Advanced Boiling Water Reactor (ABWR)

First ABWR started operation in Japan, its design is basically traditional BWR technology except for some items: the ten internal recirculation pumps are positioned inside the reactor pressure vessel. The new design permits improved control rod drive insertion capability and reduction of containment radiation.

The control room provides the operator with a wide array of support features.

The emergency core cooling system ECCS) has three full-range divisions (high/low pressure), each of which includes a diesel generator. The ECCS includes a reactor steam driven turbine pump that does not rely on AC power.

The ABWR has passive severe accident mitigation features to protect the containment from overpressurization: One system floods the lower drywell - this system is passive, initatited by high temperatures. The suppression pool traps most fission products in water and the containment has a overpressurization protection device.

Core melt frequency is estimated to be lower than 0,0000001 .