Document: NUREG-0800
Document ID: ecf7a8d4-0097-4a93-8609-630545f03f70
Document Type: srp
Title: REGULATORY TREATMENT OF NONSAFETY SYSTEMS FOR PASSIVE
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1308/ML13081A756.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.3
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n a safe stable shutdown condition1 in the post 72-hour period and following seismic events, and the methods for achieving those safety functions. The staff verifies that nonsafety-related SSCs relied upon to achieve those functions have been included in the scope of the RTNSS program (RTNSS “B”). 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 at value less than or equal to 420 degrees F. 19.3-10 Draft Rev.0 – June 2013 3. The staff reviews the applicant’s description of the Seismic Margins Analysis (SMA) documented in Chapter 19 of the FSAR to identify any nonsafety-related SSCs that have been credited in the SMA. The staff confirms that any nonsafety-related SSCs that are relied upon to meet the acceptance criteria for the SMA have been included in the scope of the RTNSS program (RTNSS “B”). 4. The PRA and Severe Accident staff reviews the results of the focused PRA sensitivity studies as described in SRP 19.0, “Probabilistic Risk Assessment and Severe Accident Evaluation for New Reactors,” Revision 3, 2013. The staff confirms that nonsafety-related design features or functional capabilities with mitigation capability sufficient to reduce the CDF or LRF below the Commission goals when credited in the focused PRA have been identified as risk-significant and included in the scope of the RTNSS program (RTNSS “C”). 5. The PRA and Severe Accident staff use information in Chapters 15 and 19 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 evaluation of risk-significance based on their contribution to initiating event frequencies. The staff then