ML19128A407
| ML19128A407 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 05/09/2019 |
| From: | Dominion Energy Nuclear Connecticut |
| To: | Plant Licensing Branch 1 |
| Guzman R | |
| References | |
| Download: ML19128A407 (17) | |
Text
Millstone Power Station Unit 2 Technical Specification Coolant Activity Changes Proposed License Amendment Request NRC Pre-Submittal Meeting May 09, 2019
Agenda
- Purpose
- Current Licensing Basis
- Identified Analyses Deficiencies
- Affected Conditions, Operability &
Proposed Changes
- Conclusion
- Milestones
- Acronyms 2
Purpose of Submittal
- Address identified issues in current analyses
- Restore full-qualification of CRE
- Increase unfiltered inleakage for operational flexibility
- Maximum iodine concentration of 30 Ci/gm DE I-131
- Revise secondary side specific activity TS 3.7.1.4 to 0.05 Ci/gm DE I-131 3
Current Licensing Basis
- Amendment No. 298 in May 2007, AST
- ADAMS Accession Number: ML071450053
- Amendment No. 307 in October 2008, Deletion of Ebar definition and revision to RCS specific activity
- No change to FSAR Chapter 14 analyses
- ADAMS Accession Number: ML082820615 4
Identified Analyses Deficiencies
- For ruptured SG cases
- Identified April 2018
- For intact SG cases during first 20 seconds
- Identified August 2018
Conditions Affecting the SGTR Analysis
- RADTRAD code input incorrectly used an iodine PC of 250 (0.4% release) instead of 100 (1% release) as cited in SGTR analysis and AST LAR
- Affects the ruptured SG iodine spike cases where the primary to secondary leak does not flash to steam
Actions Taken for Current Operability
- Corrected the iodine PC to 100 to produce dose consequences within regulatory limits
- More than a minimal increase in consequences
- Dose consequences are reduced below the AOR with the following additional change:
- Applying an admin limit of 85% on TS RCS specific activity for DE I-131
- Meeting the AOR dose consequences restores the CRE to operable (but not fully-qualified) per the TS 3.7.6 Basis 7
- Corrects to iodine PC of 100
- Reduces TS specific activity by 50%
- Increase unfiltered inleakage to 250 cfm for greater operational flexibility 8
Proposed Changes to update SGTR AOR and Restore Qualification 9
Input Current Proposed RADTRAD Version 1.1a 1.3
% of TS Activity 100%
50%
TS Primary Activity DE I-131 = 1.0 Ci/gm Pre-Accident Spike = 60 Ci/gm DE Xe-133 = 1100 Ci/gm DE I-131 = 0.5 Ci/gm Pre-Accident Spike = 30 Ci/gm DE Xe-133 = 550 Ci/gm TS Secondary Activity 0.1 Ci/gm 0.05 Ci/gm Unfiltered Inleakage 200 cfm 250 cfm EAB Breathing Rate Varies with time Constant at maximum rate Ruptured SG Iodine PC 100 (incorrectly modeled as 250) 100 (correctly modeled as 100)
MCO 0.4%
1%
Conditions Affecting the MSLB Analysis
power steam flow and beyond available correlations
- Intact SG should be feeding the break until isolation but was modeled as an ADV release instead of a break release
- Does not affect the faulted SG modeling 10
Actions Taken for Current Operability
- Correcting to 100% MCO and no iodine partitioning for first 20 seconds produced dose consequences above regulatory limits
- Dose consequences are reduced below the AOR with the following additional changes:
- Applying an admin limit of 85% on TS RCS specific activity for DE I-131
- Reducing intact SG nuclide inventory to TS concentrations
- Meeting the AOR dose consequences restores the CRE to operable (but not fully-qualified) per the TS 3.7.6 Basis 11
- Using intact SG MCO of 100% with no iodine PC produces dose consequences above the regulatory limits
- Corrects to MCO of 100% and iodine PC of 1 before 20 seconds
- Reduces TS specific activity by 50%
- Increase unfiltered inleakage to 250 cfm for greater operational flexibility 12
Proposed Changes to update MSLB AOR and Restore Qualification 13 Input Current Proposed RADTRAD Version 1.1a 1.3
% of TS Activity 100%
50%
TS Primary Activity DE I-131 = 1.0 Ci/gm Pre-Accident Spike = 60 Ci/gm DE Xe-133 = 1100 Ci/gm DE I-131 = 0.5 Ci/gm Pre-Accident Spike = 30 Ci/gm DE Xe-133 = 550 Ci/gm TS Secondary Activity 0.1 Ci/gm 0.05 Ci/gm Unfiltered Inleakage 200 cfm 250 cfm EAB Breathing Rate Varies with time Constant at maximum rate Intact SG Iodine PC 100 for all times 1 for time < 20 seconds 100 for times 20 seconds MCO 0.4% for all times 100% for time < 20 seconds 1% for times 20 seconds Intact SG X/Q ADV release for all times Break release < 20 seconds ADV release for times 20 seconds
Summary of LAR
- Major Input Changes:
- Reduce TS 3.4.8 and 3.7.1.4 specific activity by 50% of CLB
- Correct iodine PC to 100 in SGTR ruptured SG cases
- Address MCO in MSLB by modeling intact SG with 100%
MCO and no iodine partitioning before 20 seconds
- Increase control room unfiltered inleakage to 250 cfm
- Minor input changes made to more closely model plant parameters (e.g. RCS liquid mass)
- No new X/Q values or methodology 14
Summary of LAR
- Dose consequences for MSLB and SGTR meet the 10CFR50.67 and RG 1.183 acceptance criteria
- Provides a summary report documenting all inputs and assumptions for NRC confirmatory analysis
- Format is consistent with previous Dominion Energy AST submittals 15
Proposed Milestones
- Submit LAR to NRC July 2019
- Requested approval August 2020
- Implement amendment 60 days after approval 16
Acronyms ADV Atmospheric Dump Valve AOR Analysis of Record AST Alternative Source Term CLB Current Licensing Basis CRE Control Room Envelope DE Dose Equivalent EAB Exclusion Area Boundary FSAR Final Safety Analysis Report LAR Licensing Amendment Request MCO Moisture Carryover MSLB Main Steam Line Break MSIV Main Steam Isolation Valve NRC Nuclear Regulatory Commission OD Operability Determination PC Partitioning Coefficient RCS Reactor Coolant System RG Regulatory Guide SG Steam Generator SGTR Steam Generator Tube Rupture TS Technical Specifications X/Q Atmospheric Dispersion Factor 17