Document: NUREG-0800
Document ID: e32f0820-4e33-476e-aa36-4ca8c2c64af0
Document Type: srp
Title: Use of Probabilistic Risk Assessment in Plant-Specific, Risk-Informed Decisionmaking:
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0119/ML011940192.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.0
CFR Part: 
CFR Title: 

Content:
at removal may significantly contribute to CDF. In reviewing the calculation of change in LERF for a given plant type, reviewers should consider the following factors: SRP 19-A22 Containment Bypass: * Whether the proposed change affects systems that are credited in the prevention of, or in response to an initiating event involving a steam generator tube rupture (SGTR) or an ISLOCA. Whether the proposed change affects the frequency or severity of transients that could result in induced steam generator tube ruptures (ISGTR) (i.e., tube rupture in the course of an accident, caused by elevated temperatures and/or elevated pressure differentials). If the proposed change does not directly affect steam generator tube integrity, and the steam generators in the plant are not experiencing significant degradation, only a qualitative analysis may be needed to ensure that the risk of ISGTR is not significantly increased by the proposed change. However, if the plant has suffered a steam generator tube rupture, or has been shut down because of excessive steam generator tube leakage, or has detected tubes which do not meet applicable ASME Code requirements for structural integrity, or has repaired a significant amount of tubes as a result of free span degradation, the application should provide a more thorough analysis of the effects of the proposal on the risk associated with ISGTR. Containment Isolation: Whether the proposed change affects systems that perform or support the isolation function. Whether the proposed change affects systems that prevent or mitigate core damage sequences initiated during periods of reduced containment functionality (e.g., shutdown). Whether the proposed change affects the ability to restore containment function during such periods (e.g., AC power, plant procedures, etc.). Igniters: * Whether the proposed change affects the igniters or any applicable support systems. ECC Restoration Before Vessel Failure: If credit was taken in the estimate of LERF