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:
from all sources of radioactive material considered and analyzed in the PRA are included within the scope of the PRA. • Risk-significant contributors are identified to develop insights from the PRA. • Methods and codes for risk integration are selected, justified, and applied, accounting for method and code limitations and considering the hazards, POSs, and event sequences that are within the scope of the PRA. • The uncertainties related to risk metrics are identified and characterized. The objective of characterizing and quantifying the uncertainties associated with the calculated risk metrics is to provide an understanding of key assumptions and sources of model uncertainties and RG 1.247, Page 51 their potential impact on the results. The characteristics and attributes needed to achieve this objective are as follows: • A list of key sources of model uncertainties and assumptions for each PRA element in the standard is compiled, and the potential impact of these uncertainties and assumptions on risk results is assessed, including both event sequence family frequencies and consequences. Also, any items that were screened out of the PRA (e.g., hazard groups, POSs, initiating events, event sequences, basic events) are included. • Uncertainties for event sequence families do not artificially cause these families to be risk significant because of the way event sequences have been grouped into event sequence families. • A qualitative or quantitative evaluation of the effects of individual sources of uncertainty, or combinations of interest, is performed on each modeled risk metric. • The uncertainty distribution for the selected risk metric(s) is characterized or calculated. C.1.3.19 Probabilistic Risk Assessment Documentation The documentation of the PRA model provides the information necessary to easily reproduce and justify results. The sources of information used in the PRA also should be referenced and retrievable. The methodology used to perform each