同位素稀释-电感耦合等离子体质谱法测定八氧化三铀中微量钍

为了解决核燃料循环前端铀产品中痕量钍的分离、分析问题,将高分辨电感耦合等离子体质谱(HR-ICP-MS)与同位素稀释技术(ID)相结合,建立了灵敏、准确的八氧化三铀中微量钍的分析方法,方法的检出限为0.003 3 μg/g,相对标准偏差小于3%(n=3).     

氢化物发生-电感耦合等离子体质谱法测定砂岩型铀矿样品中痕量镉

在砂岩型铀矿样品中,被测元素镉含量较低,每个质量丰度都存在不同类型的质谱干扰,而且各干扰元素的含量也存在较大差异,对电感耦合等离子体质谱法准确测量痕量镉造成比较大的困难。因此为了准确测量砂岩型铀矿样品中镉的含量,需要克服样品中不同类型的质谱干扰。采用氢化物发生-电感耦合等离子体质谱联用技术,被测镉元素气化后进入质谱仪中进行测量,可以有效解决测量元素镉的质谱干扰问题,同时提高了元素镉的灵敏度。建立了微波消解样品,连续流动注射进样氢化物发生-电感耦合等离子体质谱法准确测定砂岩型铀矿样品中痕量镉的方法。以盐酸溶液为介质,加入硫脲、亚铁氰化钾掩蔽剂溶液,以磷酸氢二铵、锶离子为增敏剂,优化了介质选择及浓度、硼氢化钾浓度、镉增敏剂的选择与用量等条件,并且有效解决了共存离子的干扰问题。研究表明：建立的连续流动注射氢化物发生-电感耦合等离子体质谱法测定砂岩型铀矿样品中痕量镉的方法,具有检出限低,正确度高,精密度好和适用范围宽等特点。方法检出限为0.001μg·g^-1,精密度优于8.80%(以多次测量的相对标准偏差RSD来表征)。     

同位素稀释-多接收电感耦合等离子体质谱法测量^148Nd

本工作分别对待测离子浓度、测量次数、测量时间、炬管轴向位置、雾化气流速、碰撞气体流速和离子光学参数等参数进行实验研究，实现了同位素稀释-多接收电感耦合等离子体质谱（MC—ICP—MS）同位素丰度测量条件的优化，Nd同位素丰度测量精度可达0．01％。     

同位素稀释-多接收电感耦合等离子体质谱法测定牛血中的铅

血铅含量水平作为评价铅中毒的重要指标，越来越受到人们的关注。血铅的准确分析已经成为分析工作中的又一热点，建立国内适用的血铅浓度标准势在必行。为此，本工作研究解决了血铅含量低、有机物含量高、操作过程易污染等难题，     

同位素稀释多接收电感耦合等离子体质谱法测量红酒中的痕量铁

使用同位素稀释技术,采用配有六极杆碰撞室的多接收电感耦合等离子体质谱,对红酒标准物质中铁含量进行了测量,得到高精密度同位素丰度比测量结果。同时采用相对测量方法 ICP-MS和 ICP-OES对红酒样品中的铁含量进行了测量,并与同位素稀释质谱法进行了比较,结果符合一致。方法的不确定度分析包含了实验过程中每个步骤所产生的不确定度和使用的标准物质的不确定度,其中,流程空白对方法检测限和精密度的影响不容忽视。建立的红酒中痕量铁含量的同位素稀释质谱方法为标准物质的定值提供了技术支持。     

多接收电感耦合等离子体质谱法对铀同位素丰度的测定

为了对环境监测提供有效、可靠的手段,在多接收电感耦合等离子体质谱(MC-ICP-MS)上建立了铀同位素丰度的分析方法。对影响仪器灵敏度的因素进行了初步探索,对标准物质GBW 04227和3个同位素丰度不同的样品中铀的各种同位素组分比值进行了测量,评价了测定结果的不确定度。结果表明,对丰度为3%、质量分数为2×10-7的235U溶液,R(235U/238U)丰度比的相对实验标准偏差优于0.02%,R(236U/238U)丰度比的相对实验标准偏差优于0.2%。     

电感耦合等离子体质谱法测定硼同位素丰度

以硼同位素标准参考物质NIST SRM 951配制的标准溶液,在优化的操作条件下对电感耦合等离子体质谱(ICP-MS)测定的硼同位素质量进行校正,求出校正因子,确定了样品的线性浓度范围.在同样的仪器条件下测定了硼同位素浓缩过程中样品三氟化硼甲醚络合物中的硼同位素丰度比,测定结果的相对标准偏差为1.095%.此外考查了仪器的稳定性.实验结果表明,本文建立的测定硼同位素丰度的方法"记忆效应"小,结果可靠,测量精度高.     

同位素稀释质谱法分析环境样品中的铀

报道了采用同位素稀释质谱法分析核设施环境样品中铀的分析测量方法,包括采用HNO3,HF和HClO4混酸分解处理、TBP色层分离纯化、质谱源的制备以及质谱分析测量条件。结果表明,所测环境样品中铀的含量为河水样品0.08μg/g;长青树叶0.1μg/g;表层土壤5～11μg/g。     

多接收电感耦合等离子体质谱法精密测量铀基体中痕量钚同位素比值方法研究

准确测定经核燃料后处理得到的铀产品中的钚同位素比值，可大致判断铀的来源，这对防止核扩散、铀产品的质量控制具有重要意义。但核燃料后处理铀产品中钚的量非常低（小于1ng／g），精密测量其中痕量钚的同位素丰度比具有较大技术难度。     

电感耦合等离子体质谱测定铀样品年龄方法研究

铀样品年龄与生产时间密切相关,是核法证学调查核材料来源属性的一个重要参数。本文研究建立了利用²³⁰Th/²³⁴U原子数比测定铀样品年龄的分析方法。分别用²²⁹Th和²³³U稀释剂进行铀样品同位素稀释,利用TEVA树脂对样品中的铀和钍进行分离处理,用多接收电感耦合等离子体质谱测量²²⁹Th/²³⁰Th和²³³U/²³⁴U原子数比,根据铀年龄计算公式通过²³⁰Th/²³⁴U原子数比可得到样品的铀年龄。采用该方法对CRM U850和U010标准样品进行了年龄测定,结果与美国劳伦斯·利弗莫尔国家实验室的测量结果一致,但较实际年龄偏大,可能是由于生产时纯化过程不完全,导致有残留的²³⁰Th在样品中。本文所建立的方法可用于铀样品²³⁰Th-²³⁴U模型年龄的测定,为核法证学调查提供重要信息。     

Separation of Uranium Isotope by Plasma Centrifuge

A method of centrifugal separation of isotopes by electromagnetic means is presented. The principle proposed utilizes electromagnetic acceleration by the interaction between an electric current in a slightly ionized gas and an external magnetic field. The analysis shows that an azimuthal flow of 2.6 km/sec can be realized with a magnetic field of 200 gauss and an electric current of 1.5kA. The resulting centrifugal force is large enough to permit realization of a more compact concentration cascade than the conventional mechanical centrifuge.     

Construction of Larger Area Density-Uniform Plasma with Collisional Inductively Coupled Plasma Cells

The plasma density and electron temperature of a multi-source plasma system composed of several collisional inductively coupled plasma （ICP） cells were measured by a doubleprobe. The discharges of the ICP cells were shown to be independent of each other. Furthermore, the total plasma density at simultaneous multi-cell discharge was observed to be approximately equal to the summation of the plasma density when the cells discharge separately. Based on the linear summation phenomenon, it was shown that a larger area plasma with a uniform density and temperature profile could be constructed with multi-collisional ICP cells.     

Surface Modification of Nanometre Silicon Carbide Powder with Polystyrene by Inductively Coupled Plasma

An investigation was made into polystyrene （PS） grafted onto nanometre silicon carbide （SIC） particles. In our experiment, the grafting polymerization reaction was induced by a radio frequency （RF） inductively coupled plasma （ICP） treatment of the nanometre powder. FTIR （Fourier transform infrared spectrum） and XPS （X-ray photoelectron spectroscopy） results reveal that PS is grafted onto the surface of silicon carbide powder. An analysis is presented on the effectiveness of this approach as a function of plasma operating variables including the plasma treating power, treating time, and grafting reaction temperature and time.     

Ion Density Distribution in an Inductively Coupled Plasma Chamber

The ion density distribution in the reaction chamber was diagnosed by a Langmuir probe. The rules of the ion density distribution were obtained under the pressures of 9 Pa, 13 Pa, 27 Pa and 53 Pa in the reaction chamber, different radio-frequency powers and different positions. The result indicates that the ion density decreases as the pressure increases, and increases as the power decreases. The ion density of axial position z =0 achieves 5.8×1010 on the center of coil under the power of 200 w and pressure of 9 Pa in the reaction chamber.     

Efficient Isotope Ratio Analysis of Uranium Particles in Swipe Samples by Total-Reflection X-ray Fluorescence Spectrometry and Secondary Ion Mass Spectrometry

A new particle recovery method and a sensitive screening method were developed for subsequent isotope ratio analysis of uranium particles in safeguards swipe samples. The particles in the swipe sample were recovered onto a carrier by means of vacuum suction-impact collection method. When grease coating was applied to the carrier, the recovery efficiency was improved to 48±9%, which is superior to that of conventionally-used ultrasoneration method. Prior to isotope ratio analysis with secondary ion mass spectrometry (SIMS), total reflection X-ray fluorescence spectrometry (TXRF) was applied to screen the sample for the presence of uranium particles. By the use of Si carriers in TXRF analysis, the detection limit of 22 pg was achieved for uranium. By combining these methods with SIMS, the isotope ratios of ²³⁵U/²³⁸U for individual uranium particles were efficiently determined.     

Numerical Investigation of Flow Fields in Inductively Coupled Plasma Wind Tunnels

Numerical simulations of 10 kW and 110 kW inductively coupled plasma （ICP） wind tunnels were carried out to study physical properties of the flow inside the ICP torch and vacuum chamber with air as tile working gas. Two-dimensional compressible axisymmetric Navier- Stokes （N-S） equations that took into account 11 species and 49 chemical reactions of air, were solved. A heat source model was used to describe the heating phenomenon instead of solving the electromagnetic equations. In the vacuum chamber, a four-temperature model was coupled with N-S equations. Numerical results for tile 10 kW ICP wind tunnel are presented and discussed in detail as a representative case. It was found that the plasma flow in the vacuum chamber tended to be in local thermoehemical equilibrium. To study the influence of operation conditions on the flow field, simulations were carried out for different chamber pressures and/or input powers. The computational results for the above two ICP wind tunnels were compared with corresponding experimental data. The computational and experimental results agree well, therefore the flow fields of ICP wind tunnels can be clearly understood.