Document: NUREG-0800
Document ID: 2717fe7f-71fd-4f1e-bd08-7685b24763ba
Document Type: srp
Title: Standard Review Plans are prepared for the guidance of the Office of Nuclear Reactor Regulation staff responsible for th
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0301/ML030160606.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15
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Content:
t results apply to the full-scale plant accident conditions. Even closure relationships such as equations of state and material properties that are based on interpolating functions need to be assessed against standards for the properties. For example, a relatively small error in thermodynamic properties such as phasic densities as a function of temperature and pressure may cause a larger error when propagated to a neutron kinetics model in a main steamline break or an anticipated transient without scram (ATWS) calculation. The reviewers should ensure that integral test assessments properly demonstrate physical and code model interactions that are determined to be important for the full size plant accident scenarios. The integral test will usually not be full-scale, and therefore will contain scaling distortions. These distortions can affect both local and overall elements of the analysis, such as two-phase flow regime transitions and global dynamic response of the test facility, when compared to the full scale plant. The reviewers should ensure that 11 the documentation contains comparisons of all important experimental measurements with the code predictions in order to expose possible cases of compensating errors. Such errors may result in good predictions of key parameters, derived from poor predictions of contributing parameters. These cases are often indicative of tuning the code to an integral experiment. One example of this is described in NUREG/CR-5249 [Refs. 4 and 5], in which key parameters, namely large break LOCA (LBLOCA) reflood peak cladding temperatures were predicted well, even though an important contributing factor, the core void fraction during reflood, was not predicted accurately. In the case of LOCA evaluation models, specific assessment test cases are required in order to meet the requirements of 10 CFR 50, Appendix K. Specific test cases are also specified in the TMI action items for PWR small break LOCA (SBLOCA) evaluation models. The