Work to Start for Removing Jammed Gear from Monju N-Reactor (May 23th)
Work to Start for Removing Jammed Gear from Monju N-Reactor
Fukui, May 23 (Jiji Press)
--Workers will start preparations Tuesday to remove a piece of equipment that jams in a prototype fast-breeder nuclear reactor in central Japan, officials said Monday.
Workers at the Japan Atomic Energy Agency will install devices necessary to pull the 12-meter-long, 3.3-ton in-vessel transfer machine out of the Monju reactor in Tsuruga, Fukui Prefecture.
The machine, used in refueling work, has been stuck in the reactor vessel since an accident in August last year.
The removal work is expected to take place in mid-June after the agency gets the go-ahead from the industry ministry's Nuclear and Industrial Safety Agency, the officials said.
The agency hopes to complete all related repairs by the autumn.
Wow... This plant of Monju
Wow... This plant of Monju is a risf for Japan and for all the humanity...
Monju Nuclear Power Plant
Locale TSURUGA, Fukui Prefecture
Coordinates 35°44?25?N 135°59?17?E? / ?35.74028°N 135.98806°E? / 35.74028; 135.98806Coordinates: 35°44?25?N 135°59?17?E? / ?35.74028°N 135.98806°E? / 35.74028; 135.98806
Status Operational
Construction began May 10, 1986 (1986-05-10)
Commission date August 29, 1995
May 6, 2010 (reactivated)
Decommission date December 8, 1995 (suspended for 15 years)
Operator(s) Japan Atomic Energy Agency
Monju is a Japanese fast breeder reactor, located in Tsuruga, Fukui Prefecture. Construction started in 1986 and the reactor achieved criticality for the first time in April 1994. Its name is a reference to Manjusri.
Monju is a sodium cooled, MOX-fueled, loop-type reactor with 3 primary coolant loops, producing 280 MWe from 714 MWt.
An accident in December 1995, in which a sodium leak caused a major fire, forced a shutdown. A subsequent scandal involving a cover-up of the scope of the accident delayed its restart until May 6, 2010, with renewed criticality reached on May 8, 2010.
The plant is located on a site that spans 1.08 km2 (267 acres), the buildings occupy 28,678 m2 (7 acres), and it has 104,680 m2 of floor space. It employs 368 workers.
Monju sodium leak and fire On December 8, 1995, the reactor suffered a serious accident. Intense vibration caused a thermowell inside a pipe carrying sodium coolant to break, possibly at a defective weld point, allowing several hundred kilograms of sodium to leak out onto the floor below the pipe. Upon coming into contact with the air, the liquid sodium reacted with oxygen and moisture in the air, filling the room with caustic fumes and producing temperatures of several hundred degrees Celsius. The heat was so intense that it melted several steel structures in the room. An alarm sounded around 7:30 p.m., switching the system over to manual operations, but a full operational shutdown was not ordered until around 9:00 p.m., after the fumes were spotted. When investigators located the source of the spill they found as much as three tons of solidified sodium.
Fortunately, the leak occurred in the plant's secondary cooling system, so the sodium was not radioactive. However, there was massive public outrage in Japan when it was revealed that Power Reactor and Nuclear Fuel Development Corporation (PNC), the semigovernmental agency then in charge of Monju, had tried to cover up the extent of the accident and resulting damage. This coverup included falsifying reports and the editing of a videotape taken immediately after the accident, as well as the issuing of a gag order to employees regarding the existence of the real tapes.
November 24, 2000, Japan Atomic Energy Agency announced their intention to restart the Monju reactor. This decision was met with resistance by the public, resulting in a series of court battles. On January 27, 2003, the Nagoya High Court's Kanazawa branch made a ruling reversing its earlier 1983 approval to build the reactor, but then on May 30, 2005, Japan's Supreme Court gave the green light to reopen the Monju reactor.
The restart was scheduled for October 2008, having been moved back five months. A restart date of February 2009 was again delayed due to the discovery of holes in the reactor's auxiliary building; in August 2009 it was announced that restart might be in February 2010.
In February 2010, the JAEA officially obtained the OK from the Japanese Government to restart the reactor. The restart was definitely scheduled for the end of March. In late February, the JAEA requested the Fukui Prefecture and the Tsuruga City for deliberation aimed at resuming test operation. With a go-ahead from both entities, the JAEA will be on track for starting criticality testing in March. After testing has begun, it will take several months before commercial operation can resume - as for any new nuclear plant.
Operators started withdrawing control rods on May 6, 2010, marking the restart of the plant. The Fukui Prefecture governor, Issei Nishikawa asked the METI for additional stimulus to the prefecture including an expansion of the Shinkansen in turn for the restart of the plant. Monju achieved criticality on May 8, at 10:36 AM JST. Test runs will continue until 2013, at which point the reactor may begin to feed power into the electric grid, being "full fledged" operation.
However, on 26 August 2010, a 3.3-tonne "In?Vessel Transfer Machine" falling into the reactor vessel when being removed after a scheduled fuel replacement operation.
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