Experimental validation of the code system 'DARWIN' for spent fuel isotopic predictions in fuel cycle applications

The DARWIN package, developed by the CEA and its French partners (Cogema, EDF and FRAMATOME) provides the required parameters in fuel cycle applications and characterizing the irradiated fuels from reactors: fuel inventory, decay heat, activity, neutron, γ, α, β sources and spectrum, radiotoxicity. In order to validate this code system for spent fuel inventory calculations, a large experimental programme has been performed in France, based on spent fuel chemical assays. Experimental data are based on chemical analysis measurements from fuel rod cuts irradiated in French PWR reactors and from full assembly dissolutions at the Cogema/La Hague reprocessing plants. This enables us to cover a large range of UOx fuels with various enrichments in ²³⁵U, 3.1% to 4.5%, associated with burnups from 10 GWd/t to 60 GWd/t. Recently, MOx fuels have also been investigated, with a initial Pu amount in the central zone of 5.6 % and a maximum burnup of 45 GWd/t. Uranium, Plutonium, Americium and Curium isotopes were analysed in PWR samples. Furthermore, Fission Products involved in Burn up Credit studies were measured. (author)