Document: NUREG-0800
Document ID: c53cf2ef-5eb4-4449-bed4-17a9eff508e3
Document Type: srp
Title: SECONDARY CONTAINMENT FUNCTIONAL DESIGN
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0636/ML063600406.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.2.3
CFR Part: 
CFR Title: 

Content:
t the secondary containment as well as other areas served by the systems. B. The negative pressure differential to be maintained in the secondary containment and other contiguous plant areas should be no less than 0.063 kPa (0.25 inches water gauge) compared to adjacent regions under all wind conditions up to the wind speed at which diffusion becomes sufficient to assure site boundary exposures less than those calculated for the design basis accident even if exfiltration occurs. If the leakage rate exceeds 100 percent of the volume per day, there should be a special exfiltration analysis. C. All openings like personnel doors and equipment hatches should be under administrative control with readout position indicators and alarms in the main control room. The effect of open doors or hatches 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 a secondary containment structure or shield building completely enclosing the primary containment. These enclosures are areas into which the primary containment most likely would leak, and they may be equipped with air filtration 6.2.3-6 Revision 3 - March 2007 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 containment will be reviewed case by case. E. The external design pressure of the secondary containment structure should provide an adequate margin above the maximum expected external pressure. 4. In meeting GDC 43 and 10 CFR Part 50, Appendix J, requirements for secondary containment system testing the following criteria apply: A. The fraction of primary containment leakage