Document: NRC Regulatory Guide
Document ID: 8a2332d3-66ca-40af-84e1-507db8b26559
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:
uding errors of commission (EOCs) presumes that EOCs are not important or significant contributors to NLWR PRA; however, it is currently not known whether that is the case. Though there is significant experience with operating light- water reactors to justify the consensus approach of excluding errors of commission (EOCs) from the Level 1/LERF LWR PRA standard, there is little to no operating experience for NLWRs justifying that the same approach can be applied. It is expected that NLWRs will rely less on human actions than operating LWRs, which implies that EOCs would play a more important role in NLWR PRAs. Additionally, there is no consensus for LWRs regarding whether EOCs should be addressed in the Qualification Add the following to item HR- E4: “(c) those well-intended actions performed by control room staff that disable a system, subsystem, or component needed in an event scenario.” RG 1.247, Appendix A, Page A-17 Table A-7. Staff Position on ASME/ANS RA-S-1.4-2021, Technical Requirements for Human Reliability Analysis Index No. Issue Position Resolution accident sequence progression analysis (i.e., Level 2 PRA). Likewise, there is currently no basis for excluding EOCs from the mechanistic source term analysis in a NLWR PRA. HR-E5 through HR-E9 ------------------------ No objection ---------------------------------- Table 4.3.6.1-7 HR-F1 through HR-F5 ------------------------ No objection ---------------------------------- Table 4.3.6.1-8 HR-G1 Some HRA methods include a feasibility step during the qualitative analysis and other HRA methods do not include the step. Since it is up to the NLWR PRA developer to choose which HRA method to use, not all HRA methods include this step, and feasibility assessment is a continuous step in the HRA process, it is important to assess the feasibility of a human action (even during quantification). Further, ESQ-C7 requires that human actions be feasible in order to use their respective HEPs in event sequence