SWU

Seperative Work Units, or SWU, is a measure of the level of effort required to increase the concentration of U235 in uranium yielding a higher ratio of U235 : U238. Generally, reactors need processed uranium with a U235 content of 4-5% of the total volume. The average 1,000 MW reactor takes about 100,000 SWU of enriched uranium for one year of power. SWU is the process by which UF6 is converted to enriched UF6 or EUP. Due to the sensitive nature of enrichment technology, there are a limited number of businesses who offer this service, often in conjunction with the national government of their respective country. These businesses are USEC (USA), Urenco Limited (UK, Germany, Netherlands), AREVA (France), Rosatorn (Russia), China Nuclear Energy Industry Corporation, and Japan Nuclear Fuel, Limited. All of these plants operate on one of two enrichment methods, either gaseous diffusion or centrifuge.

Gaseous Diffusion involves the conversion of the UF6 into a gas. From there, the two isotopes are forced through a long tube with barriers. Because the U238 present in natural uranium is heavier than U235, it diffuses slower, and through this method the uranium is enriched. The second method is far more energy effective, and uses less than half of the energy of gaseous diffusion. Centrifuge uses centrifugal force to draw the heavier U238 atoms to the outside compartment, leaving the U235 atoms separate, and enriching the Uranium. Both methods are still used, but USEC is working on replacing its outmoded gaseous diffusion equipment with centrifuges for more cost-effective processing. Despite this, SWU is still the most expensive stage in the conversion of Nuclear Fuel, comprising 32% of the total cost.