耐辐射奇球菌对放射性核素铀的吸附行为研究

采用耐辐射奇球菌活体为生物吸附剂,进行了对水溶液中放射性核素铀的批量吸附实验。主要研究了溶液pH、初始铀浓度对吸附放射性核素铀效果的影响,并通过红外光谱(FTIR)和扫描电镜/能谱仪(SEM/EDS)等手段分析了其吸附机理。结果表明：在pH 5,c₀=100 mg·L-1时其吸附效果最佳,而最大饱和吸附量q_max为240 mgU·g-1。结合扫描电镜与能谱分析结果认为,耐辐射奇球菌表面附着了大量的含铀片状结晶物,并且其吸附过程主要以离子交换或表面络合的方式吸附铀。比较吸附铀前后菌体红外光谱图和红外分峰图发现,耐辐射奇球菌吸附铀后的整体谱形有了一定的变化,特别是蛋白质中酰胺基团、羟基、羧基以及磷酸基团等活性基团可能参与了吸附过程,并且在906 cm-1处出现了一个新的峰,此峰为UO2+₂的伸缩振动峰。可见,利用具有抗辐射特性的耐辐射奇球菌为生物吸附剂,以期在放射性环境中对放射性核素铀的吸附具有一定的潜在途径。     

低能质子回旋加速器内部束流测量探头的感生放射性

 为满足回旋加速器内部束流测量探头产生低放射性的要求,通过理论分析和蒙特卡罗模拟方法,研究了11 MeV,50 μA质子束轰击铜探头产生的感生放射性,得到各种感生放射性核素的饱和放射性活度,并对结果进行了比较。分析结果表明,采用软件FLUKA进行蒙特卡罗模拟,核反应考虑完全,可同时计算不同照射时间下的直接和间接感生放射性,计算结果准确。应用该方法,质子束轰击不同测量探头产生的感生放射性可以得到详细和准确的分析和预测。     

ICP-AES法测定硝酸铀酰中的微量杂质元素

据有关文献报导,发射光谱法分析铀化合物中的微量杂质元素,在国内外,一般多采用载体蒸馏法、蒸发法和化学光谱法。前两种方法,六十年代在国内颇为盛行,现已满足不了生产要求,只有化学光谱法的研究仍在深入。该方法由于已将具有放射性的大量铀分离掉,既避免了放射性对人体的损害,又除去了大量铀线对分析线的干扰,降低了杂质元素的检出限。但是,化学光谱法,手续繁杂,误差较大;同时抗干扰能力较差。 ICP-AES法测定铀化合物中的微量杂质元素正可保持其优点克服其缺点。本方法,     

低能质子回旋加速器内部束流测量探头的感生放射性

为满足回旋加速器内部束流测量探头产生低放射性的要求,通过理论分析和蒙特卡罗模拟方法,研究了11 MeV,50 μA质子束轰击铜探头产生的感生放射性,得到各种感生放射性核素的饱和放射性活度,并对结果进行了比较。分析结果表明,采用软件FLUKA进行蒙特卡罗模拟,核反应考虑完全,可同时计算不同照射时间下的直接和间接感生放射性,计算结果准确。应用该方法,质子束轰击不同测量探头产生的感生放射性可以得到详细和准确的分析和预测。     

基于X射线透射谱的铀浓度测量方法

在核燃料后处理流程中,需对工艺中的铀浓度进行准确测量。利用X射线管照射铀溶液,通过测量铀的L边界X射线透射谱确定铀浓度。文章设计了铀的L边界X射线透射谱测量系统。通过配制1~200 g·L-1铀标准溶液,建立铀浓度测量工作曲线,并对系统的精密度、准确度和稳定性进行测试。结果表明,铀浓度测量工作曲线线性拟合参数R2=0.999 9;系统对57.004 g·L-1铀溶液测量精密度为0.21%,对38.255 g·L-1铀溶液测量相对误差为0.32%;对2.236 g·L-1铀溶液进行连续测量,99.67%数据落在μ±3 s。     

基于X射线透射谱的铀浓度测量方法（英文）

在核燃料后处理流程中,需对工艺中的铀浓度进行准确测量。利用X射线管照射铀溶液,通过测量铀的L边界X射线透射谱确定铀浓度。文章设计了铀的L边界X射线透射谱测量系统。通过配制1~200g·L~(-1)铀标准溶液,建立铀浓度测量工作曲线,并对系统的精密度、准确度和稳定性进行测试。结果表明,铀浓度测量工作曲线线性拟合参数R2=0.999 9;系统对57.004g·L~(-1)铀溶液测量精密度为0.21%,对38.255g·L~(-1)铀溶液测量相对误差为0.32%;对2.236g·L~(-1)铀溶液进行连续测量,99.67%数据落在μ±3s。     

基于光谱学分析的生物磷参与暹罗芽孢杆菌对铀的去除行为及机制研究

以暹罗芽孢杆菌为研究对象,它具有较高的表面积/体积比,吸附性能良好。前人关于暹罗芽孢杆菌的研究多集中在它降解纤维素淀粉或抗菌方面,关于暹罗芽孢杆菌与放射性核素的作用及机制基本未涉及。利用等离子发射光谱和等离子发射光谱-质谱研究溶液初始pH值、铀初始浓度、菌体用量等因素对暹罗芽孢杆菌去除铀的影响及作用过程中菌体释放的生物磷与铀去除的关系;利用红外光谱和扫描电镜对与铀作用前后的暹罗芽孢杆菌形貌及基团变化进行表征;利用X射线光电子能谱和扫描电镜能谱分析菌体表面元素分布情况和元素价态,进而探讨暹罗芽孢杆菌对铀的去除机制。结果表明,由于不同pH条件下暹罗芽孢杆菌生长活性、铀存在形态和磷元素释放量的不同,其对铀的去除差异很大。在pH 5.0时,暹罗芽孢杆菌对铀的去除效果最好。菌体用量增加有利于暹罗芽孢杆菌对铀的去除。对实验结果进行Langmuir和Freundlich等温吸附拟合后发现:暹罗芽孢杆菌对铀的去除行为符合Langmuir等温吸附模型;铀浓度实验获得的最大吸附量高于理论计算的最大吸附量,说明暹罗芽孢杆菌对铀的去除可能是物理和化学行为的共同作用。暹罗芽孢杆菌能够有效去除水体中的铀,实验获得的最大去除率为96.5%,最高吸附量为450.3 mg·g~(-1),高于大部分已报道的用于吸附铀的芽孢杆菌。对反应前后菌体的扫描电镜测试发现,与铀作用后暹罗芽孢杆菌表面出现鳞片状沉淀, X射线光电子能谱和扫描电镜能谱分析表明该沉淀为含磷铀物质。结合红外光谱分析,推测暹罗芽孢杆菌去除铀的机制为:首先,通过静电作用铀被快速吸引到暹罗芽孢杆菌表面,随后以配位的形式被菌体上的磷酸基团、氨基、羟基、羧基等活性基团吸附,同时与菌体释放的含磷酸盐类物质相互作用,形成含磷铀沉淀而被固定至细菌表面。在此过程中,少部分六价铀被菌体释放的胞内物质还原成四价铀而发生沉降。推测菌体表面沉淀可能为铀的磷酸盐沉淀和含磷化合物与铀的络合物形成的混合物。     

一种分段式γ扫描系统探测效率响应函数的数值计算方法

基于SGS探测系统中放射性核废物桶、准直器及HPGe探测器的空间几何分布建立数学模型。对低、中放射性核废物桶中点源¹³⁷Cs的探测效率响应函数进行了数值公式推导,然后利用蒙特卡罗工具包MCNP模拟计算了相应的效率函数。将这两种方法模拟的结果进行了对比分析发现：数值计算方法的数据普遍高于MCNP模拟的数据,最大相对误差达143.26%,误差平均值为37.15%。对数值计算方法进行修正后,最大值相对误差为17.22%,平均值为4.54%。在误差范围内,可以认为该修正方法有效。     

材料学科研究进展

1核材料 1.1铀表面改性的抗腐蚀性能研究 金属铀因其独特的核性能而具有广泛的用途，但由于其高化学活性而极易在许多环境介质中遭受腐蚀。因此，发展铀表面改性技术，研究镀层对铀抗腐蚀特性的影响备受关注。开展了铀表面脉冲电镀镍技术，磁近代溅射镀铝膜及铝／钛双重复合膜技术和铀表面激光快速熔凝技术研究，分析了镀层的组织结构，测试了镀层的腐蚀特性。研究发现脉冲电镀镍层在铀表面上连续、致密、覆盖完整、界面清晰，具有较好的保护性能铀、铝镀层、铝／钛复合镀层在50μg／g的Cl^-溶液中的腐蚀电位，铀表面铝镀层的腐蚀电位较铀的腐蚀电位低，可以提供牺牲性保护，但铝镀层表面存在微孔隙，会产生点蚀；钛镀层的腐蚀电位较铀高，表面仍然具有微孔隙，会产生点蚀；经过激光快速熔凝处理，铀的抗氧化能力明显增强。这些研究结果为优化铀表面防腐蚀镀层体系提供了技术基础。     

多级内冷型膜式溶液除湿的热质传递强化研究

为强化膜式溶液除湿器的性能,本文基于膜的渗透特性,建立了多级内冷型膜式溶液除湿器的传热传质模型。经模型验证后,采用遗传算法对不同设计工况下的膜式除湿器结构进行了优化,并通过引入传热传质分布不均因子,分析了各运行控制参数与空气状态参数对膜式除湿器的传热传质性能影响。结果表明,除湿器处理的空气流量越大,所需的最优层数越多,最优级数越小。在最优结构下增大溶液流量与降低冷却水温度虽可提高总效能,但也加剧了传热传质驱动力的分布不均。在处理低湿度空气时,该系统总效能可达0.64。该研究揭示了传热传质效能与驱动力分布不均之间的内在关系,有助于膜式溶液除湿器的性能强化。     

Radon-222 concentration in subsoils and its exhalation rate from a soil sample

We propose a method for a laboratory determination of the actual concentration of subsoil radon and of its exhalation rate from uranium-containing sediments. The method is based on gamma-ray spectrometry paired with a systematic theoretical study of radioactive processes. It may help understand the relationship between radon exhalations and seismic activity. It also provides a low-cost technique for prospecting uranium ores, and can be used to improve the precision of thermoluminescence dating.     

紫外脉冲荧光法测定微量铀的研究

紫外脉冲荧光法是一种通过液体激光来直接测定微量铀的方法。在采用紫外脉冲荧光法分析面包酵母吸附放射性核素铀后溶液剩余铀浓度之前,研究了荧光增强剂、pH 值、以及温度对微量铀浓度工作曲线的影响。结果表明:当pH > 3时,400 μL 荧光增强剂可以充分缓冲溶液,不同pH 值下测得的荧光计数基本保持恒定,即待测溶液pH值不会影响铀浓度的测量;随着温度的升高,荧光计数近似线性下降,并在室温23.6℃时得到了铀质量浓度范围为0:120 μg/L 的工作曲线。在此基础上研究了酵母菌对放射性核素铀的吸附作用,为使吸附剂达到最高效利用,对溶液pH 值、吸附速率进行了批次实验,并通过紫外脉冲荧光分析法进行测量, 发现达到吸附平衡所需的最短时间为180 min,吸附的最佳溶液pH 值为5.8 左右。The method of pulse ultraviolet fluorescence was employed to analyze the concentration of radioactive nuclide uranium after adsorbed by baker’s yeast. Influences of fluorescent enhance reagent, pH value, and temperature on measurement of the concentration of trace uranium were investigated. The results showed that 400 μL fluorescent enhance reagent was greatly enough to buffer the solution when pH > 3 and the counts of fluorescence kept constant with the variation of pH, which indicates that the pH of solutions doesn’t affect the determination of uranium concentration, moreover, the counts of fluorescence declined linearly as the increase of the temperature. In addition, the working curve of the determination of uranium concentration within 0.1 20 μg/L was obtained when the temperature was 23.6 ℃. On this basis, the adsorption of uranium by baker’s yeast was studied. For the adsorption of radioactive nuclides of uranium by baker’s yeast to achieve the best use, the batch experiments were carried out on the rate of adsorption and pH of solutions. The method of pulse ultraviolet fluorescence was used to measure and found that the minimum time required to reach adsorption equilibrium was 180 min and the optimum pH value of solutions was about 5.8.     

2-(2-喹啉偶氮)-5-二甲氨基苯酚固相萃取光度法测定铀的研究

合成了新试剂2-(2-喹啉偶氮)-5-二甲氨基苯酚(QADMAP),用红外光谱、核磁共振氢谱、质谱、可见吸收光谱和元素分析鉴定了其结构。研究了QADMAP与铀的显色反应,在pH 7.8的三乙醇胺-盐酸缓冲介质中,Triton X-100和氟离子存在下,QADMAP与铀(Ⅵ)和氟离子反应生成1∶1∶1紫色三元稳定络合物,络合物的λ_max＝590 nm,ε＝1.05×105 L·mol-1·cm-1,铀含量在0～20 μg·10 mL-1内符合比尔定律。环境水样中的铀用TBP萃淋树脂固相萃取柱分离和富集后用该方法测定,方法相对标准偏差在2.2%～3.6%之间,标准回收率在94%～105%。     

Use of IR Absorption Laser Spectroscopy at Nuclear Fuel Cycle Plants: Problems and Prospects (Review)

The main stages of the nuclear fuel cycle from extraction of uranium ores to disposal of radioactive waste resulting from the processing of spent nuclear fuel were briefly analyzed. A list of the most probable radioactive substances and toxic chemicals that can be part of emergency emissions at each stage of the nuclear fuel cycle was composed. The basic physical principles of local and remote IR absorption laser technologies for detecting radioactive substances and toxic chemicals in the atmosphere for solving some unique problems of environmental monitoring were considered. The analytical potential of the currently most effective laser technologies for atmospheric monitoring at nuclear fuel cycle plants based on the achievements of diode laser spectroscopy, cavity ringdown laser spectroscopy, and optoacoustic laser spectroscopy using diode and quantum-cascade lasers was discussed. Current trends in the development of laser technologies for atmospheric monitoring in different IR spectral ranges were analyzed.     

The influence of fractal size distribution of covers on radon exhalation from uranium mill tailings

Tailings produced during mining and milling of uranium ores represent potentially large volumes of low level radioactive materials. A typical environmental problem associated with mill tailings is radon emanation. Covering tailings is widely applied to reduce radon exhalation rate. In this paper, the fractal theories and field covering tests are used to study the fractal characters of size distribution of six types of covering materials, including waste rock, sand, laterite, kaolin, mixture of sand and laterite, and mixture of waste rock and laterite, and their influences on radon exhalation. The size distributions of uranium tailings and the six aforementioned covering materials all exhibit a good fractal structure. The contents of fine grain increase with the increasing value of fractal dimension. The results of field radon measurement show that the radon emanation rate of tailings without covers is 14.7–18.6 Bq/m² s. Covering tests were carried out of the six abovementioned covering materials with thickness of 0.4 m, 0.8 m, 1.2 m, 1.6 m and 2.0 m. The results indicate that the application of these materials for cover layers can decrease the radon exhalation rate markedly. The effectiveness of a cover layer in reducing radon exhalation is related to its fractal texture of size distribution. Under the same thickness conditions, the attenuation coefficient of radon exhalation rate increases with the increasing fractal dimension of size distribution of covers. The empirical expressions of the attenuation coefficients in relation to fractal dimension D of size distribution and thickness x of covers is obtained for evaluating the effectiveness of final covers for uranium tailings impoundments.     

Identification of paramagnetic centers and the dating of cave dripstones by electron paramagnetic resonance

Dating of samples of cave dripstones collected from the Jaskinia Czarna (the Polish Tatra Mountains) and fossil bones was carried out by means of electron paramagnetic resonance (EPR). By this method the age of the sample is found as the ratio of the total dose (TD) to the annual dose rate (D _a). TD is established on the basis of EPR spectra, whileD _a is the sum of the internal dose rate, calculated on the basis of the concentration and activity of radioactive nuclides in the sample, and the external dose rate measured at the site of the sample collection by a calibrated γ-radiation probe. Two models of uranium accumulation were used: the model of linear accumulation and the model on the basis of the assumption of a disturbed radiation equilibrium in the uranium series. The results were compared with the age determined by the uranium-thorium method. Moreover, by the computer resolution enhancement method the dynamics of paramagnetic centers in calcite annealed in nitrogen atmosphere was studied in the range of 283–873 K, and the results were compared with earlier results for calcite annealed in the air. On the basis of the study of paramagnetic center dynamics in dripstone calcite it was established that the radicals responsible for the EPR signals were CO₂⁻ in different symmetries of the crystalline field, CO₃³⁻ in the axial symmetry, CO₃⁻ in the axial and isotropic symmetry and HCO₃²⁻. The results implied that samples to be subjected to EPR dating should be kept at room temperature.     

不同激发方式对能量色散X射线荧光法测铀的影响

针对能量色散X射线荧光法测铀过程中存在自激发效应对测量结果产生干扰的问题及以往测铀仅使用放射性同位素源作为激发源的测量限制,利用微型X射线对铀矿样品进行自激发效应测量,并分别将109Cd,241Am,微型X光管三种不同激发源测量铀矿样品的结果进行比较分析。结果表明,自激发效应产生的特征X射线峰面积计数仅为有源条件的0.01%以下,属统计涨落范畴,对测量结果的干扰可忽略不计;109Cd源由于其特征射线能量22.11和24.95 keV均在L_α吸收限能量21.75 keV附近,激发光电截面最高,相应的荧光产额也高,故109Cd源相比于241Am源对铀元素的激发效率更高;241Am源测量误差明显大于109Cd源的测量误差,原因是铀的L系能量特征峰与241Am源特征射线26.35 keV的散射峰能量区叠加,造成实测谱线本底偏高;X光管作激发源的铀矿样品中铀含量与化学分析结果之间的误差在10%以内,仅为同位素源激发X射线荧光分析误差的一半,且X光管激发谱峰面积计数值明显大于源激发条件下的峰面积计数,说明X光管作激发源的测铀质量优于源激发模式。     

Interaction of a fuel cladding with uranium carbonitride in electrogenerating channel

Samples of the fuel cladding of electrogenerating channel no. 30, which was included in the setup Ya-82 during nuclear power tests, are studied. The structure of the samples and the distribution of U, Mo, Nb, Cs, C, and N over the cladding thickness are investigated. The X-ray spectrometry microanalysis of the samples is performed at the MAR-3 modernized microanalyzer. A layered structure of the cladding is revealed using the method of scanning electron microscopy. Clusters of pores and other defects are observed at the boundaries of the layers. It is found that the uranium concentration profiles in different passages (at different points of the sample) are distinguished qualitatively. Three types of profiles are observed: firstly, profiles with no visible concentration of uranium above the background level; secondly, monotonically decaying profiles corresponding to the diffusion-induced penetration of uranium; and, thirdly, nonmonotonic concentration profiles. The depth of penetration of uranium into the cladding is ～10⁵ nm. The peaks of uranium concentration are near the boundaries of the observed layers. It is found that cesium penetrates the tungsten coating and molybdenum cladding. Domains with the increased carbon content are revealed. A stepwise growth in the nitrogen concentration is observed in the region occupied by the tungsten coating.     

新试剂N—己基—N‘—（氨基对苯磺酸钠）硫脲（HXPT）的合成及其 …

A new reagent N-Hexyl-N'-(sodium aminobenzenesulfonate) thiourea (HXPT) was synthesized. Its structure was also characterized. A new spectrophotometric method of determining Pd2+ was developed based on the new reagent. In the range of pH 5.4-5.8 Pd2+ forms a stable yellow complex with HXPT in the presence of CTMAB,and its apparent molar absorptivity is 2. 21 x 10(5) L x mol(-1) x cm(-1) at the maximum absorption wavelength 296.8 nm. Beer's law is obeyed in the range of 1-7 microg x 25 mL(-1) for Pd2+. This method has been used for the determination of trace Pd2+ in ores and catalyst with satisfactory results.     

基于实例克隆的ICSMOreg算法及在铀矿床蚀变矿物水云母中的物谱建模研究

水云母足花岗岩型铀矿床蚀变带中的一种典型蚀变矿物,它也是铀矿找矿的一个重要标志.水云母含量的大小能在一定程度上体现铀矿床水云母化的强弱.传统建模方法对水云母含量的预测效果较差.文章将回归支持向量机SMOreg应用到水云母物谱关联建模中,并在验证其有效性的基础上提出一种基于实例克隆的ICSMOreg方法,以构建水云母含量...