谈谈有关低,中放固体废物包装容器安全要求的若干问题

谈谈有关低、中放固体废物包装容器安全要求的若干问题罗上庚（中国原子能科学研究院，北京，１０２４１３）关键词包装容器低，中放固体废物，安全要求低、中放废物占放射性废物总量的９５％以上，并且多数要转形为固体贮存、运输和最终处置，因此，低、中放固体废物包装...     

钚在低碳钢包装容器腐蚀产物上的吸附行为研究进展

研究低碳钢材质容器腐蚀机理及其腐蚀产物对钚的吸附行为对评价放射性废物处置场地安全性具有重要意义。通过研究低碳钢包装容器在放射性废物处置库中的腐蚀行为以及腐蚀产物对钚的吸附行为研究，可为准确预测钚的迁移行为和处置库安全评价提供理论基础。本文综述了废物地质处置条件下包装容器材料可能的腐蚀机理，系统总结了腐蚀产物对钚的吸附行为、影响吸附的主要因素以及吸附机理等方面的国内外研究进展，为今后深入研究腐蚀产物对钚的吸附机理提供参考。     

钚在低碳钢包装容器腐蚀产物上的吸附行为研究进展

研究低碳钢材质容器腐蚀机理及其腐蚀产物对钚的吸附行为对评价放射性废物处置场地安全性具有重要意义。通过研究低碳钢包装容器在放射性废物处置库中的腐蚀行为以及腐蚀产物对钚的吸附行为研究，可为准确预测钚的迁移行为和处置库安全评价提供理论基础。本文综述了废物地质处置条件下包装容器材料可能的腐蚀机理，系统总结了腐蚀产物对钚的吸附行为、影响吸附的主要因素以及吸附机理等方面的国内外研究进展，为今后深入研究腐蚀产物对钚的吸附机理提供参考。     

我国放射性废物处理与处置技术十年进展

本文概要介绍了我国低、中放废物处理,高放废液处理、放射性废物最终处置,退役去污及有关标准法规制订等方面十年来研究开发活动和进展。     

放射性废物处理与处置标准在中放废液大体积浇注水泥固化工程中的应用探讨

本文扼要阐述了放射性废物处理与处置标准在中放废洼失体积浇注水泥固化工程中的应用,针对GB 14569.1-93<低、中水平放射性废物固化体性能要求水泥固化体>和GB 7023-86<放射性废物固化体长期浸出试验>放射性废物处理与处置标准在中放废液太体积浇注水泥固化工程应用中所存在的问题进行了探讨,并提出了建议.     

对建设低、中放废物处置场问题的探讨

本文论述了我国建设低、中放废物处置场的迫切性,概述了国外低、中放废物处置的模式;并就我国宜采取的技术路线、投资和集资等问题进行了讨论     

新型钢桶在核电站放射性废液固化系统中的应用

目前在运行核电站的放射性废液的处理通常采用水泥固化的方法,且大部分电站使用CD1型混凝土容器作为固化体包装容器,而CD1型混凝土容器本身体积较大,导致最终废物体积较大,增加废物处置负担。本文本着废物最小化的理念,为了减少废物体积,在不改动系统功能的基础上采用自行研制的新型钢桶取代原CD1型混凝土容器。现场验证结果表明,新型钢桶性能满足相关性能要求,在原固化系统上应用可行,最终废物体积减少了43%。     

压水堆核电站放射性废液水泥固化技术分析

目前,除台湾地区外,国内的所有压水堆核电站都采用水泥固化技术处理放射性废液及其他湿废物.用钢桶作为包装容器与使用混凝土桶作包装容器相比较,可以使最终废物的体积减少50%以上,且钢桶的制造成本及运输成本都比混凝土桶低得多,但对于放射性水平较高的废物需要增设附加屏蔽.选择合适的搅拌桨在桶内混合-固化废液,可以提高废物装桶率;桶外搅拌装置将不可避免地产生二次废物.用小车作为废物桶的运输工具,可以使运输设备及地面的去污更加容易,且小车的制造成本和维修成本也比传统的辊道低得多.合理选择废液的固化配方,尽量避免加入其他物质,可提高废物的包容率.     

国外浅地层处置的废物中超铀核素含量限值的导出方法

１引言核能的应用不可避免地会产生大量的低中放废物。与高放废物比较而言，低中放废物的比活度及放射性总量较小，而其体积却大得多，占总放射性废物的９９％以上，而且分布较广。低中放废物的妥善处置已为世界各国普遍关注。放射性废物处置战略制定中的一个重要问题是陆...     

低中放废物玻璃固化体性能要求及测试方法探讨

为了减少废物体积,提升废物处置安全,将玻璃固化技术用于低中放废物的处理。低中放废物玻璃固化体性能要求及测试方法,我国目前缺少相应的标准。本文通过废物固化体标准和公开发表的相关测试数据对比分析,给出了低中放废物玻璃固化体的性能要求和测试方法的建议。     

Corrosion issues in nuclear waste disposal

This paper summarized some corrosion issues specific to nuclear waste disposal and illustrates them by the French geological clay concept for the reliable prediction of container degradation rate and engineering barrier integrity over extended periods, up to several thousands years. Among the items, the following are included:

• The importance of the underground repository conditions.

• The necessity of developing comprehensive semi-empirical models and also predictive models that must be based on the mechanisms of corrosion phenomena.

• The use of archaeological artefacts to demonstrate the feasibility of long term storage and to provide a database for testing and validating the models.

Waste Package and Shipment Aspects in Relation to Transport and Disposal Requirements

Abstract

In the management of radioactive waste, different processes have to be considered such as conditioning, interim storage and final disposal together with transport as the linking process. Attention should be paid to all the relevant steps within these processes, in particular to derive appropriate waste package requirements for a safe waste management system as well as to obtain a consistent regulatory framework. Radioactive waste arising from research and development centres, nuclear power plant operation, decommissioning, the nuclear fuel cycle industry, and applications of radioisotopes in medicine, industry and research, has finally to be shipped to a final disposal site. Therefore waste packages are subject to both the regulatory requirements of transport and the requirements of disposal. Resulting consequences for waste package limitations will be discussed, in particular for low and intermediate level waste taking into account LSA/SCO regulations for transport and waste acceptance criteria for disposal in Germany. Some aspects of different package concepts, like the use of non-reusable or reusable packages, will be considered as well as the application of LSAISCO regulations and further development of LSA/SCO criteria.     

Copper canister lifetime limited by a sulfide intrusion in a deep geologic repository

Korea has continuously implemented an ambitious nuclear energy deployment program since 1978. Korea currently operates 20 units, 16 PWRs and four CANDUs and constructs four and reviews license application of two more units. Also, Korea plans to build two more units by 2016. In addition, according to the new “Green Growth Plan while reducing the emission of carbon dioxide” Korea will introduce 10–12 units by 2030. This will inevitably result in more burdens on the safe management of spent nuclear fuels. Korea Atomic Energy Research Institute has developed a final disposal concept for Spent Nuclear Fuel (SNF) named KRS. KRS proposes to emplace SNF in a deep geologic formation such as a crystalline rock. Two key engineered barriers are applied to retard the potential release of a radionuclide from an embedded SNF; a waste container and an engineered barrier. Such an engineered barrier is composed of domestic calcium bentonite and the waste container is composed of an outer copper layer and an inner steel layer. The outer layer, a copper layer is dedicated to protect a waste container against corrosion. The main corrosion mechanism to corrode a copper waste container is a pitting whose speed of corrosion is 5–25 times higher than that of a uniform corrosion. In this paper, a special mass transfer resistance model is developed to predict the migration of sulfide from a fracture to a waste container surface via a bentonite layer. Based on it the lifetime of a copper canister layer limited by a pitting corrosion is estimated. Results show that under normal conditions, a copper layer can sustain its integrity for up to more than millions of years.     

MANAGEMENT OF RADIOACTIVE WASTES IN CHINA

The policy and principles on management of radioactive wastes are stipulated.Cement solidification and bituminization unit has come into trial run.Solid radioactive waste is stored in tentative storage vault built in each of nuclear facilities.Seventeen storages associated with applications of nuclear technology and radioisotopes have been built for provinces.Disposal of low and intermediate level radioactive wastes pursues the policy of “regional disposal”.Four repositories have been planned to be built in northwest.southwest,south and east China respectively.A program for treatment and disposal of high level radioactive waste has been made.     

应用随机模拟理论计算低、中放固体废物处置场核素迁移

为了计算低、中放固体废物处置场关闭后,放射性核素在孔隙介质中迁移行为以及对公众造成的照射,应用随机数学理论,将处置场岩土体孔隙-裂隙双重介质视为一个随机场,依据流体渗流力学理论基础形成的二维定向渗流理论,建立了反映放射性核素在处置场岩土体中迁移规律的数学模型。结合计算技术,进一步建立可对放射性核素在处置场岩土体中迁移规律进行仿真分析的系统,并可以用于放射性核素在处置场岩土体中迁移规律模拟研究与预测分析,以及对公众所致辐射剂量计算。通过算例重复仿真实验分析,最后进行统计平均得出放射性核素在处置场岩土体中迁移的规律性认识,验证了所建模型是可行的、有效的。     

乏燃料处置的必要性及其处置库环境化学行为

为了确保核燃料循环的安全性,不宜处理的乏燃料也应该同玻璃固化体一样作为高放废物进行深地质处置。本文综述了一些前期工作,归纳了空气侵入和水的辐解产生氧化性产物是导致乏燃料UO₂基体氧化溶解的主要因素;核燃料浸出实验结果显示铀和锕系镧系元素每天的浸出量是相应核素总量的1/10⁷,比裂变产物的浸出速率小一个数量级。铁金属被各国选为高放废物处置容器材料的原因是其低价格、高强度和优秀的还原能力。在最不利的地下水侵入深地质处置库、近场处置容器防腐层破损的情景下,铁容器材料表面与地下水反应产生氢气,氢气通过还原反应消耗辐解产生的氧化性自由基和分子,并能还原乏燃料表面的U(Ⅳ),大幅度减缓乏燃料的腐蚀和溶解;乏燃料中裂变产物贵金属合金颗粒对氢气有催化作用;处置容器表面铁金属能还原沉积溶解的多价态核素U(Ⅵ)、Np(Ⅴ)、Tc(Ⅶ)、Se(Ⅳ)和Se(Ⅵ)。希望本文对我国确立以铁基金属为处置容器材料的包括乏燃料在内的高放废物深地质处置概念有参考作用。     

Long term stability of iron for more than 1500 years indicated by archaeological samples from the Yamato 6th tumulus

One of the candidate materials for overpack in the Japanese engineered barrier system for high-level radioactive waste (HLW) is iron and therefore its long-term stability for at least 1000 years is very important for safety analysis of the repository system. Therefore, several of the iron artifacts excavated from the Yamato 6th tumulus (ancient tomb) in Nara prefecture were analyzed using X-ray computed tomography (CT) to determine corrosion depth. The samples analyzed, both of two large and 11 smaller iron artifacts are called ‘Tetsutei’. The thickness of each rust layer was measured from a cross-section image of the sample and the difference in material density between rust and iron was shown by the image density by the X-ray CT. In the case of pitting corrosion in the sample, the depth of the pits was measured directly and estimated as total corrosion depth with general corrosion layer. The corrosion depths are 0.5–2.1 mm. These data indicate conservative predictions for the extrapolations based on experimental studies. Such corrosion data from archaeological samples are useful in analogue studies of high-level radioactive waste disposal as evidence of long-term stability of a waste container.     

The Cost Implications of Large Shielded Transport Packages for Radioactive Waste

Abstract

Total costs have been estimated, at 1990 prices, for the packaging, transport and disposal of intermediate level radioactive waste. The study covered three generic types of large package with several scenarios of interim storage and rock type at the disposal site. The concept which uses returnable shielding is calculated to be the cheapest, although the choice between self-shielded and returnable shielded concepts has less influence on cost than the repository rock type. The high projected cost of disposal is likely to have a profound effect on the volume of intermediate waste, encouraging the development of volume reduction processes. Such changes will narrow the cost differences between packages. However, the returnable shielded design is sufficiently adaptable to enable enhancement in performance for very little extra cost. It is also relatively insensitive to variations in disposal cost.