RS-12-037, Supplement to RS-12-037 and RS-12-087: Revision to Exelon Generation Company, LLC Commitment Relating to Large Break Loss of Coolant Accident: Difference between revisions

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{{Adams
#REDIRECT [[RS-12-037, Response to Request for Information Regarding Thermal Conductivity Degradation and 10 CFR 50.46 Report]]
| number = ML16349A476
| issue date = 12/14/2016
| title = Supplement to RS-12-037 and RS-12-087: Revision to Exelon Generation Company, LLC Commitment Relating to Large Break Loss of Coolant Accident
| author name = Gullott D
| author affiliation = Exelon Generation Co, LLC
| addressee name =
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000454, 05000455, 05000456, 05000457
| license number = NPF-037, NPF-066, NPF-072, NPF-077
| contact person =
| case reference number = RS-12-037, RS-12-087, RS-16-239
| document type = Letter type:RS
| page count = 7
}}
 
=Text=
{{#Wiki_filter:Exelon Generation...                                                  4300 Winfield Road Warrcnville. IL 60555 www.exeloncorp.corn RS-16-239                                                                                10 CFR 50.46 December 14, 2016 U.S. Nuclear Regulatory Commission ATTN. Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN-50-457 Byron Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455
 
==Subject:==
Supplement to RS-12-037 and RS-12-087: Revision to Exelon Generation Company, LLC Commitment Relating to Large Break Loss of Coolant Accident (LBLOCA) Analysis with an NRC Approved Emergency Core Cooling System (ECCS) Evaluation Model that Explicitly Accounts for Thermal Conductivity Degradation (TCD)
 
==References:==
: 1.      Letter from Patrick R. Simpson (Exelon Generation Company, LLC) to U.S. NRC, "Response to Request for Information Regarding the Thermal Conductivity Degradation and 10 CFR 50.46 Report," dated March 19, 2012
: 2. Letter from Patrick R Simpson (Exelon Generation Company, LLC) to U.S. NRC, "ECCS Evaluation Model Error - 10 CFR 50.46 Report," dated May 21, 2012 In Reference 1, Exelon Generation Company, LLC (EGC) responded to an information request from the NRC associated with the effect of Thermal Conductivity Degradation (TCD) on peak cladding temperature in the Westinghouse Electric Company furnished realistic Emergency Core Cooling System (ECCS) evaluation models for Braidwood Station, Unit 2 and Byron Station, Unit 2. In Reference 2, EGC provided similar information for Braidwood Station, Unit 1 and Byron Station, Unit 1. Both Reference 1 and Reference 2 estimated that the impact on the Large Break Loss of Coolant Accident (LBLOCA) evaluation model from fuel TCD represents a significant change in Peak Clad Temperature (PCT) as defined per 10 CFR 50.46, "Acceptance criteria for emergency core cooling systerns for light-water nuclear power reactors" paragraph (a)(3)(i). Therefore, EGC included a proposed schedule for providing a reanalysis to show compliance with 10 CFR 50.46.
 
December 14, 2016 U.S. Nuclear Regulatory Commission Page 2 EGC evaluated the requirements for reanalysis specified in in 10 CFR 50.46 (a)(3)(i) and the proposed schedule for reanalysis was included in a regulatory commitment. The regulatory commitment specified in both References 1 and 2 is as follows:
    "By December 15, 2016, EGC will submit to the NRC for review and approval a LBLOCA analysis that applies NRC approved methods that include the effects of fuel TCD for Braidwood Station, Unit 1 [Unit 2] and Byron Station, Unit 1 [Unit 2]. The date for the analysis submittal is contingent on the following milestones which must be completed in order to perform a revised licensing basis LBLOCA analysis with an NRC approved ECCS evaluation model that explicitly accounts for TCD:
: 1) NRC approval of a fuel performance analysis methodology that includes the effects of TCD. The new methodology for developing inputs to the LBLOCA evaluation model would replace the current licensing basis methodology for Braidwood Station, Unit 1 [Unit 2] and Byron Station, Unit 1 [Unit 2] that is described in WCAP-15063-P-A, Revision 1 with Errata, "Westinghouse Improved Performance Analysis and Design Model (PAD 4.0)."
: 2) NRC approval of a LBLOCA evaluation model that includes the effects of TCD and accommodates the rulemaking associated with the proposed 10 CFR 50.46c (Docket ID NRC-2008-0332). The new methodology would replace the current licensing basis methodology, WCAP-16009-P-A, "Realistic Large-Break LOCA Evaluation Methodology Using the Automated Statistical Treatment of Uncertainty Method (ASTRUM)."
At the time the above commitments were made in conjunction with conservative estimated PCT impacts, the new Westinghouse fuel performance analysis methodology that includes TCD (PAD 5.0) had not been approved by the NRC but had been expected to be approved by the end of 2014. As of this letter date, the new codes and methods have not yet been approved.
Additionally, the new Westinghouse LBLOCA evaluation model that includes the effects of TCD (Full Spectrum LOCA) has not been approved by the NRC. EGC has therefore revised the commitments made in References 1 and 2 to state (as noted in the Attachment):
    "EGC will submit to the NRC for review and approval a LBLOCA analysis that applies NRC approved methods that include the effects of fuel TCD for Braidwood Station, Unit 1 [Unit 2] and Byron Station, Unit 1 [Unit 2]. The date for the analysis submittal is contingent on the following milestones which must be completed in order to perform a revised licensing basis LBLOCA analysis with an NRC approved ECCS evaluation model that explicitly accounts for TCD:
: 1) NRC approval of a fuel performance analysis methodology that includes the effects of TCD. The new methodology for developing inputs to the LBLOCA evaluation model would replace the current licensing basis methodology for Braidwood Station, Unit 1
[Unit 2] and Byron Station, Unit 1 [Unit 2] that is described in WCAP-15063-P-A, Revision 1 with Errata, "Westinghouse Improved Performance Analysis and Design Model (PAD 4.0)."
 
December 14, 2016 U.S. Nuclear Regulatory Commission Page 3
: 2) NRC approval of a LBLOCA evaluation model that includes the effects of TCD. The new methodology would replace the current licensing basis methodology, WCAP-16009-P-A, "Realistic Large-Break LOCA Evaluation Methodology Using the Automated Statistical Treatment of Uncertainty Method (ASTRUM)."
The revised commitment date is two years after completion of both items 1 and 2.
The original commitment completion date was selected with the assumption that the NRC will achieve final approval of the fuel performance code and LOCA methods by the end of 2014. As of this letter date, the new codes and methods have not yet been approved. It is anticipated that this approval should occur in early 2017 with the re-analysis and submittal of the Braidwood Station and Byron Station application of the methodology within 2 years of approval. To be consistent with other industry commitments and to avoid the potential of an additional commitment extension should the NRC review and approval of the fuel performance code and LOCA methods be delayed further, a new commitment completion date based on the completion of NRC approval has been chosen.
In addition to the change in due date from December 15, 2016 to two years after completion of the above reference items; the revised commitment also includes the deletion of references to 10 CFR 50.46c.
Specifically, the second milestone has been updated to delete the reference to the NRC approval of a LBLOCA evaluation model that accommodates the rulemaking associated with 10 CFR 50.46c. The deletion of the reference to 10 CFR 50.46c is made due to the fact that the revised rule will require a re-analysis of the LBLOCA. Additionally, per the draft rule, the re-analysis will require submittal to the NRC. Since the re-analysis and submittal is redundant with what is required as part of the rulemaking, the second milestone has been updated to delete reference to 10 CFR 50.46c. Additionally, the methodology to include the effects of TCD does not hinge on the NRC issuance of revised rulemaking for 10 CFR 50.46c. Therefore, the reference to accommodating 10 CFR 50.46c is deleted.
The revised commitments do not impact the ability of a SSC to perform its intended safety function, thus the change is not significant to safety. This commitment change is being submitted for information only. There are no other new or revised regulatory commitments contained in this letter.
 
December 14, 2016 U.S. Nuclear Regulatory Commission Page 4 Should you have any questions concerning this letter, please contact Ms. Jessica Krejcie at (630) 657-2816.
Respectfully, David M. Gullott Manager  Licensing Exelon Generation Company, LLC
 
==Attachment:==
Revised Regulatory Commitments for Braidwood and Byron Stations, Units 1 and 2 cc:  NRC Regional Administrator, Region III NRC Senior Resident Inspector, Braidwood Station NRC Senior Resident Inspector, Byron Station NRC Project Manager, NRR  Braidwood and Byron Stations Illinois Emergency Management Agency  Division of Nuclear Safety
 
ATTACHMENT Revised Regulatory Commitments for Braidwood Station and Byron Station Units 1 and Unit 2 The following list identifies those actions committed to by Exelon Generation Company, LLC, (EGC) in this submittal. Any other actions discussed in the submittal represent intended or planned actions by EGC, are described only for information, and are not regulatory commitments.
COMMITMENT TYPE COMMITMENT                        COMMITTED DATE          ONE-TIME        PROGRAM-OR "OUTAGE"            ACTION          MATIC (YES/NO)        (YES/NO)
EGG will submit to the NRC for          Two years after Yes              No review and approval a LBLOCA            completion of both analysis that applies NRC              items 1 and 2.
approved methods that include the effects of fuel TCD for Braidwood Station, Unit 1 and Byron Station, Unit 1. The date for the analysis submittal is contingent on the following milestones which must be completed in order to perform a revised licensing basis LBLOCA analysis with an NRC approved ECCS evaluation model that explicitly accounts for TCD:
: 1) NRC approval of a fuel performance analysis methodology that includes the effects of TCD. The new methodology for developing inputs to the LBLOCA evaluation model would replace the current licensing basis methodology for Braidwood Station, Unit 1 and Byron Station, Unit 1 that is described in WCAP-15063-P-A, Revision 1 with Errata, "Westinghouse Improved Performance Analysis and Design Model (PAD 4.0).
: 2) NRC approval of a LBLOCA evaluation model that includes
 
COMMITMENT TYPE COMMITMENT                COMMITTED DATE  ONE-TIME  PROGRAM-OR "OUTAGE"    ACTION      MATIC (YES/NO)    (YES/NO) the effects of TCD. The new methodology would replace the current licensing basis methodology, WCAP-16009-P-A, "Realistic Large-Break LOCA Evaluation Methodology Using the Automated Statistical Treatment of Uncertainty Method (ASTRUM).
Two years after Yes        No EGG will submit to the NRC for  completion of both review and approval a LBLOCA    items 1 and 2.
analysis that applies NRC approved methods that include the effects of fuel TCD for Braidwood Station, Unit 2 and Byron Station, Unit 2. The date for the analysis submittal is contingent on the following milestones which must be completed in order to perform a revised licensing basis LBLOCA analysis with an NRC approved ECCS evaluation model that explicitly accounts for TCD:
: 1) NRC approval of a fuel performance analysis methodology that includes the effects of TCD. The new methodology for developing inputs to the LBLOCA evaluation model would replace the current licensing basis methodology for Braidwood Station, Unit 2 and Byron Station, Unit 2 that is described in WCAP-15063-P-A, Revision 1 with Errata, "Westinghouse Improved Performance Analysis and Design Model PAD 4-0).
 
COMMITMENT TYPE COW    117li~W li'4T    COMMITTED DATE ONE-TIME  PROGRAM-OR "OUTAGE"    ACTION      MATIC (YES/NO)    (YES/NO)
: 2) NRC approval of a LBLOCA evaluation model that includes the effects of TCD. The new methodology would replace the current licensing basis methodology, WCAP-16009-P-A, "Realistic Large-Break LOCA Evaluation Methodology Using the Automated Statistical Treatment of Uncertainty Method (ASTRUM).}}

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