Oxidation of powder and ceramic UO2 by KClO3 in molten (Li–Na–K)2CO3 eutectic

Abstract

The oxidation of UO2 powder and ceramic has been studied in the (Li–Na–K)2CO3 eutectic melt containing added potassium chlorate between 723 and 873 K. Complete oxidation of the powder could be achieved at 723 K and with KClO3:UO2 mole ratios between 0.25 and 0.3. Potassium monouranate was formed in the reaction and no chlorine was liberated. Although 723 K is some 50 K above the starting temperature for decomposition of KClO3 in air, tests showed that in the ternary carbonate eutectic less than 10% had decomposed in the first 30 min. Comparison with the oxidation of UO2 by KNO3, the previous best known oxidant under similar conditions, showed that the efficiency of KClO3 as an oxidising agent for UO2 powder was greater at 723 K. KClO3 was also better than KNO3 for the oxidation of ceramic UO2 at 723 K, but the reaction was not complete at this temperature, even at KClO3:UO2 mole ratios up to 3.8. Attempts to achieve complete reaction by increasing the temperature were unsuccessful because the KClO3 now decomposed too rapidly.