The MAAP4 code is a fast-running severe accident analysis and management code widely used in nuclear industrial applications. It has been used as a severe accident analysis tool with which the timing of key events and source terms in the accident are assessed in Taiwan for many years. In the case of a loss-of-coolant accident (LOCA), it needs to know its break area and break elevation prior to reconstructing the accident for further analysis. For the system with more than one unknown parameter, it is not easy to identify these parameters since their tuning work becomes sophisticated.

The purpose of this paper is to find a better solution for this problem by coupling an optimization module with the MAAP4 simulation code. In this paper, a recirculation line break LOCA of the Kuosheng nuclear power plant is cited as a reference case. Different recirculation line break areas are tested and verified. This optimization module coupled with the MAAP4 code can be used to identify the break elevation and area if the shroud water level drops below the break point.