Reprocessing of spent fuel involves the separation of uranium and plutonium from nuclear waste products by dissolving the fuel in nitric acid. The resulting materials are then stored. Commercial scale reprocessing facilities currently exist in France, at BNFL's Sellafield site in the UK and in Russia, India and Japan.
Spent Magnox, Advanced Gas-cooled Reactors (AGRs) and Pressurised Water Reactors (PWRs) fuel contains approximately 96 per cent uranium, 3 per cent nuclear waste products and 1 per cent plutonium. Some of the nuclear waste products are highly radioactive. Reprocessed uranium can be recycled once it has been converted, enriched and fabricated into new AGR or PWR fuel elements.
Plutonium from reprocessing can be stored in accordance with international safety and security requirements or combined with fresh uranium to form mixed oxide fuel ("MOX"). MOX can be used as fuel for PWRs but is not currently used in the UK.