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:
ed on use and physical characteristics of the plant-site environs. Compliance with GDC 55 requirements provides reasonable assurance that lines penetrating the containment and connected to the reactor coolant system will not be sources of excessive offsite radiation doses due to either line rupture or failure of a valve to close. 7. GDC 56, "Primary Containment Isolation," requires that each line that connects directly to the containment atmosphere and penetrates the primary reactor containment must meet specified criteria for the use and positioning of isolation valves. 6.2.4-12 Revision 3 - March 2007 GDC 56 applies to this SRP section because the reviewer evaluates the containment isolation system to ensure that (A) there is no direct connection between the containment atmosphere and the plant environs or (B) if there is direct communication (as that during containment purging or venting) that the lines can be reliably isolated. This assurance is provided by specific requirements for isolation valves (i.e., locked-closed, automatic, or a combination of locked-closed and automatic) on both sides of the containment barrier. Isolation valves outside the containment should be located as close to the containment as is practical. Upon loss of actuating power, automatic valves must take the position of greatest safety. BTP 6-4 contains specific requirements for containment purge and vent valves, providing a high degree of assurance that these valves will isolate reliably under accident conditions. Compliance with GDC 56 requirements provides reasonable assurance that lines penetrating the containment and connected to the containment atmosphere will not be sources of excessive offsite radiation doses due to either line rupture or failure of a valve to close. 8. GDC 57, "Closed System Isolation Valves," requires, for each line penetrating the primary reactor containment which is neither part of the reactor coolant pressure boundary nor connected directly to the