用HDEHP萃取色层快速测定水中90Sr方法不确定度的估计

从满足辐射环境监测的需要出发,对HDEHP萃取色层快速测定水中90Sr标准方法的不确定度进行估计.分析了结果不确定度的来源,分别对主要的不确定度分量进行量化,估计了方法的总不确定度.结果表明:对于环境水平的样品分析,影响结果不确定度的主要因素是β放射性测量,其次是仪器探测效率和样品化学回收率.     

冠醚萃取色层法分离环境水样品中90Sr

为改进环境水样品⁹⁰Sr的分离方法,在冠醚萃取法基础上将冠醚萃取液涂在硅藻土支撑体上,研究了冠醚浓度、载体量、洗脱液体积等参数对Sr元素分离的影响,建立了环境水样品中⁹⁰Sr冠醚萃取色层法。实验表明,冠醚浓度、载体量及洗脱液体积参数优化结果分别为0.89mol/L、100mg和200mL,参数优化后,该方法首次使用时对环境水样品Sr的化学回收率达90%以上,满足环境水样品低水平⁹⁰Sr常规分离分析需要。     

萃取色层法测定食品与环境样品中的钍

本文以聚三氟氯乙烯为支持剂,N-235为固定相,用萃取色层法测定食品与环境样品中的钍。文献[1]对杂质离子干扰的影响、淋洗曲线等实验条件已作了研究。本文根据叔胺萃取钍时盐析剂浓度影响不大的性质~([2])减少了盐析剂的用量,并以2N硝酸溶液代替饱和硝酸铵作为盐析剂,这样降低了硝酸盐对钍-铀试剂Ⅲ比色的影响,因而减小了分析结果的离散度,提高了化学回收率。对广东鲮鱼样品的多次测定结果的相对标准差为4％;平均化学回收率为97±4％;最小可检值为1.0×10~(-7)克。本文所用方法与中子活化法作了比较。三种样品的测试结果基本相符。     

生物样品中锶-90分析的不确定度评定

以茶叶样品锶-90分析为例,详细介绍了生物样品中锶-90分析不确定度的来源,数学模型的建立,标准不确定度的合成,不确定度分量以及扩展不确定度的计算。深入讨论了各不确定度分量对总不确定度的贡献。结果显示:该茶叶样品锶-90活度的分析结果为(68.8±2.6)Bq/kg,该样品的不确定度主要来自?计数的测量、仪器探测效率和样品化学回收率。     

用均二苯基—16—冠—5—氧代乙酸从^90Sr—^90Y中萃取^90Y的研究

用新型萃取剂均二苯基－１６－冠－５－氧代乙酸研究了Ｓｒ＾２＋和Ｙ＾３＋的萃取。结果表明，在适当ｐＨ条件下，Ｙ＾３＋可以定量地被萃取，而Ｓｒ＾２＋几乎全部留在水相中。利用斜率法确定了均二苯基－１６－冠－５－氧代乙酸与Ｙ＾３＋的配合物组成比为１：２。建立了从＾９０Ｓｒ中萃取无载体高纯放射性＾９０Ｙ的方法。     

TEVA-UTEVA萃取色层分离后处理铀产品中镎的方法研究

本文建立了有效、定量分离后处理铀产品中镎的方法。该方法采用TEVA-UTEVA萃取色层分离后处理铀产品中的微量镎,先将镎调至四价后过TEVA萃取色层柱,再用2 mol/L HNO₃-0.2 mol/L H₂C₂O₄解吸吸附在TEVA树脂上的镎,最后将镎解吸液稀释后过UTEVA萃取色层柱进一步分离。结果表明,镎的平均全程回收率约为94%,铀的去污因子＞10⁴。     

基于固相萃取片的应急状态下水中锶-90快速测定方法研究

建立了一种基于固相萃取片的应急状态下水中锶-90快速分析测量方法。1.00 L水样品经酸化处理后使用锶固相萃取片过滤,再使用低本底α/β计数器测量萃取片上锶-90的计数,同时对相关测量条件进行分析研究,提出了解决钇-90和锶-89对锶-90测量产生干扰的方法。本方法操作简单,化学回收率稳定,典型条件下方法探测下限为0.019 Bq/L,整个实验过程约2小时,适合应急情况下水中锶-90的快速测定。     

土壤中^90Sr分析方法比对

由于原行业标准EJ／T1035—1996《土壤中^90Sr的分析方法》的某些固有问题，如制备色层粉用的原料不易购买，快速法中除铋效果不佳，导致结果偏高，一定程度上影响了监测结果的准确性和可靠性。本工作为参加核行业标准《土壤中锶-90的分析方法修订版》的比对研究。该行业标准在原标准方法的基础上，采用了P204萃淋树脂替代色层粉，使用了以含高铁、钙、镁基体的土壤为对象，     

低水平环境水样中~(90)Sr含量的测定

为了加强对低于国标规定的探测下限(10 mBq/L)的低水平环境水样中90Sr含量的监测,对国标GB6766—1986《水中90Sr放射化学分析方法二-(2-乙基己基)磷酸萃取色层法》中90Sr含量测定条件进行了优化和细化。以P204树脂为分离柱分离90Sr和90Y,观察了水样取样体积,水样、探测效率和电镀源校正测量时在低本底α、β测量仪上测量时间的选择,水样前处理时加入饱和草酸溶液和调溶液pH先后顺序对形成沉淀的影响。测量条件优化后,探测下限可达到0.36 mBq/L,低于国标规定的测量下限10 mBq/L;对低水平环境水样中90Sr含量测量的加标回收率为89.8%～124.0%。以上结果说明,测量条件优化后,方法的准确度良好,可达到对低水平环境水样中90Sr含量(含低水平水样)准确测量的目的。     

核电厂废树脂中90Sr、55Fe含量的快速分析

随着我国核电机组不断投入运行,会产生大量的放射性废树脂,废树脂中含有的中、长半衰期放射性核素关系到处置场的长期安全性,是处置场安全评价的重点。本工作利用萃取色层法和低本底液闪测量法建立了一种核电厂废树脂中⁹⁰Sr和⁵⁵Fe快速分析方法,该方法Sr的化学回收率为94.94%,最小可探测比活度为5.1 Bq/kg,采用两种分离方法Fe的化学回收率分别为96.60%、87.23%,最小可探测比活度分别为10.83、11.76 Bq/kg。     

A method to eliminate the effect of radiation on thermocouple performance

In-core temperature measurements are pivotal in maintaining nuclear reactors in a safe state of operation. Thermocouples serve as the liaison in ensuring this safe state. The realization of the thermocouple's full potential is hindered by the fact that thermocouples cannot be situated in areas with high radiation fields. Radiation has the potential of generating voltages in the thermocouple wires, hence producing an error in the temperature transmitter output. In this paper, a mathematical model is developed to quantify the effect that radiation from the Canada Deuterium Uranium (CANDU) Nuclear Power Plants (NPPs) has on the thermocouple temperature reading. Subsequently, a method to offset the effect of radiation on the thermocouple is proposed. Simulation is performed to verify the effectiveness of the proposed system.     

A sensitive method for Sr-90 analysis by accelerator mass spectrometry

ABSTRACT

Strontium-90 is one of the most important fission products due to the potential health risks of its uptake and retention in the human body. Conventional analysis techniques involve β counting, which requires ingrowth of ⁹⁰Y over a period of two weeks. Accelerator mass spectrometry (AMS) has the potential to shorten the analysis time while offering a lower limit of detection than β counting. Here, Sr in samples was recovered as SrF₂ to provide sufficient negative ions in the caesium-sputtering ion source. In the sample preparation step, 95–98% of Sr was recovered and 99–100% of Zr removed by ion-exchange separation. Sr recovery was ~30% in the precipitation process, and this can be improved. A maximum 500 nA beam current of SrF₃ ^– ions was obtained from SrF₂ samples mixed with PbF₂. A five-anode gas ionization detector was used to avoid isobaric interference from ⁹⁰Zr. The ⁹⁰Sr/Sr atomic ratio background of ~6 × 10^–13 (~3 mBq ⁹⁰Sr) was comparable with that achieved at other AMS facilities. Good linearity in ⁹⁰Sr/Sr atomic ratios was obtained from 1.75 × 10^–10 to 3.38 × 10^–9. Suitable techniques for sample preparation and measurement were thus achieved for ⁹⁰Sr analysis by AMS.     

Determination of Sr90 and Ce144 in samples by extraction

A method is described for determining Sr⁹⁰ in samples of soils, terrains, muds, and ashes of biological origin, based on extracting the equilibrium Y⁹⁰ with tributyl phosphate. The proposed method is not inferior to the standard method in accuracy, and is at the same time more expressive and convenient for mass Sr⁹⁰ determinations in different samples. The method permits determining Ce¹⁴⁴ at the same time, and in the same samples, without large additional expenditures of time and reagents.Translated from Atomnaya Énergiya, Vol. 14, No. 3, pp. 285–289, March, 1963     

一种快速分析土壤样品中90Sr的方法

为了对核设施及周边环境的放射性污染水平进行有效监测,需要对大量土壤样品中的⁹⁰Sr进行分析。本工作以对锶有特效选择性的Sr·Spec树脂为主要分离纯化材料,结合浸取或全溶解预处理、草酸盐沉淀以及时间校准法与双标记法液闪测量,建立了快速分析土壤样品中⁹⁰Sr的方法。全流程对Sr的化学回收率约为60%,分析时间小于6h,方法的最小可探测比活度为8Bq/kg。