NEPTUNIUM SEPARATION THROUGH PHOTOCHEMICALLY INDUCED PROCESS

通过光化学诱导过程分离镎

• 批准号: 60470159
• 负责人: SUZUKI Atsuyuki
• 金额: $ 3.33万
• 依托单位: UNIVERSITY OF TOKYO
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1985
• 资助国家: 日本
• 起止时间: 1985 至 1987
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-60470159/
• 关键词: PHOTOCHEMISTRY; NEPTUNIUM; LASER; NUCLEAR FUEL REPROCESSING; EXTRACTION CHROMATOGTAPHY; VALANCE ADJUSTMENT; 溶媒抽出

1 Laser photochemical processes offer much promise as alternative means of valence state adjustment in nuclear fuel reprocessing The photochemically induced redox reactions of Np were shown to occur in nitric acid solution, such as used in the Purex process. Since Np distribution between organic and aqueous phases depends upon Np valence state, it is possible to control Np concentration profile in the nuclear fuel reprocessing plant using laser photolysis. Most practically important situations involve the adjustment of trace quantities of Np.2 In order to determine the valence state fraction under very low concentration where absorption spectrophotometry cannnot be used, the applicability of extraction chromatography has been studied. Np ions of different oxidation states can be qualitatively separated on chromatographic TBP-column by elution with dilute nitric acid and the fraction of valence state can be determined by alpha dosimetry. This method was used in the following experiments … More to determine the redox ratio by photolysis.3 when Np nitric acid solution adjusted completely to Np(IV) by ferrous sulfamate was exposed to KrF excimer laser radiation (249 nm), oxidation to Np(V) occurred photochemically even in the presence of a reducing reagent in the starting solutions. The experimental results show that the photo-shift exists in equilibrium oxidation ratio after adequate irradiation time. The initial amount of ferrous sulfamate had lettle effect upon the photo-shift but delayed initiation of photo-oxidation. Reaction temperature didn't affect the photo-hift either. The residual Np(VI) was oxidised further by dark reaction after the laser radiation bing off.4 Np(VI), which was prepared by KMnO4 was photochemically reduced to Np(V) in nitric acid solution by laser photolysis, even in the presence of a strong oxidising reagent in the initial solution. The most noticeable aspects of this photochemical reaction are; 1) Reduction ratio is increasing to a steady-state value governed by the solution condition. 2) Higher reaction temperature and lower acidity are preferred to obtain higher redution ratio. 3) Reduction ratio changes abruptly when laser radiation being off.5 Extraction experiments were accomplised, in order to obtain more practical data for photochemical separation of Np. Np ions were adjusted to NpnIV) or Np(VI) completely by means of chemical reagents in advance. Solvent extraction operations using 30%TBP(70%n-dodecane) as organic phase were conducted both before and after laser irradiation. The experimental results show that laser irradiation results in significant decrease of the distribution coefficients of Np. Therefore Np valence state adjustment by the laser photochemical method can be incorporated with the conventional Purex process without majour modification.6 These experimental results of Np rebox reactions were combined with the Purex process simulation code 'ADVANCED MIXSET'. Using this reformed computer code, laser irradiation in a mixser-settler has been shown of great value to control Np concentration profiles and to decontaminate Np from U in the Purex process. Less

1 激光光化学过程作为核燃料后处理中价态调整的替代方法提供了广阔的前景 Np 的光化学诱导氧化还原反应发生在硝酸溶液中，例如 Purex 过程中所使用的。由于有机相和水相之间的 Np 分布取决于 Np 价态，因此可以使用激光光解来控制核燃料后处理厂中的 Np 浓度分布。最实际重要的情况涉及痕量Np.2的调整。为了在无法使用吸收分光光度法的极低浓度下确定价态分数，对萃取色谱法的适用性进行了研究。不同氧化态的NP离子可以在色谱TBP柱上通过稀硝酸洗脱进行定性分离，并且价态分数可以通过α剂量测定法确定。该方法用于以下实验中，通过光解测定氧化还原比。3 当通过氨基磺酸亚铁完全调节为 Np(IV) 的 Np 硝酸溶液暴露于 KrF 准分子激光辐射 (249 nm) 时，即使起始溶液中存在还原剂，也会发生光化学氧化为 Np(V)。实验结果表明，经过足够的照射时间后，在平衡氧化率下存在光移。氨基磺酸亚铁的初始量对光位移影响很小，但延迟了光氧化的开始。反应温度也不影响光偏移。激光辐射关闭后，残余的 Np(VI) 通过暗反应进一步被氧化。 4 即使在初始溶液中存在强氧化剂的情况下，由 KMnO4 制备的 Np(VI) 在硝酸溶液中通过激光光解被光化学还原为 Np(V)。这种光化学反应最引人注目的方面是： 1) 减速比逐渐增加至由求解条件决定的稳态值。 2) 优选较高的反应温度和较低的酸度以获得较高的还原率。 3)关闭激光照射时还原率急剧变化。5完成了萃取实验,以获得更多用于光化学分离Np的实用数据。 Np离子预先通过化学试剂完全调节为NpnIV)或Np(VI)。在激光照射前后均进行以30%TBP(70%正十二烷)为有机相的溶剂萃取操作。实验结果表明，激光照射导致Np的分配系数显着降低。因此，通过激光光化学方法进行的 Np 价态调整可以与传统的 Purex 工艺结合，无需进行重大修改。6 Np rebox 反应的这些实验结果与 Purex 工艺模拟代码“ADVANCED MIXSET”相结合。使用这种改进的计算机代码，混合沉降器中的激光照射对于控制 Np 浓度分布以及在 Purex 工艺中从 U 中净化 Np 具有巨大的价值。较少的

项目成果

鈴木篤之: 原子力工業. 33. 27-32 (1987)

铃木敦之：核工业。33. 27-32 (1987)

Y,ENOKIDA AND A,SUZUKI: "APPLICATION OF LASER PHOTOCHEMISTRY TO NEPTUNIUM SEPARATION PROCESSES" PROCEEDINGS OF WORLD CONGRESS III OF CHEMICAL ENGINEERING. 1. 700-703 (1986)

Y,ENOKIDA 和 A,SUZUKI：“激光光化学在镎分离过程中的应用”第三届世界化学工程大会论文集。

Y. ENOKIDA;A. SUZUKI: JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY. 24. 859-861 (1987)

Y.榎木田；A.

Y. ENOKIDA;A. SUZUKI: PROCEEDINGS OF INTERNATIONAL CONFERENCE ON NUCLEAR FUEL REPROCESSING AND WASTE MANAGEMENT 'RECOD 87'. 1. 475-482 (1987)

Y.榎木田；A.

A,SUZIKI, Y,ENOKIDA AND K,KATOH: "PROCESS ANALYSIS OF LASER PHOTOCHEMICAL SEPARATION (JAPANESE)" NUCLEAR ENGINEERING. 33. 27-32 (1987)

A,SUZIKI、Y,ENOKIDA 和 K,KATOH：“激光光化学分离的过程分析（日语）”核工程。