Long-term leaching behaviour of glasses containing zirconium

Five borosilicate glasses containing up to 20% zirconium oxide and 10% non-radioactive fission products or lanthanum oxide (which simulates the behaviour of the actinides) were leached in stagnant distilled water at 20 ° C for 2 years. The leaching rates of Na, La, Mn, Cs and Mo varied with time and the chemical composition of the glass from 0.7 to 12, 0.006 to 0.14, 0.8 to 1.2, 0.4 to 0.8 and 8 to 25 mg/m²/d respectively. The glasses which showed the beast short-term resistance do not have the best long-term resistance.     

含铀氢氟酸再利用辐射影响研究

为解决核设施运行产生副产品含铀氢氟酸的处理问题,本文对我国核燃料元件生产线运行产生的含铀氢氟酸用于生产氟化氢铵的辐射影响进行了分析。结果表明,铀含量小于0.2 mg/L的氢氟酸用于生产氟化氢铵过程中对工作人员所造成的附加剂量远低于1 mSv/a,产品氟化氢铵中的铀含量小于1 Bq/g。从辐射影响角度分析,含铀氢氟酸用于氟化氢铵生产是完全可行的,有利于实现放射性废物最小化和资源利用。     

乌兹别克斯坦地浸开采铀矿山的环境保护

讨论了铀矿业的生态问题,特别集中在地浸上。与传统采矿方法相比较,从生态学的观点来看,地浸已被证明是有利的。为了降低铀矿生产周期对环境的影响,描述了纳沃伊矿冶联合企业开发和介绍的新技术,即,“强硫酸”提取法和“弱硫酸”提取法。     

On the pH dependence of leaching of nuclear waste glasses

Two simulated nuclear waste glasses were leached for periods up to one month at 90°C in high-purity water, following standard MCC-1 test procedures. The changes in composition of the surface layers were determined using ESCA and SIMS, which analyses layers of different depths. The results are discussed with reference to the different pH values in the tests performed.     

地浸采铀及地浸矿床的条件与评价

主要介绍了地浸采铀的含义及其发展历史,并对地浸矿床的条件进行详细分析,提出地浸矿床评价的三项原则.     

基于某铀矿的地浸采铀方法

简述了地浸采铀的主要影响因素,提出了一种基于高矿化度砂岩铀矿的地浸采铀工艺——淡化少试剂工艺。此工艺不仅可以有效防止管道堵塞,而且可以提高浸铀的经济效益。     

Preparation, sintering and leaching of optimized uranium thorium dioxides

Mixed actinide dioxides are currently studied as potential fuels for several concepts associated to the fourth generation of nuclear reactors. These solids are generally obtained through dry chemistry processes from powder mixtures but could present some heterogeneity in the distribution of the cations in the solid. In this context, wet chemistry methods were set up for the preparation of U_1−xTh_xO₂ solid solutions as model compounds for advanced dioxide fuels. Two chemical routes of preparation, involving the precipitation of crystallized precursor, were investigated: on the one hand, a mixture of acidic solutions containing cations and oxalic acid was introduced in an open vessel, leading to a poorly-crystallized precipitate. On the other hand, the starting mixture was placed in an acid digestion bomb then set in an oven in order to reach hydrothermal conditions. By this way, small single-crystals were obtained then characterized by several techniques including XRD and SEM. The great differences in terms of morphology and crystallization state of the samples were correlated to an important variation of the specific surface area of the oxides prepared after heating, then the microstructure of the sintered pellets prepared at high temperature. Preliminary leaching tests were finally undertaken in dynamic conditions (i.e. with high renewal of the leachate) in order to evaluate the influence of the sample morphology on the chemical durability of the final cohesive materials.     

巴音塔拉凹陷地浸砂岩型铀矿成矿条件

简要介绍巴音塔拉凹陷蚀源区岩石及年代学特征,论述了含矿地层特征、沉积物源、铀矿化类型、成矿年龄及铀成矿条件等。指出下白垩统含矿地层物源好,地质演化历史对后生水成铀矿有利,是寻找地浸砂岩型铀矿值得重视的地区。     

Chemical and radiation danger of uranium aerosols

Criteria are proposed for the acceptable risk of single intrusions of uranium compounds. The criteria take account of the chemical and radiotoxicity of the compounds. These criteria were developed on the basis of known data on the toxicity and radiotoxicity of uranium compounds and are recommended for analyzing the risk of operating dangerous industrial objects. __________ Translated from Atomnaya énergiya, Vol. 105, No. 1, pp. 48–53, July, 2008.     

Barium-borate-flyash glasses: As radiation shielding materials

The attenuation coefficients of barium-borate-flyash glasses have been measured for γ-ray photon energies of 356, 662, 1173 and 1332 keV using narrow beam transmission geometry. The photon beam was highly collimated and overall scatter acceptance angle was less than 3°. Our results have an uncertainty of less than 3%. These coefficients were then used to obtain the values of mean free path (mfp), effective atomic number and electron density. Good agreements have been observed between experimental and theoretical values of these parameters. From the studies of the obtained results it is reported here that from the shielding point of view the barium-borate-flyash glasses are better shields to γ-radiations in comparison to the standard radiation shielding concretes and also to the ordinary barium-borate glasses.     

低品位铀矿石硫酸搅拌浸出与细菌搅拌浸出研究

采用广东某矿的低品位铀矿石,分别开展了硫酸搅拌浸出和细菌搅拌浸出研究.结果表明:(1) 对于硫酸搅拌浸出,硫酸浓度为30 g/L、矿浆浓度为25%为最佳浸出条件,铀的浸出率为92.92%.(2) 对于细菌搅拌浸出,pH值为1.5、接种量为10%、矿浆浓度为10%为最佳浸出条件,铀的浸出率为95.93%.(3) 细菌搅拌浸出与硫酸搅拌浸出相比,前者的酸耗降低了17.2%,浸出率提高了3%.(4) 在硫酸搅拌浸出的最佳浸出条件下,若再加入1%的氯酸钠,则浸出率与细菌搅拌浸出的浸出率基本相同,但每吨铀矿石需另外消耗10 kg氯酸钠.     

影响地浸采铀的矿层渗透因素

通常认为砂岩型铀矿含矿层的渗透性是地浸开采技术是否可行的重要条件。因此,研究地浸采铀的可行性和提高砂岩型铀矿含矿层渗透性成为重点。系统探讨了影响砂岩型铀矿含矿层渗透性的主要因素,即:碳酸盐、黏土矿物、夹层、隔层、地下水矿化度等。这为进一步研究砂岩渗透性提供了依据,同时对地浸采铀的浸出率和资源回收率也有着重要的理论意义和实际价值。