Document: NUREG-0800
Document ID: 1877a6e5-f5a2-4394-bd63-c323831e96d0
Document Type: srp
Title: INTRODUCTION - TRANSIENT AND ACCIDENT ANALYSES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML2231/ML22319A149.pdf
Revision Date: 2023-07
Chapter: 15
Section ID: 15.0
CFR Part: 
CFR Title: 

Content:
15.0-2 Draft Revision 4 – July 2023 Initiating events are further categorized by the type of impact they have upon the reactor system. Categorization by type provides a basis for comparison between events with similar plant responses, which facilitates identification and evaluation of the limiting cases (i.e., the cases that can challenge the analysis acceptance criteria). A. Categorization According to Frequency of Occurrence. Each initiating event is categorized as either an AOO, a postulated accident, or a beyond-design- basis event. AOOs, as defined in Appendix A to 10 CFR Part 50, are those conditions of normal operation that are expected to occur one or more times during the life of the nuclear power unit. Note the regulations and the SRP use the term AOO while RG 1.70 (Ref. 2) uses the terms incidents of moderate frequency (i.e., events that are expected to occur several times during the plant’s lifetime) and infrequent incidents (i.e., events that may occur during the lifetime of the plant). For facilities that were licensed using different categorizations, the reviewer will continue to evaluate applications according to their licensing bases, unless the licensee proposes to adopt the categorizations and acceptance criteria of this SRP section. The reviewer will evaluate new applications (i.e., those pertaining to plants that are not yet constructed) according to the categorizations and acceptance criteria of this SRP section. The reviewer ensures the applicant or licensee has conducted a systematic and comprehensive search for initiating events based on plant-specific design features and site characteristics. The events specified in the relevant 10 CFR Part 50, Appendix A, General Design Criteria (GDC) identified in this SRP establish minimum requirements for the principal design criteria for water- cooled nuclear power plants similar in design and location to plants for which construction permits have been issued by the Commission when the GDC were