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:
rent function. The diverse or different function may be performed by a non-safety system if the system is of sufficient quality to perform the necessary function under the associated event conditions. [Emphasis in original.] 4. A set of displays and controls located in the main control room shall be provided for manual, system-level actuation of critical safety functions and monitoring of parameters that support the safety functions. The displays and controls shall be independent and diverse from the safety computer system identified in items 1 and 3 above.7 The guiding principles in SECY-18-0090 clarify that the D3 assessment described in point 1 should be commensurate with the safety significance of the proposed DI&C system or component. Section B.2 provides guidance for reviewing an applicant’s safety-significance determinations, if any are used, and Section B.3.1 contains guidance for reviewing an applicant’s use of those determinations in the D3 assessment. Section B.2 also covers the review of an applicant’s determination that a D3 assessment is not necessary, based on a failure analysis. Point 2 uses the term “best estimate methods,” but this term is somewhat out of date; the same 7 While SRM-SECY-93-087 uses the terms “safety” and “non-safety,” from the context it is clear that these terms refer to safety-related and NSR SSCs, respectively. BTP 7-19-11 Revision 8 – January 2021 methods are now typically described as methods that use “realistic assumptions,” which are defined as the initial plant conditions corresponding to the onset of the event being analyzed. Point 2 also includes acceptance criteria that are less conservative than the acceptance criteria defined in the updated final safety analysis report (FSAR) for the applicable limiting events within the design basis. Initial plant event conditions include, but are not limited to, the following: • power levels • temperatures • pressures • flows • alignment of equipment