Analysis of Main Steam Line Break Accident at Hot Shutdown State Using a Coupled Method

This paper describes the analysis of main steam line break at hot shutdown state performed using a new developed method where a 3D core neutronics code, a core thermal-hydraulics code and a plant simulation computer code are fully coupled. Models, main hypothesis applied and calculation results of the main steam line break (MSLB) accident analysis are presented. To cover as many as states points a new parameter named Transient Reactivity Variation (TRV) is introduced, the conservatism of this parameter when doing safety analysis are evaluated also. The study shows that the coupled method using some best estimate parameters can get more margins compared with the traditional analysis method, and the TRV can be used as a key parameter to determine which core configuration is the most penalizing case.