Document: NUREG-0800
Document ID: 8dd882f4-a34f-4415-acd1-ebb441c72786
Document Type: srp
Title: PROBABILISTIC RISK ASSESSMENT AND SEVERE ACCIDENT
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1213/ML12132A481.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.0
CFR Part: 
CFR Title: 

Content:
rates (including CCF) will likely be more robust than the software failure data. Review of applicant claims regarding data should be proportional to the use made of the PRA results. If limited use is made, limited review is necessary. If the applicant claims CCF rates that are more than an order of magnitude lower than other component groups (especially for software), an NRC audit of data calculations may be warranted. Data (either public or system-specific) have been a limiting factor in the evaluation of risk for DI&C systems. The guidelines in Subsection 4.5.6, “Data analysis,” of the ASME standard for PRA, ASME RA-S-2002 and Addenda, for nuclear power plant applications should be satisfied consistent with the clarifications and qualifications of RG 1.200. Determine if the process used to determine basic event probabilities is reasonable. Check the assumptions made in calculating the probabilities of basic events (unavailabilities). Confirm that the data used in the PRA are appropriate for the hardware and software version being modeled, or that adequate justification is provided. Note that a fault-tolerant feature of a DI&C system (or one of its components) can be explicitly included either in the logic model or in the probabilistic data of the components in the model. It should not be included in both because this would result in double-counting the feature’s contribution. H. If the values of the data used appear to be skewed and use of different values might change the insights drawn from the DI&C risk assessment, confirm that the data meet the following criteria: a. The data are obtained from the operating experience of the same equipment as that being evaluated, and preferably in the same or similar applications and operating environment. Uncertainty bounds should appropriately reflect the level of uncertainty. (Applies to both component- specific and generic data) 19.0-33 Draft Revision 3 – September 2012 b. The sources for raw data or generic