Abstract

A plasma technology for the synthesis of mixed uranium and plutonium oxides UO₂–PuO₂ by denitration of mixed solutions of these metals has been developed at the Siberian Chemical Combine. The production process of U and Pu oxides includes the preparation of mixed initial solutions, their denitration in a plasma reactor with an inductive high-frequency discharge, and isolation of powders from the vapor–gas flow in vortex precipitators or filters with metal–fabric meshes. The particles of the obtained oxide powders possess the features of nanocrystalline and nanoscale materials containing crystalline and amorphous phases in the structure. The equipment for the implementation of this technology has been developed (Zenith plasma plant), on which mixed U and Pu oxides have been produced, and over 60 kg of oxides UO₂–PuO₂ with the plutonium content of 25 wt % has been synthesized, from which industrial fuel rods for the BN-600 reactor have been fabricated. After the operation of the fuel rods in the BN-600 reactor and corresponding exposure, the cores of the irradiated fuel rods should be dissolved for subsequent radiochemical treatment. The results of the studies on the search for the conditions of dissolution and effective solvents for mixed U and Pu oxides obtained by the plasma technology of decomposition of mixed solutions of uranium and plutonium are presented. It has been found that no complete dissolution of the synthesized oxides occurs in solutions of HNO₃ and HNO₃ with the addition of the reducing agents for tetravalent plutonium—ascorbic acid and hydrazine. Complete dissolution of the mixed oxides most effectively occurs in solutions of 10 M HNO₃ with the addition of 0.25–1.0 g/L HF.

中文翻译：

---

等离子体化学法制得的铀和氧化Ox均质混合物的技术开发

摘要

等离子体技术，用于合成铀和p的混合氧化物UO ₂ -PuO ₂西伯利亚化学联合公司已经开发出通过脱硝这些金属的混合溶液的方法。铀和Pu氧化物的生产过程包括混合溶液的制备，在带有感应高频放电的等离子反应器中的脱硝，以及从旋涡式除尘器或带金属织物网的过滤器中的蒸气流中分离出粉末。 。所获得的氧化物粉末的颗粒具有在结构中包含结晶相和非晶相的纳米晶体和纳米级材料的特征。已经开发出用于实施该技术的设备（Zenith等离子工厂），在该设备上已生产了U和Pu混合氧化物，以及60 kg以上的氧化物UO ₂ –PuO ₂合成了content含量为25 wt％的金属，由此制成了用于BN-600反应堆的工业燃料棒。在BN-600反应堆中运行燃料棒并进行相应的照射后，应溶解受辐照的燃料棒的芯，以进行后续的放射化学处理。提出了通过等离子体分解铀和and混合溶液获得的U和Pu混合氧化物的溶解条件和有效溶剂的研究结果。已经发现在HNO ₃和HNO _3的溶液中没有发生合成氧化物的完全溶解。加入四价p的还原剂-抗坏血酸和肼。在添加了0.25–1.0 g / L HF的10 M HNO ₃溶液中，混合氧化物完全溶解最有效。