Document: NRC Regulatory Guide
Document ID: cde52d5a-adf9-49be-9d1f-59449dfca895
Document Type: regulatory_guide
Title: TRIAL - Acceptability of Probabilistic Risk Assessment Results for Non-Light Water Reactor Risk-Informed Activities
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2123/ML21235A008.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.247
CFR Part: 
CFR Title: 

Content:
eaningfully applied to NLWRs, if they can be used at all. • Large release frequency (LRF) is used as a risk metric for 10 CFR Part 52 DC and COL applications for LWRs, as approved in SRM-SECY-90-16, “SECY-90-16—Evolutionary Light Water Reactor (LWR) Certification Issues and Their Relationships to Current Regulatory Requirements,” dated June 26, 1990 (Ref. 30). As discussed in SECY-13-0029, “History of the Use and Consideration of the Large Release Frequency Metric by the U.S. Nuclear Regulatory Commission,” dated March 22, 2013 (Ref. 31), the staff has not developed a definition of LRF. Staff practice has been to allow 10 CFR Part 52 applicants to define LRF. • In SECY-89-102, “Implementation of Safety Goal Policy,” (Ref. 32) the staff proposed a general framework for implementing the Safety Goal Policy Statement that consisted of four principal elements. The fourth principal element addressed the use of subsidiary quantitative targets, which were defined as “…targets that are compatible with but subsidiary to the quantitative safety goal objectives themselves. Subsidiary targets represent a partitioning of safety goal objectives.” In SRM-SECY-89-102, “Secy-89-102 – Implementation of the Safety Goals,” (Ref. 33) the Commission approved the staff’s proposal but noted that “Such subsidiary objectives should be consistent with the large release guideline, and not introduce additional conservatism so as to create a de facto new Large Release Guideline.” The Commission further commented that: o Within a particular design class (e.g., LWRs, liquid metal reactors (LMRs), high- temperature gas-cooled reactors (HGTRs)), the same subsidiary objectives should apply to both current as well as future designs. A specific subsidiary objective might differ from one specific design class to another specific design class to account for different mitigating concepts (e.g., confinement instead of containment). However, the Large Release Guideline