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:
ame CCF as) the equipment performing the same function within the DI&C system. c. The credited SSC is accessible to the operator during the associated event conditions, is capable of functioning under the expected conditions, and is of adequate quality. d. The indications and controls needed to support the manual operator action have the functional characteristics necessary to maintain the plant within the facility operating limits. BTP 7-19-27 Revision 9 — May 2024 3.2.3 Crediting a New Diverse Instrumentation and Control System The applicant may propose a new diverse system (e.g., a diverse actuation system) as a diverse means either of accomplishing a function that is the same as or is different from the function credited in the D3 assessment; or of mitigating spurious operation due to CCF. In this case, the reviewer should determine whether the application demonstrates that (1) the functions performed by this diverse means suffice to maintain plant conditions within specified acceptance criteria for the associated DBE, and (2) sufficient diversity exists between the new system and the proposed DI&C system so that they are not vulnerable to the same postulated CCF. The reviewer should determine whether the diverse means credited and the digital design of the proposed system are vulnerable to the same CCF. The new diverse I&C system may be a system that is not safety related if it is of sufficient quality to perform the necessary functions under the associated event conditions. The reviewer should consider whether the new diverse I&C system can function under the event conditions expected and whether it is of adequate quality. Prioritization If a new diverse I&C system is implemented, the reviewer should verify that the signals to actuate components coming from the 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),