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:
mportant contributing factor, the core void fraction during reflood, was not predicted accurately. 15.0.2-12 Initial Issuance - December 2005 In the case of LOCA evaluation models, specific assessment test cases are required in order to meet the requirements of Appendix K to 10 CFR Part 50. Specific test cases are also specified in the TMI action items for PWR small-break LOCA (SBLOCA) evaluation models. The reviewers should confirm that these assessments have been performed where applicable. The reviewers should refer to published literature for sources of assessment data for specific phenomena, accident scenarios, and plant types. These include the ECCS Compendium [Ref. 6], NEA validation data documents [Refs. 7, 8, and 9], and International Standard problems. e. Uncertainty Analysis The reviewers should confirm that the method for calculating uncertainty contains all important sources of uncertainty and that a sample uncertainty calculation for a prototypical plant gives a reasonable estimate of the calculation uncertainty. The reviewers should confirm that the accident scenario identification process was used in identifying the important sources of uncertainty. The reviewers should confirm that sources of code uncertainty have been addressed. These include uncertainties in theoretical models or closure relationships determined from 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