1、乏燃料后處理的概念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.全球核電生產(chǎn)發(fā)展前景表明，到2030 年，每年將有兩到三個(gè)新核電站投入運(yùn)

5、營。這一設(shè)想使俄羅斯封閉核燃料循環(huán)的最后階段發(fā)揮了更大的作用，即對乏核燃料進(jìn)行再處理，以便分 離鈾和钚并將它們再循環(huán)用于電力生產(chǎn)。目前有幾種SNF 后處理工藝，主要是水處理工藝，主要是PUREX 工藝1。接下來是無水或干燥過程，如氟化物氣體SNF 再處理和電化學(xué)分離鈾和钚從堿性氯熔體2。這些過程既有優(yōu)點(diǎn)也有缺點(diǎn);消除這些弱點(diǎn)將大大促進(jìn)這些進(jìn)程的發(fā)展。我們的 SNF 后處理策略發(fā)展了水處理工藝，是一種主要替代廣泛使用的PUREX 工藝的方法。 這一戰(zhàn)略的基本思想是使用碳酸鹽溶液而不是硝酸鹽溶液，后者廣泛用于從裂變產(chǎn)物中凈化鈾和钚，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.從 20 世紀(jì) 50 年代末到60 年代初，通過對碳酸鹽巖溶液中季銨鹽萃取鈾和釷的研究，開始了對一些可用于SNF 碳酸鹽巖后處理工藝的研究;這些研究在3中進(jìn)行了綜述。上野和Saito4 試圖確定從碳酸鹽巖溶液中的主要裂變產(chǎn)物中提取分離鈾和钚的可能性。Machajan等人研究了Aliquat 336 從碳酸鹽巖溶液中提取钚。Karalova 等人在 B.F. Myasoedov 院士的指導(dǎo)下，對碳酸鹽巖和堿液中錒系元素的提取進(jìn)行了一

12、系列研究;這些作品在3中進(jìn)行了綜述。日本在碳酸鹽巖SNF 后處理方面取得了相當(dāng)大的進(jìn)展;提出了一種工藝流程6,7，包括 uo2 基 SNF 在碳酸鹽巖溶液中的陽極溶解，然后用沉淀法分離鈾及其與裂變產(chǎn)物的分離。碳酸鹽 SNF 后處理技術(shù)的進(jìn)一步發(fā)展發(fā)生在美國洛斯阿拉莫斯國家實(shí)驗(yàn)室8-10 。報(bào)道的用于 SNF 后處理的碳酸鹽工藝包括SNF 在碳酸鹽-過氧化物溶液中的溶解以及隨后從裂變材料中析出裂變產(chǎn)物。因此，沉淀碳酸鹽巖精制是SNF 后處理碳酸鹽巖新工藝的基礎(chǔ)。請注意， 這些研究仍在繼續(xù)，這一進(jìn)程有可能得到進(jìn)一步的改進(jìn)。上述工作為開發(fā)改進(jìn)的SNF后處理碳酸鹽巖工藝奠定了基礎(chǔ)。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.碳酸鹽巖的潛在的新戰(zhàn)略后處理鈾和鈾钚燃料碳酸鈾和钚的選擇性轉(zhuǎn)移到解決方案,其次是提取與季銨碳酸鹽碳酸解決自由從裂變產(chǎn)物和固相剝離的鈾和钚酰從有機(jī)相碳酸鹽。所得的鈾酰和碳酸钚酰配合物粉末可直接用于陶瓷核燃料的常規(guī)制備工藝從 SNF 中選擇性提取鈾、钚后的固體殘?jiān)泻凶疃嗟牧炎儺a(chǎn)物。此外，它可

17、以被送去處理，長期儲(chǔ)存，或回收利用，以分離有價(jià)值的產(chǎn)品，用于科學(xué)和工程的各個(gè)領(lǐng)域通過與 PUREX 工藝的比較，我們使用CARBEX 工藝對碳酸鹽溶液中的SNF 進(jìn)行了萃取后處理 ;這是由季銨鹽萃取精制碳酸鹽巖的縮寫。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:綜上所述，碳 bex 工藝的基礎(chǔ)是SNF 后處理水工藝中常用的常規(guī)操作:氧化六價(jià)鈾和钚的狀態(tài)在 voloxidation 解散之前,解散碳酸鹽水溶液氧化SNF 的鈾和钚的精煉裂變產(chǎn)物的提取碳酸鹽巖的解決方案,和提取(合并或個(gè)人)碳酸鈾和钚的季銨緊隨其后的固相剝離金屬碳酸鹽碳酸銨。由此產(chǎn)生的鈾和碳酸钚粉末被回收，用于生產(chǎn)uo2 基陶瓷核燃料或

22、MOX 燃料。SNF 后處理新工藝具有以下特點(diǎn):所有的水處理都在沒有很強(qiáng)的氧化劑的情況下進(jìn)行，如PUREX 工藝中的硝酸;碳酸鹽巖溶液中所有組分的溶解度都發(fā)生了變化;碳酸鹽巖溶液組分的選擇性有利于鈾和缽的提取。這些特點(diǎn)的結(jié)合意味著新技術(shù)的以下優(yōu)點(diǎn)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