Fukushima Daiichi nuclear disaster (Unit 3 Reactor) 13 March an official of the Japan Nuclear and Industrial Safety Agency (NISA) told at a news conference that the emergency cooling system of Unit 3 had failed, spurring an urgent search for a means to supply cooling water to the reactor vessel to prevent a meltdown of its reactor core. At 05:38 there was no means of adding coolant to the reactor, owing to loss of power. Work to restore power and to vent excessive pressure continued. At one point, the top three meters of the uranium/mixed oxide (MOX) fuel rods were not covered by coolant. At 07:30 JST,
Integral reactor often deliberately small, allowing passive cooling in emergencies. Integral reactor In the nuclear power field, an integral reactor is a nuclear reactor design principle where the reactor core, primary cooling loop, steam generators and any required emergency cooling are contained within a single reactor vessel. The concept can be applied to any sort of underlying reactor design, there are examples of integral pressurized water reactors, sodium-cooled fast reactors, and others. The main goals are mass production of the reactor, as the entire working design can be delivered as a single unit and then connected to the non-nuclear generation sections of