Analysis of the Possibility of Using Carbamide for Separation of U and Pu in Extractive Processing of SNF

Autor: V. I. Marchenko, K. N. Dvoeglazov
Rok vydání: 2020
Předmět:
Zdroj: Radiochemistry. 62:308-316
ISSN: 1608-3288
1066-3622
DOI: 10.1134/s1066362220030030
Popis: Behavior of carbamide in HNO3 solutions on Pt and SnO2 electrodes was studied. It was found that the oxidation rate of Co(NH2)2 on the SnO2 electrode is approximately two orders of magnitude lower than that on the Pt electrode. The electrochemical reduction of U(VI) in a cell having no diaphragm on a Ti (cathode)–SbO2 (anode) pair of electrodes was examined at its concentration of 10 to 100 g/L in HNO3 solutions (0.5–2.0 M) containing carbamide (5–30 g/L). It was found that the concentration of these components affects the completeness and rate of U(IV) formation and the current efficiency. It was shown that the reduction efficiency decreases in the presence of technetium ions, and, after the current is switched off, the already formed U(IV) is oxidized to U(VI). The rate of this process grows with increasing concentration of Te and HNO3. The electrochemical behavior of carbamide on an insulated Ti cathode was examined in aqueous nitric acid solutions. It was found that, in this case, the carbamide solutions acquire on being subjected to electrolysis reducing properties toward Pu(IV) and Np(VI). A laboratory installation of mixers-settlers, assembled in accordance with the technological scheme of the first cycle of SNF processing at RT-1 plant was used to perform experiments with the use of electrochemically processed carbamide as a re-extractive agent in the procedure of Pu and Np separation from uranium. It was found that a high rate of U purification to remove Np is reached in this case, but a satisfactory mutual separation of U and Pu is not provided.
Databáze: OpenAIRE
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