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:
t or review process many code options may be determined to be inappropriate for specific licensing calculations. The reviewers should confirm that the guidance in the manual specifies the required and acceptable code options for the specific licensing calculations. The reviewers should also confirm that required input settings are hardwired into the input processor so that the code stops with an error message if the required input is not provided or if the input is not within an acceptable range of values or that administrative controls ( an independent reviewer QA check) are in place that accomplish the same purpose. The reviewers should confirm that computer codes that are used for multiple accidents and transients include guidelines that are specific to each transient or accident. Code assessment cases can be examined to ensure that the modeling used in the assessment cases is consistent with the user guidelines. b. Evaluation Model The reviewers should determine whether the mathematical modeling and computer codes used to analyze the transient or accident have been previously reviewed and accepted. For changes to previously approved models, the reviewers can limit their review to the new material if they determine that there is nothing new that will invalidate the previous approval, including the range of applicability for the analysis method. Otherwise the entire model must be reviewed. For a new model that has not been previously reviewed, the reviewers initiate an evaluation of the entire analytical model. The reviewers should determine if the physical modeling described in the theory manual and contained in the mathematical models is adequate to calculate the physical phenomena influencing the accident scenario for which the code is used. A scenario will have a set of governing physical phenomena that drive the results of the calculation. The key physical phenomena, including constitutive equations needed for model closure, must be defined for the