Document: NUREG-0800
Document ID: 7e0d3b3e-62c3-4492-ba89-6cebb4e82234
Document Type: srp
Title: SECONDARY CONTAINMENT FUNCTIONAL DESIGN
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340701.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.2.3
CFR Part: 
CFR Title: 

Content:
es on the functional capability of the depressurization and filtration systems should be evaluated and confirmatory preoperational tests conducted. d. Some plants may have only portions of the primary containment enclosed, rather than having a secondary containment structure or shield building that completely encloses the primary containment. These enclosed areas are areas into which the primary containment would most likely leak, and they may be equipped with air filtration systems. Quantitative credit cannot be given for the holdup effect of these enclosed areas or for the air filtration systems, to mitigate the radiological consequences of a postulated accident, unless the magnitude of unprocessed leakage can be adequately demonstrated. Quantitative credit for leakage collection in a partial-dual contain- ment will be reviewed on a case-by-case basis. 6.2.3-4 Rev. 2 - July 1981 e. The external design pressure of the secondary containment structure should provide an adequate margin above the maximum expected external pressure. 4. In meeting the requirements of GDC 43 and 10 CFR Part 50, Appendix J, regarding the inspection and testing of the secondary containment system, the following criteria apply: a. The fraction of primary containment leakage bypassing the secondary containment and escaping directly to the environment should be speci- fied. Branch Technical Position (BTP) CSB 6-3 (Ref. 5) provides guidance for identifying the leakage paths to the environment which may bypass the secondary containment. The periodic leakage rate testing program for measuring the fraction of primary containment leakage that may directly bypass the secondary containment and other contiguous areas served by ventilation and filtration systems should be described. b. Provisions should be made in the design of the secondary containment system to permit inspections and monitoring of the functional capability. The determination of the depressurization time, the secondary contain- ment