Advanced Head End for the Treatment of Used LWR Fuel

A novel dry head-end process is being developed. The main goals are the separation of cladding from fuel and the upfront removal of problematic fission products while facilitating the downstream processing. Cold tests using surrogate pellets and tests on a scale of tens of milligrams using actual used fuel are very promising. The initial tests showed that the process can be performed at significantly lower temperatures than those for standard voloxidation by using a mixture of NO2/O2 or NO2/O3 to produce a fine red powder of UO3 and to release all the tritium and iodine. This powder - containing the uranium as UO3, transuranium actinides, and nonvolatile fission product oxides - is readily soluble in dilute acids. Alternatively, the tests showed that the UO3 powder can be contacted with NO2(N2O4) gas or liquid at room temperature to produce metal nitrates.