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NRC RIN: 3150-AH43 Publication ID: Fall 2016 
Title: Decoupling of Assumed Loss of Offsite Power (LOOP) From Loss-of-Coolant Accidents (LOCA) [NRC-2008-0606] 
Abstract:

The proposed rule would amend part 50, appendix A, Criterion 35, to eliminate, based on appropriate risk considerations, the assumption of a LOOP coincident with a postulated large-break (low-frequency) loss-of-coolant accident.  The proposed rule would provide a voluntary alternative to existing requirements for satisfying specified acceptance criteria, and would consider, in part, Petition for Rulemaking (PRM)-50-77.  Commission direction in SRM-SECY-09-0140 approved placing this rulemaking on hold pending further development on other related rulemakings.

 

 
Agency: Nuclear Regulatory Commission(NRC)  Priority: Substantive, Nonsignificant 
RIN Status: Previously published in the Unified Agenda Agenda Stage of Rulemaking: Long-Term Actions 
Major: Undetermined  Unfunded Mandates: No 
CFR Citation: 10 CFR 50   
Legal Authority: 42 U.S.C. 2201    42 U.S.C. 5841   
Legal Deadline:  None
Timetable:
Action Date FR Cite
NPRM  To Be Determined    
Additional Information: In a Staff Requirements Memorandum (SRM) dated March 31, 2003, the Commission directed the staff to prepare a proposed LOOP/LOCA rule. On April 27, 2004, the Boiling Water Reactor (BWR) Owners Group (BWROG) submitted the topical report, "Separation of Loss of Offsite Power from Large Break LOCA" for staff review. The BWROG indicated that the topical report would support plant-specific exemption requests to implement specific plant changes that are currently not possible with the existing rule requirements. The staff recommended in SECY-04-0037, that it be allowed to finish its review of the topical report and pilot exemption request before initiating rulemaking. In its SRM of July 1, 2004, the Commission approved the staff to begin rulemaking after review of the BWROG pilot exemption request. After an ongoing dialogue, on June 12, 2008, the BWROG withdrew its topical report, stating that "continued development of this LTR [Licensing Topical Report] is no longer cost effective and, if ultimately approved in the form presently desired by NRC staff, adoption by licensees would most likely be prohibitively expensive." Upon this withdrawal, the NRC staff reevaluated the rulemaking effort. As a result of this reevaluation, the NRC staff recommended in SECY-09-0140, dated October 1, 2009, that this rulemaking effort be discontinued. The Commission issued its SRM on SECY-09-014 on July 2, 2010, directing the staff to defer the decision on continuing the rulemaking until after the 10 CFR 50.46a rule is implemented and the staff obtains feedback from industry on the potential incremental benefit of a separate LOOP/LOCA rule. The staff provided the draft 10 CFR 50.46a final rule to the Commission on December 10, 2010. On April 26, 2012, the NRC staff withdrew the draft final rule intending to resubmit it to the Commission after ensuring that any potential changes to NRC's regulatory framework resulting from Fukushima Near-Term Task Force Recommendation 1 or the Risk-Management Regulatory Framework proposed in NUREG-2150 are consistent with the approach in the draft final rule. If promulgated in its present form, the draft final 10 CFR 50.46a risk-informed emergency core cooling system rule would not require the assumption of a LOOP when analyzing large-break LOCAs larger than the transition break size. The Commission approved discontinuation of the 10 CFR 50.46a rule. The staff held a public meeting on June 28, 2016, to discuss whether and/or how to proceed on any future efforts to decouple the assumption of LOOP from LOCA analyses. The staff plans to hold a second public meeting on the same topic in fall 2016. This rulemaking activity would consider the issues raised in a petition for rulemaking submitted by Bob Christie (PRM- 50-77).
Regulatory Flexibility Analysis Required: No  Government Levels Affected: None 
Small Entities Affected: No  Federalism: No 
Included in the Regulatory Plan: No 
RIN Data Printed in the FR: No 
Related RINs: Related to 3150-AH29 
Agency Contact:
Robert Beall
Nuclear Regulatory Commission
Office of Nuclear Material Safety and Safeguards,
Washington, DC 20555-0001
Phone:301 415-3874
Email: robert.beall@nrc.gov