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Nuclear Power - Uranium Enrichment

Nuclear power plant fuel rods contain enriched Uranium, and nuclear weapons require highly enriched Uranium. Therefore Uranium enrichment is a highly sensitive, secretive technology.

Historically, a number of enrichment processes have been demonstrated produced in the laboratory, but only two, the gaseous diffusion process and the centrifuge process, have operated on a commercial scale and only centrifugation is used today.

One chemical process had been demonstrated to the pilot plant stage but in the end was not used commercially. The French Chemex process exploited a very slight difference in the two isotopes' propensity to change valency in oxidation/reduction, utilising aqueous (III valency) and organic (IV) phases.

In both gaseous diffusion and centrifuge processes, UF6 gas is used.

Molecules of UF6 with U-235 atoms are about one percent lighter than the majority U-238. Therefore when made to move in a circle they have a different radius of path. See circular motion.

 

The gas centrifuge process was first demonstrated in the 1940s but was 'put on the back shelf' in favour of the simpler diffusion process. It was then developed and brought on stream in the 1960s as the second-generation enrichment technology.

It is economic on a smaller scale, e.g. under 2 million SWU/yr, which enables staged development of larger plants.

It is also much more energy efficient than diffusion, requiring only about 40-50 kWh per SWU.All currently operating enrichment facilities use the centrifuge process.

For more details see here