ML22235A703

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NEI Presentation for Aug 26, 2022 Public Meeting - Source Terms and Radiological Consequence Analyses
ML22235A703
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Site: Nuclear Energy Institute
Issue date: 08/24/2022
From:
Nuclear Energy Institute
To: Sean Meighan
NRC/NRR/DRA/ARCB
Meighan S
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Download: ML22235A703 (15)
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Source Terms and Radiological Consequence Analyses

-Frankie Pimentel, Sr. Project Manager -

Engineering & Risk, NEI

-Greg Broadbent, Senior Staff Engineer -

Corporate Nuclear Analysis, Entergy

-Chad Burns, Sr. Fuels Engineer, Constellation Safety Analysis

-Brian L. Mount, Consulting Engineer, Nuclear Safety Analysis II, Dominion Energy August 24, 2022

©2022 Nuclear Energy Institute

Source Terms and Radiological Consequence Analyses DG-1389 contains significant changes to BWR release fractions and timing Doubling halogen releases can have wide-ranging impacts

  • Charcoal/HEPA loadings and heat loads, EQ
  • NEI Comment #4 suggests incorporating results from supporting analyses performed by staff Many BWR plants may not be able to adopt Rev. 1 without significant licensing basis changes or plant modifications
  • Example 1: demonstrates when applying the proposed release fractions and timing, plant will not meet the CR dose criteria for current BU and enrichment conditions
  • Example 2: demonstrates applying credit for the condenser using the proposed methods in conjunction with the proposed release fractions and timing, plant will meet the CR dose criteria for current BU and enrichment conditions
  • Example 3: demonstrates applying the proposed release fractions and timing to a plant already using credit for the condenser will not meet the CR dose criteria for current BU and enrichment conditions

©2022 Nuclear Energy Institute 2

Changes for BWR MHA-LOCA Scenario BWR Release Fractions Nuclide Groups Reg Guide 1.183, Rev. 0 Draft Guide DG-1389 Table 5 of Reg Guide Table 14 of SAND Nuclide Group Nuclide Group Gap In-Vessel Total Gap In-Vessel Total 1.183 Rev. 0 2011-0158 Noble Gases 5.00E-02 9.50E-01 1.00E+00 8.00E-03 9.60E-01 9.68E-01 Noble Gases Xe, Kr Xe, Kr Halogens 5.00E-02 2.50E-01 3.00E-01 3.00E-03 5.40E-01 5.43E-01 Halogens I, Br I, Br Alkali Metals 5.00E-02 2.00E-01 2.50E-01 3.00E-03 1.40E-01 1.43E-01 Alkali Metals Cs, Rb Cs, Rb Tellurium Metals Te, Sb, Se Te, Sb, Se Tellurium Metals 0.00E+00 5.00E-02 5.00E-02 3.00E-03 3.90E-01 3.93E-01 Barium, Strontium Ba, Sr Ba, Sr Barium, Strontium 0.00E+00 2.00E-02 2.00E-02 0.00E+00 5.00E-03 5.00E-03 Noble Metals Ru, Rh, Pd, Mo, Tc, Co Ru, Rh, Pd, Co Noble Metals 0.00E+00 2.50E-03 2.50E-03 0.00E+00 2.70E-03 2.70E-03 Ceriums Ce, Pu, Np Ce, Pu, Np, Zr Cerium 0.00E+00 5.00E-04 5.00E-04 0.00E+00 1.60E-07 1.60E-07 La, Zr, Nd, Eu,Nb, Pm, La, Nd, Eu, Pm, Pr, Lanthanides 0.00E+00 2.00E-04 2.00E-04 0.00E+00 2.00E-07 2.00E-07 Lanthanides Pr, Sm, Y, Cm, Am Sm, Y, Cm, Am Molybdenum 0.00E+00 0.00E+00 0.00E+00 0.00E+00 3.00E-02 3.00E-02 Molybdenum Mo, Tc, Nb Release Timing Table 4 of Reg Guide Table 5 of Draft Guide Release Phase 1.183 Rev. 0 DG-1389 Onset Duration Onset Duration Gap 2 min 30 min 2 min 0.16 hrs Early In-Vessel 30 min 1.5 hrs 0.16 hrs 8.0 hrs

©2022 Nuclear Energy Institute 3

Example 1: BWR-6, Mark-III Containment BWR/6, Mark-III Containment Standard Leakage Paths

  • Containment leakage
  • No credit for MSL deposition past the outboard MSIV
  • Credit for MSIV Leakage Control System initiation at 20 minutes 99% SGTS filters, ~1 hour holdup

©2022 Nuclear Energy Institute 4

Results from Proposed Reg Guide Changes Offsite Doses Control Room Doses Reg Guide Reg Guide Dose Location DG-1389 DG-1389 1.183 Rev. 0 Release Group 1.183 Rev. 0 9.71 9.55 Noble Gases 1.12E+00 1.42E+00 Exclusion Area Boundary (2-4 hrs) (7.9-9.9 hrs) Halogens 2.30E+00 3.86E+00 Low Population Zone 6.20 8.00 Alkali Metals 4.46E-01 1.48E-01 Control Room 4.11 5.83 Other 2.46E-01 3.97E-01 Total 4.11E+00 5.83E+00 Offsite Doses Reg Guide 1.183 Rev. 0 10 Control Room Dose DG-1389 9 7 Control Room Dose (Rem TEDE) 8 6 10CFR50.67 Acceptance Criterion 7

Dose (Rem TEDE) 5 6

5 4 Other 4 Alkali Metals 3

Halogens 3

2 Noble Gases 2

1 1 0

0 Exclusion Area Boundary Low Population Zone Reg Guide 1.183 Rev. 0 DG-1389 Location

©2022 Nuclear Energy Institute 5

Results from Proposed Reg Guide Changes DG Release Rates Lower than Rev. 0 Extended-Release Duration leads to later EAB peak BWR Halogen Release Rates Exclusion Area Boundary Dose 0.18 10 9

0.16 Fraction of Core Inventory per Hour 8

0.14 Reg Guide 1.183 Rev. 0 7

DG-1389 Dose (Rem TEDE) 0.12 DG Release Rates Lower than6Rev. 0 0.1 5

0.08 4 Reg Guide 1.183 Rev. 0 0.06 3 DG-1389 0.04 2 0.02 1 0

0 0 2 4 6 8 10 12 14 0 1 2 3 4 5 6 7 8 9 Hours Ending Time of 2-hour Window (Hours)

©2022 Nuclear Energy Institute 6

Example 2: BWR-4, Mark-I Containment Main Steam Credit

  • 300 scfh total / 150 max individual line
  • Credit for Aerosol Deposition between intact MSIVs, MSIV to TSV, and TSV through Condenser using RG 1.183 Table A-1
  • Addition of Condenser Removal Mechanisms
  • Containment Elemental Iodine Plateout from Wetted Surface
  • Containment Aerosol Deposition (Powers 10% model)
  • No Suppression Pool Scrubbing Leakage Paths
  • Containment leakage

©2022 Nuclear Energy Institute 7

Example 2: BWR-4, Mark-I Containment MSIV Aerosol Changes Removal Leak Effective Filter RG 1.183 Coefficient Rate Volume Efficiency Rev. 0 Leak Path [1/hr] [scfh] [ft^3] [%] [AEB 98-03]

0-10 hr 10+hr 0-10 hr 10+hr 0-96 hr Intact inner MSIV to intact outer MSIV 1.8 1 150 66.05 44.2% 30.6% 93.8%

Intact outer MSIV to TSVs 1 0.7 150 869.96 85.3% 80.2% 97.5%

Failed line outer MSIV to TSVs 1 0.7 150 869.96 85.3% 80.2% 97.5%

TSV to Condenser 0.015 0.012 300 300000 93.8% 92.3% 0%

Elemental Deposition - no change to MSL methods, no credit in condenser

©2022 Nuclear Energy Institute 8

Results from Proposed Reg Guide Changes No Condenser

  • Strict reduction in deposition
  • Unviable increase in CR dose Control Room LPZ EAB RG 1.183 R0 4.44E+00 2.59E+00 5.42E+00 RG 1.183 R1 5.16E+01 1.99E+01 1.11E+01 Delta 1061% 667% 105%

©2022 Nuclear Energy Institute 9

Results from Proposed Reg Guide Changes Results with condenser compartment added to Rev. 1 case RG 1.183 Rev. 1 RG 1.183 Rev. 0 Control Control Room EAB LPZ Room EAB LPZ Containment Containment Leakage 9.80E-02 1.42E+00 3.25E+00 Leakage 2.61E-01 2.92E+00 3.14E+00 ESF Leakage 3.05E-02 1.09E+00 5.95E+00 ESF Leakage 5.84E-02 6.74E-01 3.87E+00 MSIV Leakage 2.89E+00 4.51E-01 4.76E-01 MSIV Leakage 4.44E+00 5.42E+00 2.59E+00 Containment Containment Shine 3.17E-02 0.00E+00 0.00E+00 Shine 3.17E-02 0.00E+00 0.00E+00 External Cloud 1.30E-02 0.00E+00 0.00E+00 External Cloud 1.30E-02 0.00E+00 0.00E+00 CR Filter Shine 3.15E-03 0.00E+00 0.00E+00 CR Filter Shine 3.15E-03 0.00E+00 0.00E+00 TOTAL 3.07E+00 2.96E+00 9.68E+00 TOTAL 4.81E+00 9.01E+00 9.60E+00

©2022 Nuclear Energy Institute 10

Results from Proposed Reg Guide Changes Results with condenser compartment added to Rev. 1 case BWR/4, Mark 1 1.20E+01 1.00E+01 8.00E+00 REM TEDE 6.00E+00 RG 1.183 Rev. 0 4.00E+00 RG 1.183 Rev. 1 2.00E+00 0.00E+00 Control Room EAB LPZ Dose Location

©2022 Nuclear Energy Institute 11

Example 3: BWR-5, Mark-II Containment 400 scfh total / 200 max individual line Currently credits condenser for aerosol & elemental I removal Current model is AEB 98-03 for deposition Table A-1 applied directly to compartments

©2022 Nuclear Energy Institute 12

Results from Proposed Reg Guide Changes Control Room resulting dose very high through failed line (MSL B)

Control Room LPZ EAB MSIV A 3.20E+00 2.54E-02 6.18E-02 MSIV B 1.61E+01 5.61E-02 2.99E-01 ECCS 2.47E-02 1.73E-02 3.09E-02 Containment Leakage 5.12E-01 9.89E-02 6.96E-01 Total 1.98E+01 1.98E-01 1.09E+00 Overall decrease in Iodine removal without compensation.

©2022 Nuclear Energy Institute 13

Discussion State-of-the-Art Reactor Consequence Analyses (SOARCA) project results1 include the suppression pool in their models and indicate that all modeled accident scenarios, progress more slowly and release smaller amounts of radioactive material than calculated in earlier studies PWRs saw these expected impacts while BWRs did not Reg Guide should not unduly penalize BWRs Potential Resolutions Update BWR release fractions with more applicable accident scenario selection Consider suppression pool scrubbing credit in BWR release fractions

  • A small DF of just 2 would be adequate to resolve the issue 1 ML20304A339 - NRC Brochure- State-of-the-Art Reactor Consequence Analyses: Using decades of research and experience to model accident progression, mitigation, emergency response, and health effects

©2022 Nuclear Energy Institute 14

Source Terms and Radiological Consequence Analyses Additional concerns with addressing TFGR - no guidance is provided in the DG to address TFGR due to high burnup pellet fragmentation in non-LOCA accidents that predict fuel failure aside from reactivity insertion accidents that are addressed in RG 1.236 High burnup-related TFGR guidance for non-LOCA DBAs should be provided For non-LOCA DBA with fuel overheating, guidance should identify the specific non-LOCA DBAs that are impacted and include applicable TFGR guidance in the relevant Appendices

©2022 Nuclear Energy Institute 15

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