乏燃料后处理的概念

1、乏燃料后处理的概念Prospects for the worldwide development of nuclear power production suggest that two orthree new nuclear power plants will be put into operation yearly till 2030. This scenariogives a greater role to the final stage of the closed nuclear fuel cycle in Russia, namely, the reprocessing of spe

2、nt nuclear fuel (SNF) in order to separate uranium and plutonium and recycle them into power production.Several processes are now used for SNF reprocessing, primarily, aqueous processes, themain being the PUREX process 1. Next are anhydrous or dry processes, such as fluoride gas SNF reprocessing and

3、 the electrochemical separation of uranium and plutonium from alkali chloride melts 2. These processes have both strengths and weaknesses; the elimination of these weaknesses will considerably enhance the development of the processes.Our strategy of SNF reprocessing develops aqueous processes and is

4、 an alternative primarily to the widely used PUREX process. The underlying idea of this strategy is the use of carbonate solutions instead of nitrate solutions, which are widely used for decontaminating uranium and plutonium from fission products, plus extraction.全球核电生产发展前景表明，到2030 年，每年将有两到三个新核电站投入运

5、营。这一设想使俄罗斯封闭核燃料循环的最后阶段发挥了更大的作用，即对乏核燃料进行再处理，以便分 离铀和钚并将它们再循环用于电力生产。目前有几种SNF 后处理工艺，主要是水处理工艺，主要是PUREX 工艺1。接下来是无水或干燥过程，如氟化物气体SNF 再处理和电化学分离铀和钚从碱性氯熔体2。这些过程既有优点也有缺点;消除这些弱点将大大促进这些进程的发展。我们的 SNF 后处理策略发展了水处理工艺，是一种主要替代广泛使用的PUREX 工艺的方法。 这一战略的基本思想是使用碳酸盐溶液而不是硝酸盐溶液，后者广泛用于从裂变产物中净化铀和钚，并用于萃取。Studies of some processes t

6、hat could be used for carbonate reprocessing of SNF startedin the late 1950s and early 1960s with studies of the extraction of uranium and thorium by quaternary ammonium salts from carbonate solutions; these studies are reviewed in 3.Ueno and Saito 4 attempted to ascertain the possibility of the ext

7、raction separation of uranium and plutonium from main fission products in carbonate solutions. Machajan et al.5 studied plutonium extraction by Aliquat 336 from carbonate solutions. Karalova et al.under the supervision of Academician B.F. Myasoedov performed a series of works on actinide extraction

8、from carbonate and alkali solutions; these works are reviewed in 3.Considerable advances in carbonate SNF reprocessing were made in Japan; a flowsheet was proposed 6, 7 including the anodic dissolution of UO2-based SNF in a carbonate solution followed by the isolation of uranium and its separation f

9、rom fission products by precipitation methods.Further development of carbonate SNF reprocessing occurred at Los Alamos NationalLaboratory in the United States 8 T0. The reported carbonate process for SNF reprocessing included the dissolution of SNF in carbonate -peroxide solutions and subsequent pre

10、cipitation separation of fission products from fissile materials. Thus, precipitation carbonate refining is the basis of the new carbonate process of SNF reprocessing. Note that these studies are still continuing and further improvements in the process are possible. The above-cited works served as t

11、he basis for the development of an improved carbonate process for SNF reprocessing.从 20 世纪 50 年代末到60 年代初，通过对碳酸盐岩溶液中季铵盐萃取铀和钍的研究，开始了对一些可用于SNF 碳酸盐岩后处理工艺的研究;这些研究在3中进行了综述。上野和Saito4 试图确定从碳酸盐岩溶液中的主要裂变产物中提取分离铀和钚的可能性。Machajan等人研究了Aliquat 336 从碳酸盐岩溶液中提取钚。Karalova 等人在 B.F. Myasoedov 院士的指导下，对碳酸盐岩和碱液中锕系元素的提取进行了一

12、系列研究;这些作品在3中进行了综述。日本在碳酸盐岩SNF 后处理方面取得了相当大的进展;提出了一种工艺流程6,7，包括 uo2 基 SNF 在碳酸盐岩溶液中的阳极溶解，然后用沉淀法分离铀及其与裂变产物的分离。碳酸盐 SNF 后处理技术的进一步发展发生在美国洛斯阿拉莫斯国家实验室8-10 。报道的用于 SNF 后处理的碳酸盐工艺包括SNF 在碳酸盐-过氧化物溶液中的溶解以及随后从裂变材料中析出裂变产物。因此，沉淀碳酸盐岩精制是SNF 后处理碳酸盐岩新工艺的基础。请注意， 这些研究仍在继续，这一进程有可能得到进一步的改进。上述工作为开发改进的SNF后处理碳酸盐岩工艺奠定了基础。The underl

13、ying idea of the new strategy of carbonate reprocessing of uranium and uranium -plutonium fuels is selective transfer of uranium and plutonium to a carbonate solution, followed by their extraction with quaternary ammonium carbonates from carbonate solutions to free them from fission products and the

14、 solidphase stripping of uranyl and plutonyl carbonates from the organic phase. The resulting powders of uranyl and plutonyl carbonate complexes can be directly used in the conventional technology of ceramic nuclear fuel manufacturingThe solid residue after the selective extraction of uranium and pl

15、utonium from SNF into carbonate solution contains most fission products. Further, it can be sent for disposal, long-term storage, or recycling for separating valuable products for use in various fields of science and engineeringBy analogy with the PUREX process, we used the name CARBEX process for S

16、NF reprocessing in carbonate solutions with the use of extraction; this is an abbreviation for carbonate extraction refining by quaternary ammonium salts.碳酸盐岩的潜在的新战略后处理铀和铀钚燃料碳酸铀和钚的选择性转移到解决方案,其次是提取与季铵碳酸盐碳酸解决自由从裂变产物和固相剥离的铀和钚酰从有机相碳酸盐。所得的铀酰和碳酸钚酰配合物粉末可直接用于陶瓷核燃料的常规制备工艺从 SNF 中选择性提取铀、钚后的固体残渣中含有最多的裂变产物。此外，它可

17、以被送去处理，长期储存，或回收利用，以分离有价值的产品，用于科学和工程的各个领域通过与 PUREX 工艺的比较，我们使用CARBEX 工艺对碳酸盐溶液中的SNF 进行了萃取后处理 ;这是由季铵盐萃取精制碳酸盐岩的缩写。As follows from the above, the basis of the CARBEX process is provided by conventional operations used in aqueous processes of SNF reprocessing: the oxidation of uranium and plutonium to the

18、hexavalent state during voloxidation before dissolution, the dissolution of the oxidized SNF in carbonate aqueous solutions, the refining of uranium and plutonium from fission products by extraction from carbonate solutions, and the extraction (combined or individual) of uranium and plutonium by qua

19、ternary ammonium carbonate followed by the solid-phase stripping of metal carbonates by ammonium carbonate. The resulting uranium and plutonium carbonate powders are recycled to produce UO2-based ceramic nuclear fuels or MOX fuels.The new process for SNF reprocessing has the following distinctive fe

20、atures: all aqueous processes are carried out in the absence of very strong oxidizers, such as nitric acid in the PUREX process; the solubilities of all components involved in the process change in carbonate solutions; and the selectivity of the components of carbonate solutions changes in favor of

21、the extraction of uranium and plutonium. The combination of these features implies the following strengths of the new technology:综上所述，碳 bex 工艺的基础是SNF 后处理水工艺中常用的常规操作:氧化六价铀和钚的状态在 voloxidation 解散之前,解散碳酸盐水溶液氧化SNF 的铀和钚的精炼裂变产物的提取碳酸盐岩的解决方案,和提取(合并或个人)碳酸铀和钚的季铵紧随其后的固相剥离金属碳酸盐碳酸铵。由此产生的铀和碳酸钚粉末被回收，用于生产uo2 基陶瓷核燃料或

22、MOX 燃料。SNF 后处理新工艺具有以下特点:所有的水处理都在没有很强的氧化剂的情况下进行，如PUREX 工艺中的硝酸;碳酸盐岩溶液中所有组分的溶解度都发生了变化;碳酸盐岩溶液组分的选择性有利于铀和钵的提取。这些特点的结合意味着新技术的以下优点The flowsheet of the new SNF reprocessing technology is much shorter, which simplifies the entire process. Most fission products remain in the solid residue in the upstream oper

23、ations and can be disposed of without any processing.The CARBEX process can be implemented in two flowsheets. One flowsheet, referred toas the short one, comprises the following reprocessing stages:The long flowsheet of the CARBEX process, in addition, includes recycling of the solidresidue that contains fission products for recove