- Lucens reactor
The Lucens reactor at
Lucens ,Vaud ,Switzerland , was anuclear reactor destroyed by a serious accident in1969 .In
1962 the construction of a Swiss-designed pilotnuclear power plant began. The heavy-water moderated,carbon dioxide cooled, reactor was built in an underground cavern [ [http://www.sapierr.net/files1/results_swiss.htm Summary of Swiss nuclear reactors] , SAPIERR Support Action: Pilot Initiative for European Regional Repositories] and produced 30megawatt s of heat (which was used to generate 8.3megawatt s of electricity). [ [http://www.nea.fr/html/general/profiles/switzerland.html Swiss nuclear power] , French Nuclear Energy Agency] It became critical in1966 and the plant was commissioned in1968 . It was fueled by 0.96% enriched uranium alloyed with chromium cased inzircalloy (magnesium with 0.6% zirconium) inserted into a graphite matrix. Carbon dioxide gas was pumped into the top of the channels at 6.28 MPa and 223°C and exited the channels at a pressure of 5.79 MPa and at a temperature of 378°C.It was intended to operate until the end of
1969 , but during a startup onJanuary 21 ,1969 it suffered aloss of coolant accident , leading to a partialcore meltdown and massiveradioactive contamination of the cavern, which was then sealed.The accident was caused by water condensation forming on some of the magnesium alloy fuel element components during shutdown and corroding them. The corrosion products from this accumulated in some of the fuel channels. One of the 73 vertical fuel channels was sufficiently blocked by it to impede the flow of carbon dioxide coolant so that the magnesium alloy cladding melted and further blocked the channel. The increase in temperature and exposure of the uranium metal fuel to the coolant eventually caused the fuel to catch fire in the carbon dioxide coolant atmosphere. The pressure tube surrounding the fuel channel split because of overheating and bowing of the burning fuel assembly, and the carbon dioxide coolant leaked out of the reactor. [ [http://www.nucleartourist.com/events/part-melt.htm Description of events] , Nuclear tourist] [ [http://canteach.candu.org/library/D407_scr1.pdf Heavy water reactors: Status and projected development] , IAEA, 2002]
No
irradiation of workers or the population occurred, though the cavern containing the reactor was seriously contaminated. The cavern was decontaminated and the reactor dismantled over the next few years.External links
* [http://www.nucleartourist.com/events/part-melt.htm List of Partial Fuel Meltdown Events] , Nuclear Tourist
* [http://www.insc.anl.gov/pwrmaps/map/switzerland.php Maps of Nuclear Power Reactors: Switzerland]
* [http://www.atomicarchive.com/Reports/Japan/Accidents.shtml Major Nuclear Power Plant Accidents]
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