|
The is a disabled BWR nuclear power plant located on a site〔Tepco site (Japanese). (One Week Plant Grounds Course ).〕 in the towns of Ōkuma and Futaba in the Futaba District of Fukushima Prefecture, Japan. First commissioned in 1971, the plant consists of six boiling water reactors (BWR). These light water reactors〔(【引用サイトリンク】title=Tokyo Electric Power Co. Fukushima Daiichi Nuclear Power Station )〕 drove electrical generators with a combined power of 4.7 GWe, making Fukushima Daiichi one of the 15 largest nuclear power stations in the world. Fukushima was the first nuclear plant to be designed, constructed and run in conjunction with General Electric, Boise, and Tokyo Electric Power Company (TEPCO).〔(Fukushima No. 1 plant designed on 'trial-and-error' basis )〕 The plant suffered major damage from the magnitude 9.0 earthquake and tsunami that hit Japan on March 11, 2011. The incident permanently damaged several reactors making them impossible to restart. Due to the political climate, the remaining reactors will not be restarted. The disaster disabled the reactor cooling systems, leading to releases of radioactivity and triggering a 30 km evacuation zone surrounding the plant; the releases continue to this day. On April 20, 2011, the Japanese authorities declared the 20 km evacuation zone a no-go area which may only be entered under government supervision. In April 2012, Units 1-4 were decommissioned. Units 2-4 were decommissioned on April 19, while Unit 1 was the last of these four units to be decommissioned on April 20 at midnight.〔TEPCO abolished based on the law at midnight April 20, 2012.〕 In December 2013 TEPCO decided none of the undamaged units will reopen. The sister plant Fukushima II Nuclear Power Plant, or Fukushima Dai-ni ("number two"), is located to the south and also run by TEPCO. It did not suffer a serious accident during the tsunami as cooling continued uninterrupted after the disaster. ==Power plant information== The reactors for Units 1, 2, and 6 were supplied by General Electric, those for Units 3 and 5 by Toshiba, and Unit 4 by Hitachi. All six reactors were designed by General Electric.〔 〕〔Asami, Eiichi (Kyodo News), "(American's Fukushima legacy lives on )", ''Japan Times'', September 14, 2011, p. 3.〕 Architectural design for General Electric's units was done by Ebasco. All construction was done by Kajima.〔(【引用サイトリンク】title=Nuclear Reactor Maps: Fukushima-Daiichi )〕 Since September 2010, Unit 3 has been fueled by a small fraction (6%) of plutonium containing mixed-oxide (MOX) fuel, rather than the low enriched uranium (LEU) used in the other reactors.〔 〕 Units 1–5 were built with Mark I type (light bulb torus) containment structures.〔 The Mark I containment structure was slightly increased in volume by Japanese engineers.〔Lahey, R.T. and Moody, F.J., "The Thermal-Hydraulics of a Boiling Water Reactor", second edition, 1993.〕 Unit 6 has a Mark II type (over/under) containment structure.〔〔 Unit 1 is a 460 MW boiling water reactor (BWR-3) constructed in July 1967. It commenced commercial electrical production on March 26, 1971, and was initially scheduled for shutdown in early 2011.〔(【引用サイトリンク】title=Fukushima Daiichi Information Screen )〕 In February 2011, Japanese regulators granted an extension of ten years for the continued operation of the reactor. It was damaged during the 2011 Tōhoku earthquake and tsunami.〔(【引用サイトリンク】title= Nuke database system: fukushima daiichi-1 )〕 Unit 1 was designed for a peak ground acceleration of 0.18 g (1.74 m/s2) and a response spectrum based on the 1952 Kern County earthquake, but rated for 0.498 g.〔()〕 The design basis for Units 3 and 6 were 0.45 g (4.41 m/s2) and 0.46 g (4.48 m/s2) respectively. All units were inspected after the 1978 Miyagi earthquake when the ground acceleration was 0.125 g (1.22 m/s2) for 30 seconds, but no damage to the critical parts of the reactor was discovered.〔 The design basis for tsunamis was 5.7 meters. The reactor's emergency diesel generators and DC batteries, crucial components in helping keep the reactors cool in the event of a power loss, were located in the basements of the reactor turbine buildings. The reactor design plans provided by General Electric specified placing the generators and batteries in that location, but mid-level engineers working on the construction of the plant were concerned that this made the backup power systems vulnerable to flooding. TEPCO elected to strictly follow General Electric's design in the construction of the reactors.〔Yoshida, Reiji, "(GE plan followed with inflexibility )", ''Japan Times'', July 14, 2011, p. 1.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Fukushima Daiichi Nuclear Power Plant」の詳細全文を読む スポンサード リンク
|