METHOD FOR DISSOLVING MIXTURE OF URANIUM OXIDE WITH PLUTONIUM OXIDE AND DEVICE THEREFOR

摘要

A mixture of UO2, PuO2 and/or bimetallic oxide (U,Pu)O2 in powder or suspension form is dissolved in HNO3 solution as it flows round a closed circuit which includes the upstream side of a filter (5). During a first stage the oxide (P) and acid (A) are continuously fed into the circuit while a solution (S) containing mainly UO2 is drawn from the downstream side of the filter. The feed of oxide and acid and the withdrawal of solution are stopped, and during a second stage electrolytic cell (6) is activated to feed bivalent Ag ions into the circulating liquid, which facilitates dissolving of the PuO2 remaining from the first stage. Also claimed is the appts. comprising cell (6), filter (5) and agitator (3) in respective chambers connected in a closed circuit, their geometry precluding criticality. During the first stage the acid strength is held constant at around 6N. During the second step Ag is fed to cell (6) in the form of AgNO3 solution, and the acid level is held between 4 and 6N. The circuit includes a sub-critical feed chamber (1) for the oxides, whose lower outlet leads through a jacket (9) supplied with secondary heating or cooling fluid (F), which enables the circulating liquid to be maintained at 80 degrees C during the first stage and 25 degrees C during the second. The liquid circulates from the chamber (1) and jacket (9) to flow up through mixer chamber (2), tangentially down the outside of filter (5) in chamber (4) and up through cell (6) to chamber (1).