| Abstract: | A simplified method for obtaining thermal-hydraulic plant responses for light water reactors is described. The method combines the application of detailed and simplified plant models, using an advanced computer code (such as RELAP5), to simulate plant responses to accident or operational transient events. Calculations using a simplified plant model are performed to extend the results obtained with a detailed plant model. The simplified model is then used to investigate the effects of minor changes in event sequences. The method is an accurate, economical means of determining thermal-hydraulic plant responses for groups of sequences that share common controlling thermal-hydraulic phenomena. The methods described here are therefore valuable in assisting probabilistic risk assessments that typically require deterministic evaluation of large numbers of sequences grouped in this manner. |
