Reprocessing used fuel: devil or saint?

Reprocessing advocates claim that the closed fuel cycle is the most sustainable approach for nuclear energy, as it reduces recourse to natural uranium resources and optimises waste management. The advantages and disadvantages of used nuclear fuel reprocessing have been debated since the dawn of the nuclear era. There is a range of issues involved, notably the sound management of wastes, the conservation of resources, economics, hazards of radioactive materials and potential proliferation of nuclear weapons. Sifting through these is not easy, with strong counter-claims made by opposing parties, but it is undoubtedly true that in recent years, the reprocessing advocates appear to be winning once again, perhaps most clearly demonstrated by the apparent change in position of the USA under the Global Nuclear Energy Partnership (GNEP) programme.
To begin with, it’s important conceptually to distinguish reprocessing from recycling. Reprocessing is stage one – the separation of uranium and plutonium out of used fuel and conditioning of the remaining material as waste. Fuel assemblies removed from a reactor are very radioactive and produce heat, so are cooled (mostly at the reactor site or otherwise at a central storage facility or at the reprocessing plant) for a number of years as the level of radioactivity decreases considerably. For most types of fuel, reprocessing occurs anything from 5 to 25 years after reactor discharge. Recycling is then stage two – the use of the uranium and plutonium from the reprocessing plant, which can be either as mixed oxide (MOX) fuel or reprocessed uranium (RepU) fuel in current reactors or as fuel for future Generation IV reactors. Reprocessing effectively sets up the possibility of recycling. This doesn’t necessarily have to follow, but in practice, the two stages are bound together as reprocessing will likely only be undertaken with a view to eventual recycling.
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(Steve Kidd, Nuclear Engineering International)