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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can be subjective. Therefore, iteration of the process, based on experimentation and analysis, is important. One example of an acceptable structured process is the phenomena identification and ranking table (PIRT) process, which is described in NUREG/CR-5249, “Quantifying Reactor Safety Margins: Application of Code Scaling, Applicability, and Uncertainty Evaluation Methodology to a Large-Break, Loss-of-Coolant Accident” [Ref. 4]. The process is also described in a series of papers in the journal Nuclear Engineering Design [Ref. 5]. d. Code Assessment The reviewers should confirm that the code assessment adequately covers all of the important code models and the full range of conditions encountered in the accident scenarios. The assessment must be consistent with the accident scenario identification process in that all models must have assessment commensurate with their importance and required fidelity. The reviewers should also verify that all assessment cases were performed with a single version of the evaluation model. The reviewers should confirm that the numerical solution conserves all important quantities. Even when the mathematical equations conserve mass, momentum, and energy, the numerical method used to solve the equations may not conserve any of these quantities. The reviewers should also confirm that all code options that are to be used in the accident simulation are appropriate and are not used merely for code tuning. The reviewers should ensure that all code closure relationships based in part on experimental data or more detailed calculations have been assessed over the full range of conditions encountered in the accident scenario by means of comparison to separate effects test data. Scaling analyses may be needed to demonstrate that the assessment 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