Document: NUREG-0800
Document ID: 6c5a07e2-91cf-49ae-a450-62551ed6bcef
Document Type: srp
Title: CONTAINMENT ISOLATION SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340703.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.2.4
CFR Part: 
CFR Title: 

Content:
to the require- ments of SRP Section 3.6.2. Design of the valve and/or the piping compartment should provide the capability to detect leakage from the valve shaft and/or bonnet seals and terminate the leakage. f. Sealed closed barriers may be used in place of automatic isolation valves. Sealed closed barriers include blind flanges and sealed closed isolation valves which may be closed manual valves, closed remote-manual valves, and closed automatic valves which remain closed after a loss-of-coolant accident. Sealed closed isolation valves should be under administrative control to assure that they cannot be inadvertently opened. Administra- tive control includes mechanical devices to seal or lock the valve closed, or to prevent power from being supplied to the valve operator. g. Relief valves may be used as isolation valves provided the relief setpoint is greater than 1.5 times the containment design pressure. h. Item II.E.4.2 of NUREG-0737 and NUREG-0718 requires that systems penetrat- ing the containment be classified as either essential or nonessential. Regulatory Guide 1.141 will contain guidance on the classification of essential and nonessential systems. Essential systems, such as those des- cribed in items b and c, may include remote-manual containment isolation valves, but provisions should be made to detect possible leakage from the lines outside containment. Item II.E.4.2 of NUREG-0737 and NUREG-0718 also requires that nonessential systems be.automatically isolated by the containment isolation signal. ;. Isolation valves outside contaiment should be located as close to the con- tainment as practical, as required by General Design Criteria 55, 56, and 57. j. In meeting the requirements of General Design Criteria 55 and 56, upon loss of actuating power, automatic isolation valves should take the posi- tion that provides greater safety. The position of an isolation valve for normal and shutdown plant operating conditions and postaccident condi- tions.depends