Document: NRC Regulatory Guide
Document ID: 22ccfd5e-c5d8-4615-a02c-32369aa9f533
Document Type: regulatory_guide
Title: Acceptability of Probabilistic Risk Assessment Results for Risk-Informed Activities (Rev. 3)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1930/ML19308B636.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.200
CFR Part: 
CFR Title: 

Content:
nt progression models and source term evaluation to provide estimates of the frequency of radionuclide releases that could be expected following the identified core damage accidents. This quantitative evaluation reflects the different magnitudes and timing of radionuclide releases and specifically allows for identification of LERF or LRF. Table 3 provides a summary of the characteristics and attributes needed for the technical elements for a Level 2 PRA for internal events. The characteristics and attributes are provided for both at-power conditions. Table 3. Summary of Technical Characteristics and Attributes of a Level 2, Internal Events PRA Element Technical Characteristics and Attributes Plant Damage State Analysis • Identification of the attributes of the core damage scenarios that influence severe accident progression, containment performance, and any subsequent radionuclide releases • Grouping of core damage scenarios with similar attributes into plant damage states • Carryover of relevant information from Level 1 to Level 2 Severe Accident Progression Analysis • Use of appropriate codes by qualified trained users with an understanding of the code limitations and the means for addressing the limitations • Assessment of the credible severe accident phenomena via a structured process • Assessment of containment system performance including linkage with failure modes on non-containment systems • Establishment of the capacity of the containment to withstand severe accident environments • Assessment of accident progression timing, including timing of loss of containment failure integrity Source Term Analysis • Assessment of radionuclide releases including appreciation of timing, location, amount, and form of release • Grouping of radionuclide releases into smaller subsets of representative source terms with emphasis on large early release and large late release Quantification • Estimation of the frequency of different containment failure