OXIDATION OF URANIUM CARBIDE BY CARBON DIOXIDE

The oxidation of UC by CO/sub 2/ has been investigated as a possible first step in a low-decontamination cycle. Reactive'' UC begins to react with CO/sub 2/ at about 350 deg C. Between 375 and 500 deg C, the activation energy for the reaction was determined to be 25 kcal. At about 525 deg C, ignition occurs. Below about 670 deg C, the reaction is: UC + 2 CO/sub 2/ yields UO/sub 2/ + 2 CO + C. Above about 670 deg C, free C is also removed; however, only 30% of the C is oxidized at the completion of the UC oxidation. Between 375 and 500 deg C, the oxidation reaction can be formally represented by a first order rate equation. At 450 deg C, the reaction is approximately proportional to the 0.7 power of the CO/sub 2/ pressure from 10 to 600 mm. Freshly arc-melted UC does not react appreciably with CO/sub 2/ at temperatures up to 600 deg C. However, exposure to air, saturated with water at room temperature, converts UC to the reactive state. The oxidized product, which is over 95% --400 mesh, should be suitable for carbothermic reduction without further size reduction. (auth)