When was fukushima built

The fuel assemblies were about 4 m long, and there were in unit 1, in units , and in unit 6. Each assembly had 60 fuel rods containing the uranium oxide fuel within zirconium alloy cladding. The operating pressure was about half that in a PWR. The BWR Mark I has a primary containment system comprising a free-standing bulb-shaped drywell of 30 mm steel backed by a reinforced concrete shell, and connected to a torus-shaped wetwell beneath it containing the suppression pool with m 3 of water in units For simplicity, the term 'dry containment' is used here.

The water in the suppression pool acts as an energy-absorbing medium in the event of an accident. The wetwell is connected to the dry containment by a system of vents, which discharge under the suppression pool water in the event of high pressure in the dry containment. The function of the primary containment system is to contain the energy released during any loss of coolant accident LOCA of any size reactor coolant pipe, and to protect the reactor from external assaults.

During normal operation, the dry containment atmosphere and the wetwell atmosphere are filled with inert nitrogen, and the wetwell water is at ambient temperature. A small amount of hydrogen is routinely formed by radiolytic decay of water, and this is normally dealt with by recombiners in the containment vessel. They would be insufficient for countering major hydrogen formation due to oxidation of zirconium fuel cladding.

Apart from this, at low containment pressures hydrogen and other gases are routinely vented through charcoal filters which trap most radionuclides. If a LOCA occurs, steam flows from the dry containment drywell through a set of vent lines and pipes into the suppression pool, where the steam is condensed.

Steam can also be released from the reactor vessel through the safety relief valves and associated piping directly into the suppression pool. During the peak production period of the late s, a total of coal mines were in operation, with annual output reaching 4. The shift toward oil in the s, however, led to one mine closing after another. In , the history of coal mining in Fukushima Prefecture came to an end with the closure of the last mining operation.

Around the time the coal industry was entering its period of decline, Fukushima Prefecture began to focus on attracting nuclear power plants, which were seen as a source of energy for a new era. This meant that Fukushima continued to play the role of an energy supplier to Tokyo.

The nuclear accident at the Fukushima Daiichi Nuclear Power Plant, caused by the tsunami of March , led to severe radioactive contamination. This forced the long-term evacuation of local residents and dealt a serious blow to agriculture and fishing in the surrounding area. Translated from Japanese. The reactor fuel used by all units was low enriched uranium LEU , except for unit three, which used plutonium mixed-oxide MOx fuel from onwards.

The power station fed electricity to the national grid via the kV Shin-Fukushima substation. Contractors involved with the Fukushima Daiichi nuclear power plant GE provided the reactor design for all six generating units of the nuclear power plant. The architectural design for all the reactor units was provided by Ebasco. GE supplied the units one, two and six, whereas units three and five were supplied by Toshiba and unit 4 by Hitachi. Kajima was responsible for the construction of the nuclear complex.

BWRs work as direct cycle reactors, which pass the steam generated inside the reactor directly to the turbine for power generation, unlike pressurised water reactors PWR. As of August , a total of 75 boiling water reactor units were in operation worldwide and four units two in Taiwan and two in Japan were under construction, with several new nuclear power plants, including the Wylfa Newydd nuclear power plant in the UK, proposed to use ABWR technology.

Fukushima Daiichi nuclear disaster details The Fukushima Daiichi nuclear disaster was triggered by the 9. The power station, built approximately 10m above sea level, was flooded with tsunami.

The units 1, 2 and 3, which were in operation at the time of the disaster, were automatically shut down. The supply of off-site power to the Fukushima Daiichi nuclear power plant was cut off meanwhile, while emergency diesel generators located at the basement of the turbine building, roughly 5m above the sea level, which are intended to provide back-up electricity to the plant's cooling system, were disabled by tsunami flooding.

The absence of cooling led to melt down of units 1, 2 and 3 within the following three days. The unit 1 suffered a massive hydrogen explosion on 12 March , which caused extensive damage to the 1m-thick reactor building walls. It was followed by another hydrogen explosion at the unit 3 reactor on 14 March , which led to the explosion of unit 4 with gas flowing from unit 3 into the unit 4 reactor.