HBMPPT—DOSO—甲苯体系对铀（Ⅵ）的萃取及铀（Ⅵ）,钍（Ⅳ）之间的分离

以４－苯甲酰基－２,４－二氢－５－甲基－２－苯基－３Ｈ－吡唑唑酮－３（ＨＢＭＰＰＴ）为萃取剂,二正辛基亚砚为协萃剂,研究其在硝酸介质中对铀的萃取行为,以及萃取剂浓度、酸度等各种对萃取分配比的影响,以确定两种萃取剂的协同取及分离效果。     

溶剂萃取法分离铀中钌的研究

一、前言 在核燃料后处理Purex流程中,铀纯化段的回收铀中常含有少量钌,使铀钌分离成为纯化铀的一个重要问题。实验表明,辐照铀经HNO_3溶解后,裂变产物钌主要以亚硝酰钌RuNO~(3+)状态存在。它与溶液中的NO_3~-,NO_2~-,OH~-和H_2O等离子或分子形成配位数为6的多种配合物。各种RuNO~(3+)的硝酸基配合物的比例取决于溶液中NO~-和H~+离子的浓度。而NO_2~-与RuNO~(3+)的配合能力比NO_3~-与RuNO~(3+)的强。在一定条件下,两类配合物之间可以相互转化。铀主要是以UO_2~(2+)的NO_3~-配合物存在。     

冠醚萃取法分离铀同位素的研究

本文研究了二环已基24冠8(DCH24C8)和二环已基18冠6(DCH18C6)的1,2-二氯乙烷溶剂萃取铀(VI)和铀(IV)的同位素效应,通过多级富集和贫化级联测定了铀同位素的平均单级分离因子,证实了在不变价态铀同位素分离体系中,冠醚体系的铀同位素效应显著大于其它体系。     

铀基体中痕量钚的分离

为了从铀基体中分离痕量钚,采用由TBP 色层柱和7402季铵盐色层柱组成的萃取色层法及低本底α谱仪对模拟铀样品中铀钚分离方法进行了研究,并确定了分离流程的条件;对影响流程分离效果的主要因素,如料液和洗涤液酸度、流速、解吸液浓度等进行了研究,确定了最佳分离流程.当料液中铀和钚分别为0.1 g和6 ng时, 对铀的去污因子大于107,钚的收率大于95%,满足了质谱法测量铀基体中杂质钚同位素丰度比值的要求.使用该流程对后处理铀产品进行了铀钚分离及质谱测量.     

反应堆科学技术 铀溶液临界装置主容器热分析

为分析铀溶液临界装置主容器的热稳定性,并为综合应力评定提供数据,在设计结构、温度载荷和规范要求条件下,对2号和3号容器进行了热应力分析。由于二者结构基本相似,但3号容器的平底结构比2号容器的弧底结构更能产生较高的热应力,所以,仅对3号容器进行计算。     

四氟化铀转换为硝酸铀酰溶液

四氟化铀转换为硝酸铀酰溶液徐志昌，刘克宽，周丹（清华大学核能技术设计研究院）关键词六氟化铀，四氟化铀转换，溶胶－凝胶制球工艺，热解法，萃取法１弓ｌ言目前，溶胶一凝胶制球工艺［“ｊ已在制造二氧化铀核燃料中获得了工业应用。该工艺对其原料ＵＯ。（ＮＯ。）。...     

铀同位素浓缩试验装置退役金属零部件化学去污剂的选择和去污程序

为了回收利用退疫的设备和减少放射性固体废物体积,对退役设备的各种金属零部件需进行去污处理.本文通过实验选择了铜、镍、钢和合金铝等材料构件的去污剂并推荐了去污程序.     

乙异羟肟酸改善Purex流程铀产品中U-Pu的分离

研究采用新的无盐络合剂乙异羟肟酸（ＡＨＡ）来改善Ｐｕｒｅｘ流程铀线Ｕ－Ｐｕ分离。萃取及洗涤体系中Ｐｕ（Ⅳ）及Ｕ（Ⅵ）的分配实验结果表明：ＡＨＡ能够很好地络合Ｐｕ（Ⅳ）,它既能抑制水相中Ｐｕ（Ⅳ）被３０％ＴＢＰ／ＯＫ萃取,又能有效地把萃取到３０％ＴＢＰ／ＯＫ中的Ｐｕ（Ⅳ）洗涤到水相。同时,ＡＨＡ的存在不影响３０％ＴＢＰ／ＯＫ对Ｕ（Ⅵ）的萃取。     

HDEHP萃取法从裂变产物中分离~(142)La

用二 (2 乙基己基 )磷酸 (HDEHP)作萃取剂 ,二甲苯作稀释剂 ,在盐酸介质中 ,研究了从裂变产物中分离14 2 La的最佳条件 ,提出了“两步延迟分离法”的分离流程。流程所需时间约 1h ,14 2 La的化学回收率约80 % ,对主要γ核素的去污因子大于 1× 10 3 。     

超临界CO_2从含铀氧化物粉末中直接萃取铀方法研究

采用超临界CO2/硝酸-磷酸三丁酯(SC-CO2/HNO3-TBP)为萃取体系,研究各影响因素对其直接从含铀氧化物粉末中萃取铀的影响规律。结果表明:HNO3/TBP比值增大,铀萃取效率(EU)明显增大,比值为1.4时有利于萃取;比值一定时,随有机相总体积增加EU呈线性增加;萃取反应大致分为3个阶段:体系趋于稳定时的较慢阶段,稳定状态下的快速萃取阶段以及受粉末状态影响的缓慢阶段;随温度升高,EU在60℃时达到最大值91.4%;随萃取体系压力增大,EU在12 MPa时达到萃取峰值94.7%;萃取产物分离采用二级减压分离方式,在1#分离器8 MPa、2#分离器5 MPa条件下,能对萃取产物实现很好地分离。     

Extraction of uranium（VI）from nitric acid with N—decanoylpyrrolidine（DPOD）in toluene

The extraction behaviors of uranium(VI) from nitric acid by N-decanoylpyrrolidine (DPOD) in toluene has been studied at varying concentrations of nitric acid,extractant,salting out agent LiNo3 and at different temperatures.The mechanism of extraction is discussed in the light of the results obtained.     

Pulse electrodecontamination of the surface of steel

Electrochemical decontamination is a new technology for removing heavy metal from the surface of conductor. The optimum parameters are explored by studying the working mode with pulsed power supply. For testing and verifying advantages of this technology, we have made an experment on removing uranium pollution from metal surface of a polluted equipment, which has been used for over 20 years. A good decontamination result has been obtained even if a lower current density is supplied.     

固相萃取α能谱法快速测定环境样品中铀放射性核素

为了对环境中放射性污染水平进行有效监测,需要对环境样品中铀放射性核素进行分析。本实验采用浓硝酸溶液加热浸取样品中的铀,UTEVA树脂对铀进行吸附并用稀盐酸溶液进行解吸,有机物TTA萃取制成α测量源,通过示踪剂铀-232的计数来校正铀(铀-234、铀-235和铀-238)的化学回收率。本方法实现了对环境样品中铀放射性核素的快速分析,同时进行了条件实验,确定了最佳测量条件:浸取液为8.0 mol/L硝酸溶液,解吸液为0.01 mol/L盐酸溶液,示踪剂用量为180 mBq。结果表明,当样品用量为0.5 g,测量时间100000 s时,该方法的最小可探测活度浓度为0.13 Bq/kg,满足环境样品中铀放射性核素的分析要求。     

321不锈钢在低酸度硝酸铀酰溶液中的腐蚀特性

用称量法和电化学法研究了321不锈钢在不同浓度和pH值的硝酸铀酰溶液中的高温均匀腐蚀和电化学府蚀行为。均匀腐蚀试验结果表明．在选定的腐蚀条件下，321不锈钢样品在960h内，其表面光洁度无明显变化．腐蚀速率小于0．04mg/m^2.h，在低酸度的硝酸铀酰溶液中耐蚀。用腐蚀电入学法研究了321不锈钢在有溶解氧的硝酸铀酰溶液中的腐蚀电化学特性，测量了电极的腐蚀电位、腐蚀电流密度。经AES分析表明，电化学腐蚀后的样品在腐蚀膜中有一定量的铀．深度剖析含铀腐蚀膜的厚度为10—15nm。     

Separation of Uranium from Fission Products

A simple procedure has been developed for separating U from F.P. and neutron-irradiated Th. The separation is performed with tri-n-butyl phosphate in a system of dodecane-mixture of sulfuric acid and aluminium nitrate.

Uranium dioxide was irradiated with 20 MeV bremsstrahlung, which produced both ²³⁷U and F.P. The target was dissolved in dilute nitric acid and U was extracted into the organic phase of the above mentioned system. Finally, U in the organic phase was back-extracted into an aqueous phase. The γ-ray spectrum and decay curve of the separated U fraction show no radioactive nuclides other than U isotopes and its decay products.

This method can also be applied to the preliminary separation of ²³⁸U from neutron- irradiated Th.

The distribution ratios (Kd) for U, Th and some other elements in the extraction system are also given.     

Separation of Transplutonium and Rare-Earth Elements by Extraction with Di-isodecyl Phosphoric Acid from DTPA Solution

The distribution ratio Df and the separation factor β for Nd(III) to Am(III) were studied in DIDPA-DTPA systems to determine optimum conditions for applying DIDPA to the TALSPEAK type extraction process to separate transplutonides from lanthanoids in the partitioning of high-level waste of nuclear fuel reprocessing.

Extraction of lanthanoids from 0.05–0.1 M DTPA-1 M lactic acid (pH 3.0) aqueous solution into 0.2–0.3 M DIDPA in DIPB gives the separation factor of 20 revealing practicability of this system in the partitioning. The nature of diluent affects greatly Df, and DIPB proved to be the most appropriate one for the separation of transplutonides from lanthanoids. The presence of lactic acid in the aqueous phase improved the extraction kinetics in DIDPA-DTPA system.     

International Symposium on Isotope Separation and Chemical Exchange Uranium Enrichment

From the viewpoint of nuclear criticality safety, it is important to comprehend the reactivity of fuel solutions induced by oscillatory movements such as earthquakes. This paper intends to figure out the reactivity of a fuel solution system with a free surface formed by oscillation by evaluating the fluctuation of the neutron multiplication factor (k _eff ) obtained from a static calculation. To fulfill this intension, criticality calculations with reflecting fluid calculation results have been carried out. In the fluid calculations, the finite volume method and the volume of fluid (VOF) method have been applied in tracking the free surface formed by oscillation. The continuous energy Monte Carlo calculation method has been applied in the criticality calculations. As a result, it has been found that the variation patterns of the k _eff and those of the shape of fuel solutions are classified according to oscillation frequency and the ratio of solution height to the width of the tank (H/L). If a sloshing motion is generated, the k _eff fluctuates widely and has a threshold, with which we can classify the fluctuation type of the k _eff , despite the kind of reflector. If H/L is above the threshold, i.e., H/L =0.4, the k _eff fluctuates to a value below that obtained in the resting state. On the contrary, if H/L is below the threshold, the k _eff fluctuates to a value above that obtained in the resting state. This result implies the criticality calculation for a fuel solution with a free surface using the Monte Carlo method may give a slightly smaller threshold than using other approaches.