Document: NUREG-0800
Document ID: 7916b088-fb90-4163-84fe-027bd315bcc5
Document Type: srp
Title: REVIEW OF RISK INFORMATION USED TO SUPPORT PERMANENT PLANT-
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0717/ML071700658.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.2
CFR Part: 
CFR Title: 

Content:
ruptures and interfacing system LOCAs). • Change the frequency of core damage sequences that pose severe challenges to containment (e.g., sequences resulting in elevated reactor coolant system (RCS) pressure during core damage and at vessel failure). • Change the performance of systems involved in containment safety functions (e.g., containment isolation, containment heat removal, containment sprays, hydrogen control). • Change the performance of systems or operator actions that affect accident management strategies (e.g., depressurization, venting). • Change the frequency of core damage sequences occurring at shutdown with containment functionality reduced. The guidance provided below focuses, for each plant type, on particular examples of these general categories. Based on previous PRAs, NUREG/CR-6595 developed some insights on the factors that most strongly affect the estimated likelihood of a large early release. Although plant-specific details may become significant in some cases, it was found that plants of each major containment type tend to be similar in the types of sequences that could lead to a large early release, reflecting strengths and weaknesses of that containment structure and particular features of the core damage sequences that characterize that plant type. Based on these insights, NUREG/CR-6595 presents a screening approach to evaluate the frequencies of dominant containment failure modes and bypass events. The purpose of this approach is to provide estimates of LERF, given certain characteristics of core damage sequences as input. 19.2-60 June 2007 The review approach presented in this section builds upon the underlying insights from NUREG/CR-6595. For each major containment type, particular considerations are suggested for attention in the review process. However, it is not intended to suggest that these considerations exhaust the technical issues that affect the potential for large early release. For example, where plant-specific PRA