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
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ection and safety systems functions that are 5 For an example, see SECY-18-0099, “NuScale Power Exemption Request from 10 CFR Part 50, Appendix A, General Design Criterion 27, ‘Combined Reactivity Control Systems Capability’” (ADAMS Accession No. ML18065A540). 15.0-8 Draft Revision 4 – July 2023 used (i.e., credited) in the safety analysis. Typical protection and safety systems functions include reactor trips, isolation valve closures, emergency core cooling system (ECCS) and decay heat removal system initiation and performance. In evaluations of AOOs and postulated accidents, the performance of each credited protection or safety system is required to include the effects of the most limiting postulated single failure. This verifies satisfaction of the GDC that require protection and safety systems to adequately perform their intended safety functions in the presence of single failures. The reviewer also ascertains that the application lists the expected limiting delay time for each protection or safety system function and describes the methodology for determining uncertainties (from the combined effects of calibration error, drift, instrumentation error, and other factors) to be included in the establishment of the trip setpoints and allowable values specified in the plant technical specifications. Review of the instrumentation setpoint methodology is performed in accordance with Chapter 7 of the SRP. 5. Evaluation of Individual Events. The reviewer ensures that the application includes an evaluation of each analyzed event, using the format in Subsection I.6 of this SRP section. For events that are determined to be not limiting, the reviewer may evaluate qualitative justifications and conduct comparisons with more limiting events in the same event category. 6. Event Evaluation A. Identification of Causes and Frequency Classification. For each initiating event evaluated, the reviewer ensures that the application includes a description of the occurrences