ML20098D508
| ML20098D508 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 04/09/2020 |
| From: | Exelon Generation Co |
| To: | Marshall M Plant Licensing Branch 1 |
| Marhsall M, NRR/DORL/LPL, 415-2871 | |
| References | |
| Download: ML20098D508 (5) | |
Text
Nine Mile Point Unit 2 AST LOCA Approach to Elemental Iodine Removal NRC Public Meeting on RAI 6 April 9, 2020
Summary of Current Licensing Basis Elemental Iodine Removal Current Licensing Basis (CLB) analysis of record, H21C-106 Revision 2, models elemental iodine removal in bypass leakage pathways as follows:
Modeled as two pathways in RADTRAD; one for MSIV stuck open and one representing the other three lines No compartments; holdup was accounted for with delayed release timing Elemental iodine is conservatively capped at a constant 50% (only piping between the MSIVs credited)
Other bypass leakage pathways Grouped together into drywell (DW) bypass, wetwell (WW) bypass, and delayed DW bypass leakage pathways in RADTRAD with the delayed pathway accounting for transit time similar to MSLs Elemental iodine in all bypass leakage pathways capped at a constant 50%
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Summary of Current Licensing Basis Elemental Iodine Removal H21C-106, Appendix C, Page C1:
NMP2 SER (ML081230439) Section 3.2.1.2.5.2, Page 18:
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Summary of Changes to H21C-106 Revision 3 to Be Consistent with CLB Elemental Iodine Removal Changes will be made as follows to make the models from H21C-106 Rev. 3 consistent with the CLB for elemental iodine removal:
Time-dependent elemental removal associated with each MSL volume will be replaced with a constant 50% removal in a single pathway for each MSL (DF=2 for each pathway)
Time-dependent elemental removal modeled in the DW and WW bypass leakage pathways will be replaced with a constant 50%
Discussion in Sections 2.3.1.4 and 7.10 of H21C-106 Rev. 3 and associated tables and results will be modified or removed to be consistent with the discussion in H21C-106 Rev.
2 with regards to elemental iodine removal in the leakage pathways It is expected that the impact of the change will be a slight decrease in doses from those presented in the LAR; elemental iodine removal in leakage pathways is not a significant factor in the offsite and Control Room doses.
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LAR Impacts with Implementing CLB Elemental Iodine Removal Enclosure A (H21C-106 calculation revision) updated
- , Technical Evaluation Table 1 on Page 3 of 22 Discussion on Page 10 Changes planned to be submitted Only updated Enclosure A RAI response discussion 4