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,
Office of Nuclear Reactor Regulation crisis zone in person in order to demonstrate that the dangers were not as high as many believed. These events occurred at approximately the same time as the beginning of the J. Samuel Walker term of service as the official historian of the NRC and are documented by him in "". Office of Nuclear Reactor Regulation The Office of Nuclear Reactor Regulation, usually known by the acronym NRR, is a subordinate part of the United States Nuclear Regulatory Commission. The Office should not be confused with the NRC's Nuclear Regulatory Research. The Office's current Director is William Dean. It has