Document: NUREG-0800
Document ID: 96afb1d6-6ce9-41e4-b4ec-1fc7747bc0b2
Document Type: srp
Title: Revision 8 – January 2021
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML2033/ML20339A647.pdf
Revision Date: 2023-05
Chapter: 7
Section ID: 7
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Content:
&C system that is credited for mitigating an AOO or PA in the accident analysis. Typically, the automatic safety-related I&C system is credited, but for some events, manual safety-related controls are credited. 1.2 Critical Safety Functions SECY-93-0087 identified the following critical safety functions to be managed from the MCR in accordance with point 4: • reactivity control • core heat removal • reactor coolant inventory • containment isolation • containment integrity Other safety functions an applicant identifies in the SAR may not always be “critical safety functions” in the terminology of SRM-SECY-93-087. NUREG-0737, Supplement 1, “Clarification of TMI Action Plan Requirements: Requirements for Emergency Response Capability,” issued January 1983, provides additional guidance on identifying critical safety functions. 2. Safety Significance and Effects of Failure This section provides guidance to reviewers on implementing Principle 3 in SECY-18-0090, which explains that a D3 assessment should be “commensurate with the safety significance of the system” and “may not be necessary for some low-safety-significance l&C systems whose failure would not adversely affect a safety function or place a plant in a condition that cannot be reasonably mitigated.” Specifically, this section provides guidance on how to evaluate the relative safety significance of the functions performed by an SSC and how to evaluate an 9 While SRM-SECY-93-087 uses the terms “safety” and “non-safety,” these terms in context refer to safety-related and NSR SSCs, respectively. 10 SECY-18-0090 did not elaborate on point 4. BTP 7-19-13 Revision 8 – January 2021 application that does not include a D3 assessment for a low-safety-significant SSC, based on the potential effects of the SSC’s failure. 2.1 Safety-Significance Determination For the purposes of this BTP, a safety-significant function is one whose degradation or loss could have a significant adverse