Abstract

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.

中文翻译：

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SNF萃取工艺中使用尿素分离U和Pu的可能性分析

摘要

研究了氨水在Pt和SnO ₂电极上的HNO ₃溶液中的行为。发现SnO ₂电极上的Co（NH ₂）₂的氧化速率比Pt电极上的氧化速率低大约两个数量级。在HNO _3中浓度为10至100 g / L的情况下，检查了在Ti（阴极）-SbO ₂（阳极）电极对上没有隔膜的电池中U（VI）的电化学还原含尿素（5–30 g / L）的溶液（0.5–2.0 M）。发现这些组分的浓度影响U（IV）形成的完整性和速率以及电流效率。结果表明，在存在离子的情况下，还原效率降低，并且在切断电流之后，已经形成的U（IV）被氧化为U（VI）。此过程的速率随Te和HNO ₃浓度的增加而增加。在硝酸水溶液中检查了尿素在绝缘Ti阴极上的电化学行为。已经发现，在这种情况下，通过对Pu（IV）和Np（VI）进行电解还原性能，获得了氨基甲酸酯溶液。根据在RT-1工厂进行SNF加工的第一个循环的技术方案组装的混合器-沉降器的实验室装置用于在Pu程序中使用电化学处理的尿素作为再萃取剂进行实验从铀中分离出Np 已经发现，在这种情况下，达到了高的U纯化率以去除Np，但是没有提供令人满意的U和Pu的相互分离。