After having been given by the CEA a complete overview of back end fuel cycle R&D activities in Marcoule, the second day of Atoms for the Future was dedicated to the front end of the fuel cycle, with the visit of AREVA industrial facilities located in the Tricastin nuclear site.

Situated in the Rhône valley, the Tricastin nuclear site concentrates on 600 hectares all the facilities needed to transform uranium into nuclear fuel. In order to explain how this site has been built up to become a unique industrial platform in Europe, a first presentation of the history of the Tricastin site has been given by AREVA Tricastin Communication Representatives Annie Mousset and Julien Gonzalez. It enables the participants to quickly understand why, how and when all these complementary facilities have been created :
 CEA in 1962, to perform nuclear and industrial R&D
 COMURHEX in 1962, to transform uranium concentrate into UF6
 SOCATRI in 1974, for nuclear maintenance, solid waste management and liquid effluents treatment
 AREVA NC in 1976, for chemical activities on natural and reprocessed uranium
 EURODIF in 1979, for uranium enrichment
 EDF in 1979, for nuclear power generation

A status of new investment projects COMURHEX II and Georges Besse II has also been presented.

View of the Tricastin Site

After this overview of the site, Guillaume Vaast, Project Manager in the AREVA Engineering & Projects Division, made two technical presentations. The first one focused on Uranium conversion process technology which is being operated by AREVA COMURHEX plants located in Malvési near Narbonne and Tricastin. The Malvési plant is transforming the uranium ore concentrate into uranium tetrafluoride powder while the Tricastin plant is then converted this UF4 into uranium hexafluoride UF6, a chemical compound suitable for the isotopic separation process called enrichment. The presentation described step by step the chemical process (chemical reaction principle, main process parameters such as temperature, flowrates, etc.) and also illustrated with schemes and pictures the equipment and the specifications requested due to the nature of the compounds handled, which are highly corrosive.

The subject of the second presentation was uranium enrichment technology, that is to say how to increase the quantity of the 235U isotope up to an amount needed to maintain a fission reaction inside a light water reactor. A first part of this presentation was dedicated to the gaseous diffusion process, which is operated by AREVA EURODIF plant. The technical principle consists in separating 238U and 235U, the two main isotopes, by pushing the UF6 gas through a micro porous membrane called diffusion barrier. In order to get the isotopic grade requested by the utilities, 1 400 separation stages are assembled in series. A separation stage is composed of three main components : a heat exchanger, a compressor, and the diffuser.

The second part of the enrichment presentation focused on the other main technique : centrifugation. The centrifugation technique is now also used by AREVA through its new Georges Besse II Plant. This new plant, still under construction, will gradually replace the EURODIF plant. This process relies on the high speed rotation of a cylindrical device containing the UF6. The centrifuge force concentrates the “heavy” molecules (238U) at the periphery, while the “light” molecules (235U) move to the centre.

After lunch, an opportunity to discover the whole Tricastin site has been offered to the participants by having a complete commented tour of the site by bus. The interest was to explain how all these facilities are linked together to optimize the French front end activities.

Georges Besse II

Eurodif

Comhurex II

Then the participants split into three groups. The first one visited EURODIF enrichment plant, the second one the new Georges Besse II plant, and the third one COMURHEX II plant which is under construction.

Guillaume Vaast, for the SFEN-JG