Recovery of U/Pu in radiative wastes by incineration in molten sulfates and electrolysis. Application to uranium mainly

In the process of recovery of alpha wastes a solution of wastes is obtained by pyrolysis in a molten sulfate bath at about 6000C, then, in the same bath, alpha elements are recovered by electrolysis. Here the process is applied essentially to uranium. The process was developed by Agip Nucleare and carried on by a collaboration Agip (for pyrolysis) - CEA (for electrolysis). Important reduction factors are obtained by Agip: 50 for the volume and 5 for the weight. For wastes contaminated by uranium Agip realized a pilot plant with a capacity of 1 to 2 kg of wastes per hour. A serie of experiments on Pu was conducted by Agip on a small scale. Electrolysis was investigated by the CEA with several molten sulfate baths diluted (0.5% U) or concentrated (10% U) in uranium pure or with an admixture of pyrolysis ashes. Results show that with concentrated bath (including real Agip's pyrolysates) good quality uranium oxide deposits are obtained (from U4O9 to UO2 during electrolysis). They are several millimeter thick, well crystallyzed and extraction yields reach 95 to 99%. Electrolysis is an efficient process for uranium recovery. Polarization curves and corrosion tests complete the study