Document: NUREG-0800
Document ID: ac43f632-9db1-4857-9f56-bfba45965456
Document Type: srp
Title: * These are modifications to a plant’s design, operations, or other activities that require NRC approval. These modifica
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0232/ML023250195.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19
CFR Part: 
CFR Title: 

Content:
before vessel failure PWR Ice Condenser: Containment isolation Containment bypass Hydrogen igniters RCS depressurization ECC restoration before vessel failure BWR Mark I and II: Containment isolation Containment bypass Venting Containment heat removal: decay heat Containment heat removal: ATWS RCS depressurization ECC restoration before vessel failure BWR Mark III: All Mark I and Mark II issues Igniters It should be noted that, at some BWRs, many sequences that result in vessel breach have a significant probability of also failing the containment. Also, the reader should note that a loss of containment heat 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-A23 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 that 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