Document: NUREG-0800
Document ID: 632e6c59-03bd-4648-b0b3-e8b2efd6fa04
Document Type: srp
Title: CONTAINMENT ISOLATION SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0703/ML070380197.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.2.4
CFR Part: 
CFR Title: 

Content:
signated seismic Category I in accordance with RG 1.29. 17. GDC 54 requires reliable isolation capability; therefore, for remote-manual isolation valves, the design of the containment isolation system is acceptable if there are 6.2.4-9 Revision 3 - March 2007 provisions to allow the operator in the main control room to know when to isolate fluid systems equipped with remote-manual isolation valves. Such provisions may include instruments to measure flow rate, sump water level, temperature, pressure, and radiation level. 18. GDC 54 specifies requirements for the containment isolation system; therefore, to satisfy GDC 54, the design of the containment isolation system should provide for operability testing of the containment isolation valves and leakage rate testing of the isolation barriers. The isolation valve testing program should be consistent with that proposed for other engineered safety features. SRP Section 6.2.6 presents acceptance criteria for the leakage rate testing program for containment isolation barriers. 19. GDC 54 requires reliable isolation capability. To satisfy this requirement, the design of the containment isolation system should reduce the possibility of unintended isolation valve reopening following isolation. 10 CFR 50.34(f)(2)(xiv) requires control systems for automatic containment isolation valves be designed for resetting the isolation signal without automatically reopening the valves. Reopening of containment isolation valves should require deliberate operator action and combined reopening of containment isolation valves is not acceptable. Reopening of isolation valves must be valve by valve or line by line, provided that electrical independence and other single-failure criteria remain satisfied. Administrative provisions to close all isolation valves manually before resetting the isolation signals is not an acceptable method for meeting this design requirement. 20. In meeting 10 CFR 50.34(f)(2)(xv) purging requirements, the regulatory