Document: NUREG-0800
Document ID: c23d52ec-d83f-4468-b35e-e8c97fdf2f09
Document Type: srp
Title: CONTAINMENT ISOLATION SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070461.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.2.4
CFR Part: 
CFR Title: 

Content:
r evaluates the containment isolation system to ensure that there is no direct communication between the fluids in the closed system and the plant environment. This assurance is provided by specifying requirements for a closed system and for an isolation valve that is locked-closed, automatic, or capable of remote-manual operation. A single valve is specified because the system is closed; hence, failure of the valve to close would not, by itself, allow communication between fluids in the closed system and the plant environment. DRAFT Rev. 3 - April 1996 6.2.4-14 Meeting the requirements of GDC 57 provides assurance that lines penetrating the containment and connected to closed systems will not be a source of excessive offsite radiation doses due to either line rupture or failure of a valve to close.71 9. 10 CFR 50.63 requires that all light-water-cooled nuclear power plants be able to withstand and recover from a station blackout and that necessary systems be capable of ensuring that the core is cooled and that appropriate containment integrity is maintained in the event of a station blackout. Guidance for compliance with 10 CFR 50.63 is provided in Regulatory Guide 1.155. Since many safety systems necessary to support safe operation and shutdown of the reactor are dependent on ac power, the consequences of a station blackout could be severe, particularly if the integrity of barriers to prevent the release of fission products (e.g., fuel cladding, reactor coolant pressure boundary, containment) are not maintained throughout the event and its associated recovery period. The containment isolation system, including its provisions for control, indication, and performance under loss/restoration of power conditions, is instrumental in ensuring that integrity of the containment barrier is maintained without undue interference with flow paths essential for cooling the reactor core. Compliance with 10 CFR 50.63 and the positions of Regulatory Guide 1.155 regarding the