The Analysis of Valence State of Np and Pu in Chinese High‐Level Liquid Waste

Abstract

The valence states of neptunium and plutonium in simulated and genuine Chinese high‐level liquid waste (HLLW) have been studied by solvent extraction. A TRPO process has been developed in our laboratory in recent years in which 30% TRPO‐kerosene was used as extractant. This process demonstrates good extraction efficiency for neptunium as well as uranium, plutonium, and americium. A countercurrent solvent extraction experiment with genuine HLLW has been carried out with 16 stages of centrifugal extractors. The results of valence state experiments showed that the neptunium and plutonium were mainly in the tetravalent state respectively. It is not necessary to regulate the valence state of neptunium before HLLW treatment by the Chinese TRPO process.     

Co-extraction of strontium and cesium from simulated high-level liquid waste (HLLW) by calixcrown and crown ether

The co-extraction performance of Sr and Cs from simulated high-level liquid waste (HLLW) was studied. The extraction solvent consists of 0.1 mol/L dicyclohexano-18-crown-6 (DCH18C-6) and 0.025 mol/L 25,27-bis (isopropoxy) calix[4]-26,28-crown-6 (iPr-C[4]C-6) in n-octanol as a diluent. Testing included the extraction performance of Sr and Cs in nitric acid and in the simulated HLLW medium, and the countercurrent cascade tests. The countercurrent cascade tests included 10 stages for Sr and Cs co-extraction, 2 stages for scrubbing and 8 stages for Sr and Cs co-stripping, or 2 stages for the supplementary extraction of Cs, 4 stages for stripping Sr and 8 stages for stripping Cs were carried out on a miniature centrifugal contactor set. The removal efficiencies of Sr and Cs in the simulated HLLW were 99.0% and 99.9%, respectively, and Sr and Cs could be co-stripped together completely or individually stripped by two stripping sections. Thus, the above extractants could be used to achieve the efficiency required for co-extracting Sr and Cs from HLLW. This process is simpler than the original extracting processes of Sr and Cs.     

分离法处理我国高放废液概念流程

文章描述分离法处理我国高放废液概念流程。经此流程分离处理后，废液中绝大部分组分降级为非α中低放短寿命废物，可作水泥固化地表处置。剩下极少量。废物和少量含Ｓｒ、Ｃｓ的非ａ。高放废物，使需玻璃固化并于深地层贮库的废物减少到很小数量。高放废物的减容（重）倍数为１２．５，α废物减容（重）系数为３９．４。     

二环己基—18—冠—6在硝酸和模拟高放废液中溶解度的测定

用溶剂萃取法测定了二环己基－１８－冠－６（ＤＣＨ１８Ｃ６）在硝酸和模拟高放废液（ＨＬＬＷ）中的溶解度。实验结果表明，ＤＣＨ１８Ｃ６在水溶液中的溶解度不仅与溶液的酸度、含盐量有关，而且还与冠醚的形态有关。     

时间分辨荧光法测定高放废液中的铀

采用时间分辨荧光法分析了高放废液中的铀含量。在2～3mol/L HNO3介质中,高放废液经30%TBP-加氢煤油(OK)萃取除去裂变产物和大量盐分后,用盐析剂4mol/L NaNO3-2mol/L HNO3洗涤有机相,最后用w=5%(NH4)2CO3溶液作为反萃剂反萃有机相中的铀,反萃水相在微量铀分析仪上测定铀含量。方法重加回收率为95%～101%,精密度低于2%。该方法已用于乏燃料后处理中间试验厂高放废液、中和池水样铀的测定,还有望用于含盐量高、组成复杂的其他样品(如环境样品等)铀含量的分析。     

钌在玻璃固化过程中的行为研究

研究模拟强放废液中的钌在玻璃固化过程中的行为及抑制。在实验给定的条件下,钌的挥发率为60%左右。影响挥发率的因素有固化温度、排气系统的负压及料液组份,其中主要是那些分解温度与硝酸硝酰钌分解温度相近的硝酸盐等。钌的挥发形式主要是 RuO_4。X-射线衍射分析结果表明,钌在排气管道上的沉积物是 RuO_2。料液经甲酸脱硝可使钌的挥发减至20%左右,如再加入某些还原剂如铁粉、硅粉等,可进一步降低钌的挥发。     

高放泥浆研究：I.模拟高放泥浆的配制及性能研究

依据高放废液化学组分分析结果,配制了模拟高放废液.采用甲酸脱硝模拟高放废液浓缩方法,研究了高放废液及泥浆的物理性质和化学组成,探讨了高放泥浆的形成机理及溶解方法,为高放泥浆的处理处置提供了基础数据.     

浅析高放废液玻璃固化技术

介绍了当前核废料玻璃固化技术的现状,并以焦耳加热陶瓷熔炉玻璃固化工艺为例,从工程应用和科研开发角度对玻璃固化关键技术进行分析,为相关工作提供了研究思路。     

Evaluation study on properties of a macroporous silica-based CMPO extraction resin to be used forminor actinides separation from high level liquid waste

Basic properties of a silica-based octyl(phenyl)-N,N-diisobutylcarbamoyl-methylphosphine oxide (CMPO) extraction resin (CMPO/SiO2-P) was investigated.Adsorption behavior for some rare earth elements (RE) which are constituents of high level liquid waste (HLLW) and the long-term stability of the extraction resin in nitric acid solution were examined.The CMPO extraction resin was significantly stable in 3 mol·L?1 HNO3 solution at 50oC.Furthermore,the RE(III) were efficiently separated from non-adsorptive fission product (FP) elements such as Sr(II) in a column experiment using a highly nitric acid solution.The separation behaviors of the elements are considered to result from the difference in their adsorption and elution selectivity based on the complex formation with CMPO.There was no strong dependency of RE(III) separation efficiency on feed solution flow rate.Only from the perspectives of the acid-resistant behavior of CMPO extraction resin and the elution kinetics for the metal ions with the extraction resin,the CMPO extraction resin can be used in the modified MAREC process for HLLW partitioning.     

用亚铁氰化钾钛从高放废液中去除铯的研究

合成了一种球形亚铁氰化钾钛无机离子交换剂，研究了它对模拟酸性高放废液中铯的离子交换性能。结果表明，该材料具有良好的机械稳定性和水力学性能，对铯的离子交换选择性高。在硝酸盐含量达４５０ｇ／ｌ的模型酸性高放废液中，Ｃｓ＾＋的静态交换容量为１．０ｍｍｏｌ／ｇ（干树脂），动态（柱式流动实验）交换容量为０．８１ｍｍｏｌ／ｇ（干树脂）。