Control room of the Lucens reactor in April 1968
|Official name||Versuchsatomkraftwerk Lucens|
|Construction began||1 April 1962|
|Commission date||10 May 1968|
|Decommission date||3 March 1969|
|Owner(s)||Nationale Gesellschaft zur Förderung der industriellen Atomtechnik|
|Operator(s)||Energie Ouest Suisse|
|Nuclear power station|
|Fuel type||Low enriched uranium|
|Cooling source||Carbon dioxide|
|Units decommissioned||1 x 6 MW|
|Nameplate capacity||6 MW|
|Suffered a nuclear accident on 21 January 1969, leading to a partial core meltdown and massive radioactive contamination|
The Lucens reactor was a 6 MW experimental nuclear power reactor built next to Lucens, Vaud, Switzerland. After its connection to the electrical grid on 29 January 1968, the reactor only operated for a few months before it suffered a loss-of-coolant accident on 21 January 1969, leading to a partial core meltdown and massive radioactive contamination of the cavern.
In 1962 the construction of a Swiss-designed pilot nuclear power plant began. The heavy-water moderated, carbon dioxide gas-cooled reactor was built in an underground cavern and produced 30 MW of heat (which was used to generate 8.3 MW of electricity). It became critical 29 December 1966. It was fueled by 0.96% enriched uranium alloyed with chromium cased in magnesium alloy (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 on 21 January 1969, it suffered a loss-of-coolant accident, leading to a partial core meltdown and massive radioactive contamination of the cavern, which was then sealed. The accident was rated 4–5 on the International Nuclear Event Scale introduced in 1990 by the International Atomic Energy Agency.
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.
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. The plant was totally decommissioned in 1988 and the last radioactive waste was removed in 2003.
- "LUCENS – Reactor Details". IAEA Power Reactor Information System. International Atomic Energy Agency. Retrieved 2016-10-08.
- Anthony, L. J. (1966). Sources of Information on Atomic Energy – International Series of Monographs in Library and Information Science. 2. Elsevier. p. 85. ISBN 978-1-4831-5600-2.
- Wildi, Tobias (2003). "Der Traum vom eigenen Reaktor – die schweizerische Atomtechnologieentwicklung 1945–1969" (PDF). PhD dissertation (in German). Chronos. ISBN 3-0340-0594-6. doi:10.3929/ethz-a-004459704.
- Hug, Peter (2009). "Energie nucléaire". Dictionnaire historique de la Suisse (in French). Hauterive: Gilles Attinger. Retrieved 2016-10-09.
- Summary of Swiss nuclear reactors, SAPIERR Support Action: Pilot Initiative for European Regional Repositories Archived 19 July 2011 at the Wayback Machine.
- Swiss nuclear power, French Nuclear Energy Agency
- Heavy water reactors : status and projected development (PDF). Vienna: International Atomic Energy Agency. 2002. ISBN 9201115024.
- Ha-Duong, Minh; Journé, Venance (2014-05-14). "Calculating nuclear accident probabilities from empirical frequencies". Environment Systems and Decisions. 34 (2): 249–258. ISSN 2194-5403. doi:10.1007/s10669-014-9499-0.
- Description of events, Nuclear tourist
- Heavy water reactors: Status and projected development Archived 13 April 2007 at the Wayback Machine., IAEA, 2002
- "On-site disposal as a decommissioning strategy" (PDF). International Atomic Energy Agency. November 1999: 67. Retrieved 6 January 2013.
- "Switzerland’s first nuclear plant decommissioned". SWI swissinfo.ch. Retrieved 2016-10-11.
|Wikimedia Commons has media related to Lucens nuclear reactor.|