Document: NUREG-0800
Document ID: dc63e8aa-2a74-4078-9e19-9a26ed1b4d8c
Document Type: srp
Title: Revision 6 – July 2012
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1105/ML110550791.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
ation of guidance from DI&C-ISG-02, Revision 2, the outline format was expanded. Section 1.1 was added to collect and organize an improved description of the Echelons of Defense. Section 1.2 was added to list the “plant critical safety functions” from NUREG-0737, Supplement No. 1. Section 1.3 added criteria for combining RTS and ESFAS in one divisional controller or computer, or using a limited number of digital components in a division for the combined RTS and ESFAS logic. Section 1.4 was added to present the NRC position on D3 by quoting the four points directly from the SRM on SECY-97-087 followed by comments and positions providing interpretations on Points 2, 3, and 4 including a definition of best-estimate or realistic assumptions in D3 analysis. Specifically, guidance was provided on independence as it applies to a diverse means. System level (or division level depending on the design) was retained as compared to component level for actuation of Point 4 controls. Section 1.5 was added to discuss the potential for the need for two different manual initiation means of initiating the automatic protective actions and the acceptance criteria for having only one manual initiation means. Figure 1 was added to help illustrate this concept as requested by the ACRS. Section 1.6 was added to collect and organize information about the D3 assessment using NUREG/CR-6303 and state that if the analysis determined there was a potential for CCF, then a diverse means was needed. Section 1.7 was added to specifically state that if a diverse means is needed to be available to replace an automatic system used to accomplish a credited safety function due to a potential CCF, then the diverse means may be accomplished by either an automated system or manual operator actions. The preferred means was an automated system. Section 1.8 was added to address potential effects of CCF concerning failure to actuate and spurious actuations. This section was updated based on the ACRS