Inter-laboratory comparisons: Determination of actinides in excreta

Inter-laboratory tests are a means of assessing the analytical coherence of medical laboratories. In radiotoxicology, this kind of exercise makes it possible to keep up with laboratory know-how and with the evolution and relative performances of analytical techniques (precision and reproducibility). However, the goal of the laboratories taking part in these annual exercises is not only to check the accuracy of their results. The analytical discussions and the chance to compare experiences enrich the group's general competence.French biologists have been organizing annual radiotoxicology intercomparison exercises since 1978. The exercises are carried out within the framework of a working group (GT1) operating under the aegis of the French Atomic Energy Commission's (CEA) Medical Coordinator. Using reports and diagrams which present the results obtained by the participants in the form of syntheses, the authors describe how the exercises for determining actinides in excreta (urine and faeces) are organized, how the results are evaluated in terms of the analytical methods used, and the improvements made in analytical and metrological performance.Up until 1985, these exercises were limited to French laboratories. Since then, the exercises have acquired an international dimension, opening up to include interested foreign radiochemists, initially from European laboratories, and now from laboratories worldwide. At the present time, 35 laboratories representing 9 countries take part regularly in these intercomparison exercises.     

Determination of the operating parameters of an evaporator crystallizer

This work involves the study of the solid/liquid equilibrium in the NaCl–NaOH–H₂O ternary system. The aim is to optimize the operating conditions of an evaporator–crystallizer used in a hydrazine extraction process. The latter is conducted at industrial scale using the Raschig method, a general method for preparing hydrazines for aerospace and pharmaceutical applications. The extraction process includes the use of a Kestner type evaporator–crystallizer to first isolate hydrazine and water by evaporation and then separate two salts: sodium hydroxide, recovered as an aqueous solution, and sodium chloride which crystallizes. However, problems related to the co-precipitation of NaCl–NaOH may be encountered in industry, leading to the clogging of installations. Therefore, it is necessary to ensure that only NaCl crystallizes while maintaining NaOH in liquid state. Knowledge of the equilibrium phases of the NaCl–NaOH–H₂O ternary system is thus required, particularly the liquid/solid phase. Phase equilibrium experiments were performed by isoplethic thermal analysis (ITA) and chemical titrations over the temperature range of 313 to 353 K at atmospheric pressure. ITA is an isobaric and isothermal method developed in our laboratory and based on the measurement of the thermal effects associated with transformations in a system (appearance or disappearance of a phase) when its composition is changed. The NaCl crystallization domain was fully determined and the operating parameters of the device were defined precisely as a function of temperature and composition of the Kestner loop.     

稀土精矿检测方法

综述了近年来稀土精矿中稀土总量、15种稀土氧化物配分量以及非稀土杂质含量分析测定的国家标准以及最新方法。电感耦合等离子体原子发射光谱法精密度高,检测速度快,为测定稀土精矿中稀土总量的常用方法。电感耦合等离子体质谱法不受基体干扰,更适用于痕量和超痕量稀土元素含量的测定,满足中、重稀土精矿的测定需求。分光光度法测定稀土精矿中非稀土杂质Th,Ti含量准确度高。对稀土精矿分析检测发展趋势进行了展望。     

Determination of fission-products and actinides in the Black Sea following the Cherynobyl accident

Radiochemical procedures are discussed for the isolation and determination of a suite of radionuclides in samples from the Black Sea following their input from the Chernobyl reactor accident. The samples analyzed include discrete water samples and both suspended and dissolved phases collected by in-situ chemisorption techniques. The radiochemical scheme permits the separation and analysis of¹³⁴Cs,¹³⁷Cs,⁹⁰Sr,¹⁴⁴Ce,¹⁴⁷Pm,¹⁰⁶Ru,²³⁹Pu,²⁴⁰Pu, and in some instances²⁴²Cm,²³⁸Pu, and²⁴¹Am. The detection techniques employed include various instrumental gamma spectrometric methods, low-level beta counting, alpha spectrometry, and mass spectrometry.The method's developments are described and data are presented on some representative samples from the Black Sea. The sensitivity of the analysis for the various nuclides and sample types is summarized and questions of radiochemical interferences are addressed.     

ICP-OES测定俄罗斯某地金精矿中砷的含量

用HCl-HNO3混和酸溶解金精矿样品,用电感耦合等离子体发射光谱法(ICP-OES)测定。在选定的操作条件下,砷的检出限0.018μg/mL。相对标准偏差( n=11),RSD<2%,加标回收率在98.2％-103.0％之间。用该法测定金精矿中砷元素的含量,操作简单易行,能够满足日常生产需要。     

高效液相色谱法测定浓缩胡萝卜汁中辛硫磷残留量

建立了浓缩胡萝卜汁中辛硫磷残留量的高效液相-二极管阵列检测方法.样品经乙酸乙酯提取,硅胶柱净化,采用反向C18色谱柱,流动相为V（甲醇）：V（水）=7：3,波长为285 nm.结果表明：在0.1～10.0μg/mL范围内回归方程为：Y=48.676ρ-1.4548,r=0.99985,呈良好的线性关系,方法检出限为0.02 mg/kg,平均回收率为76.5%～89.3%,相对标准偏差为2.8%～4.5%.     

Radiation chemistry of actinides

The paper presents data on the development of a mathematical model describing the radiation-chemical behaviour of plutonium in 3–6 mol/l HNO₃ with uranium present and absent. Using experimental data on the kinetics of Pu(VI) reduction and Pu(IV) oxidation, and comparing them with the calculated values, we succeeded in finding the previously unknown rate constants of many reactions between plutonium ions and HNO₃ radiolysis products, between plutonium ions and between plutonium ions and uranium ions. The mechanism of the radiation-chemical processes has been established.     

Simultaneous electrodeposition of actinides

A new system for simultaneous electrodeposition of U, Np, Pu, Am and Cm has been developed. The system consists of (NH₄)₂C₂O₄–H₂SO₄–HCl. The effects on recovery of pH, current density, interfering ions and the amount of added HCl have been studied. The optimum condition for simultaneous electrodeposition of actinides has been recommended. Under the recommended condition recoveries of U, Np, Pu, Am and Cm have been obtained by using²³²U,²³⁷Np,²⁴¹Am,²⁴²Pu and²⁴⁴Cm. The counting sources prepared are uniform, adherent and suitable for -spectrometry.     

Immobilisation of actinides in phosphate matrices

In the field of the immobilisation of high-activity-level and long-life radwaste (HAVL) for a deep underground repository, several phosphate matrices were already proposed as good candidates to delay the release of actinides in the near-field of such disposal. Among them, thorium phosphate–diphosphate (TPD), monazites/brabantites, britholites, and TPD/monazite composites were extensively studied. The synthesis of samples doped with actinides (Th, U...) through wet and dry chemistry methods then their complete characterisation are reported. Their chemical durability is also examined. These materials appear as promising matrices to immobilise tetravalent and/or trivalent actinides. To cite this article: N. Dacheux et al., C. R. Chimie 7 (2004).

Résumé

Immobilisation des actinides dans des matrices phosphatées. Dans l'optique d'un stockage de déchets radioactifs de haute activité et de vie longue en site géologique profond, plusieurs matrices phosphatées de type céramique ont été proposées afin de retarder le relâchement des actinides dans le champ proche d'un tel stockage. Parmi celles-ci, le phosphate-diphosphate de thorium (PDT), les monazites, les brabantites et les britholites présentent plusieurs des propriétés recherchées pour assurer la rétention de ces éléments sur le long terme. La préparation d'échantillons dopés avec des actinides par voie sèche et/ou humide, leur caractérisation à l'état pulvérulent ou fritté et leur durabilité chimique lors de tests de lixiviation sont examinées ici. Sur la base des propriétés physico-chimiques de ces matrices, des matériaux composites à base de PDT et de monazite ont été préparés puis caractérisés. Tous ces matériaux apparaissent comme des candidats prometteurs pour l'immobilisation des actinides tri- et tétravalents. Pour citer cet article : N. Dacheux et al., C. R. Chimie 7 (2004).     

Determination of 99Tc in evaporator concentrates using solid phase extraction techniques

This paper describes a simple and rapid method of ⁹⁹Tc pre-concentration, separation and purification by using AnaLig^? Tc02 gel in two stages or AnaLig^? Tc02 gel in a first stage and TEVA^? resin in a second stage, which are commercially available from IBC advanced technologies, Inc. and Eichrom technologies, Inc., respectively. The method is suitable for analyzing large volume concentrate samples in a relatively short time. The use and effectiveness of AnaLig^? Tc02 and Eichrom’s TEVA^? resin were successfully tested by analysis of evaporator concentrate samples which belong to the class of most difficult matrices to analyze.     

锌精矿中铟的测定

应用电感耦合等离子体发射光谱法测定锌精矿中的铟,确定了最佳工作条件,选择了最佳分析谱线,并利用标准加入法和基体匹配法确定了该方法的准确性。样品用氟化氢铵、盐酸、硝酸、高氯酸溶样,用盐酸浸取。本法与萃取分离盐酸羟胺示波极谱法测定的铟含量结果一致。方法准确,快速,加标回收率为99.6%~101.7%,相对标准偏差为0.97%~2.1%。     

Determination of 90Sr in radioactive concentrate from Nuclear Power Plant Mochovce

This paper describes the use of molecular recognition technology product AnaLig^®Sr-01 gel from IBC Advanced Technologies, Inc. to effectively and selectively pre-concentrate, separate and recover strontium from evaporator concentrate samples from Nuclear Power Plant Mochovce which belongs to the most difficult matrices to analyze. The method is suitable for analyzing highly contaminated samples of radioactive waste in a relatively short time and with high decontamination factors. Activity of ⁹⁰Sr was measured using Cherenkov counting on TRI CARB 2900 TR liquid scintillation counter.     

石墨消解-电感耦合等离子体质谱(ICP-MS)法测定铜精矿中汞的含量

称取0.2g样品于50mL样品管中,以5mL硝酸-盐酸(1∶1)混合溶液为溶剂,采用石墨消解仪对样品进行前处理。以159 Tb作内标元素补偿基体效应,用电感耦合等离子体质谱(ICP-MS)法对铜精矿中的202 Hg进行测定。结果显示,在0～50μg/L的浓度范围内,校准曲线线性相关系数在0.999 9以上,方法检出限0.019μg/L。对铜精矿标准样品的检测结果与标准值相符。铜精矿中汞的浓度在0.94～15.06μg/g时,与直接测汞仪检测结果对比基本一致。     

Coordination chemistry of actinides in molten salts

The problems of actinide molten salt coordination chemistry are considered in terms of spectroscopic parameters as functions of melt composition and temperature. Parameters connected with energy, intensity and fine structure of 5f-5f transitions have been obtained for molten alkali metal chlorides, fluorides and chloride-fluoride mixtures. The regularities of variation of both actinide-chlorine distances and actinide fluorocomplex stability have been studied.     

Speciation methods of actinides in trace concentrations

The development of actinide speciation methods in the environment is discussed. The results on speciation and migration of radionuclides in near-surface and deep conditions at the Krasnoyarsk mining and chemical plant and at the Production Association ‘Mayak’ (southern Ural) are reported. For surface conditions, the mobile plutonium fraction is mostly associated with inorganic complexes (carbonate) of the higher plutonium oxidation state, while less mobile fraction is associated with low-soluble Pu(IV) complexes with humic acids. The mobile fraction of americium consists of complexes with low molecular weight fulvic acids of non-specific nature with molecular weights lower than 10 kDa. Plutonium and americium behaviour in deep conditions is governed by colloid migration. To cite this article: A.P. Novikov et al., C. R. Chimie 7 (2004).

Résumé

Méthodes de spéciation des actinides en traces. Le développement de méthodes pour la spéciation des actinides dans l’environnement est discuté. Nous présentons des résultats concernant la spéciation et la migration des radionucléides dans des conditions de sub-surface et en milieux géologiques profonds à la mine de Krasnoyarsk et à l’usine chimique de Mayak (Oural du Sud). En conditions de sub-surface, la fraction mobile contient essentiellement des complexes inorganiques (carbonates) de Pu dans ses degrés d’oxydation élevés, tandis que la fraction moins mobile contient des complexes insolubles du Pu(IV), avec des acides humiques. La fraction mobile de Am comporte des complexes d’acides fulviques de nature non précisée, mais d’une masse molaire inférieure à 10 kDa. En conditions de milieu profond, le comportement de Am et de Pu est influencé par la migration des colloïdes. Pour citer cet article : A.P. Novikov et al., C. R. Chimie 7 (2004).     

Extraction of actinides with tropolone

The partition coefficient of tropolone in xylene, dichloroethane and chloroform was determined from 0.05M HCl medium. The values obtained were 5.6, 25.5 and 43, respectively. In the extraction of UO ₂ ²⁺ using tropolone (HT) in xylene from an aqueous medium of ionic strength 0.05, the species UO₂T₂·HT was established. The species extracted in presence of a neutral donor was found to be UO₂T₂·S[S+dioctyl sulfide (DOS), dibutylhexanamide (DBHA), tri-n-butyl phosphate (TBP), dioctyl sulfoxide (DOSO), and tri-n-octylphosphine oxide (TOPO)]. The equilibrium constant of complex formation between the self-adduct and the neutral donor was calculated and was found to follow the basicity order (DOS«DBHA<TBP<DOSO»TOPO). The thermodynamic parameters of the adduct UO₂T₂·DOSO were also calculated by the temperature coefficient method. The values of free energy, enthalpy and entropy changes obtained were ?1.26 kJ·mol^?1, ?1.98 kJ/mol and ?2.5 J·mol^?1·deg^?1, respectively.     

Rapid determination of actinides in seawater samples

A new rapid method for the determination of actinides in seawater samples has been developed at the Savannah River National Laboratory. The actinides can be measured by alpha spectrometry or inductively-coupled plasma mass spectrometry. The new method employs novel pre-concentration steps to collect the actinide isotopes quickly from 80 L or more of seawater. Actinides are co-precipitated using an iron hydroxide co-precipitation step enhanced with Ti⁺³ reductant, followed by lanthanum fluoride co-precipitation. Stacked TEVA Resin and TRU Resin cartridges are used to rapidly separate Pu, U, and Np isotopes from seawater samples. TEVA Resin and DGA Resin were used to separate and measure Pu, Am and Cm isotopes in seawater volumes up to 80 L. This robust method is ideal for emergency seawater samples following a radiological incident. It can also be used, however, for the routine analysis of seawater samples for oceanographic studies to enhance efficiency and productivity. In contrast, many current methods to determine actinides in seawater can take 1–2 weeks and provide chemical yields of ~30–60 %. This new sample preparation method can be performed in 4–8 h with tracer yields of ~85–95 %. By employing a rapid, robust sample preparation method with high chemical yields, less seawater is needed to achieve lower or comparable detection limits for actinide isotopes with less time and effort.