Document: NUREG-0800
Document ID: d563bf0f-7b24-4ff5-99a2-4f822eb86bd9
Document Type: srp
Title: INTERLOCK SYSTEMS IMPORTANT TO SAFETY
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052360612.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.6
CFR Part: 
CFR Title: 

Content:
t to safety are reviewed as follows: 1. The interlocks to prevent overpressurization of low pressure systems are reviewed. Guidance for the'review of this area is provided in BTP ICSB 3, "Isolation of Low Pressure Systems from the High Pressure Reactor Coolant System." 2. The interlocks to prevent overpressure of the primary coolant system during low temperature operations of this vessel are reviewed. Guidance for the review of this area is provided in BTP RSB 5-2. 3. The interlocks for ECCS accumulator valves are reviewed. Guidance for the review of this area is provided in BTP ICSB 4, "Requirements of Motor Operated Valves in the ECCS Accumulator Lines." 4. Any interlocks required to isolate safety systems from non-safety systems and any interlock required to preclude inadvertent interties between redundant or diverse safety systems are addressed on an individual case basis. For those interlock systems for which the staff has taken the position that they should conform to the requirements of IEEE-279, review guidance is provided in Appendix B of SRP Section 7.1 (Ref. 5) for evaluating conformance. The design basis for'all interlock systems important to. safety are reviewed to confirm the adequacy of the system design consistent with the importance to safety of the functions performed. Design considerations such as redundancy, independence, single failures, qualification, bypasses, status indication, and testing should be considered. To the extent applicable, the guidelines used 7.6-3 Rev. 2 - July 1981 to demonstrate conformance to the acceptance criteria for safety systems may be used as a guide to address the adequacy of the design features for interlock systems important to safety. An important part of the review is the engineering drawing review at the OL stage. The drawing review should confirm that the design and layout meet the applicable criteria listed under subsection II. A site visit should be performed before the evaluation findings are written for an