Kuosheng Mark III containment analyses using GOTHIC

Kuosheng nuclear power plant in Taiwan is a twin-unit BWR/6 plant, and both units utilize the Mark III containment. Currently, the plant is performing a stretch power uprate (SPU) project to increase the core thermal power to 103.7% OLTP (original licensed thermal power). However, the containment response in the Kuosheng Final Safety Analysis Report (FSAR) was completed more than twenty-five years ago. The purpose of this study is to establish a Kuosheng Mark III containment model using the containment program GOTHIC. The containment pressure and temperature responses under the design-basis accidents, which are the main steam line break (MSLB) and the recirculation line break (RCLB) accidents, are investigated. Short-term and long-term analyses are presented in this study. The short-term analysis is to calculate the drywell peak pressure and temperature which happen in the early stage of the LOCAs. The long-term analysis is to calculate the peak pressure and temperature of the reactor building space. In the short-term analysis, the calculated peak drywell to wetwell differential pressure is 140.6 kPa for the MSLB, which is below than the design value of 189.6 kPa. The calculated peak drywell temperature is 158 °C, which is still below the design value of 165.6 °C. In addition, in the long-term analysis, the calculated peak containment pressure is 47 kPa G, which is below the design value of 103.4 kPa G. The calculated peak values of containment temperatures are 74.7 °C, which is lower than the design value of 93.3 °C. Therefore, the Kuosheng Mark III containment can maintain the integrity after the design-basis accidents under the stretch power uprate condition.