Document: NUREG-0800
Document ID: 8dd882f4-a34f-4415-acd1-ebb441c72786
Document Type: srp
Title: PROBABILISTIC RISK ASSESSMENT AND SEVERE ACCIDENT
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1213/ML12132A481.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.0
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ved and show that MAAP is able to capture the important T-H phenomana and the timing of such phenomena in simulations of accident sequences included in the PRA. If a small set of accident scenarios is used in the studies, the reviewer confirms that the applicant has provided an adequate rationale for its selection of scenarios, including a discussion of the criteria used for selection. 2. For passive plant designs, the staff reviews the applicant’s use of the PRA to identify non-safety systems, structures and components that require regulatory treatment (i.e., to support the RTNSS program). Specifically this includes the following evaluations performed by the applicant as described in SRP 19.3; A. Evaluation of the risk significance of non-safety systems using the Focused PRA B. Evaluation of uncertainties associated with assumptions made in the PRA models of passive systems C. PRA Initiating Event Frequency Evaluation Design-Specific PRA (Procedures Specific to Integral Pressurized Water Reactors) 1. For small, modular integral pressurized water reactor designs, the staff reviews the results and description of the applicant’s risk assessment for a single reactor module; and, if the applicant is seeking approval of an application for a plant containing multiple modules, the staff reviews the applicant’s assessment of risk from accidents that could affect multiple modules 2. Shutdown and refueling operations for small, modular reactor designs may be performed in ways which are new and completely different from those used at large traditional LWRs either licensed or under review by the NRC. In these cases, a more in-depth 19.0-23 Draft Revision 3 – September 2012 review will be needed to assure the validity of the PRA model. Reviewers should confirm that applicants identify and describe all the specific plant operating states (POS) in a refueling outage between the time the output breaker to the grid is opened for plant shutdown and when it is closed to resume