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:
Revision 5 - March 2007 the applicant/licensee's failure modes and effects analysis. The analysis should justify the acceptability of each failure effect. RTS functions should typically fail in the tripped state. ESFAS functions should fail to a predefined safe state. For many ESFAS functions this predefined safe state will be that the actuated component remains as-is. 4.6. Channel Independence (IEEE Std. 279-1971 Clause 4.6) Two aspects of independence should be addressed: • Physical independence. • Electrical independence. Guidance for evaluation of physical and electrical channel independence is provided in Regulatory Guide 1.75, Revision 3, "Criteria for Independence of Electrical Safety Systems," which endorses IEEE Std. 384-1992, "IEEE Standard Criteria for Independence of Class 1E Equipment and Circuits." The applicant/licensee should confirm that the protection system design precludes the use of components that are common to redundant channels, such as common switches for actuation, reset, mode, or test; common sensing lines; or any other features that could compromise the independence of redundant channels. Physical independence is attained by physical separation and physical barriers. Electrical independence shall include the utilization of separate power sources. The organization responsible for the review of electrical systems reviews power source requirements. Reviewers in the organization responsible for the review of I&Cs should coordinate with the electrical systems reviewers to confirm that I&C protection system power sources are adequate. Transmission of signals between independent channels should be through isolation devices. SRP BTP 7-11 provides guidance for the application and qualification of isolation devices. 4.7. Control and Protection 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