CAJ | 학술논문

在后处理流程的众多化学分离中，Np的走向和控制是国际后处理界关注的重点研究课题。根据我国和其他国家的研究成果，综合分析了后处理中Np的走向和控制。Np在辐照燃料溶解液中的价态分布主要取决于溶解液中HNO3与HNO2之比，通常情况下，溶解液中Np（Ⅴ）占主要份额；Np在共去污阶段的走向有两种可能，一是将Np控制为Np（Ⅴ），使其进入高放废液（1AW），二是将Np控制为Np（Ⅵ），则Np将与U，Pu一起进入有机相，但两者至今为止都难以实现定量分离。Np在U/Pu分离阶段部分随U，部分随Pu。在U纯化循环中，理想的方法是采用低酸加热氧化Np（Ⅳ）至Np（Ⅴ），以实现与铀的有效分离。
재후처리류정적음다화학분리중，Np적주향화공제시국제후처리계관주적중점연구과제。근거아국화기타국가적연구성과，종합분석료후처리중Np적주향화공제。Np재복조연료용해액중적개태분포주요취결우용해액중HNO3여HNO2지비，통상정황하，용해액중Np（Ⅴ）점주요빈액；Np재공거오계단적주향유량충가능，일시장Np공제위Np（Ⅴ），사기진입고방폐액（1AW），이시장Np공제위Np（Ⅵ），칙Np장여U，Pu일기진입유궤상，단량자지금위지도난이실현정량분리。Np재U/Pu분리계단부분수U，부분수Pu。재U순화순배중，이상적방법시채용저산가열양화Np（Ⅳ）지Np（Ⅴ），이실현여유적유효분리。
The process chemistry and routing of Np in current reprocessingare described. Based on the present chemical flowsheet, neptunium splits over the whole process, part in 1 AW, part in uranium stream and small part in plutonium stream. The reason leading to such unpresentable situation is the complex chemistry of neptunium in HNO3 solution, which makes it very difficult to stabilize valence of neptunium required in different steps of reprocessing. In the co-decontamination step, it is hard to overcome catalytic oxidation of Np（Ⅴ）to Np（Ⅵ） by HNO3. So, neptunium will split partially into 1 AW and partially into uranium and plutonium stream. Best way to solve such problem is to add scavenger of HNO2 before starting extraction. In the U/Pu separation step, it is better to drive neptunium into plutonium stream in order to minimize contamination of uranium by neptunium. A new technology must be found to selectively reduce Np(Ⅵ) only to unextractable Np(Ⅴ), but not to Np(Ⅳ). The research program in this direction is going now, nevertheless, the possible reductin of Np（Ⅴ） to Np(Ⅳ) by Pu(Ⅲ) must be taken into consideration if Pu(Ⅳ)/Pu(Ⅲ) ratio is less than 10-3. The separation of neptunium from uranium product is main task in second uranium purification cycle. A new technology, that is the oxidation of Np(Ⅳ) to Np（Ⅴ） by salt free process, has been developed and applied in reprocessing process having high DF(Np) in uranium.