Document: NUREG-0800
Document ID: 07e6bf87-51bb-4023-80a2-2a67ca4a9f80
Document Type: srp
Title: Revision 3 - March 2007
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0707/ML070740319.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6
CFR Part: 
CFR Title: 

Content:
ria) to reflect the importance to safety of isolating these lines. GDC 56 establishes explicit requirements for isolation barriers in purge system lines. E. To improve the reliability of the isolation function addressed in GDC 54, instrumentation and control systems isolating the purge system lines should be independent and actuated by diverse parameters (e.g., containment pressure, safety injection actuation, and containment radiation level). Furthermore, if energy is required to close the valves, at least two sources of energy must be provided, either of which can effect the isolation function. F. Purge system isolation valve closure times, including instrumentation delays, should not exceed five seconds to facilitate compliance with 10 CFR Part 100 for offsite radiological consequences. G. Isolation valve closure must not be prevented by debris which could become entrained in the escaping air and steam. BTP 6-4-4 Revision 3 - March 2007 2. The purge system should not be relied on for temperature and humidity control within the containment. 3. The need for purging of the containment should be minimized by containment atmosphere cleanup systems within the containment. 4. The availability of the isolation function and the leakage rate of the isolation valves during reactor operation should be tested. 5. The following analyses should justify the containment purge system design: A. An analysis of the radiological consequences of a LOCA should be done for a spectrum of break sizes, and the instrumentation and setpoints that will actuate the purge valve closures should be identified. The source term in the radiological calculations should be based on a calculation under the terms of 10 CFR Part 50, Appendix K, to the extent of fuel failure and the concomitant release of fission products and the fission product activity in the primary coolant. A pre-existing iodine spike should be considered in determining primary coolant activity. The volume of containment in which