- UNGG reactor
The UNGG ("Uranium Naturel Graphite Gaz") is an obsolete design of
nuclear power reactordeveloped by France. It was graphitemoderated, cooled by carbon dioxide, and fueled with natural uranium metal.
It was developed independently of and in parallel to the British
Magnoxdesign, and to meet similar requirements. The main difference between the two designs is the fuel cladding material, which was magnesium- zirconiumalloy in the UNGG, as opposed to magnesium-aluminium in the Magnox reactor. Both claddings react with water, making short-term reprocessing of the fuel essential, and requiring heavily shielded facilities for this.
The UNGG and the Magnox are the two main types of GCR. A UNGG reactor is often referred to simply as a "GCR" in English documents, or sometimes loosely as a "Magnox".
The first generation of French nuclear power stations were UNGGs, as was
Vandellosunit 1 in Spain. Of ten units built, all are now shut down.
* G1, G2 and G3 at
Marcoule. G1 was the first UNGG to go critical, in 1956.
Chinon Nuclear Power PlantA1, A2, and A3 in Indre-et-Loire.
Saint-Laurent Nuclear Power PlantA1 and A2 in Loir-et-Cher.
Bugey Nuclear Power Plant1 in Ain, the last UNGG built in France, first criticality 1972.
Vandellòs Nuclear Power Plant1 in Spain, the only UNGG built outside of France.
The earlier units, at Chinon and Marcoule, had heat exchangers outside the main pressure vessel; Later units (Saint-Laurent, Bugeye and Vandellos) moved these heat exchangers to inside the pressure vessel.
Gas cooled reactor.
Nuclear power in France
* [http://fr.wikipedia.org/wiki/UNGG UNGG] on the french part of Wikipedia (in French).
* [http://www.iaea.org/inis/aws/htgr/abstracts/abst_28008789.html French activities on gas cooled reactors] , D Bastien, IAEA-TECDOC--899, pp:51-53, 30 Oct - 2 Nov 1995
* [http://www.iaea.org/inis/aws/htgr/abstracts/abst_iwggcr19_16.html Twenty-nine years of French experience in operating gas-cooled reactors] , D Bastien, IWGGCR--19, pp:113-119 21-23 Sep 1988
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