Fuel reprocessing - Main operations

The fate of spent fuel from nuclear reactors is a major concern for the nuclear industry, with the alternatives of reprocessing it or disposing of it in its present state (direct storage). The choice between these two strategies involves political, economic and ecological issues.

Unlike direct disposal, reprocessing —— has the dual advantage of recovering nuclear energy materials (uranium, plutonium, thorium where applicable) to a degree of purity that enables them to be recycled in new fuels, and of conditioning radioactive waste in the form best suited to final disposal, with a significant reduction in its total volume and radiotoxicity.

This solution also paves the way for an even greater reduction in the potential long-term harmfulness of waste, by separating long-lived radioactive elements more completely and transmuting them into stable or short-lived elements.

Originally, the sole purpose of reprocessing was to obtain plutonium for the manufacture of nuclear weapons. The development of reprocessing for civilian purposes is closely linked to that of nuclear power reactors, taking into account the quantities and characteristics of discharged irradiated fuel and energy requirements.

Today, light-water reactors make up the vast majority of the world's nuclear power plants, and all of France's except for the Phénix prototype fast-neutron reactor, since the end of the natural uranium graphite-gas line in 1994 and the abandonment of the Superphénix fast-neutron reactor in 1998.

The PUREX (Plutonium Uranium Refining by Extraction) process, involving the nitric dissolution of irradiated fuel followed by a series of selective extractions using tributyl phosphate, rapidly superseded all others. For almost fifty years, it has been the basis for processes used in industrial plants. This is currently the case for plants in service (La Hague in France and Sellafield in the UK), or under construction (Rokkasho-Mura in Japan), dedicated to the reprocessing of fuel from light-water reactors.

This first part, devoted to a description of the main stages in the process, from fuel reception to the production of finished products (uranium and plutonium), focuses on their implementation in these plants, while also mentioning the main variants used in earlier facilities, as well as the specific aspects of reprocessing other types of fuel, in particular those from other reactors that have been developed in France: natural uranium graphite-gas and fast neutrons.