Document: NUREG-0800
Document ID: 2bca792d-0e88-4e2d-b437-be572ed57a48
Document Type: srp
Title: REVIEW OF TRANSIENT AND ACCIDENT ANALYSIS METHODS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0708/ML070820123.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.0.2
CFR Part: 
CFR Title: 

Content:
comparison to separate effects tests, uncertainties due to scaling of the basic models and closure relationships, and uncertainties due to plant nodalization and solution techniques. The reviewers can sometimes determine whether the code uncertainty is reasonable by applying a simple analytical model. This can be done if the dominant contribution to uncertainty is confined to a small number of models. In other cases, detailed audit calculations may be needed to confirm the estimate of uncertainty in a calculation. The reviewers should confirm that sources of calculation uncertainties have been addressed, including uncertainties in plant model input parameters for plant operating conditions (e.g., accident initial conditions, set points, and boundary conditions). Calculation uncertainties are specific to a given licensing calculation. Therefore, it is sometimes acceptable to use bounding values in the licensing calculation for these types of uncertainties. 15.0.2-12 March 2007 The reviewers should confirm that the uncertainties in the experimental data base have been addressed. These uncertainties arise from such items as measurement errors and experimental distortions. For separate effects tests and integral effects tests, the reviewers should confirm that the differences between calculated results and experimental data for important phenomena have been quantified for bias and deviation. The reviewers should confirm that data sets and correlations with experimental uncertainties that are too large when compared to the requirements for evaluation model assessment are not used. When the code is used in a licensing calculation, the reviewers should confirm that the combined code and application uncertainty is less than the design margin for the safety parameter of interest in the calculation. For best estimate LOCA analyses, uncertainty determination description and guidance are described in NUREG/CR-5249, Regulatory Guide 1.157, and Appendix A to Regulatory Guide