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1、-.z.乏燃料后处理的概念 Prospects for the worldwide development of nuclear power production suggest that two or three new nuclear power plants will be put into operation yearly till 2030.This scenario gives a greater role to the final stage of the closed nuclear fuel cycle in Russia,namely,the reprocessing of
2、 spent 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,the main being the PURE*process 1.Ne*t are anhydrous or dry processes,such as fluoride gas SNF reprocessing and th
3、e 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 an a
4、lternative primarily to the widely used PURE*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 e*traction.全球核电生产开展前景说明，到 2030 年，每年将有两到三个新核电站投入运营。这一设想使俄
5、罗斯封闭核燃料循环的最后阶段发挥了更大的作用，即对乏核燃料进展再处理，以便别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 PURE*工艺1。接下来是无水或枯燥过程，如氟化物气体 SNF 再处理和电化学别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开展。我们的 SNF 后处理策略开展了水处理工艺，是一种主要替代广泛使用的 PURE*工艺的方法。这一战略的根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 that coul
6、d be used for carbonate reprocessing of SNF started in the late 1950s and early 1960s with studies of the e*traction 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 e*traction
7、separation of uranium and plutonium from main fission products in carbonate solutions.Machajan et al.5 studied plutonium e*traction by Aliquat 336 from carbonate solutions.Karalova et al.under the supervision of Academician B.F.Myasoedov performed a series of works on actinide e*traction from carbon
8、ate 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 from fission pr
9、oducts by precipitation methods.Further development of carbonate SNF reprocessing occurred at Los Alamos National Laboratory in the United States 810.The reported carbonate process for SNF reprocessing included the dissolution of SNF in carbonatepero*ide solutions and subsequent precipitation separa
10、tion 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 the basis for the deve
11、lopment 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，开场-.z.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中进展了综述。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别离铀和钚的可能性。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展了一系列研究;这些作品在3中进展了综
12、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，然后用沉淀法别离铀及其与裂变产物的别离。碳酸盐 SNF 后处理技术的进一步开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根底。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根底。The underlying idea of the n
13、ew strategy of carbonate reprocessing of uranium and uraniumplutonium fuels is selective transfer of uranium and plutonium to a carbonate solution,followed by their e*traction with quaternary ammonium carbonates from carbonate solutions to free them from fission products and the solidphase stripping
14、 of uranyl and plutonyl carbonates from the organic phase.The resulting powders of uranyl and plutonyl carbonate ple*es can be directly used in the conventional technology of ceramic nuclear fuel manufacturing The solid residue after the selective e*traction of uranium and plutonium from SNF into ca
15、rbonate 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 engineering By analogy with the PURE*process,we used the name CARBE*process for SNF reprocessing in carbonate s
16、olutions with the use of e*traction;this is an abbreviation for carbonate e*traction 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，它可以被送去处理，长期储存，或回收利用，以别离有价值的产品，用于
17、科学和工程的各个领域 通过与 PURE*工艺的比较，我们使用 CARBE*工艺对碳酸盐溶液中的 SNF 进展了萃取后处理;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 CARBE*process is provided by conventional operations used in aqueous processes of SNF reprocessing:the o*idation of uranium and plutonium to the he*avalent state during volo*idat
18、ion before dissolution,the dissolution of the o*idized SNF in carbonate aqueous solutions,the refining of uranium and plutonium from fission products by e*traction from carbonate solutions,and the e*traction(bined or individual)of uranium and plutonium by quaternary ammonium carbonate followed by th
19、e 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 MO*fuels.The new process for SNF reprocessing has the following distinctive features:all aqueous processes are carried ou
20、t in the absence of very strong o*idizers,such as nitric acid in the PURE*process;the solubilities of all ponents involved in the process change in carbonate-.z.solutions;and the selectivity of the ponents of carbonate solutions changes in favor of the e*traction of uranium and plutonium.The binatio
21、n of these features implies the following strengths of the new technology:综上所述，碳 be*工艺的根底是 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 volo*idation 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 MO*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展，如PURE*
22、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钚的提取。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 operations and can be disposed of without any processing.Th
23、e CARBE*process can be implemented in two flowsheets.One flowsheet,referred to as the short one,prises the following reprocessing stages:The long flowsheet of the CARBE*process,in addition,includes recycling of the solid residue that contains fission products for recovering valuable ponents by means
24、 of e*traction,in particular,from carbonate solutions.In summary,the new concept of SNF reprocessing in carbonate solutions is more efficient than the conventional strategy implemented in the PURE*process Currently,a considerable amount of e*perimental research is required for all stages of the CARB
25、E*process.However,the set of potential engineering solutions for separate stages will bring hydrometallurgical SNF reprocessing technologies to a new level.新的 SNF 后处理工艺流程大大缩短，简化了整个过程。在上游作业中，大多数裂变产物仍留在固体残渣中，无需任何处理即可处理。CARBE*流程可以在两个流程图中实现。一个流程，称为短流程，包括以下再处理阶段:此外，CARBE*工艺的长流程还包括回收含有裂变产物的固体残渣，特别是通过从碳酸盐溶液中萃取来回收有价值的成分。综上所述，在碳酸盐岩溶液中 SNF 再处理的新概念比在 PURE*过程中采用的传统策略更有效。目前，CARBE*工艺的各个阶段都需要大量的实验研究。然而，一套分阶段的潜在工程解决方案将把湿法冶金 SNF 后处理技术提高到一个新的水平。