Document: NUREG-0800
Document ID: 39eaebb5-884c-4731-895a-8df4686b7293
Document Type: srp
Title: REGULATORY TREATMENT OF NONSAFETY SYSTEMS FOR PASSIVE
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1403/ML14035A149.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.3
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of the FSAR pertaining to initiators of transients and accidents affecting the nuclear steam supply system, and consult as necessary with reviewers of those sections, to verify that the applicant has correctly identified the SSCs that require 1 The NRC considers a “safe stable shutdown condition” for advanced passive LWRs to be a condition by which all plant conditions are stable and within regulatory limits, and the reactor coolant system pressure is stabilized and reactor coolant temperature is less than or equal to 420 degrees Fahrenheit (SECY-94-084). 19.3-10 Revision 0 – June 2014 evaluation of risk-significance based on their contribution to initiating event frequencies. The staff then verifies that the applicant has completely addressed the following screening criteria for assessing risk significance of those SSCs with respect to initiating event frequency: a. Does the calculation of the initiating event frequency consider the nonsafety-related SSCs? b. Does the unavailability of the nonsafety-related SSCs significantly affect the calculation of the initiating event frequency? c. Does the initiating event significantly2 affect the CDF and the LRF? The staff verifies that the applicant has included nonsafety-related SSCs in the scope of the RTNSS program that satisfy the screening criteria listed above (RTNSS “C”). 6. The Staff responsible for review of the applicant’s PRA reviews the applicant’s evaluation of potential uncertainties associated with assumptions made in the PRA regarding passive systems and verifies that the applicant has included nonsafety-related SSCs in the scope of the RTNSS program to compensate for the uncertainties in the PRA and in the modeling of severe accident phenomenology, or provided a reasonable justification for not doing so (RTNSS “C”). 7. The staff verifies that the applicant included any nonsafety-related SSCs credited in meeting the Commission’s containment performance goals in the scope of the RTNSS