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:
ystem design attributes and requirements and for any potential interconnectivities, including resource sharing, with other systems. The reviewer should pay particular attention to whether there may be interconnectivities (including resource sharing) not accounted for in the LAR that could result in the existing I&C system being subject to the same CCF as the proposed DI&C system. The reviewer should verify that the application identifies all the features of the existing I&C system that are relevant to demonstrating diversity. In addition, if crediting an existing I&C system could affect the facility’s existing licensing basis, then the reviewer should verify that the LAR addresses how the existing I&C system functions would be credited and justified in a revised licensing basis. The credited existing I&C system may be a system that is not safety related, as long as it is of sufficient quality and can reliably perform the credited functions under the associated event conditions. If the applicant credits existing I&C systems that are not safety related that are in continuous use (e.g., the normal control systems for the reactor coolant system inventory or the steam generator level), these systems need not meet augmented quality standards. However, if the applicant credits existing I&C systems that are not safety related and that are not in continuous use (i.e., that are normally in standby mode), then the reviewer should verify that the applicant has demonstrated that the system will reliably perform its intended function. For example, the applicant may credit the plant ATWS system as a diverse means of achieving reactor shutdown, provided that the ATWS system is capable of responding to the same analyzed events as the proposed DI&C system. In this case, the reviewer should consider whether the D3 analysis demonstrates that the ATWS system (1) is not vulnerable to the same CCF as the equipment performing the reactor trip function within the proposed DI&C system, (2)