Separation of Actinides from LWR Spent Fuel Using Molten-Salt-Based Electrochemical Processes

Results are presented of work done at Argonne National Laboratory to develop a molten-salt-based electrochemical technology for extracting uranium and transuranic elements from spent light water reactor fuel. In this process, the actinide oxides in the spent fuel are reduced using lithium at 650°C in the presence of molten LiCl, yielding the corresponding actinides and Li₂O. The actinides are then extracted from the reduction product by means of electrorefining. Associated with the reduction step is an ancillary salt-recovery step designed to electrochemically reduce the Li₂O concentration of the salt and recover the lithium metal.

Experiments were performed at the laboratory scale (50 to 150 g of fuel and 0.5 to 3.5 l of salt) and engineering scale (3.7 to 5.2 kg of fuel and 50 l of salt). Laboratory-scale experiments were designed to obtain information on the fundamental factors affecting process rates. Engineering-scale experiments were conducted to verify that the parameters controlling process scaleup are sufficiently understood, and to test equipment and operating concepts at or near full scale. All indications are that the electrochemical-based process should be workable at practical plant sizes.