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,
Zoé (reactor) 60 aluminum-cased vertical rods containing three tons of uranium oxide pellets, controlled by cadmium rods. The heavy water was purchased from Norsk Hydro. A cooling system was added after the reactor had operated for a time, allowing it to run at a heat release rate of 200 kilowatts. The name Zoé was an acronym, from Zéro de puissance" (zero power, that is, very little capacity to produce electricity, which made it easier and faster to build); Oxyde d'uranium" (uranium oxide), "Eau lourde" (heavy water). The Châtillon site was superseded for later nuclear research by a new site at Saclay. The