Document: NUREG-0800
Document ID: 643ab154-682e-480f-a57b-a5fd7390a34e
Document Type: srp
Title: REVIEW OF TRANSIENT AND ACCIDENT ANALYSIS METHODS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0535/ML053550265.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.0.2
CFR Part: 
CFR Title: 

Content:
o identify and rank the reactor component and physical phenomena modeling requirements based on their importance to acceptable modeling of the scenario and their impact on the figures of merit for the calculation. This process is highly dependent on the type of reactor and the accident scenario of interest. Often a single computer code is used to analyze multiple accident or transient classes. A separate accident scenario identification description is needed for each accident or transient class for which the code is to be used in order to describe the accident progression and dominant physical phenomena for that particular accident. This description must explicitly reference code models and assessment cases that are specifically applicable to each scenario to avoid confusion when the same code is used for multiple accident scenarios. The processes and phenomena that evaluation models should simulate are found by examining experimental data and experience, as well as code simulations related to the specific scenario. Independent techniques to accomplish the ranking include expert opinion, selected calculations, and decision-making methods. The reviewers should confirm that the process used for accident scenario identification is a structured process. The reviewers should confirm that the description of each accident scenario provides a complete and accurate description of the plant initial and boundary conditions and the accident progression. The specified initial and boundary conditions must comply with values required by regulations or specified as acceptable in a regulatory guide or SRP section that covers the accident. The reviewers should confirm that the dominant physical phenomena influencing the outcome of the accident are correctly identified and ranked. The reviewers should keep in mind that the initial phases of the accident scenario identification process can rely heavily on expert opinion and can be subjective. Therefore, iteration of the process, based