某UO2 芯块研制实验室计划退役,为初步掌握该实验室内放射性污染情况,对其进行了初步源项调查,调查内容包括实验室运行历史、表面污染水平、γ辐射剂量水平、气溶胶浓度水平,以及污染面积和污染物项估算等.调查结果显示:该实验室主要污染核素为234 U、235 U 和238 U,放射性污染核素单一;实验室内的表面污染水平、γ辐射剂量水平、气溶胶浓度水平较低;地面及墙面污染面积总计约 1 000 m2;退役时需进行去污操作的设备约 300 台;内部积存各类放射性固体废物约 80 m3.因实验室内污染物项种类繁多,各类污染物污染程度差异较大,在进行退役治理时,应将废物做好分类处理,防止交叉污染.
在以氡为特征污染物的大气扩散数值模拟中,因其湿沉降参数一般采用缺省值而造成了计算精度的不确定性.为了确定氡湿沉降参数的影响因素和特征值,自主研制了试验装置模拟降水过程,综合分析了初始氡活度浓度、降水强度、降水pH 与氡湿沉降率和清除效率的关系.结果表明,氡在大气环境中的湿沉降率与初始氡活度浓度和降水强度呈线性相关(R2＞0.99),清除效率与初始氡活度浓度、pH 均表现出弱相关性.以气相氡为典型对象,当湿沉降率在 31～2 653 Bq/(m2·h)时,可预测氡的清除效率保持在 0.55%～0.65%.研究得到的降水强度与湿沉降参数的指数函数关系式可为氡的大气扩散数值模拟提供参数依据.
采用滴定法,以电极测量判断终点,研制了一种测定淋氟尾液中碳酸根和碳酸氢根浓度的在线分析仪,实现了对 0.01～1.00 mol/L碱度的测定,测量重复性误差为 1.5%,测量精度误差为 4.8%,仪器的检测下限为 0.04 mol/L.现场测试结果表明,仪器运行稳定,测量精度高,测量数据与现场滴定分析结果基本一致,满足现场分析要求,加标回收率为 96.0%～104.0%.
某铅锌矿采用平硐+竖井+斜坡道开拓,采用分段空场法和浅孔留矿法回采.该方法采场空区暴露面积大、安全性差,回采形成的空区为矿山生产埋下了安全隐患;且随着深度的增加,围岩稳固性变差,矿体变薄、变分散,造成回采贫化率增大,采选矿成本大幅提高,原有采矿方法已不适用.根据矿体特征和矿山生产现状,对矿山 2 522m中段以下的矿体采用机械化盘区上向水平分层充填法开采,并使用大型无轨设备进行采掘作业,减少了采场暴露面积,提高了井下作业安全性,避免了产生大量采空区,解决了生产安全隐患,提高了资源回收率,盘区生产能力、综合回采率、综合贫化率等指标均得到优化.研究结果对该区其他矿山的开采具有示范作用.
随着铀矿开采和冶炼工业的发展,铀尾矿库的数量不断增加.铀尾矿库对周边环境具有潜在危害,其退役治理迫在眉睫.铀尾矿库滩面覆盖是目前公认的有效方法之一,也是大多数实际退役工程采用的主要技术.笔者分析了铀矿库滩面覆盖技术的国内外现状,对铀尾矿库退役治理中的常用材料、技术措施及治理成效进行了阐述,旨在为铀尾矿库滩面覆盖工程提供技术参考.
退役治理经费管理办法实施以来,有效规范了退役治理项目经费的管理.通过对退役治理相关经费科目测算的分析,发现存在废物运输与处置项目经费暂无适用规定、人工费科目重复且口径不一致、相关经费科目费率偏离实际水平、未考虑提前实施项目自筹资金资金成本等问题.对存在的问题,给出了相关修订建议.
根据露天矿山排土场边坡形变监测需要,在排土场地质条件及周边环境勘察结果的基础上,应用北斗高精度定位技术,分别在排土场 1590、1586、1580 平台边坡布设 5 个北斗位移监测点,实现对排土场边坡形变的实时监测.对连续 10 个月的形变监测数据的统计分析表明,排土场施工作业导致各监测点边坡垂直方向形变,1590 平台边坡垂直形变显著(垂直形变月累积量平均约为 6.0 mm),其他平台边坡垂直形变月累积量平均值小于 3.0mm,各监测点均未出现形变加速或阶跃变化,排土场边坡尚处于平稳期.北斗卫星系统在排土场位移监测中的应用,为边坡形变趋势预测和安全预警提供了自动化的监测手段和原始监测数据,保障了露天矿山排土场堆放作业的安全.
共价有机骨架作为一种新型的有机孔状材料,因其比表面积大、有序的孔状结构以及可控的骨架而被广泛应用于环境领域,可吸附、分离及光催化降解污染物.综述了共价有机骨架基材料对环境中放射性污染物的去除,探讨了其对铀、铕、钍、锝以及碘的去除研究进展.
地应力测量是确定工程岩体力学属性,进行围岩稳定性分析,实现岩石工程开挖设计和决策科学化的前提条件.随着棉花坑矿井开采深度的不断增加,复杂构造应力对巷道和采场围岩稳定性产生的影响日趋显现.为了掌握该矿深部岩体地应力分布情况,提高井下工程设计的科学性、安全性和经济合理性,采用空心包体应力解除法对该矿开展地应力测量研究,分析其应力状态和分布规律.研究结果表明,在该矿区埋深 615～715 m范围内,水平最大主应力为 22.5～29.8 MPa,最大主应力与垂直应力分量之比为 1.5～1.7;各主应力大小随深度增加呈线性增长;各测点水平最大主应力方向具有较强的一致性,介于 91.2～110.3°,为北西西-南东东方向.
同位素在核医学科的成像、诊断和治疗方面的应用越来越普遍,同位素的应用给辐射工作者和公众带来了潜在辐射危害.通过探究某医院核医学科的放射防护措施,在监测、分析及现场调查的基础上,评估了该医院放射性同位素应用场所的辐射防护效果.结果表明,该核医学科放射工作场所周围的辐射水平低于标准中规定的剂量限值,估算的年有效剂量小于管理目标值,符合辐射防护相关标准.该医院各场所屏蔽体的屏蔽效果良好,核医学科场所的屏蔽是可行的.
铀尾矿砂覆盖材料优化选择对铀矿山尾矿砂治理有着重要意义.通过构建铀尾矿砂覆盖层氡浓度分布模型,采用单层和三层覆盖层材料,以氡析出率和综合成本为决策目标构建了多目标决策模型,基于多目标非支配排序方法,寻找可行方案的最优解.对于铀尾矿砂,若采用单层覆盖材料,只有黏土、水泥砂浆和沥青 3 种材料能够在合理厚度范围内满足氡析出率国标限值要求;与单层覆盖材料相比,三层覆盖层材料外的氡析出率满足国标限值要求,且综合成本降低了 75.9%.
原地浸出采铀工艺已被广泛应用于砂岩型铀矿的开采,地浸采铀过程对地下水环境的影响一直受到社会各界广泛关注.笔者总结了地浸铀矿山地下水修复技术的研究方向及研究进展,对国内外地浸铀矿山地下水场地修复案例所采用的技术及修复效果进行了分析.结果表明,抽出—处理技术具有修复效率高,修复周期短等优势,但其修复成本高,修复后期因含水层固相介质中污染物的持续释放而出现修复反弹和拖尾等问题;自然衰减技术的优点是修复效果显著,对放射性及非放射性元素均有效果,但存在修复周期长,修复效果需进行长期监测等缺点.单一修复技术的应用会受到各种因素的制约,多种修复技术联合应用,在不同的修复阶段选用不同的修复技术将成为未来趋势.中国地浸铀矿山地下水修复可考虑抽出—处理技术和自然衰减技术相结合的修复方案.
在采用深孔爆破回采时,爆破参数一般由炮孔直径推导的经验值确定,存在爆破质量偏低的问题.笔者进行了爆破漏斗试验,由单孔爆破漏斗试验得到装药质量为 300 g的药包的最佳埋深为 0.65 m,最佳漏斗半径为 0.63 m;由变孔距多孔同段爆破试验得出最佳孔间距为 0.9～1.0 m,最佳孔间距与最佳漏斗半径的比为1.43～1.59;由斜面台阶爆破试验初步得到最佳的最小抵抗线为 0.41 m.基于爆破相似定律,计算得到直径65mm深孔的最佳孔间距为 1.7m;考虑到斜面台阶爆破试验结果不理想,采用扇形布孔的孔底密集系数经验值(1.0～1.3)计算后,推荐深孔爆破排距为 1.3m.
The special material handling system of the uranium enrichment factory was systematicly analyzed, the characteristics of special materials were analyzed in detail, the handling lines and logistics conditions were defined, the influencing factors and practical handling methods were distinguished, and a viable overall scheme of the special material handling was obtained. The economic and intangible factors of the handling scheme were analyzed and evaluated. The SHA provides theoretical supports for improving the special material handling, and provides a logical handling scheme for the rebuilding and expanding plan. It improves the handling efficiency and reduces the labor intensity. It also provides a certain reference for reducing the production cost.
Aiming at the problems of high turbidity and organic phase content in the uranium-molybdenum raffinate, which affect the return utilization, the experimental study on the removal of organic phase in the raffinate by flocculation pretreatment was carried out. The results show that the turbidity and organic phase contents in the raffinate can be reduced from 1 500 NTU and 294 mg/L to 0 NTU and 44.8 mg/L respectively under the conditions that the dosage of C6140 is 2.0 g/m~3 raffinate, stirring speed is 60 r/min, stirring time is 10 s, and static time is 40 min after stirring. The process parameters obtained from the study have strong adaptability to the change of turbidity of raffinate, and the flocculation pretreatment process parameters can be used in production.
In order to recover uranium from uranium-beryllium flotation tailings and reduce the content of beryllium in uranium products,the occurrence state of uranium and beryllium in uranium-beryllium flotation tailings was analyzed by process mineralogy,and uranium was leached by sulfuric acid leaching process.The effects of acid concentration,leaching time,leaching temperature and liquid-solid ratio on the leaching rate of uranium and beryllium were investigated,and the feasibility of recovering uranium from leaching solution was studied by anion exchange resin.The results show that the uranium in the uranium-beryllium flotation tailings is more easily leached by sulfuric acid,but the beryllium is not easily leached,the uranium can be recovered and the uranium-beryllium can be separated by ion exchange method.
In order to improve the cutting efficiency of deep and tight ore beds, the conventional cutting technology and screw motor composite cutting technology were studied by using the ISL wells in Bayinqinggeli deposit in the northern Ordos Basin, and the application parameters of screw motor composite cutting technology were obtained. The results show that the cutting speed of screw motor composite cutting technology is 102.8% higher than that of conventional cutting technology, and the cutting quality can meet the requirements of the ISL. The screw motor composite cutting technology has wide application prospect. According to the cutting effect in research area, it is suggested to introduce screw motor with centralizer, design a new cutting tool, and establish the corresponding casing cutting procedures to further improve the cutting quality.
Uranium（U） can be readily adsorbed and retained in plant roots. A high concentration of U causes phytotoxicity. Plants have evolved a number of defence strategies operate separately or cooperate with each other to alleviate U-induced phytotoxicity. The defense mechanisms of plants in response to uranium stress were summarized, including compartmentalization, chelation of plants, antioxidant system, chemical form conversion of uranium. The related research direction was also prospected. The results are helpful to clarify the molecular genetic basis of plant tolerance to uranium and provide reference for plant response to uranium stress.
According to the requirements of safety monitoring in the decommissioning of uranium tailings pond, the first dam of a uranium tailings pond is taken as a pilot project. By deploying Beidou displacement monitoring terminals and various sensors at key points such as the surface of uranium tailings dam and the reservoir area, the real-time monitoring of the tailings pond and the prediction and early warning of the trend of surface deformation, the settlement trend of the dam and the variation trend of water level in the reservoir are realized, so as to predict the stability of the dam in advance and master the safety of the dam. Under the guidance of the intelligent monitoring and prevention system, a comprehensive monitoring platform is developed to provide advanced technical means for the decommissioning and management of the uranium tailings pond in the uranium industry, thus transforming passive “supervision” into active “monitoring”. The research results can provide reference for safety monitoring and intelligent prevention of other uranium tailings ponds.
It is difficult to treat radioactive wastewater by increasing the area of evaporation pool alone when using natural evaporation process. Taking the concentrated water of electrodialysis and the wastewater of evaporation pond in a neutral in-situ leaching uranium mine as the research object, MVR evaporation process was used to investigate the quality of condensate water and evaporation effect under different pressures and temperatures. The results show that the condensate water can meet discharge or reuse standards, the volume reduction rate reaches 95%, and the MVR has the best evaporation effect at 0.07 MPa and 90 ℃.
