Document: NUREG-0800
Document ID: 55688d47-80f6-498a-af38-5bfb9d7420aa
Document Type: srp
Title: Revision 3 - March 2007
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0707/ML070740004.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6
CFR Part: 
CFR Title: 

Content:
ion 3 - March 2007 postulated LOCA whenever the secondary containment volume is at a "positive" pressure (i.e., greater than -0.063 kPa (-0.25 inches water gauge)). Positive pressure periods should be determined by a pressure response analysis of the secondary containment volume including thermal loads from the primary containment and infiltration leakage. 3. The secondary containment depressurization and filtration systems should be designed in accordance with Regulatory Guide (RG) 1.52, "Design, Testing, and Maintenance Criteria for Atmosphere Cleanup System Air Filtration and Adsorption Units of Light-Water Cooled Nuclear Power Plants." Preoperational and periodic inservice inspection and test programs should be proposed for these systems and should include means for determining the secondary containment infiltration rate and the capability of the systems to draw down the secondary containment to the prescribed negative pressure in a prescribed time. 4. For secondary containments with design leakage rates greater than 100 volume percent per day, there should be an exfiltration analysis. 5. The following leakage barriers in paths which do not terminate within the secondary containment should be considered potential bypass leakage paths around the leakage collection and filtration systems of the secondary containment: A. Isolation valves in piping which penetrates both the primary and secondary containment barriers. B. Seals and gaskets on penetrations which pass through both the primary and secondary containment barriers. C. Welded joints on penetrations (e.g., guard pipes) which pass through both the primary and secondary containment barriers. 6. The total leakage rate for all potential bypass leakage paths, as identified in item 5, should be determined realistically, considering equipment design limitations and test sensitivities. This value should be used in calculating the offsite radiological consequences of postulated LOCAs and in setting technical