Optimizing the Initial Pressure of Accumulators for the Atucha-2 Nuclear Power Plant using an Optimization Method

Abstract

Accumulators (ACC) constitute passive systems essential part of the Emergency Core Cooling Systems (ECCS) of any water cooled and moderated reactor. Key design parameters for the ACC are the pressure and the volume; in this last case liquid and gas volumes are distinguished. In relation to pressure: a high initial value brings to early ACC intervention in case of Loss of Coolant Accident (LOCA), increasing the ACC fluid mass lost to the break; a low initial value brings to late actuation and danger of high rod surface temperature at the time of actuation. The optimized design value of initial pressure is more difficult to be attained in case of Small Break LOCA because of the several possible accident scenarios. A procedure based on ‘analytical optimization methods’ has been set up and tested to identify the best initial pressure for the Atucha-II Nuclear Power Plant under final stage of construction in Argentina