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
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ty data, and parameter values both at the component and system level. The reviewer should evaluate the sensitivity studies performed by the applicant on the PRA models and data to assess the effect of uncertainty on CDF, risk, and PRA insights. Sensitivity studies may be particularly helpful in assessing the effectiveness of design attributes. Additional support for the review and treatment of uncertainties is provided by NUREG-1855, “Guidance on the Treatment of Uncertainties Associated with PRAs in Risk-Informed Decision making,” dated November 2007. 19.0-29 Draft Revision 3 – September 2012 E. The DI&C reviewer should confirm that DI&C system equipment is capable of meeting its safety function in environments associated with accident sequences modeled in the PRA. This is done in collaboration with the reviewer for the PRA and severe accident evaluation who provides input on the expected environments that need to be considered. F. The reviewer should confirm that the impact of external events (i.e., seismic, fire, high winds, flood and others) has been addressed with regard to DI&C. A specific concern is the impact of fire on DI&C systems. Important scope, boundary condition, and modeling assumptions need to be determined and evaluated. Verify that the assumptions made in developing the PRA model and data are realistic, and that the associated technical justifications are sound and documented. The reviewer should pay attention to assumptions about the potential effects from failure of defensive measures.6 A DI&C defensive measure may have the unintended consequence of causing spurious trips or spuriously failing functional capabilities. The applicant should describe the segregation process that prevents this from occurring. The PRA reviewer should work with the I&C reviewer to evaluate the process discussed by the applicant. G. The PRA reviewer should evaluate the treatment of the recovery actions taken for loss of DI&C functions, referring to RG 1.200 and