Application of chemical processes to separate the valuable substances – the still existing uranium and the newly generated fissile material plutonium – from the fission products, the radioactive waste in the spent nuclear fuel after its use in the reactor. The PUREX process for reprocessing underwent several years of large-scale trial. A spent fuel element has, apart from the structural material, approximately the following composition: 96% uranium, 3% fission products (waste), 1% plutonium and small amount of transuranium elements. The recovered uranium and the plutonium can be reused as fuel in a nuclear power plant following appropriate further chemical treatment. The nuclear fuel recoverable in a reprocessing plant with an annual throughput of 350 t corresponds, in the case of use in modern light water reactors, to an energy quantity of approx. 10 million t hard coal. In the reprocessing, the high active waste (fission products) is separated and by vitrification brought into a form suitable for safe ultimate disposal.

Scheme of the reprocessing of irradiated fuel elements

Composition of nuclear fuel for light water reactors prior and after the use in a reactor