Development of the advanced accumulator for the pressurized water reactor

With the increased requirement for nuclear power generation as an effective countermeasure against global warming, Mitsubishi has developed the advanced pressurized water reactor (APWR) by adopting a new component of the emergency core cooling system (ECCS), a new instrumentation and control system, and other newfound improvements. The ECCS introduces a new passive component called the advanced accumulator which integrates both functions of the conventional accumulator and the low-pressure pump without any moving parts. The advanced accumulator uses a new fluidic device that automatically regulates flow rates of injected water in case of a loss of coolant accident (LOCA). This fluidic device is referred to as a flow damper. The design method of the flow damper and the standpipe was separately published (Shiraishi, 2011). This paper, then, describes the development and experiments with scale models of the advanced accumulator, and the satisfactory results obtained.