Document: NUREG-0800
Document ID: 3e34268a-a6f4-4ce5-ba4d-7f2cec5a192e
Document Type: srp
Title: NUREG-0800
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070481.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6
CFR Part: 
CFR Title: 

Content:
advertent actuation of this system.29 The SCSB performs confirmatory containment response analyses when necessary using the CONTEMPT-LT computer code (References 5 and 66 and 7 ). The purpose of these analyses is 30 to confirm the applicant's predictions of the response of the containment to loss-of-coolant accidents and main steam and feedwater line breaks. In general, only the limiting pipe breaks, i.e., the pipe breaks which establish the containment design pressure and containment depressurization time, are analyzed. However, if in the judgment of the SCSB the worst break 31 has not been identified, other pipe breaks will be analyzed. The SCSB reviews analyses of the external pressure of the containment structure caused by pressure and temperature changes inside the containment due to inadvertent operation of containment heat removal systems. The SCSB determines whether the most severe condition has been identified and whether the analysis was done in a conservative manner. For plants at the construction permit (CP) or design certification (DC) stage of review the external design pressure margin should be at least 10%. For plants at the operating license (OL) stage of review, the maximum expected external pressure should be less than the containment external design pressure. In general, the maximum expected external pressure should be approximately the same as at the construction permit or design certification stage of review. However, revised or upgraded analytical models or minor changes in the as-built design of the plant may result in a decrease in the margin. If the primary containment is not designed to withstand the maximum 32 external pressure, the SCSB will evaluate the acceptability of the provisions made in the plant 33 design to mitigate or withstand the consequences of the above postulated events, and will evaluate in conjunction with the HICSB , the administrative controls and instrumentation and 34 control provisions to preclude these events. The