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:
ce on the modeling of such hazards. Appendix D of this RG provides a listing of and general description for the internal and external hazards that should be considered during the development of a base PRA. Initiating events are perturbations to the steady state operation of the plant that challenges plant control and safety systems that could lead to core damage and or radioactivity release. They also include failures of plant control and safety systems that may cause perturbation to the steady state operation of the DG-1362, Page 14 plant that could lead to core damage and or radioactivity release. Initiating events may be caused by internal hazards such as equipment failure, operator actions, or a flood or fire internal to the plant; or external hazards such as an earthquake, external flood, or high wind. The risk perspective is based on a consideration of total risk, which includes risk contributions from both internal and external hazards. Technical Elements of a Base PRA and Associated Characteristics and Attributes The PRA technical elements are defined in terms of the fundamental technical analyses needed to develop and quantify the base PRA model for its intended purpose (e.g., determination of a specific risk metric). The characteristics and attributes of the PRA technical elements define specific requirements that should be met to successfully perform those technical analyses and achieve a defined objective. Table 1 provides the list of general technical elements that are necessary for an acceptable Level 1 and Level 2 base PRA. A base PRA that is missing one or more of these elements would not be considered a complete base PRA. Table 1. Technical Elements of a Base PRA SCOPE OF ANALYSIS TECHNICAL ELEMENT Level 1 • Initiating event analysis • Success criteria analysis • Accident sequence analysis • Systems analysis • Parameter estimation analysis • Human reliability analysis • Quantification Level 2 • Plant damage state analysis • Severe