The Dissolving Test of the Uranium Oxide using Amide System Extraction Solvent

Mizuno, Mineo*; Kosaka, Yuji*; Mori, Yukihide*; Shimada, Takashi*

/The process (the UPRISE method) of dissolving uranium and plutonium selectively and separating from oxide fuel using the amide system extraction solvent have been investigated. By the cold test which used Nd oxide so far, the dissolving of Nd with about 0.2 mol to the solvent of 250mL is confirmed. In this work, the investigations of the dissolving tendency of uranium to the amide system extraction solvent and decontamination factor (DF) of the typical fission product (FP) such as Nd were carried out, and following results are obtained. (1)In the test of the same dissolving conditions, the uranium dissolving rate to extraction solvent DOBA was approximately equivalent to the case of the DOiBA. (2)Three kinds of extraction solvent were examined in the same dissolving condition, the difference of the uranium dissolving rate was observed. The results of the dissolving rates indicated the order of NN'-hexyl-2, ethyl-hexan-amid-1.6 mol/L nitric acid complex NN'-dibutyl-butyl-amid-1.7 mol/L nitric acid complex NN'-di-isobutyl-isobutyl-amid-1.5 mol/L nitric acid complex. (3)In the case of DOBA extraction solvent, the dissolving rate increased by about 2 order with the increase of the nitric acid concentration from 1mol/L up to 3.5mol/L and strong influence of the nitric acid concentration was confirmed to the dissolving rate. (4)In the tests with the NN'-dibutyl-butyl-amid-1.7 mol/L nitrie acid complex and NN'-di-isobutyl-isobutyl-amid-1.5 mol/L nitric acid complex, the DF values of Zr, Ru and Ce increased with the elapse of the test duration and exceeded 100 after 150 hours of test duration. On the other hand, the DF value indicated around 1 for Sr, Mo and Pd, and around 0.1 for Nd. (5)In the test with the NN'-hexyl-2-ehyl-hexan-amid-1.6 mol/L nitric acid complex, significant difference wasn't observed in the tendency of the elapsed change among the DF values of the FP elements. The DF values of all FP elements except Nd and Pd exceeded 100 after 100 ...