Site activities

To perform its enrichment services, the Enrichment business unit uses the Georges Besse plant, a subsidiary of EURODIF, with 59.7% of shares owned by AREVA and 40.3% owned by foreign partners.

The Georges Besse plant, which runs 24 hours a day, has produced over 150 million SWUs over more than 30 years. It enriches uranium for close to 100 nuclear reactors in France and around the world, using the gaseous diffusion process, the highest performance enrichment technology available at the time of its construction.

Why enrich uranium?

Nuclear reactors cannot use uranium in its natural form. It must be enriched in order to produce a fuel that can be used by power plants.

Enrichment increases natural uranium's U-235 isotope content (the only isotope capable of releasing energy via fission), from around 0.7% to 3-5% after enrichment.

Enrichment by gaseous diffusion

Since 1979, the Georges Besse plant has been enriching uranium using the gaseous diffusion process, the highest performance enrichment technology available at that time.

The principle

Enrichment by gaseous diffusion consists in forcing gaseous UF₆ against a cascade of porous barriers.

The gas molecules are in constant motion and strike the inner walls of the container where they are confined. The lighter U-235 molecules in the UF₆ gas move more quickly and will strike the wall more often than the heavier U-238 molecules in the UF₆. If the wall is porous, then the lighter molecules will pass through it more frequently than the heavier molecules and the gas will become enriched with U-235.

The diffuser is the device in which isotope separation takes place.

• A compressor forces the gas into porous tubes called diffusion barriers.
• The depleted gas exits towards the preceding stages.
• The enriched gas is forced on towards the next diffuser.

Since the unitary enrichment coefficient is quite low, the process must be repeated 1,400 times to achieve the uranium-235 content levels customers require.

An enrichment plant's output is expressed in SWUs (Separative Work Units). SWUs measure the effort required to separate molecules of U-235 and U-238 from natural uranium in order to create a final product that is richer in U-235. Georges Besse plant's maximum enrichment capacity is 10.8 MSWUs/year.

The Georges Besse II Plant

To consolidate its position as an industry leader, AREVA has opted to replace its gaseous diffusion technology with another enrichment process: centrifugation.

This technology, tried and tested in an industrial setting for over 30 years in Germany, the Netherlands and the United Kingdom, offers better assurances in terms of: 

• competitiveness,
• energy savings,
• technical reliability,
• environmental impact.

Implementation of this technology will become a reality with the construction of the Georges Besse II plant on the site in Tricastin. At a total cost of 3 billion euros, it marks one of the most significant industrial investments of the decade for France. It will gradually take over the plant currently in operation, thus ensuring continuous, long-term deliveries for the group's customers.

GB II is operated by the SET company (Société d'Enrichissement du Tricastin), with AREVA as its major shareholder. It uses the centrifugation technology owned by ETC.

Located on the Tricastin site, the Georges Besse II plant whose construction was started 3 years ago will eventually be made up of 2 units of enrichment. Thanks to its modular nature it will reach a total production of 7.5 million SWU per year in 2016, 2 years earlier than originally planned.The Georges Besse II plant produced its first SWU in December 2009.

Enrichment by centrifugation

In centrifugation, gaseous UF₆ is introduced into an elongated cylinder spinning at very high speeds in a vacuum inside an air-tight chamber.

Due to the effect of centrifugal force:

• The gas containing the lighter U-235 molecules remains concentrated near the center of the cylinder and rises towards the top of the machine.
• The gas containing the heavier U-238 molecules is projected towards the walls of the cylinder and descends.
• The enriched and depleted products are recovered from the top and bottom of the cylinder, respectively.

Just as with gaseous diffusion, the unitary enrichment coefficient is quite low, so the process must be repeated multiple times to achieve the uranium-235 content levels customers require.