铀矿地质样品的稳定同位素组成测试方法

介绍了铀矿地质进行稳定同位素组成分析时,所需样品的种类和用量,以及测定C、H、O、S、N、Si同位素组成的离线方法和连续流(在线)方法。利用稳定同位素组成研究岩石、矿物成因及物质来源时,样品应选择无后期改造的适量矿物或岩石。利用矿物对研究成岩、成矿温度时,样品要选择同一时代的共生矿物对,样品新鲜且无后期改造。离线方法分析的同位素组成测试种类包括:不含氧矿物包裹体中水、硅酸盐、氧化物、硫酸盐中氧、硫化物及硫酸盐、全岩中硫,碳酸盐矿物中碳、氧,不含碳的矿物包裹体中碳,硅酸盐或含硅矿物中硅。在线方法分析的同位素组成测试种类包括:石英包裹体中氢,水的氢、氧,碳酸盐及碳酸盐胶结物中碳、氧,溶解无机碳中碳,有机质中碳、氮,水中硝酸盐氮,烃类样品中碳、氢。     

微量氙低温分凝条件的优化

利用自行研制的FNQ-01型气体分凝器实验平台研究了不同条件组合对微量氙收集效率的影响，通过正交法设计优化了稀有气体氙分凝取样条件，选出最佳条件为原料气中氙的体积分数为1.046×10^-3，冷凝温度-198 ℃，原料气进气流速0.3 L/min，分凝器收集压力55 kPa，蒸发温度-50 ℃。在此条件下，Xe的平均收集效率为73％。此外，还研究了不同进气方式对氙收集效率和分凝的影响。     

岩石和矿物中氧同位素组成分析制样装置改进及分析方法

对五氟化溴法氧同位素组成样品制备装置进行改进并对分析方法进行优化。改进的样品制备装置包含12个镍反应器,可完成12件氧同位素样品制备,提高了制备效率;采用O 2作为工作气体对样品中的氧同位素组成进行测定,避免了向CO 2转化过程中潜在的氧同位素分馏,还可同时获取δ18 O与δ17 O值;通过5A分子筛直接对O 2进行吸附,提高了收集效率;采用电容真空规对提取的O 2进行产率测量,确定了制样装置中石英单矿物质量与O 2压强之间的线性关系。以国家标准物质GBW 04409、石英单矿物以及花岗岩地质样品为参考,在改进的装置上进行氧同位素样品制备分析,其分析精度分别为0.09‰、0.09‰和0.10‰,均优于0.2‰,标准物质δ18 O VSMOW的测量平均值为11.09‰,在误差范围内与标准值11.11‰相吻合。样品制备效率及分析结果表明:改进的氧同位素样品制备装置及分析方法测量结果准确。     

GasBench Ⅱ-IRMS测定微量碳酸盐中碳氧同位素比值方法研究

采用Delta V Advantage 质谱仪与GasBench Ⅱ在线制样装置,分别用12 mL和3.7 mL的样品瓶,对不同质量（5~50 μg）的碳酸盐标准样品（IAEA-CO-1）进行碳氧同位素组成测定。测试结果表明,当取样量小于40 μg,且用12 mL样品瓶进行酸化测试时,δ¹³C和δ¹⁸O测量结果的内部标准偏差一半以上大于0.1‰,不能满足测试要求。当改用3.7 mL样品瓶,样品取样量在15～50 μg时,δ¹³C的内部标准偏差为0.01‰~0.07‰,δ¹⁸O的内部标准偏差为0.01‰~0.08‰,满足测试要求。所以,当样品量较少时,GasBench Ⅱ在线制样装置可以通过改用3.7 mL样品瓶,实现对低至15 μg微量碳酸盐样品的碳氧同位素精确测量。同时,碳酸盐样品的质量与峰面积具有很好的线性关系（R²＞0.993 2）,表明该方法也可用于样品中碳酸盐含量的测定。     

土壤硝酸盐中15N同位素测定前处理自动化辅助装置设计和验证

随着稳定同位素质谱技术在土壤氮循环研究中的广泛应用,氮稳定同位素分析对样品前处理方法提出了更高要求,而合适的样品处理方法是确保分析结果准确可靠的关键。设计开发1种适用于土壤微量硝酸盐中氮稳定同位素分析前处理辅助装置,将基于光电感应装置的自动进样系统与注液、抽真空-气体置换系统相融合,将原前处理方法中液体试剂注入,反应体系抽真空及氦气置换等人为操作过程改为自动化处理环节。系统测试结果表明:该套辅助装置具有良好的自动抽真空、注气和加液重复性。装置抽真空系统的真空度绝对误差可控制在0.5 Pa以内,气体注入体积绝对误差可控制在0.2 mL以内,而注液系统的注液体积绝对误差也可控制在0.1 mL以内,变异系数(CV)均小于1%。使用标准参比样品测试整套系统的准确度和精密度,所有测试样品均获得了较好的准确度和精密度,CV<1%。研制的装置结合痕量气体预浓缩装置—稳定同位素质谱(PreCon-IRMS)联用仪,可以建立方便快捷的低样品量下硝酸盐中15 N同位素质谱检测方法,可为土壤氮循环过程研究提供关键技术支撑。     

土壤硝酸盐中~(15)N同位素测定前处理自动化辅助装置设计和验证

随着稳定同位素质谱技术在土壤氮循环研究中的广泛应用,氮稳定同位素分析对样品前处理方法提出了更高要求,而合适的样品处理方法是确保分析结果准确可靠的关键。设计开发1种适用于土壤微量硝酸盐中氮稳定同位素分析前处理辅助装置,将基于光电感应装置的自动进样系统与注液、抽真空-气体置换系统相融合,将原前处理方法中液体试剂注入,反应体系抽真空及氦气置换等人为操作过程改为自动化处理环节。系统测试结果表明:该套辅助装置具有良好的自动抽真空、注气和加液重复性。装置抽真空系统的真空度绝对误差可控制在0.5 Pa以内,气体注入体积绝对误差可控制在0.2 mL以内,而注液系统的注液体积绝对误差也可控制在0.1 mL以内,变异系数(CV)均小于1%。使用标准参比样品测试整套系统的准确度和精密度,所有测试样品均获得了较好的准确度和精密度,CV1%。研制的装置结合痕量气体预浓缩装置—稳定同位素质谱(PreCon-IRMS)联用仪,可以建立方便快捷的低样品量下硝酸盐中~(15)N同位素质谱检测方法,可为土壤氮循环过程研究提供关键技术支撑。     

放射性氙同位素取样装置的建立及其效率标定

为了在常温至低温条件下进行大气中氙同位素取样,研制了一套稀有气体取样实验装置(Experimental Sampler for Rare Gases,RSRG),并以^129Xe为分析对象,利用感应耦合等离子体质谱仪进行了取样效率标定。实验结果表明,在采用再生吸附剂条件下,ESRG装置对大气本底水平浓度氙同位素的取样效率可达40％。     

地下水测氦可作为一种铀矿普查手段

美国地质调查局瑞斯和瑞米尔著文谈测水中氦作为一种铀矿普查手段,内容如下: 对已知铀矿床地区,进行地下水分折,并与区域底数值作比较,表现出明显的氦异常。前人的工作表明,铀矿床和水中氦两者之间存在着相关关系。所描述的野外研究包括家庭用水,畜牧用水井,水泉、池塘、河流和矿山排水。不同类型的密封容器——圆形塑料筒、罐头盒、钢瓶和抽空的玻璃试管都可取水样。使用哪一类容器,取决于从取样到分析的时间间隔。不锈钢瓶密封最好,能保持几个月,而圆形塑料筒密封最坏,只能保持几个小时。这些容器装到大约75％容量密封住。用力振荡,使水与空气混合,从而使溶解的气体从水中排出,留在容器内的大气起载体的作     

Carlin型金矿床的流体包裹体研究

Carlin型金矿床不同成矿阶段矿物组合的流体包裹体和氢、氧同位素研究可以使我们推断成矿时的物理化学条件,鉴别成矿流体的挥发性成分和潜在的流体源以及推测成矿的深度。样品分别取自美国内华达州的北部Getchell矿床周围的地表、采坑的钻孔岩心和Meikle、Betze/Post矿床。     

相山云际矿床铀成矿流体同位素特征及成因

通过对相山矿田云际矿床成矿期脉石矿物方解石C、O同位素及其流体包裹体He、Ar同位素组成测试研究,探讨了矿床铀成矿流体来源。分析测试结果表明,方解石的δ~(13)C_(V-PDB)和δ~(18)O_(V-SMOW)值分别为-9.4‰~-3.1‰和4.7‰~15.4‰,成矿流体中的碳主要来源于地幔;方解石流体包裹体的★~3He/~4He值为0.061 5~0.376 0 Ra,明显高于地壳特征值(0.01~0.05 Ra),显示出地幔流体与地壳流体混合特征;~(40)Ar/~(36)Ar值为314.4~334.1,略高于大气Ar的同位素组成(~(40)Ar/~(36)Ar=295.5),说明成矿流体中存在大气降水成分,并有地幔Ar的加入。综合分析认为云际矿床铀成矿流体为深源成因,其来源具有壳幔混合的特点。     

Fission gas production in reactor fuels including the effects of ternary fission

An understanding of gas bubble formation and migration in nuclear fuel and its impacts on fuel and cladding materials requires knowledge of the isotopic composition of the gases and their generation rates. In this paper, we present results of simulations for the production of the dominant noble gases (helium, xenon, krypton) in nuclear fuels for different reactor core configurations and fuel compositions. The calculations were performed using detailed nuclear burn simulations with Monte Carlo nuclear transport, and included ternary fission to ensure an accurate treatment of helium production. For all reactor designs and fuels considered xenon was found to be the most dominant gas produced. Variation in the composition of fission gases is quantified for: (1) the burn time, (2) the composition of the fuel, and (3) the neutron energy spectrum. These three factors determine the relative fraction of each gas and its transmutation into or from stable gas by subsequent neutron capture.     

New Near-Infrared and Ultraviolet Gas-Proportional Scintillation Counters

New studies of gas-proportional scintillation counters have been performed using a large alpha source, reasonable spectral resolution (< 25-k), and including the strong near-infrared transitions in noble gases excluded in all previous studies. The results indicate that several new gas mixtures show promise for detectors to measure the neutron fluxes in a reactor over a wide range of values and in many nuclear physics applications where fast response and good energy resolution are desired. When used with an isotopic source the device can be used as a portable, variable-intensity light source or to detect trace amounts of atmospheric contaminants such as CO, NO, and Hg. The work also has provided useful data for laser systems pumped by ionizing radiation as well as for the operation of plasma display panels.     

SAUNA移动氙取样系统的性能实验

介绍了SAUNA惰性气体氙移动取样系统的组成和基本功能,684 h取样性能研究结果表明,该系统拆卸、组装方便,性能稳定,氙取样量的平均值为2.2 mL/d,具备连续多天高效取样的能力.可用于大气中惰性气体氙活度的日常和应急监测.     

The Hydrothermal System Beneath Owakudani on Hakone Volcano,Japan; Traced by Stable Isotopic Ratios of H2O

In this study, we sampled natural fumarolic gases, the gas from a steam well drilled to 800 m depth and natural hot spring waters from the Owakudani geothermal area, Hakone Volcano, Japan. We then measured the chemical composition and the D/H and ¹⁸O/¹⁶O ratios of H₂O within the samples. On the basis of the analytical results, we investigated the differentiation processes of the magmatic fluid during ascent to the surface. Volcanic gas discharged from the No. 52 steam well has a CO₂/H₂O ratio that is much higher than those from fumarolic gases. The isotopic ratio of H₂O in the gas are also much higher than those in the fumarolic gases, and the gas also contains high concentrations of SO₂ and HCl. The above observations indicate a magmatic origin for the gas from the No. 52 steam well. The hydrothermal system is principally explained by the mixing of a magmatic vapor, represented by the gas from the No. 52 steam well, and cold local meteoric water. Following mixing of the fluids, a separation of primary vapor and liquid occurs. The primary liquid is discharged as a component of hot spring water, and has high isotopic ratios. The primary vapor is mixed with vapor derived from the boiling of local meteoric water. The mixed vapor is then discharged to the surface, interacting with shallow meteoric water and undergoing partial condensation of H2O vapor. Hot spring water with isotopic ratios lower than those of the primary liquid is derived from the boiling of local meteoric water.     

Nuclide analysis in high burnup fuel samples irradiated in Vandellós 2

In the framework of a high burnup fuel demonstration programme, rods with an enrichment of 4.5% ²³⁵U were operated to a rod average burnup of about 70 MWd/kgU in the Spanish Vandellós 2 pressurised water reactor. The rods were sent to hot cells and used for different research projects. This paper describes the isotopic composition measurements performed on samples of those rods, and the analysis of the measurement results based on comparison against calculated values.The fraction and composition of fission gases released to the rod free volume was determined for two of the rods. About 8% of Kr and Xe produced by fission were released. From the isotopic composition of the gases, it could be concluded that the gases were not preferentially released from the peripheral part of the fuel column.Local burnup and isotopic content of gamma emitting nuclides were determined by quantitatively evaluating axial gamma scans of the full rods. Nine samples were cut at different axial levels from three of the rods and analysed in two campaigns. More than 50 isotopes of 16 different elements were assessed, most of them by Inductively Coupled Plasma Mass Spectrometry after separation with High Performance Liquid Chromatography. In general, these over 400 data points gave a consistent picture of the isotopic content of irradiated fuel as a function of burnup. Only in a few cases, the analysis provided unexpected results that seem to be wrong, in most cases due to unidentified reasons. Sample burnup analysis was performed by comparing experimental isotopic abundances of uranium and plutonium composition as well as neodymium isotopic concentrations with corresponding CASMO based data. The results were in agreement with values derived independently from gamma scanning and from core design data and plant operating records.Measured isotope abundances were finally assessed using the industry standard SAS2H sequence of the SCALE code system. This exercise showed good agreement between measured and calculated values for most of the analysed isotopes, similar to those reported previously for lower burnup ranges. Thus, it could be concluded, that SAS2H results for high burnup samples are not subject to higher uncertainty and/or different biases than for lower burnup samples, and that the different isotopic experimental measurement methods provide accurate results with acceptable precision.     

后处理厂释放气体中稳定惰性气体同位素在核保障监督中的应用研究

用Origen2．1计算模式对压水堆元件中Kr,Xe相关同位素与燃耗的关系进行了计算，并估算了后处理厂烟囱释放气体中Kr,Xe各稳定同位素的来源，丰度和原子浓度.^82Kr，^129Xe可用作环境样品中惰性气体同位素的天然本底；裂片^83Kr／^86Kr．^84Kr／^86Kr、^131Xe／^134Xe和^132Xe／^134Xe的丰度比值，可用于指示乏燃料燃耗，进而估算正在被分离的钚同位素组成，并有可能对后处理厂实行保障监督。     

基于激光光谱分析的一种水中硝酸盐氮同位素比值测定新方法

稳定同位素质谱法是氮同位素分析通用的方法之一,然而水中硝态氮同位素检测涉及的前处理方法中的化学转化法或细菌反硝化法都存在样品量消耗大、操作过程复杂,难于快速测定等问题。本研究基于稳定同位素激光光谱分析技术,结合自主研发的自动样品制备和进样前端,建立一种冷冻干燥浓缩结合化学转化N₂O产生法的水体硝态氮稳定同位素丰度测定方法。利用新建的方法,分析硝酸钾参比溶液和不同来源水样中硝酸盐的δ15N值。结果表明,经冷冻干燥浓缩后的样品,通过制备前处理,N₂O产率>50%,当反应体系硝酸盐氮量在1.0~2.5 μmol范围时,转化产生的N₂O气体浓度符合仪器检测限要求,且两种硝酸钾参比溶液均能获得较好精度,标准偏差小于0.5‰,与参比溶液的给定值基本一致,无同位素分馏（差值小于0.5‰）。对于不同来源水样中硝酸盐氮稳定同位素比值的测定也可获得较好的重现性,标准偏差小于0.5‰,且与经典质谱测定值偏差小于0.5‰。新建立的方法采用激光光谱分析,可即时得到样品的氮同位素比值,避免了传统质谱法涉及的样品气低温冷阱预浓缩过程,测试时间较质谱法快速,且操作简单,可实现纳摩尔级硝酸盐浓度的水样批量检测。     

用碳稳定同位素估算大气细颗粒物中多环芳烃的来源

建立了用碳稳定同位素比估算大气颗粒物中多环芳烃（PAHs）的方法,该方法包括二氯甲烷提取、薄层色谱纯化和气相色谱-燃烧系统-同位素质谱测定碳稳定同位素组成(δ¹³C);并用该方法对上海市大气颗粒物PM_2.5中PAHs的来源进行估算。结果表明:采样点PM_2.5中PAHs的δ¹³C值随着分子量的增加而减小;与潜在污染源中相应值相比,更接近于燃煤和生物质燃烧的相应值,表明采样点处PM_2.5中的PAHs受燃煤和生物质燃烧的影响大于机动车尾气。PAHs来自燃煤、机动车尾气和生物质的贡献分别为3%-21%、29%-33%和46%-67%。这一结果与采样点的特殊环境一致,表明碳稳定同位素比能够定量估算大气细颗粒物中PAHs的来源。     

用于核电站放射性惰性气体处理的常温活性炭滞留床研究

本文介绍了用于核电站放射性惰性气体处理的常温活性炭滞留床，试验结果表明，１１种市售国产活性炭大多数可用于常温活性炭滞留床，其中椰壳０１、０２炭，果壳１１、１２炭较好，滞留床吸附性能的主要影响因素包括：气流比速、压力、温度、活性炭含水量。设计的滞留床具有以下特点；常温操作，设备与操作过程较简单，操作压力低，比较安全；炭床体积小，活性炭更换次数少。     

Determination of the plutonium mass in containers with plutonium dioxide according to the γ radiation from spontaneous-fission products

A nondestructive method of determining the mass of large plutonium samples which is based on measuring their characteristic γ radiation is presented. The mass and the isotopic composition of the plutonium were determined according to a single measured γ spectrum in two energy ranges: the middle range, where the isotopic composition of plutonium is determined from the lines of the plutonium isotopes, and high-energy, where the radiation of the products of the spontaneous fission of plutonium gives information about the mass of the sample. The dependence of the counting rate in the peaks of the fission products on the effective mass of ²⁴⁰Pu was calibrated according to measurements performed with standard samples of the enterprise. As a result of the measurements, corrections were made for the self-absorption of γ radiation and induced fission, which were calculated by the Monte Carlo method. The error in determining the plutonium dioxide mass is 3–10% for containers with different cool-down times and isotopic composition of plutonium.