Spent fuel reprocessing is derived from a process called the PUREX process, which was initially developed to extract plutonium for military purposes. Used on an industrial scale, it is now used simply to separate uranium and plutonium. Once separated, uranium and plutonium are considered as recoverable materials. The highly radioactive residue is considered as real waste made up of fission products and minor actinides. Extracting plutonium divides the volume and radiotoxicity of high-level waste by about ten. While this process can be used to recover plutonium and depleted uranium, and even recycled uranium after re-enrichment, if the plutonium in question is not intended for burning in a reactor, then it becomes the main waste product. In that case, much larger geological waste repositories will be needed than those required for fission products and minor actinides alone.
Separating plutonium is only justified if the plutonium is to be reused. Besides, there would be little sense in extracting this highly radiotoxic element simply to dispose of it in a geological repository. Most of the plutonium produced by French reactors is currently used to make MOX, fuel, which is only a moderately effective way of consuming plutonium.
Slightly radioactive uranium makes up 95% of the mass of spent fuel. Separating it significantly reduces the volume of waste. The facilities eventually required for disposing of glass packages will be smaller and less expensive than if spent fuel is not reprocessed.
The very high-level waste from reprocessing is vitrified, in other words immobilised in a glass matrix capable of trapping radioactivity for thousands of years. This glass material is highly resistant to radiation and chemical attack.
Fuel from civil reactors is currently reprocessed at two industrial facilities, La Hague in France and Sellafield in England. A third plant is currently being commissioned in Rokashomura, Japan. Other facilities exist in the nuclear defence sector. In France, weapons-grade materials are processed in a special facility at La Hague.
The road to advanced reprocessing Projects for what are known as Generation IV reactors are being investigated. Some of these reactors would be able to regenerate - or breed - their fuel and burn actinides as well as plutonium. Fuel reprocessing would become unavoidable with most Generation IV reactor concepts that would replace today’s slow (or thermal) reactors using uranium. Reprocessing in the future will be more advanced than the existing process and would also separate actinides and some long-lived fission products. It would then be possible to destroy these elements at specialised facilities or condition them in appropriate materials. There is no doubt that reprocessing is the key to clean nuclear power. The United States, which has long been clearly against or hesitant, about reprocessing, is changing its view.
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