Genetic Relationship between Natural Gas Dispersal Zone and Uranium Accumulation in the Northern Ordos Basin, China

The Ordos Basin is well-known for the coexistence of oil, natural gas, coal and uranium. However, there has been little research to discuss the genetic relationship between them. In this paper, a case study of the Zaohuohao area in Dongsheng, Inner Mongolia, China, is conducted to investigate the genetic relationship between the natural gas and the uranium accumulation. Fluid inclusion data from the uranium-bearing sandstone samples indicate that the fluid inclusions formed in a gas-water transition zone. Using the homogeneous temperatures of aqueous inclusions coeval with hydrocarbon-bearing inclusions, combined with the buried history and paleo-temperature data, the gas-water transition zone reached the area at about 110 Ma. On the basis of this, the contents of Uranium （U） and Total Organic Carbon （TOC） of the samples were analyzed, and there was no obvious relation between them. With regard to the available data from both publications and this study, it is found that the U mineralization has a spatiotemporal accordance with the gas-water dispersal zone. Thus, it is believed that the natural gas in the gas-water zone is an effective reducer to the U-bearing ground water abundant in oxygen, which is the main factor to U accumulation. This result can be used as the reference to the U mines predicting and prospecting.

Assessment of Natural Uranium in the Ground Water around Jaduguda Uranium Mining Complex, India

Ground water ecosystem surrounding the uranium processing facility at Jaduguda, India has been studied for natural uranium distribution. Annual intake of uranium through drinking water for members of public residing around the uranium complex is found to be in the range of 41.8 Bquy–1 - 44.4 Bquy–1. The intake and ingestion dose is appreciably low (–1) which is far below the WHO recommended level of 100 uSv.y–1. The excess life time radiological risk due to uranium natural in drinking water is insignificant and found to be of the order of 10–6. Even the highest concentration of uranium was found to be 28 ug.l–1 is away (at 1.5 to 5 km distance) from mining industry and well below the acceptable limit. The ground water in the area around the uranium facility is not affected by the mining activity. The ground water in three zones is safe and reflects the natural distribution of uranium.

Natural Radioactivity in Miscanthus floridulu Plant from the Uranium Tailing Pile at Guangdong, South China

Large amounts of uranium waste rocks and tailings resulting from the exploitation and treatment of uranium ore at the Northern Guangdong mine (South China) have been accumulated in dams (tailing ponds). To reduce the dispersion of natural radionuclides into the environment, some dams were revegetated with arbor, bush and sward. Besides these plants, Miscanthus floridulu is the dominant plant growing in some of the dams. The uptake and distribution of naturally occurring uranium (238U), thorium (232Th), radium (226Ra) and potassium (40K) by Miscanthus floridulu plant from different sample sites of uranium mine were studied under native conditions. The bioconcentration factors (BCFs) of soil to Miscanthus floridulu above-ground and root were calculated and observed to be in the range of 0.14 to 7.74 and 2.71 to 17.83 for 238U, 0 to 3.02 and 0 to 3.29 for 232Th, 0.15 to 79.76 and 1.01 to 50.22 for 226Ra and 3.00 to 8.41 and 2.69 to 11.22 for 40K, respectively. The transfer factors (TFs) of Miscanthus floridulu root to aboveground were also calculated and observed to be in the range of 0.01 to 0.73 for 238U, 0 to 0.99 for 232Th, 0.08 to 1.50 for 226Ra and 0.57 to 1.94 for 40K, respectively. The results showed that, Miscanthus floridulu is 238U and 226Ra-accumulating plant with significant absorption and accumulation characteristics.

Effect of Natural Zeolite on Pore Structure of Cemented Uranium Tailings Backfill

The use of some environmental functional minerals as backfill-modified materials may improve the leaching resistance of cemented uranium tailings backfill created from alkali-activated slag(CUTB),but these materials may participate in the hydration reaction of the cementitious materials,which could have a certain impact on the pore structure of the CUTB,thus affecting its mechanical properties and leaching resistance.In this paper,natural zeolite is selected as the backfill-modified material,and it is added to alkali-activated slag paste(AASP)and CUTB in cementitious material proportions of 4%,8%,12%,and 16%to prepare AASP mixtures and CUTB mixtures containing environmental functional minerals.After the addition of natural zeolite,the porosity of the CUTB generally increases,but when the content is 4%,the porosity decreases to 22.30%.The uniaxial compressive strength(UCS)of the CUTB generally decreases,but the decrease is the smallest when the content is 4%,and the UCS is 12.37 MPa.The addition of natural zeolite mainly reduces the number of fine pores in the CUTB,but the pores with relaxation times T_(2)of greater than 10 ms account for about 10%of the total pores,and there are a certain number of large pores in the CUTB.The main product of alkali-activated slag is calcium(alumino)silicate hydrate(C-(A)-S-H gel).When natural zeolite is added,the hydration products develop towards denser products with a high degree of polymerization and the formation of low polymerization products is reduced.This affects the internal fracture pores of the hydration products and the interface pores of the CUTB,has an irregular effect on the pore characteristics of the CUTB,and influences the UCS.

Comparison of Radionuclide’s Inventories and Activities With Slightly Enriched Uranium and Plutonium Fuel in CANDU Reactors

In these studies the isotopic inventories and corresponding activities of important nuclides for different fuel cycles of a CANDU reactor have been compared. The calculations have been performed using the computer code WIMSD4. The isotopic inventories and activities have been calculated versus the fuel burn-up for the natural UO2 fuel, 1.2% enriched UO2 fuel and for the 0.45% PuO2-UO2 fuel. It is found that 1.2% enriched uranium fuel has the lowest activity as compared to other two fuel cycles and vice versa for the 0.45% PuO2-UO2 fuel.

Obtaining and Reviewing X-ray Diffraction Analysis of the Uranium Catalyst SAPO-U, W, V Based on Natural Zeolite Chankanayskoe Deposits for the Oxidation of S02 to S03

We first obtained by impregnating the zeolite with salts U, W and V and examined the X-ray uranium catalyst SAPO-U, W, V based on natural zeolite Chankanayskogoe deposits for the oxidation of SO2 to SO3.

Study of elastic wave propagation in two phase anisotropic media by numerical modeling of pseudospectral method

When there exists anisotropy in underground media elastic parameters of the observed coordinate possibly do not coincide with that of the natural coordinate. According to the theory that the density of potential energy, dissipating energy is independent of the coordinate, the relationship of elastic parameters between two coordinates is derived for two-phase anisotropic media. Then, pseudospectral method to solve wave equations of two-phase anisotropic media is derived. At last, we use this method to simulate wave propagation in two-phase anisotropic media four types of waves are observed in the snapshots, i.e., fast P wave and slow P wave, fast S wave and slow S wave. Shear wave splitting, SV wave cusps and elastic wave reflection and transmission are also observed.

Radiogenesis of Low Maturity Natural Gas in the Turpan-Hami Basin,NW China

The origin of the Jurassic low maturity natural gas in the Turpan-Hami Basin has attracted scientists’attention for some time,and it is known that radiogenesis may have played a role.However,little has been done on the uranium-rich background of the whole basin.Based on plentiful logging and geological data for the Jurassic strata in the Turpan-Hami Basin,this research examined the features and factors controlling the distribution of rocks with high gamma reading.The results show that 70%-100%of the rocks with high gamma readings correspond to mudstones in the prodelta subfacies rather than those in semideep-deep lacustrine subfacies rich in mudstones.Therefore,we propose that the distribution of rocks with high gamma readings is mainly controlled by sedimentary facies rather than by lithology.Further analysis of the gamma spectrometry logging data shows that high gamma values are more strongly correlated with U content than with Th or K content.By comparing the U and Th contents of felsic rocks in peripheral provenances,we find that the Jueluotage Mountain and Harlik Mountain were the dominant uranium sources for the Jurassic Turpan-Hami Basin.Radiolysis due to high-level uranium in the prodelta subfacies can make the low maturity source rocks generate H2 and CH4,thus contributing to the production of low maturity natural gas in the Turpan-Hami Basin.

Applications of Natural Radiation-Induced Paramagnetic Defects in Quartz to Exploration in Sedimentary Basins

Quartz grains in contact with uranium-bearing minerals or fluids are characterized by natural radiation-induced paramagnetic defects （e. g. , oxygen vacancy centers, silicon vacancy centers, and peroxy radicals）, which are amenable to study by electron paramagnetic resonance （EPR） spectroscopy. These natural radiation-induced paramagnetic defects, except for the oxygen vacancy centers, in quartz are concentrated in narrow bands penetrated by α particles： （1） in halos around U- and Th-bearing mineral inclusions and （2） in outer rims or along fractures. The second type of occurrence provides information about uranium mineralization or remobilization （i. e. , sources of uranium, timing of mineralization or remobilization, pathways of uranium-bearing fluids）. It can also be used to evaluate sedimentary basins for potential of uranium mineralization. In particular, the peroxy radicals are stable up to 800℃ and, therefore, are useful for evaluating metasedimentary rocks （e. g. , Paleoproterozoic metasedimentary sequences in the central zone of the North China craton）. EPR study of the Changcheng Series can focus on quartz from the sediment-basement unconformity and faults to determine the presence and types of natural radiation-induced paramagnetic defects, with which to identify and prioritize uranium anomalies. Other potential applications of natural radiation-induced paramagnetic defects in quartz include uranium-bearing hydrocarbon deposits in sedimentary basins. For example, the Junggar, Ordos, and Tarim basins in northwestern China all contain important oil and natural gas fields and are well known for elevated uranium concentrations, including economic sandstone-hosted uranium deposits. Therefore, systematic studies on the distribution of natural radiation-induced paramagnetic defects in quartz from host sedimentary sequences are expected to provide information about the migration of oil and natural gas in those basins.

Precise Determination of Uranium Isotopes in Suez Canal Sediment

The streambed sediments of the Suez Canal have been analyzed for determining the natural radionuclides and long-lived radionuclides such as uranium by gamma and alpha spectrometric techniques. The specific activities of 238U series, 232Th series and 40K (Bq/kg) were measured by gamma spectrometry based on Hyper-Pure Germanium detector (HPGe). The average specific activities of 226Ra(238U) series, 232Th series and 40K were ranged from 3.04 ± 1.10 to 14.70 ± 1.24 Bq/kg, from 1.12 ± 0.66 to 16.10 ± 1.30 and from 77 ± 4.90 to 350.50 ± 8.90 Bq/kg respectively. The concentration of 238U and 234U in the streambed sediments are ranged from 3.24 ± 0.21 to 13.34 ± 0.61 ppm and from 3.18 ± 0.02 to 13.77 ± 0.03 ppm in dry weight respectively. 234U/238U ratios of the sediments are relatively lower than unity in many locations indicating the preferential uranium leaching process. The results with the high ratios for 234U/238U were observed in the sediment collected from Port Said. This may be attributed to the sorption of uranium by sediment which has a relatively high content of organic matter. The geochemical behavior of sediment, the chemistry of uranium and the flow rates of water are considered as the most important factors controlling uranium isotopic composition of the streambed sediment. The result of radioactivity in sediment samples can be used to distinguish any future changes due to non-nuclear industries on the Suez Canal area.

Assessment of natural radioactivity levels in Yemen rocks

Studies on radiation level and radionuclide distribution in Yemen were studied. The samples were collected from eight locations： Ma＇rib, A1 Jawf, Sana＇a, Dhamar, Amran, Ibb, Al Bayda and Al Dalea. The purpose of this study is to provide a baseline map of radioactivity background levels in the investigated area and this study will be used as reference information to assess any change in the radioactive background level due to geological processes. The highest values of 22~ and 2~l＇h concentrations （8797.2 and 24984.1 Bq.kg＂l, respectively） were observed at A1 Jawf, region, whereas the highest average value of 40K concentration was 1561.9 Bq.kg-1. The investigation of the geological maps of the area under study showed that the surface rock outcrops consist mainly of granites, diorite, granodiorite, gneisses, and schists. All these rock types arc known to be rich in radioactive materials, which are considered natural sources for gamma radiation. The low mdiological background characterizing some Yemeni rocks could be attributed to nature of these rocks which consist of lime stone （sands and gravels）. The absorbed dose rate in air was found to be in the range between 5.40 and 45.11 nGy.h-1 depending on the geological features, and radium equivalent activity concentration was found in the range between 29.57 and 71.85 Bq.kg-1. Also the representative extcmal hazard index values for the corresponding samples were also estinlated and given.

Analysis of CANDU Reactor Performance Using Thorium Fuel:Comparison with Natural UO2 Case

The purpose of the paper is to study the performance of the CANDU(Canada Deuterium Uranium)reactor when the reactor core is loaded with thorium fuel mixed with plutonium isotopes with ratio 3 and 5%.A three dimensional model is designed for the core of CANDU reactor.The computer code MCNPX(Monte Carlo N–Particle Transport)is used to calculate the processes in its core.The results are compared with natural UO2 case which is the typical fuel of the reactor.The results show that the multiplication factor of the reactor is higher even in the case of thorium fuel mixed with 3%plutonium isotopes,which indicates longer neutron life cycle length and more economic utilization of the reactor.

砂岩型铀矿形成的新模式:来自深部有机流体的成矿作用

已有的铀成矿模式大多认为,砂岩型铀矿是浅表层含氧水从盆地周邻蚀源区析出携带的外源铀汇入盆地而成矿。本研究发现,鄂尔多斯盆地北部伊盟隆起东部砂岩型铀矿矿集区的地质演化、地貌特征和铀成矿与此成矿模式相悖。其中令人困惑的关键问题是铀成矿物质的来源。对研究区的代表性矿物铀石(形成于强还原环境)及其共生的矿物进行多种地球化学测试分析发现:铀矿区存在淡水低温和中高盐度热液两类截然不同的铀矿化环境;铀成矿年龄主体小于80 Ma。结合盆地煤系气源岩富铀、天然气耗散量巨大和在伊盟隆起发现大面积分布的多种与成熟煤型气耗散有关的蚀变产物和凝析油苗,综合相关模拟实验和测试分析,提出了铀源来自深部的铀成矿新模式:来自盆地中部深层富铀煤系地层中的溶气热流体,在向伊盟隆起东部高部位运移耗散过程中,萃取并携带母岩和沿途围岩富铀地层中的铀元素运移到浅层,随温压降低亮晶方解石与铀石相伴沉淀完成了热液成矿过程,被析出的大规模有机天然气则在浅表层低温成矿同时为铀矿的保存创造了还原环境。此铀成矿新模式拓展了盆地勘探铀矿的思路和领域,提升了多种能源矿产相互作用的成矿效应和综合评价预测的科学性。

煤系铝土矿中铀与钍富集特征及其自然伽马异常响应

山西省煤系铝土矿资源丰富,深部铝土矿资源评价正逐步开展,为进一步确定煤中铝资源禀赋,探求高效勘查方法,以山西孝义地区上石炭统煤系铝土矿层为研究对象,选取并采集了3个钻孔的37个样品,应用显微光学分析、XRD、SEM、XRF和ICP-MS等技术方法,在分析煤系铝土矿层沉积环境和成矿物源的基础上,研究铝土矿中铀(U)、钍(Th)元素的赋存状态与富集成因,探讨U、Th元素的地球化学特征与自然伽马异常的响应关系。结果表明,研究区铝土矿层形成于海相碱性弱氧化为主的沉积环境,沉积过程中存在氧化、弱氧化–弱还原和还原环境,且氧化还原条件不断发生微弱变化;铝土矿与其顶板黏土岩(矿)物源相似,主要源自酸性岩浆岩,而底板铁质岩的物源则与玄武岩或钙质泥岩有关;铝土矿层U、Th元素异常富集主要受控于物源母岩类型及铝土矿、黏土矿物和含钛矿物的吸附能力;铝土矿中富集的U、Th元素是自然伽马高异常的主要原因,且Th元素的贡献较U元素明显。研究结果对划分煤系铝土矿和围岩、确定煤系铝土矿的层位及推测矿体厚度具有实际意义,并对开展深部煤系铝土矿勘探与开发也具有理论指导意义。

基于CPFD方法的U_(3)O_(8)氢还原流化床反应器数值模拟

气固流化床因具有气固接触效率高、相间传质传热快等优点已用于天然铀转化工艺的多个环节,但目前对这类高密度颗粒系统的流化反应性能认识不足,难以对其精确设计和操控。采用计算颗粒流体力学(computational particle fluid dynamics,CPFD)方法对工业尺度连续U_(3)O_(8)还原流化床进行全三维数值模拟,对不同颗粒粒径分布的流化床还原系统中宏观气固流动、传热、反应特性等重要参数进行统计分析。结果显示,在氢气过量80%的条件下,3种不同粒径的颗粒在流化床中的流化状态均表现不佳,大部分区域颗粒处于非流化状态,床层膨胀率低。分析出口处产物分布发现,颗粒粒径越小产物的转化率越高,然而由于流化状态普遍较差,即便是在粒径较小的条件下转化率的总体水平仍然偏低。以上结果表明,在实际操作中可能需要进一步优化流化床的操作条件和结构形式,以提高流化效果和反应转化率。本研究期望能够为高密度颗粒在流化床中的流动与反应特性的深入认识提供新的视角和方法,为核化工及相关领域的技术进步提供有力支持。

背景地下水作用下铀在砂岩铀矿微界面上的扩散模式

上游背景地下水流入酸法地浸采铀退役采区地下水中时产生了稀释和冲洗作用。为探究背景地下水作用下酸法地浸退役采区地下水中铀在水岩微界面上的扩散模式和控制机理,开展了静态稀释实验和动态冲洗实验。静态稀释实验结果显示,背景地下水与污染地下水比例为50∶1时,1440 min内铀浓度降到背景值60μg/L以下;初期阶段(0~20 min),反应速率主要受膜扩散控制;中期阶段(20~150 min),反应速率受膜扩散和颗粒内扩散共同控制;后期阶段(150~600 min),反应速率主要受颗粒内扩散控制。动态冲洗实验结果表明,用25个孔隙体积的背景地下水,10 d内铀浓度降至50μg/L;初期阶段(0~4 d),反应速率主要受膜扩散控制;中期阶段(4~7 d),反应速率同时受膜扩散与颗粒内扩散控制;后期阶段(7~10 d),反应速率主要受颗粒内扩散控制。这些研究结果揭示了上游背景地下水流入酸法地浸采铀退役采区地下水中后铀的扩散和迁移规律,为酸法地浸采铀退役采区地下水自然净化的可行性评估提供了理论依据。

伞蜥颈部褶皱自然对流换热的数值模拟

对伞蜥这一有特殊散热结构的爬行动物进行物理建模,并对该模型展开自然对流传热特性的数值研究。研究发现,调节模拟伞蜥颈部褶皱的不同张角(45°~85°)时,换热系数在65°附近达到唯一最大值。同时改变伞蜥颈部褶皱的大小,显示对流传热系数的唯一最大值出现在6.3≤L_(0)/d≤6.6范围内,模拟得到的最大传热速率对应的张角和面积均接近选取亚种的自然状态,由此推测伞蜥颈部褶皱的进化方向可能朝有利于提高自然对流传热速率的方向进行,而伞蜥与外界环境的自然对流可能是影响伞蜥颈部褶皱进化方向的重要原因之一。

溶液制样—波长色散X射线荧光光谱法测定天然铀产品中的铀含量

采用溶液制样,以碳酸锶为内标物,建立了用波长色散X射线荧光光谱法测定天然铀产品(U_(3)O_(8))中铀含量的方法。样品称样质量为1.00 g,内标物碳酸锶称样质量为0.600 g,采用15 mL磷酸和2 mL硝酸消解样品,定容至200 mL后,用磁力搅拌混匀,采用一次性塑料吸管和电子秤控制取液体积。仪器测量条件选择特征X谱线:U-L_(α1),Sr-K_(α1),通道面罩34 mm,初级准直器150μm。该方法工作曲线的线性相关系数为0.999 8,相对标准偏差(RSD)为0.031%~0.050%,精密度较好;测定结果与标准物质推荐值之间的相对误差不劣于0.034%,准确度较好。与电位滴定法对比,该法绝对偏差为0.010%~0.126%,结果准确可靠,能够满足天然铀产品快速批量分析的要求。

基于模型融合的国际短期天然铀价格预测研究

天然铀是核电发展的重要矿产物质基础,对核电发展速度和运行成本具有重要影响,因此国际天然铀价格(简称天然铀价格)预测工作对核电发展有重要的应用价值。数据驱动模型是目前效果较好的价格预测方法之一,通过分析历史天然铀价格及其协变量数据特征,可以预测得到未来天然铀价格的趋势和具体数值。一般而言,为了提升数据驱动模型的预测效果,需要从数据内容和模型结构两方面着手进行改进。首先,深入分析影响天然铀价格的协变量因素,将天然铀价格协变量因素分为基本供需关系、市场交易情况和经济金融环境三类,选择较为完善的协变量数据构建天然铀价格数据库,通过相关性检验验证有效性。然后,根据协变量时序数据的时间维度自相关和变量间互相关特点,基于机器学习的模型融合方法,提出在模型中引入卷积神经网络(Convolutional neural network,CNN)深入挖掘互相关和自相关特征,以改善预测模型对数据特征分析能力。最后,以长短期记忆(Long and short-term memory,LSTM)网络为时间序列预测的基础,建立5种不同的模型融合结构并预测未来天然铀价格,结合敏感性测试方法进行分析对比,发现采用CNN插入的LSTM-CNN-LSTM模型的天然铀价格预测效果最好且受超前预测步和时间窗的影响较小。研究表明,通过模型融合和敏感性测试方法构建的优化数据驱动预测模型,可以稳定、准确地预测未来6个月的短期天然铀价格,为核电发展和运行提供数据参考。