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:
ctives of the technical elements for a Level 1 or Level 2 low-power and shutdown PRA are similar to the objectives of the technical elements for a Level 1, internal events, at-power PRA and a Level 2, internal events PRA, as described in regulatory positions C.1.2.1 and C.1.2.2, respectively. Table 11 provides the technical characteristics and attributes needed for accomplishing the objectives of the technical elements, with respect to a Level 1 or Level 2 low-power and shutdown PRA. Table 11. Summary of Technical Characteristics and Attributes of a Level 1 and Level 2, Internal Events PRA for the Low Power and Shutdown Operating Modes Element Technical Characteristic and Attributes Level 1 Internal Events Plant Operating States • The Level 1 PRA involves identification and characterization of a set of plant operational states during LPSD operations that are representative of all the plant states not covered in the full-power PRA • The LPSD evolution is divided into POSs based on the unique impact on plant response to facilitate the practicality and efficiency of the PRA • Each LPSD POS required to be considered for the specific application is identified and characterized as to all important conditions affecting the delineation and evaluation of core damage and large early release DG-1362, Page 32 Table 11. Summary of Technical Characteristics and Attributes of a Level 1 and Level 2, Internal Events PRA for the Low Power and Shutdown Operating Modes Element Technical Characteristic and Attributes • The conditions include decay heat level, reactor coolant system configuration, reactor level, pressure and temperature, containment configuration, and the assumed representative plant system configurations within the POS • LPSD POSs that are subsumed into each other are shown to be represented by the characteristics of the subsuming group • The duration and number of entries into each POS are determined • The development, grouping, and quantification of the