TRANSMUTATION OF NEPTUNIUM AND AMERICIUM IN A FAST-NEUTRON FLUX - EPMA RESULTS AND KORIGEN PREDICTIONS FOR THE SUPERFACT FUELS

In the Superfact Experiment four oxide targets containing high and low concentrations of Np-237 and Am-241 and representing the homogeneous and heterogeneous in-pile recycling concepts were irradiated in the PH ENIX reactor. The burnup reached 6.4% FIMA in the targets with low con centrations of Np and Am and 4.5% FIMA in the targets with high concen trations of Np and Am. About 25% of initial concentration of Np-237 an d Am-241 was transmuted. Generally, the radial distribution of Np and Am was quite flat indicating an even rate of transmutation over the pe llet cross section. In the targets with 45% and 20% Np, 10 and 12 wt% Pu was created; most of this was Pu-238 with a half-life of 88 y. All the targets exhibited high fission gas release of 67 to 77%. As with s tandard LMFBR oxide fuel, Cr2O3 was the main product of fuel-cladding chemical interaction. In the target containing 20% Am, an Fe-Pd alloy was present in all the major radial cracks.