Document: NUREG-0800
Document ID: b2a0ee3d-abd7-482f-bdbe-eafd11e379b8
Document Type: srp
Title: B-8
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550087.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.1
CFR Part: 
CFR Title: 

Content:
on System Interaction (IEEE Std. 279-1971 Clause 4.7) Control and protection system interaction involves more than examining the electrical isolation and interconnection. The functional performance of control systems must be such that a control system cannot prevent proper action of a protection system. Clause 4.7 of IEEE Std. 279-1971, with regard to isolation devices and multiple failures resulting from a credible single event, is explained by example in the document (See Clause 4.2 of IEEE Std. 279-1971). The applicant/licensee's analysis should confirm that the requirements for control and protection system interaction are satisfied. 4.8. Derivation of System Inputs (IEEE Std. 279-1971 Clause 4.8) A protection system that requires loss of flow protection would, for example, normally derive its signal from flow sensors. A design might use an indirect parameter such as a pressure signal or pump speed. However, the applicant/licensee should verify that any indirect parameter is a valid representation of the desired direct parameter for all events. Even a directly measured variable should be reviewed and its response to postulated events compared with the credit taken for the parameter in the events for which it provides protection.