leakage (ground-level during drawdown, stack thereafter)
- ESF leakage (ground-level during drawdown, stack thereafter)
- MSIV leakage (ground-level)
- Direct Shine
- Notable plant input changes
- MSIV leak rate increase
- SGT and CR filter efficiency increased
- More conservative core radionuclide inventory for future implementation 7
Detailed Technical Review: MSL Aerosol Deposition
- Uses 20-group model previously approved at Clinton (ML052570461), Limerick (ML062210214), and LaSalle (ML101750625)
- Model is based on AEB 98-03 using JAF-specific inputs, which is acceptable per RIS 2006-04. Assumptions and justifications for applicability to the revised analysis provided in accordance with RIS 2006-04
- The settling velocity is a randomly sampled range of the three (3) critical aerosol parameters, density/weight (logarithmically distributed), diameter/size (uniformly distributed), and shape (uniformly distributed); and three (3) constants; gravitational acceleration, Cunningham slip factor, and viscosity.
- A distribution of removal factors are calculated using the typical AEB 98-03 formulations and are combined statistically to determine a net removal fraction. This accounts for a range of aerosol particle parameters and also accounts for change in the aerosol characteristics as the particles transport through the MSL 8
Detailed Technical Review: MSL Aerosol Deposition Cont.
(NMP2 Example) 100.00%
90.00%
80.00%
70.00%
Particles are Cumulative Probability 60.00%
shifting from 50.00%
larger/heavier to 40.00% smaller/lighter 30.00%
20.00%
10.00%
0.00%
0.00E+00 5.00E-04 1.00E-03 1.50E-03 2.00E-03 2.50E-03 3.00E-03 3.50E-03 4.00E-03 Settling Velocity (m/s) 1st Node 2nd Node Exit 9
Detailed Technical Review: Other Analyses & Changes
- Drawdown Analysis
- Required for TSTF-551 & RG 1.183 Appendix A
- GOTHIC based analysis; 4 external environment cases for conservatism
- Follows Quad Cities LAR as precedent
- Result: 20 minute drawdown time in dose model
- Post-LOCA pH Analysis
- Methodology is based on NUREG/CR-5950
- Maximum injection duration of SLC buffer (< 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />) before 71 hours8.217593e-4 days <br />0.0197 hours <br />1.173942e-4 weeks <br />2.70155e-5 months <br />
- Result: Minimum pH: 8.1 at 30 days
- SLC Evaluation
- Guidance on the Assessment of a BWR SLC system for pH Control, Dated February 12, 2004, (ADAMS Accession No. ML040640364)
- All requirements met, including 50.49 Environmental Qualification
- An attachment detailing this evaluation will be provided in the LAR
- SGT and CR Filter Efficiency Changes
- TS change to lower charcoal penetration to 1.5%
- Filter efficiencies credited in AST dose analysis increased 10
Detailed Technical Review: Other Analyses & Changes
- Leakage Collection System Removal EQ Evaluation
- Change results in a post-LOCA source term in the TB
- LOCA dose in the TB not previously evaluated
- Analysis is performed to determine radiological environment using TID Methodology
- EQ Evaluation is performed to evaluate SR equipment for inclusion
- EQ documentation will be updated to reflect the new evaluation and disposition of equipment 11
Overview of Licensing Schedule and Outage Needs
- Goal is to implement at first outage opportunity
- Submit LAR according to schedule outlined below
- Request NRC review and approval in 12 months Plant LAR Submittal NRC Approval First Opportunity Fitzpatrick June 2019 July 2020 September 2020 12
Summary and Wrap-up Summary
- Reduce outage dose and increase safety
- Reduce number of reportable MSIV LLRT events
- Reduce MSIV maintenance costs
- Extend effective MSIV service life
- A revised AST LOCA dose analysis is planned that supports increased MSIV leakage while maintaining margin by:
- Beneficially optimizing Control Room dose while retaining substantial margin to the limits
- Adjusting inputs and elements of the method to provide additional margin in some cases and extract margins in other cases
- Aggregate effect of all revisions maintains reasonable conservatism Recap of Actions 13
Fitzpatrick Full Scope AST DISCUSSION 14
Fitzpatrick Full Scope AST Backup Slides 15
Scope of Technical Specification Changes Preliminary MSIV leakage rate 200 100 16
Scope of Technical Specification Changes Continued Exemption to Appendix J to remove MSIV leakage from La requirement.
17
Scope of Technical Specification Changes Continued Deletion of Main Steam Leakage Collection System. No longer credited in safety analysis.
18
Scope of Technical Specification Changes Continued Ventilation Filter Testing Program penetration requirement reduction 19
Scope of Technical Specification Changes Continued Standby Liquid Control System mode requirements 20
Scope of Technical Specification Changes Continued TSTF-551 associated modifications 21
Scope of Technical Specification Changes Continued Dose Equivalent I-131 definition update for AST 22
Detailed Technical Review: Overview of Revised Core Inventory
- Revised core radionuclide inventory
- Increases the range of Core AVerage EXposure (CAVEX) and enrichment previously evaluated
- Provides margin for future optimization of core design
- Utilizes ORIGEN-ARP in accordance with RG 1.183 Section 3.1 23
Detailed Technical Review: Overview of MSIV Model 24
Detailed Technical Review: Comparison of LOCA AST Analysis (Preliminary)
Design Input CLB Analysis Revised Analysis 8.77 rem Thyroid, 1.01E-2 rem Whole CR Dose 4.55 rem TEDE Body, appx. 0.27 rem TEDE 62.5 rem Thyroid, 2.34 rem Whole Body, EAB Dose 0.70 rem TEDE appx. 4.2 rem TEDE 200 scfh total @ 25 psig M SIV Leak Rate 46 scfh total @ 25 psig (including 50% reduction at 24 hrs)
M SIV Leak Rate Distribution N/A via LCS Among two M SLs (100/100/0/0)
Release via one (1) M SIV failed & one M SIV Release Pathways N/A via LCS (1) intact M SL Two well mixed volumes for each Well M ixed Volume N/A pathway Inboard, Interstitial, & outboard M SL M SL Credited for Aerosol Deposition N/A segments 20-group M onte Carlo probabilistic settling velocity distribution M SIV Aerosol Settling Velocity N/A Leakage (using 100% leak rate 0-720 hrs) 25
Detailed Technical Review: Comparison of LOCA AST Analysis Design Input CLB Analysis Revised Analysis System Bypass Leak Aerosol Removal N/A - System Bypass Leakage is not part of Technical Specifications and not Efficiencies modeled (RG 1.183 App. A 4.5)
Time-dependent elemental iodine M SL Elemental Iodine Removal N/A removal (J.E. Cline) 1.5% per day 0 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />; 0.75% per Containment Leakage 1.5% per day 0 to 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> day 24 to 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> 5 gpm program; 50 gpm passive failure for ESF Leakage 5 gpm program 30 minutes Credited 20 minutes to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> using Drywell Spray N/A conservative application of SRP 6.5.2 models SGTS Exhaust Flowrate for Containment N/A - No credit for reactor building 6,000 cfm Leakage holdup SGTS Exhaust Flowrate for ESF Leakage 6,000 cfm 6,000 cfm CR Ventilation Unfiltered Inleakage Same 300 cfm for both analyses - Not effected CR Ventilation M odeling 15,000 cfm (includes recirculation) 2,112 cfm (outside air component) 26
Detailed Technical Review: Comparison of LOCA AST Analysis Design Input CLB Analysis Revised Analysis CR Charcoal Efficiencies 90% 97%
SGTS Charcoal Efficiencies 90% 97%
SGTS and CR HEPA Efficiencies 90% 98%
27
Detailed Technical Review: Drawdown Analysis
- Required to fully implement TSTF-551, Revise Secondary Containment Surveillance Requirements
- GOTHIC v8.2 analysis to determine time that Secondary Containment is positive with respect to ambient pressure
- RG 1.183 requirements that lead to the four cases evaluated (summer, no wind; summer, with wind; winter, no wind; winter, with wind)
- Evaluate high wind impact on ability to maintain negative pressure
- Conservative ambient temperature assumption
- Conservative assumptions for heat transfer, initial temperatures, heat loads, etc. within the GOTHIC model
- Assume ground-level release anytime Secondary Containment does not meet TS defined criteria for negative pressure
- 20 minute drawdown time used in dose analysis 28
Detailed Technical Review: Drawdown Analysis 29
Detailed Technical Review: Post-LOCA Suppression Pool pH
- Methodology is based on NUREG/CR-5950
- Acids: Hydriodic, Carbonic, Nitric, Hydrochloric (cable jacket), Boric (from Sodium Pentaborate)
- Bases: Cesium Hydroxide (fuel), Sodium Pentaborate (SLC buffer)
- Fuel inputs include increased CAVEX
- Calculate buffered and unbuffered pH response
- Maximum injection duration of SLC buffer ( < 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />)
- Maximum time to inject 71 hours8.217593e-4 days <br />0.0197 hours <br />1.173942e-4 weeks <br />2.70155e-5 months <br />
- Validate pH remains > 7
- Minimum pH: 8.1 at 30 days
- Notable Assumptions
- Nitric acid production rate conservatively assumed at 86 deg. F rather than high T
- Minimum suppression pool water volume; no credit for additions
- 100 gal of buffer solution held up in SLC piping for conservatism 30
Detailed Technical Review: Post-LOCA Suppression Pool pH 31
Detailed Technical Review: SLC Design Evaluation
- System Capability Evaluated
- Guidance on the Assessment of a BWR SLC system for pH Control, Dated February 12, 2004, (ADAMS Accession No. ML040640364)
- All requirements met, without issue
- 50.49 Environmental Qualification
- Bounding SLC radiation environment established
- Equipment evaluated against EQ service environments
- Procedure to ensure SLC injection evaluated and are acceptable or will be updated accordingly as part of the engineering change
- An attachment detailing this evaluation will be provided in the LAR 32
Detailed Technical Review: Filter Efficiency Changes
- Proposed change to Technical Specification 5.5.8 to reduce filter penetration testing
- This is supported based on review of filter capability and past testing
- Charcoal penetration changed from 5% to 1.5% (charcoal).
- Generic Letter (GL) 99-02 safety factor of 2 included
- New charcoal filter efficiency of 97% is determined
- New HEPA filter efficiency of 98% is determined
- Filter efficiency changes applied to SGT and CR models 33