中国高放废物地质处置研究进展:1985～2004

如何安全处置高放废物是核工业可持续发展面临的挑战性问题。我国的高放废物深地质处置研究从1985年开始，提出的计划目标是：于21世纪中叶建成我国高放废物地质处置库，处置的对象是玻璃固化块、超铀废物和部分乏燃料，处置库为竖井一坑道型，候选围岩为花岗岩，位于饱和带中。在1985～2004的20a中，我国高放废物地质处置研究取得了进展，已确定我国高放废物最终处置走“深地质处置”，并且是“三步曲”式的技术路线，即处置库选址和场址评价一地下实验室一处置库。经过全国筛选对比，已初步选定甘肃北山地区为重点预选区，该区地处戈壁，地壳结构完整，地壳稳定，人烟稀少，地质条件和水文地质条件均有利。20世纪90年代初期，开展了地下实验室的选址工作，初步选择了北京郊区2处地点为我国高放废物地质处置“普通地下实验室”的场址。已确定使用膨润土作为处置库的回填材料，并初步确定内蒙古高庙子膨润土为我国高放废物处置库的首选缓冲回填材料。对膨润土的矿物学、岩土力学、物理力学性质和热学性质进行了研究。已获得一批放射性核素(主要是Np、Pu、Tc)在北山花岗岩和膨润土上的吸附分配比、扩散系数和弥散系数等参数，建立了低氧手套箱和模拟处置库温度、压力和氧化一还原条件的小型实验装置。高放废物中的关键核素的化学行为研究也取得进展。花岗岩接触带核素迁移、铀矿床中超铀元素迁移、青铜器腐蚀等天然类比研究取得了成果。还开展了高放废物地质处置系统总性能评价源项和生物圈模式的调研。概念设计研究仅在20世纪90年代初开展了部分研究。从1999年开始，与国际原子能机构开展了2期高放废物地质处置技术合作项目，极大地提高了我们的技术水平。20a的科研工作为我国在21世纪完成高放废物地质处置奠定了一定基础。     

中国高放废物地质处置21世纪进展

21世纪近20年，我国高放废物深地质处置进入了一稳步发展的新阶段，在法律法规、技术标准、战略规划、选址和场址评价、工程屏障研究、处置库和地下实验室概念设计、核素迁移和安全评价研究等方面取得了显著进展。其主要亮点包括颁布了《中华人民共和国放射性污染防治法》和《中华人民共和国核安全法》，制定了《高放废物地质处置研究开发规划指南》，颁布了《高放废物地质处置设施选址》核安全导则，确定了2020年前开工建设地下实验室、2050年建成高放废物处置库的目标，甘肃北山预选区被确定为我国高放废物地质处置库首选预选区，建立了场址评价方法技术体系，确定了内蒙古高庙子膨润土为我国高放废物处置库的首选缓冲回填材料，建立了我国首台缓冲回填材料热 水-力-化学耦合条件下特性研究大型实验台架（China-Mock-Up），获得了一批关键放射性核素的迁移行为数据，开展了初步的安全评价，完成了地下实验室安全技术研究。确定甘肃北山的新场为我国高放废物地质处置地下实验室的场址。2019年5月6日，国家国防科工局批复中国北山高放废物地质处置地下实验室工程建设立项建议书，标志着我国高放废物地质处置正式进入地下实验室阶段。这一系列工作进展和取得的成绩为我国2020年开工建设地下实验室、掌握高放废物地质处置技术奠定了坚实的基础。     

好书推荐·《新世纪中国高放废物地质处置》

正本书收录了进入21世纪以来,主要是2000-2011年期间,我国在高放废物地质处置各领域有代表性的重要论文,包括高放废物地质处置战略和规划研究、地下实验室规划、高放废物处置库选址和场址评价、处置库工程屏障、玻璃固化体性能、缓冲回填材料性能、处置工程、放射性核素迁移行为、安全评价等领域的论文。基本反映了这一时期我国高放废物地质处置     

高放废物地质处置库预选场址水文地质研究进展

深地质处置是目前国际上普遍接受的高放废物最终处置方案。对于这种处置方案而言，最有可能使处置库系统中放射性核素释放并进入生物圈的机制是地下水的作用。本文阐述了这种地下水的作用，包括地下水与工程屏障的相互作用、地下水在地质屏障中的核素迁移作用及核素滞留作用；介绍了处置库场址评价中水文地质研究的国际进展和动向；重点介绍了我国高放废物处置库预选场址水文地质研究进程和概况。     

高放废物处置库甘肃北山预选区综合水文地质研究

在野外水文地质调查基础上,开展了北山地区地下水系统特征、岩体渗透性能、地下水动态、水文地球化学、地下水同位素、地下水CFC以及地下水流场模拟等综合性水文地质研究。依据大量资料的科学分析,综合论述了研究区水文地质条件、地下水循环交替特征、地下水化学特征和动力学特征,并对北山地区作为高放废物处置库场址预选区的适宜性进行了评价。通过这些工作,不仅为我国高放废物地质处置库选址建立了系统的水文地质研究和评价方法,也为在该区筛选最适宜的高放废物处置库场址提供了重要的水文地质依据。     

高放废物地质处置库缓冲／回填材料性能测定

根据矿床位置、交通、矿区地质特征、矿床成因、矿床储量、我自然地理与开采技术条件等因素综合对比研究，研究内蒙古兴和县高庙子膨润土矿床为我国高放废物地质处置库缓冲／回填材料供给基地的首选矿床。本文对主要矿层进行了物质成分、物理化学性能等方面的研究。对测试结果分析可知，高庙子膨润土的蒙脱石含量较高，物理化学性能和物理水理性质较好。因此，高庙子膨润土矿床作为高放废物地质处置库缓冲／回填材料的供给基地是可行     

建议我国重点研究粘土岩处置库预选场址

高放废物地质处置库的围岩选择至关重要.近年来,我国的重点研究对象是花岗岩.作者在列举了国际上正、反两方面的经验教训之后,分析了围岩选择方面的诸多重要因素.在此基础上,建议我国在最终决策前,进一步研究粘土岩处置库作为预选场址.     

德国放射性废物地质处置的研究历程

本文简要介绍了德国放射性废物地质处置及相关研究的历程和现状,包括中低放废物和高放废物的处置情况,同时从技术层面分析了德国高放废物处置库场址评价所面临的问题。希望对于我国放射性废物地质处置的研究有所启示。     

高放废物处置预选区地学信息数据模型构建

针对高放废物地质处置选址与场址评价阶段的信息化建设工作,采用GIS技术、数据管理技术、数据分析技术等,旨在基于地学信息数据模型的构建,建立统一的、一体化的、高度综合的高放废物地质处置预选区地学信息库,以覆盖地质、水文地质、地球物理、地球化学等多学科研究内容。着重讨论了预选区地学信息数据模型建设的方法和技术,并通过预选区地学信息库的工程实例说明了数据模型的成功应用。预选区地学信息数据模型的建设可以为场址筛选、场址性能评价等研究工作提供技术支持,对高放废物地质处置研发工作的推进也将起到积极作用。     

U(Ⅵ)在缓冲回填材料高庙子膨润土胶体上的吸附

甘肃北山地区是目前我国高放废物地质处置库的重点预选场址,内蒙古高庙子膨润土为首选缓冲回填材料。在处置库安全评价中需要考虑可能存在的地下水侵蚀形成膨润土胶体负载核素迁移的情况。以产自内蒙古自治区兴和县高庙子矿区Ⅲ号矿层的膨润土为原料提取膨润土胶体,研究其稳定性,通过批式吸附实验研究了溶液pH、背景电解质浓度等对U（Ⅵ）在高庙子膨润土胶体上吸附的影响。结果表明：酸性条件下,高庙子膨润土胶体对U（Ⅵ）的吸附随pH上升而增强,吸附分配系数在pH≈7时达到峰值;碱性条件下,胶体对U（Ⅵ）的吸附则随pH上升而减弱;在本研究所选取范围内,背景电解质NaClO₄浓度对U（Ⅵ）在高庙子膨润土胶体上的吸附影响不大。     

Identification of radiation treatment of wheat （Triticum aestivum. L）and rice （Oryza sativa. L） samples using thermoluminescence of contaminating minerals

Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food. Because of the rapid commercialization of irradiated foods throughout the world, compliance of different regulations relating to use of technology in different countries and demand of consumers for clear labelling of irradiated foods, there is need for the development of analytical methods to detect radiation treatment of food. Among several methods studied so far, thermoluminescence （TL） is an important method that can be used to find out the irradiation history of food that contain even a very minute amount of dust particles. In this study, the irradiated and unirradiated wheat and rice samples were analyzed using the TL method. The samples were purchased from the local market of Peshawar and irradiated to radiation doses of 0.5 and 1.0 kGy using Co-60 gamma irradiator at the Nuclear Institute for Food and Agriculture （NIFA）, Peshawar. The mineral contaminants were isolated by jet water, ultrasonic treatment, and density gradient. TL glow curves of the isolated minerals from irradiated and unirradiated samples were recorded between the temperature ranges of 50-500℃ using a TL reader. Generally, the glow curves for irradiated samples showed much higher TL intensities （TL1） than the unirradiated samples. The results were normalized by rerradiation of mineral samples to gamma-ray dose of 1.0 kGy followed by determination of the second glow curves （TL2）. The ratio of the area of first glow curve to that of second glow curve （TL1/TL2） was calculated for selected temperature intervals and compared with the recommended values for unirradiated and irradiated samples. Finally, the shapes of the glow curves for irradiated and unirradiated samples were also analyzed. On the basis of these results （comparison of TL-intensities, TL1/TL2 ratios and shapes of the glow curves）, all the irradiated and unirradiated samples of wheat and rice were unequivocally identified.     

有效探测面积大于1000 cm2的正比计数器测量系统性能测试

为对自制的活性面积高达1 000 cm²的大面积源进行表面发射率定值,同时作为现有2πα、2πβ表面发射率标准装置能力的扩充,研制了一套内置式大面积2π多丝正比计数器测量系统,并利用活性区直径为8 mm的²⁴¹Am点源及活性区面积为10 cm×15 cm的大面积²⁴¹Am和⁹⁰Sr-⁹⁰Y源对其进行计量学性能测试。结果表明：计数器内计数响应均匀性优于±0.4%,有效探测面积达1 400 cm²;所得²⁴¹Am源高压坪曲线的坪长为1 400 V,坪斜为0.27%/100 V,坪区内计数变化为0.87%;⁹⁰Sr-⁹⁰Y源高压坪曲线的坪长为300 V,坪斜为0.75%/100 V,坪区内计数变化为0.80%;10次测量重复性好于0.4%,8 h内短期稳定性好于0.3%,1 a内长期稳定性好于0.8%。     

Preparation of Zn/TiO2 powder and its photocatalytic performance for oxidation of P-nitrophenol

Zn-doped TiO2 catalysts were prepared using a sol-gel method and characterized by XPS,UV-Vis, BET, XRD in this study. Under the irradiation of simulant sunlight, the photocatalytic activity for the degradation of p-nitrophenol was studied too. After irradiation for 2.5 h, the degradation percentage of p-nitrophenol could rise to more than 80 %. The results showed that the spectrum absorption band edge of Zn/TiO2 powder does not broaden obviously comparing with pure TiO2 powder. Zinc exists as Zn （11）. When calcined at 973 K, there is a new phase as ZnTiO3 in Zn/TiO2 catalyst. The order of photocatalytic activity of Zn/TiO2 catalysts calcined at different temperatures for p-nitrophenol is 773 K 〉 673 K 〉 873 K 〉 573 K 〉 973 K and the photocatalytic activity of Zn/TiO2 catalyst calcined at 773 K is better than TiO2 catalysts heated at the same temperature, and outclasses that of commercial TiO2 catalyst. It also showed that the photocatalytic degradation of p-nitrophenol follows first-order kinetics under the irradiation of simulant sunlight.     

Current status of radiation therapy for prostate cancer

Radiotherapy for the treatment of prostate cancer has been extensively explored in the past. Along with the comprehensive understanding of the biology of prostate cancer and rapid advances in terms of technology, the out- come of treatment for the patients with prostate cancer has improved. The authors review radiotherapy as the primary treatment for the disease, with particular emphasis on the technological advances from both the radiobiological and radiophysics aspects. Nonconventional fractionated irradiation like hyper- or hypo-fractionation has been imple- mented in the clinic, the final results still need to be confirmed in the future. Technological advances like IMRT, IGRT, in the last two decades have significantly improved the delivery of external radiotherapy to the prostate. This has re- sulted in an overall increase in the total dose that can be safely delivered to the prostate, which has led to modest im- provements in the biochemical outcome. However, establishing the standard therapy for prostate cancer remains con- troversial. It is hoped that the next decades will bring continued advances in the development of biologicals that will further improve current clinical outcomes.     

The control system for SSRF injection and extraction

This paper introduces the injection and extraction control system design for SSRF,which is a distributed control system aimed at stability and reliability of the pulse power supplies,PPS(Personnel Protection System)and MPS(Machine Protection System).The hardware environment is mainly based on PLC(Programmable Logic Con- troller),and ARM(Advanced RISC Machine)is also applied for studying stability of the power supplies.WinCC and EPICS(Experimental Physics and Industrial Control System)have been selected as the platforms of SCADA(Super- visory Control and Data Acquisition).For unifying the interfacing to the control computer,all front-end equipments are connected via Industrial Ethemet.     

Interaction between uranium and humic acid (Ⅰ): Adsorption behaviors of U(Ⅵ) in soil humic acids

The adsorption behaviors of uranium on three soil humic acids (HAs), which were extracted from soils of different depths at the same site, were investigated under various experimental conditions. The adsorption results showed that U(Ⅵ) in solutions can be adsorbed by the three soil HAs, with the order of FHA (HA from 5 m depth of soil) ＞SHA (HA from the surface) ＞THA (HA from 10 m depth of soil) for adsorption efficiency in each desirable condition, and the adsorption reached equilibrium in about 240 min. Although the maximum adsorption efficiency was adsorption could be described with Langmiur isotherm or Freundlich isotherm equation. The L/S (liquid/solid, mL/g)ratio and pH were important factors influencing the adsorption in our adsorption system besides uranium concentration. The adsorption efficiency decreased with the increase of the L/S ratio and pH at the pH range of 2.0-3.0 for SHA and THA or 2.5 - 6.0 for FHA. However, no significant difference in adsorption of U(Ⅵ) was observed at the experimental temperature. All the results implied that humic substances have different characteristics in samples even collected at the same site.     

水平管内含空气蒸汽强制对流冷凝换热模型研究

为研究含空气蒸汽在水平管内强制对流冷凝换热特性,基于对传热传质过程的分析,建立了管内为环状流与波状流条件下的流动冷凝换热模型。从潜热、显热和液膜3个环节对整个换热过程进行建模,最终得到计算局部冷凝换热系数的理论关系式。模型预测结果与实验数据的对比表明,二者相对偏差在±20%以内,验证了该换热模型的准确性与适用性。通过进一步的研究发现：从换热管入口至出口,随着冷凝的进行,管内换热主要热阻由液膜热阻向气液界面的凝结热阻转变;主流气体对流换热过程基本可忽略。     

Web Services interface of SSRF archive data analysis system

Accelerator database stores various static parameters and real-time data of accelerator. SSRF (Shanghai Synchrotron Radiation Facility) adopts relational database to save the data. We developed a data retrieval system based on XML Web Services for accessing the archive data. It includes a bottom layer interface and an interface applicable for accelerator physics. Client samples exemplifying how to consume the interface are given. The users can browse, retrieve and plot data by the client samples. Also, we give a method to test its stability. The test result and performance are described.     

Investigations on landmine detection by BF3 detector

Experiments were carried out to investigate the possible use of neutron backscattering for the detection of polyethylene (PE) sample buried in the soil. In detection of landmine by neutrons, the neutron detector and its shield play an important role. In this paper, the effects of graphite, heavy water, polyethylene and boric acid moderators on the flux of back scattered neutrons were investigated. We have also experimentally verified the effect of BF3 detector shield and obtained good agreement with theory.     

Information for authors

<正>1.NUCLEAR SCIENCE AND TECHNIQUES(NST),a bimonthly journal,is devoted to all aspects of nuclear science and technology,theoretical or experimental.Its special interest lies in the subjects of synchrotron radiation science and technology;low energy accelerators,radiation technology and applications;radiochemistry,radiopharmaceuticals and nuclear medicine;nuclear electronics and instrumen-