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Study on Nuclear Fuel Reprocessing Using Photochemical Reactions

利用光化学反应进行核燃料后处理的研究

基本信息

批准号：
06559006
负责人：
TOMIYASU Hiroshi
金额：
$ 5.89万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

项目摘要

In the nuclear fuel reprocessing, interest has been focused on the recovery of transuranium elements, such as Pu, Np, Am and Cm, because of their hazardous radioactive neture. In order to recover these transuranium elements, the valence adjustments are of primary importance. For example, in the Purex method using tributylphosphate (TBP) as an extracting reagent, Pu(VI), Pu(IV) and Np(VI) are extracted to the organic phase with U(VI), but Pu(III) and Np(V) remain in the aqueous phase. Am(VI) is also extracted to the organic phase, if oxidized by a strong oxidant.In the present study, a photochemical method of adjusting the oxidation states of actinide ions has been investigated. It was found that the irradiation of high pressure mercury lamp to the nitric acid solution containing Pu^3+ and NpO_2+ oxidized only Pu^3+ to Pu^4+ keeping NpO_2+ at pentavalent ion under suitable irradiation conditions. Therefore, the selective extraction of Pu is possible from the solution containing Pu and Np. Under the irradiation of high intensity of light in the similar solution described above, both Pu and Np were oxidized to hexa-valent ions, MO_2^2+. This means that both Pu and Np are extracted to the organic phase and it was confirmed by extraction experiments. On the other hand, in the irradiation of the organic solution containing Pu(VI) and Np(VI) ions, resulted in the back extraction of Np to the aqueous phase accompanied by the photo-reaction of Np(VI) to Np(V).

在核燃料后处理中，超铀元素Pu、Np、Am、Cm等由于其有害的放射性性质，一直受到人们的关注。为了回收这些超铀元素，价态调整是至关重要的。例如，在使用磷酸三丁酯（TBP）作为萃取剂的Purex方法中，用U（VI）将Pu（VI）、Pu（IV）和Np（VI）萃取到有机相中，但是Pu（III）和Np（V）保留在水相中。Am（VI）被强氧化剂氧化后，也被萃取到有机相中。本文研究了一种光化学方法来调节锕系元素离子的氧化态。结果表明，在适宜的照射条件下，高压汞灯照射含Pu^3+和NpO_2+的硝酸溶液时，只有Pu^3+被氧化成Pu^4+，而NpO_2+保持五价。因此，从含Pu和Np的溶液中选择性萃取Pu是可能的。在上述类似溶液中的高强度光照射下，Pu和Np都被氧化成六价离子MO_2^2+。这意味着Pu和Np都被萃取到有机相中，并且通过萃取实验证实了这一点。另一方面，在含有Pu（VI）和Np（VI）离子的有机溶液的照射下，导致Np反萃取到水相中，伴随着Np（VI）到Np（V）的光反应。