Document: NUREG-0800
Document ID: fe8ec6c2-e960-404c-854f-55c77bde1672
Document Type: srp
Title: NUREG-0800
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML2400/ML24005A077.pdf
Revision Date: 2024-05
Chapter: 7
Section ID: 7
CFR Part: 
CFR Title: 

Content:
different systems are appropriately prioritized to maintain the overall defense-in-depth strategy. If the proposed DI&C system and the new diverse I&C system share resources (e.g., priority modules), the reviewer should consider the priority in the use of shared resources in regard to its safety and protection functions, so that safety and protection functions are always carried out first. RG 1.152 provides guidance on prioritization of control and protection systems sharing components. (In some cases, certain components may have more than one safe state; the reviewer should consider whether the priority scheme describes all safe states.) Acceptance Criteria for Crediting a New Diverse Instrumentation and Control System If the following acceptance criteria are met, the reviewer should conclude that the use of a new diverse I&C system is acceptable: a. If the diverse I&C system uses equipment that is not safety related, the equipment is of sufficient quality to perform the necessary function(s) during the associated event conditions. b. Sufficient diversity exists between the diverse system and the proposed system so that they are not vulnerable to the same postulated CCF. c. The equipment credited has functional capabilities sufficient to maintain the plant within the acceptance criteria defined in the FSAR or the LAR for the limiting events applicable to the proposed DI&C system. d. Resources shared by the proposed DI&C system(s), other systems, and manual operator actions are controlled by prioritization of commands consistent with the guidance in RG 1.152. The basis for the prioritization should be documented. BTP 7-19-28 Revision 9 — May 2024 3.3 Consequences of a Digital Instrumentation and Control System Common-Cause Failure May Be Acceptable This section addresses applications that propose that the consequences of a residual identified CCF remain acceptable. For such applications, the reviewer should consider whether the applicant’s analysis demonstrates