基于NPL-NMC系统的γ测量子系统的建模与优化

在军控核查中,核部件的质量、丰度、年龄属性需采用无损方法进行核查,NPL-NMC系统是一套利用中子多重性测量核部件质量属性的装置,为建立完善的属性测量系统,还需在NPL-NMC系统的基础上建立γ测量子系统。本文通过设计γ测量子系统在NPL-NMC系统上的布局及对中子屏蔽的优化,使系统能对铀部件的丰度、年龄属性进行测量。模拟计算结果表明,该γ测量子系统能很好地满足军控核查对铀部件丰度、年龄属性测量的要求。     

Measurement of the isotopic abundance of boron-10 by inductively coupled plasma-quadrupole mass spectrometry

This article describes the method for measuring the isotopic abundance of ¹⁰B in nuclear grade boron carbide using inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS). The results of investigation revealed that both the integration time and the dwell time have a major influence on the reproducibility of ICP-QMS measurements. As a result of optimization of the measurement conditions, reproducibility below 0.2% relative standard deviation (RSD) (0.17% RSD maximum) was achieved. In addition, the measured value of the isotopic abundance of ¹⁰B for each sample well agreed with the values measured by the TIMS. Thus, the method described in the present investigation was very effective in the analysis of isotopic abundance of ¹⁰B in B₄C or H₃BO₃. The results of this study suggest that ICP-QMS could be applied to the precise analysis of the isotopic abundance of ¹⁰B required in the field of nuclear applications.     

锌同位素丰度比测量中的几个关键问题

采用多接收-电感耦合等离子体质谱仪(MC-ICP-MS)和多接收-热电离同位素质谱仪(MS-TIMS)对溶液中锌同位素丰度比测量结果进行实验室间比对,5个样品68Zn与66Zn的丰度比为0.02~15.00。比对结果显示,5个实验室的测量结果相符性较差,测量不确定度为1.29%~0.03%(以64Zn/66Zn为例),呈现与样品丰度比相关的趋势,相同仪器测量结果的不相符性主要受是否扣除空白及扣除的准确性影响。另外,MC-ICP-MS系统误差校正条件也影响测量的准确性,MC-ICP-MS质量歧视校正系数为非线性。     

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。     

Utilization of rock-like oxide fuel in the phase-out scenario

Utilization of rock-like oxide (ROX) fuel in light water reactors for plutonium (Pu) burning was studied by nuclear material balance (NMB) analysis for a case of Japanese phase-out scenario under investigation after the Fukushima accident. For the analysis, the NMB code was developed with features of accurate burn-up calculation, flexible combination of reactors and fuels, and an ability to estimate waste and repository. Three scenario groups of once-through Pu burning in mixed oxide (MOX) fuel and in ROX fuel were analyzed. Using two full-MOX or full-ROX reactors the Pu amount is reduced to about one-half and the isotopic vector of Pu deteriorated for being used as a nuclear weapon, especially in terms of spontaneous fission neutron generation. Effects of ROX reactors are more significant than MOX reactors in terms of both reduction in the Pu amount and deterioration of the isotopic vector. Repository footprint and potential radiotoxicity are not reduced by the MOX and ROX reactors because the heat and toxicity of MOX and ROX spent fuels are considerably high.     

稳定同位素氘标记苏丹红I的同位素丰度和化学纯度分析

为建立高灵敏度、高选择性的食品中非法添加物的分析检测方法,采用"质量簇"计算分类方法,利用液质联用仪检测稳定同位素氘标记苏丹红Ⅰ的同位素丰度,用于同位素稀释质谱法的内标试剂。针对不同操作人员、不同仪器进行重复性和再现性实验,RSD均0.1%,重复性和再现性良好。对结果进行了F检验和t检验,结果表明,苏丹红I-D_5的同位索丰度分析方法的准确度和精密度良好。利用高效液相色谱仪,采用外标法,建立标准曲线,确立稳定同位素氘标记苏丹红I-D_5的化学纯度分析方法。结果表明,制备的稳定同位素氘标记苏丹红I-D_5可作为同位素稀释质谱法的内标物质。     

A Method for the Burnup Analysis of Power Reactors in Equilibrium Operation Cycles

This paper describes a method based on the consistent thermal neutron flux concept for burnup analysis of power reactors in equilibrium operation cycle. Radial flux distributions are discussed, as well as the variation of isotopic densities in the fuel, and considerations are given on control rod distribution for maintaining a consistent thermal flux distribution. The present method can be applied to most power reactors like BWR and PWR in which a multiple-batch refueling scheme is adopted.     

Complete symmetry and isotopic spin conservation in the nonleptonic decay of hyperons

The possibility is considered that there exists a universal V-A interaction and complete symmetry in the nonleptonic decay of hyperons. The departure from the expected symmetry that is observed in actual decays Is explained by effects caused by the mesonic structure of hyperons. In close connection with the idea of complete symmetry, a new isotopic spin is defined, which is equal to 1/2 for all baryons and to 0 or 1 for K mesons. The law of conservation of this isotopic spin holds in nonleptonic decays.     

Validation of a Monte Carlo based depletion methodology via High Flux Isotope Reactor HEU post-irradiation examination measurements

The purpose of this study is to validate a Monte Carlo based depletion methodology by comparing calculated post-irradiation uranium isotopic compositions in the fuel elements of the High Flux Isotope Reactor (HFIR) core to values measured using uranium mass-spectrographic analysis. Three fuel plates were analyzed: two from the outer fuel element (OFE) and one from the inner fuel element (IFE). Fuel plates O-111-8, O-350-I, and I-417-24 from outer fuel elements 5-O and 21-O and inner fuel element 49-I, respectively, were selected for examination. Fuel elements 5-O, 21-O, and 49-I were loaded into HFIR during cycles 4, 16, and 35, respectively (mid to late 1960s). Approximately one year after each of these elements were irradiated, they were transferred to the High Radiation Level Examination Laboratory (HRLEL) where samples from these fuel plates were sectioned and examined via uranium mass-spectrographic analysis. The isotopic composition of each of the samples was used to determine the atomic percent of the uranium isotopes.A Monte Carlo based depletion computer program, ALEPH, which couples the MCNP and ORIGEN codes, was utilized to calculate the nuclide inventory at the end-of-cycle (EOC). A current ALEPH/MCNP input for HFIR fuel cycle 400 was modified to replicate cycles 4, 16, and 35. The control element withdrawal curves and flux trap loadings were revised, as well as the radial zone boundaries and nuclide concentrations in the MCNP model. The calculated EOC uranium isotopic compositions for the analyzed plates were found to be in good agreement with measurements, which reveals that ALEPH/MCNP can accurately calculate burn-up dependent uranium isotopic concentrations for the HFIR core.The spatial power distribution in HFIR changes significantly as irradiation time increases due to control element movement. Accurate calculation of the end-of-life uranium isotopic inventory is a good indicator that the power distribution variation as a function of space and time is accurately calculated, i.e. an integral check. Hence, the time dependent heat generation source terms needed for reactor core thermal hydraulic analysis, if derived from this methodology, have been shown to be accurate for highly enriched uranium (HEU) fuel.     

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.     

Quantitative spectral analysis of the isotopic composition of enriched uranium

A photographic method has been developed for the spectral analysis of the isotopic composition of the enriched uranium U²³⁵ in the range of concentrations from 2 to 90% and higher. The behavior of standard calibrating curves has been investigated over a wide range of concentration. It has been established that the presence of a contaminant in the sample being analyzed does not distort the results of the analysis, It is shown that even though photographic spectral analysis is faster and less costly than other methods, its accuracy compares favorably, (the mean-square relative error of the measurement of a concentration in the region from 4 to 90% varies from ± 2.2 to ± 0.3%).     

热表面电离质谱法对锂同位素的测

为建立一套适用于实验室锂同位素的分析方法,选定Li 为检测离子,对热电离质谱法(TIMS)分析锂同位素的实验条件进行探索,包括单、双带测量,加载H3PO4和锂样品用量,建立了质谱分析条件。并采用此方法测定了标准物质样品的丰度和浓度,对塑料闪烁体中掺杂6Li的质量分数进行分析,给出测量方法的不确定度(U)为0.024,方法相对标准偏差(sr)小于0.3%。     

Simulation of Cryogenic Rectification of Tritium-Containing Isotopic Hydrogen Mixtures

A method is presented for calculating the basic technological parameters of rectification systems for separating tritium-containing mixtures of hydrogen isotopes with intermediate homomolecular isotopic exchange stages. The method of independent determination of the concentrations was used in simulating the rectification process. The liquid-vapor equilibrium problem was solved with a correction for the nonideality of the mixtures. Heat release due to tritium decay is taken into account in the heat balance equations. The quantum-statistical method was used to calculate the equilibrium constants for simulating the homomolecular isotopic exchange. The CRYDIST computer code implementing this method is used to determine the optimal parameters of the apparatus for separative processing of two isotopic mixtures with different composition and including two low-temperature rectification columns and two homomolecular isotopic exchange units.     

稳定同位素标记多肽的合成及应用

同位素稀释质谱法避免了基质效应和分析条件的影响,在定量分析和准确度方面具有特殊优势,在生物分子定量分析领域得到了普遍应用。稳定同位素标记肽段作为重要内标试剂广泛应用于蛋白质组学定量及食品过敏原检测。同位素稀释质谱技术的发展将会进一步推动稳定同位素标签技术在新药研发、临床病理、蛋白质组学、食品安全等领域的研究应用。本文从生物合成法和化学合成法方面综述了稳定同位素标记多肽的合成,并分别对细胞代谢标记法、高等真核生物标记法、酶催化标记法、乙酰化标记、标记氨基酸缩合法等合成方法进行了评述;同时介绍了稳定同位素标记多肽在乳制品检测、生物蛋白定量、蛋白测序及药物代谢、食品过敏原检测中的应用。     

湖泊沉积物中污染有机质及碳酸盐的δ13C影响因素分析

摘要：本文以松嫩平原湖泊表层沉积为研究对象。通过对沉积物有机质正构烷烃组分的分析,了解湖泊中有机质的来源和沉积环境。结合湖泊水介质和沉积物特征,综合分析了沉积物有机质和碳酸盐碳同位素组成的影响因素。结果显示出湖泊沉积物中不同有机质类型对碳同位素组成有较大的作用,生物有机质的大量输入使碳酸盐的碳同位素组成明显偏轻,而石油类污染的输入对应于碳酸盐中的碳同位素组成稍偏重。     

Isotopic Mixture Properties and their Variation in the Separation Process

Atomic Energy - The properties of a multicomponent isotopic mixture are considered, parameters for determining its value are proposed, and the variation in the properties of an isotopic mixture in...     

可活化稳定同位素^70Zn示踪研究儿童膳食中锌的生物利用率

使用中子活化分析法,以国内仅有的低深缩度^70Zn（18．3％）作为可活化稳定浓缩同位素示踪剂,对我国儿童膳食中锌的生物利用率进行了研究。建立了以阴离子树脂交换法对儿童便样中的锌元素进行富集,经反应堆中了辐照、测量和放射化学分离、测定锌的生物利率方法。提出了普适于各种^70Zn浓缩度锌作为示踪剂、以^70Zn和^68Zn和^64Zn的质量丰度进行生物利率率的计算公式。克服了以^68Zn作为唯一的天然锌指示而引入的计算误差。     

系列铀同位素基准物质的研制

利用高纯²³⁵U和²³⁸U研制系列铀同位素基准物质,其相对不确定度优于0.05％。采用以基准物质重铬酸钾为滴定剂的自动电位滴定法对基准物质中的铀含量进行准确定值。所研制的铀同位素基准物质可用以对我国现有的26种铀同位素标准物质重新进行定值,从而使这些标准物质中铀同位素测量值的不确定度降低,并使其具有可溯源性。     

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.     

氢-水同位素催化交换速率及过程模拟的研究进展

氢-水同位素催化交换在处理ITER聚变堆废水以及核裂变反应堆重水升级方面具有应用前景。该交换过程及核心设备催化交换塔的模型化研究,对工艺和工程优化设计具有十分重要的意义。本文重点介绍了氢-水同位素催化交换过程模拟的研究进展,讨论了同位素催化交换速率的计算方式以及吸收塔模型和滴流床模型在同位素催化交换过程模拟中的应用,探讨了氢-水同位素催化交换过程模拟今后的研究方向。通过各类模型的比较,滴流床模型被认为在催化交换过程模拟中有良好应用前景。氢-水同位素催化交换机理及速率计算方法和催化交换塔模型化等方面有待进一步研究。