Separation of Americium and Some Rare Earths from Lanthanum by Reversed Phase Chromatography

Reversed phase column chromatography was applied to the separation of Am, Pr, Pm and Eu from 5 to 110 mg of La carrier after coprecipitation. HDEHP and TOPO-xylene solutions held on kieselguhr were used as the stationary phase and the elutions were carried out with 0.1 to 1 N nitric acid solutions. In the HDEHP system, Am can be separated from the rare earths except from Pr. Am can also be separated from Eu in the TOPO system.     

增压排空阴离子交换法分离-ICP-MS测定铀基体中痕量稀土

采用增压排空的阴离子交换柱实现了铀基体与痕量稀土元素的分离。结果表明,全流程对稀土的回收率在96%～106%之间,整个分离过程可在20min内完成。用ICP MS测量铀基体中痕量稀土的检测限为1×10-12g/mL。用该方法分析U3O8成分分析标准参考物质GBW04207中的痕量稀土含量,测量结果与参考值符合良好。     

仪器中子活化分析法测定金属钇中的稀土元素

采用仪器中子活化分析法测定了金属钇中Pr,Gd,Lu,Ho,Ce,La,Er等7种稀土元素的含量,计算了这些元素的检出限。标准参考物质的分析结果与推荐值基本相符。     

聚锑酸离子交换剂的制备及分离锶和钇

以三氧化二锑为原料,双氧水为氧化剂,经氧化回流法制备聚锑酸无机离子交换剂.该聚锑酸离子交换剂对锶-钇混合溶液中的锶具有较好的选择性吸附能力.通过正交实验设计法对反应影响因素进行了优化,结果表明,在60 ℃时加入40 mL水和12 mL H_2O_2氧化10 g Sb_2O_3固体,反应120 min可制得对Sr~(2+)和Y~(3+)具有较高分离系数的聚锑酸离子交换剂.理化性能研究表明,产物是一种阳离子交换剂,对溶液中的Sr~(2+)和Y~(3+)的动态吸附分离具有较高的选择性.     

Radioactive Rare Gas Separation Performance of a Two-Unit Series-Type Separation Cell

Enhancement of the separation factor in a separation cell has been desired as one means of reducing the cascade scale required for a radioactive rare gas membrane separation. It is already known that the separation factor of the separation cell increases as cut increases. Hence, in a series-type separation cell which consists of two-unit cells, an appropriate selection of cuts for each unit cell can be expected to provide a marked improvement in separation factor under symmetric separation. This paper presents analytical and experimental results for separation characteristics of a series-type separation cell whose separation factors are far from unity. It was found that the series-type separation cell has a larger separation factor than other types of separation cells, such as recycle separation cell and conventional separation cell. The series-type separation cell requires less power consumption and membrane area than the recycle separation cell while it requires more than the conventional separation cell. As both the two-unit series-type separation cell and the conventional separation cell have individual merits and demerits, a comparison is also made between the cascade consisting of series-type separation cells and that of conventional separation cells. The cascade of series-type separation cells requires fewer stages and less power consumption but somewhat more membrane area than that of conventional separation cells. Based on results of this study, the scale of a cascade can be reduced by using series-type separation cell.     

Studies on Isotope Separation of Lithium by Electromigration in Fused Lithium Bromide and Potassium Bromide Mixture, (II)

Accurate knowledge on the salt composition in the anode compartment is indispensable when ⁶Li is to be highly enriched by electromigration in fused LiBr-KBr mixture. A study was made on the dependence on temperature shown by the salt composition in the anode compartment. It was observed that sustained electromigration led to a salt composition in the anode compartment that was determined by the prevailing temperature. The composition was observed for various temperatures between 380° and 740°C: In terms of the ratio Li/K in chemical equivalent, the values were 1.31 at 380°C, 1.29 at 420°C, 1.31 at 460°C, 1.41 at 500°C, 1.76 at 540°C, 1.82 at 580°C, 1.95 at 620°C, 2.16 at 680°C and 2.34 at 740°C. These results can be explained by assuming that the fused LiBr-KBr mixture is a system composed of two simple salts and their eutectic, and that at temperatures below 550°C, which is the melting point of LiBr, LiBr and KBr are dissolved in fused eutectic, while KBr is dissolved in the fused eutectic and LiBr at temperatures between 550° and 738°C, which latter is the melting point of KBr.     

Studies on Isotope Separation of Lithium by Electromigration in Fused Lithium Bromide and Potassium Bromide Mixture, (III)

Enrichment of ⁶Li by means of electromigration was carried out in fused LiBr-KBr mixture of a composition of 1.54 (Li/K in chemical equivalent ratio).

The electromigration brought about by 847,000 C of charge transported at 520°C, produced in the cathode compartment 38.4 meq. of Li salt with an abundance ratio of the isotopes (⁷Li/⁶Li) of 7.03, as compared with the initial value of 12.58. The distribution of the total amount of salt and of the salt composition in the migration tube agreed well with the results previously obtained on the enrichment of ⁷Li. It is suggested that, in veiw of the similarity in phase diagrams between UCl₄-CaCl₂ and LiBr-KBr systems, there are logical possibilities of ²³⁵U enrichment by analogous procedure.     

Studies on Isotope Separation of Lithium by Electromigration in Fused Lithium Bromide and Potassium Bromide Mixture, (I) Enrichment of Lithium-7

Lithium-7 was enriched by electromigration at 500° C in fused LiBr-KBr mixture.

The migration cell was made of Pyrex glass; zircon sand (100–200 mesh) was used for packing material, and graphite rods as electrodes.

The electromigration was carried out for 13.4 days at a constant electric current of 165 mA.

The distribution of the abundance ratio of the Li isotopes and of the composition of the salt in the migration cell were investigated. The abundance ratio of the Li isotopes (⁷Li/⁶Li) in the anode compartment was found to change from the original value of 12.20 to 46.9. The composition (Li/K in chemical equivalent ratio) of the salt reached roughly constant at 1.41 throughout the migration cell except in the vicinity of the cathode, and the value was not affected by the composition of the feed salt. It is the selective transport of salt of this composition toward the anode compartment by capillary action in the migration cell that is considered the mechanism that makes sustained electromigration possible. The mechanism of the accumulation of the isotope effect is also discussed.     

Adsorption Characteristics of Trivalent Rare Earths and Chemical Stability of a Silica-Based Macroporous TODGA Adsorbent in HNO3 Solution

In order to separate trivalent minor actinides (Am and Cm) from high-level liquid waste generated in a nuclear fuel reprocessing process, a silica-based macroporous TODGA (N,N,N′,N′-tetraoctyl-3-oxapentane-1,5-diamide) adsorbent (TODGA/SiO₂-P) was prepared. In this study, the adsorption characteristics of some trivalent rare earths (Y, Nd, and Eu), whose separation behaviors were similar to those of the minor actinides from HNO₃ solution with the TODGA/SiO₂-P adsorbent, and the chemical stability of the adsorbent against the HNO₃ solution were evaluated experimentally. It was found that the adsorbent exhibited a quite strong adsorption especially for Y(III). The standard enthalpy change for the Y(III) adsorption was determined to be ?2.5kJ·mol^?1 using the van't Hoff equation, which indicates that the adsorption was an exothermic reaction. The results of chemical stability experiments showed that the adsorbent had relatively excellent properties in long-time contact with the HNO₃ solution.     

离子液体浮选分离模拟乏燃料中的稀土元素

从乏燃料中高效分离稀土元素（中子毒物）是实现乏燃料再生循环利用的关键步骤。利用双有机相离子液体选择性浮选分离乏燃料中的稀土元素,使氧化铀和稀土氧化物几乎不被溶解,实现两者固相之间的分离,避免了二次废液的产生,具有节能和环保的双重意义。以2-乙基己基膦酸单-2-乙基己基酯（P507）为稀土元素的捕收剂、煤油或油酸为稀释剂,以1-丁基-3-甲基咪唑六氟磷酸盐（［C₄mim］［PF₆］）和1-丁基-3-甲基咪唑双三氟甲烷磺酰亚胺盐（［C₄mim］［Tf₂N］）两种离子液体作为浮选体系的另一相,优化得到了浮选分离稀土氧化物的最佳条件。结果发现：浮选分离去除率随着混合物中初始Nd含量以及浮选次数的增加而增加。另外,对所有稀土元素与U₃O₈分别组成的二元体系混合物进行了浮选分离研究,发现在相同条件下,该体系对不同稀土元素的分离也不同,浮选分离的去除率与稀土氧化物的密度有一定的相关性。在此基础上,利用浮选机开展了工艺化的初步探索,发现该浮选体系对Nd的去除率可达80%以上。     

一种快速放化分离~(72)Ga的方法

以Fe(OH)3沉淀和异丙醚萃取为主要分离方法,建立了一种简单、有效的快速放化分离微量72 Ga的流程。流程对Ga的化学回收率大于90%,对裂变产物元素的去污因子均大于103,对土壤基体的去污因子为4.1×103,分离时间小于50min,可以满足快速放化分离72 Ga的需求。     

离子液体浮选分离模拟乏燃料中的稀土元素

从乏燃料中高效分离稀土元素（中子毒物）是实现乏燃料再生循环利用的关键步骤。利用双有机相离子液体选择性浮选分离乏燃料中的稀土元素,使氧化铀和稀土氧化物几乎不被溶解,实现两者固相之间的分离,避免了二次废液的产生,具有节能和环保的双重意义。以2-乙基己基膦酸单-2-乙基己基酯（P507）为稀土元素的捕收剂、煤油或油酸为稀释剂,以1-丁基-3-甲基咪唑六氟磷酸盐（［C₄mim］［PF₆］）和1-丁基-3-甲基咪唑双三氟甲烷磺酰亚胺盐（［C₄mim］［Tf₂N］）两种离子液体作为浮选体系的另一相,优化得到了浮选分离稀土氧化物的最佳条件。结果发现：浮选分离去除率随着混合物中初始Nd含量以及浮选次数的增加而增加。另外,对所有稀土元素与U₃O₈分别组成的二元体系混合物进行了浮选分离研究,发现在相同条件下,该体系对不同稀土元素的分离也不同,浮选分离的去除率与稀土氧化物的密度有一定的相关性。在此基础上,利用浮选机开展了工艺化的初步探索,发现该浮选体系对Nd的去除率可达80%以上。     

南方离子型稀土分离企业环境放射性水平调查

对广西两家使用南方离子吸附型稀土精矿作为原料的稀土分离企业的外围环境放射性水平进行调查, 主要指标包括企业外围环境γ辐射空气吸收剂量率、空气中氡浓度、外排废水流出物、地表水和地下水、周围土壤、纳污河流监测断面底泥。调查结果表明, 两家企业外围环境放射性水平在正常范围内。     

Radioactive Rare Gas Separation Using a Separation Cell with Two Kinds of Membrane Differing in Gas Permeability Tendency

A separation cell embodying two kinds of membrane—porous and nonporous, i.e. differing in gas permeability—has a separation factor higher than possible with a conventional separation cell with a single kind of membrane. The performance of such separation cells and of cascades constituted thereof are analyzed theoretically and measured experimentally for different conditions of operation, to determine the applicability of the concept to the separation of rare gases from gaseous waste out of nuclear plants.

Theoretical considerations indicate that, in a cascade composed of symmetric separation cells, the separation performance can be improved by recycling part of the effluent from a cell back through the same cell (recycling cascade). It is shown that its performance is better than with the arrangement of diverting another effluent several stages upstream. With the recycling cascade, the symmetric separation recycling rate is determined by the depletion separation and enrichment separation factors relevant to the respective membranes.

The separation performance of a 9-stage recycling cascade composed of separation cells with silicone rubber tubular membranes and cellulose acetate tubular membranes is derived for a case of Kr separation from N₂-Kr mixture. The experimental data coincide well with the analytical results.

From both the experimental and the analytical results, it is found that the attainable separation coefficient per stage of the cascade comes to average approximately 0.97.     

Enrichment of the Uranium Isotopes by Electromigration in a Cation Exchange Membrane

The γ-radiolysis of water subjected to gas bubbling has been studied using a specially desinged gasloop. During the irradiation, N₂ gas was bubbled from the bottom of the irradiation vessel. As the N₂ gas feed rate was raised, the apparent G(H₂) value increased in keeping therewith, from 5 × l0^?3 to 0.26. However in the presence of a sufficient amount of O₂ or H₂O₂, G(H₂) was raised almost to the level of the molecular yield. With reasonable assumptions, it could be concluded that 3～5 × 10^?6 mol/l of H₂O₂ was sufficient to reduce the back reaction of molecular products to less than 10% under the present experimental conditions. It was also found that the G(H₂) value increased with CH₃OH concentration roughly in proportion to log(CH₃OH), and reached 3.1 with 0.1 mol/l CH₃OH.     

裂变产物中90Rb的快速放化分离方法研究

为精确测量⁹⁰Rb的衰变数据,需制备出放化纯的⁹⁰Rb样品。本文利用“两步延迟分离法”,建立了一套从新生成的裂变产物中快速分离高丰度⁹⁰Rb的放化流程。该流程先采用抽气法从辐照靶内提取出气体裂变产物⁹⁰Kr,再利用水洗法提取出⁹⁰Kr衰变生成的子体⁹⁰Rb。研制了一套⁹⁰Kr快速提取装置,最终得到了无载体、高比活度的⁹⁰Rb样品。整个分离流程收率约为20%,对主要杂质核素的去污因子达到了10³,操作时间在2.5 min内。     

从裂变产物中快速放化分离~(144)La的方法研究

为测量短寿命核素~(144) La的衰变数据,需要制备出高丰度、高活度的~(144) La样品。本工作采用"两步延迟分离法"分离流程,以二(2-乙基己基)磷酸酯(HDEHP)萃取为手段,利用SISAK装置在10s内实现~(144 )Ba-~(144 )La的分离,放置20s后再采用P204萃取色层柱提取由~(144 )Ba新生长出来的~(144 )La。通过详细研究萃取时间、萃取剂浓度、介质条件等因素对萃取分配比的影响,确定了从新生裂变产物中快速放化分离~(144) La的流程。流程所需时间约50s,La的化学回收率约为75%。     

电迁移技术在获取核素迁移参数中的应用

电迁移技术可快速、高效获取核素迁移参数,在核素迁移研究领域具有广阔应用前景。传统电迁移方法利用电场驱动核素离子快速定向运移,通过土体精确切割、浓度定量测定及理论模型拟合可快速获取核素在土体中的扩散迁移参数,目前该技术在单一种态核素的迁移研究中已得到成功应用,但仍无法满足强吸附性核素的迁移实验研究需要。为此,本文对传统电迁移技术进行改进,设计了cm级流出法电迁移实验装置,并建立了相应的迁移模型与参数求解方法,开展了以⁸⁸Sr为示踪剂、柯尔碱膨润土为介质载体的电迁移实验,验证了流出法在电迁移研究中的可行性,为后续钚等多种态、强吸附性核素的电迁移实验研究奠定了理论基础。