Document: NUREG-0800
Document ID: 47be7233-5326-4a7d-a9c5-f3b91d565a72
Document Type: srp
Title: MINIMUM CONTAINMENT PRESSURE ANALYSIS FOR EMERGENCY CORE
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070492.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.2.1.5
CFR Part: 
CFR Title: 

Content:
Containment Pressure Model for PWR ECCS Performance Evaluation," delineates the calculational approach that should be followed to assure a conservative prediction of the minimum containment pressure. Technical Rationale:14 The technical rationale for application of the above acceptance criteria to the minimum containment pressure analysis for Emergency Core Cooling System performance capability studies is discussed in the following paragraphs. 1. 10 CFR 50.46(a)(1)(i) requires that plants be provided with an emergency core cooling system (ECCS) whose cooling performance is evaluated to meet the most severe loss-of- coolant accident (LOCA). 10 CFR 50.46(a)(1)(i) allows the ECCS evaluation to use a realistic model that describes the behavior of the reactor coolant system during a LOCA. Containment minimum pressure directly affects ECCS performance. Calculation and analysis of this parameter, therefore, is an integral part of the ECCS performance evaluation. Regulatory Guide 1.157 provides specific methods that have been found acceptable by the staff in meeting 10 CFR 50.46(a)(1)(i). Complying with this regulation will assure that, in the event of a LOCA, the ECCS will perform as predicted, thereby ensuring limits on maximum peak cladding temperature, maximum cladding oxidation, and maximum hydrogen generation are met and a coolable geometry is maintained. 2. 10 CFR 50.46(a)(1)(ii) requires that plants be provided with an emergency core cooling system (ECCS) whose cooling performance is evaluated to meet the most severe loss-of- coolant accident (LOCA). 10 CFR 50.46(a)(1)(ii) requires the ECCS performance evaluation to utilize a model based on 10 CFR 50 Appendix K. This Appendix, which provides specific calculational methods for evaluating ECCS performance, contains significant conservatisms to address the uncertainties regarding post-LOCA plant behavior that existed at the time it was developed. Containment minimum pressure directly affects ECCS performance.