湖南省四地区室内氡调查

采用ＣＲ－３９固体径迹探测器，在湖南省４地区进行了居室内氡浓度调查，统计学分析表明，４地区室内氡浓度呈对数正态分布。在地形分布上，有西北高、东南低的特点，反映了地质构造和建筑材料等对室内氡浓度的影响。     

室内氡的来源、水平和控制

本文介绍室内氡的来源、水平和控制方法。根据文献资料汇集得出了截至1994年中国室内、室外和地下室氡浓度平均值（分别为23．7、12．6和373Bq/m^3）、氡子体平衡因子（分别为0．47、0．59和0．43）以及室内氡浓度水平的地区分布,室内氡的季节变化和昼夜变化。讨论了室内氡浓度控制的必要性、控制依据和控制措施,指出了建筑材料按放射性比活度分类对控制室内氡的意义。     

氡析出率测量过程中抽气采集容器内氡运移的数值研究

氡及其子体是人类所受到的来自天然辐射的主要辐射照射源,近年来我国掺渣建材的广泛使用使得室内氡平均水平有所提高。建筑工程上的防护和减缓是降低室内氡的关键及低成本方法。GB50325-2010首次给出了建材氡析出率检测方法标准。其中主动抽气采集型测定建筑材料表面氡析出率步骤要求抽气采集容器的平均高度为0.5 m。论文通过数值模拟得到较高的高度有利于减少222Rn测量中220Rn的干扰,而且可以降低采气容器内的222Rn浓度,减少反扩散效应。因此222Rn的析出率可以利用低成本的仪器和简洁的计算得到。     

福州市室内氡浓度调查

2003年2月-2005年6月，对福州市区109间房间进行了室内氡浓度调查测量。调查结果表明：福州市室内氡浓度范围为16．0-191Bq／m^3，平均值为59．3Bq／m^3，低于我国现行相关标准中室内氡浓度的限制值。     

建筑材料中放射性核素限量标准的探讨

《建筑材料放射性核素限量》（GB6566—2001）结束了我国建材标准长期不统一的局面，规定了对建材中放射性实现强制检定的要求，但在装修材料分类、空心材料、废渣利用、测量方法等方面存在着一些不合理的规定。与以往的国家标准相比。对建材中的放射性控制明显放宽，甚至比原来的建材行业标准对石材的控制还要宽，影响了公众的辐射防护安全。对此进行了详细的分析和讨论。     

减少氡的来源是防治室内氡危害的关键

介绍了氡的物理化学性质、环境中氡的来源及浓度水平、各种建筑材料中放射性核素的含量,讨论了通风对室内氡水平的影响,认为依靠住宅建筑和装修完成后的补救措施来防治室内氡危害的效能是有限的,防治室内氡危害的关键措施是从源头上减少氡的来源.     

乌鲁木齐地区居室内氡浓度影响因素再研究及防治对策探讨

在前期研究的基础上,对乌鲁木齐地区室内氡浓度的空间分布规律、以及室内氡在不同建筑构成、墙体建筑材料、室内装修程度及开窗习惯间的分布差异等进行了再研究,综合乌鲁木齐地区住宅内氡浓度的影响因素,有针对性的提出了乌鲁木齐地区的已建住宅的降氡措施和新建住宅的防氡措施。     

成都市城乡室内氡浓度和γ剂量率调查研究

采用固体核径迹探测器和热释光剂量计,对成都市城镇和乡村的室内氡浓度与γ剂量率进行了测量。按测量时间、建筑结构、楼层、墙体建筑材料以及墙体装修材料对测量结果进行了比较分析。结果表明:成都市城镇和乡村室内氡浓度的均值分别为(39.5±18.1)Bq/m³和(38.2±16.3)Bq/m³,均低于世界平均水平;城镇和乡村的γ剂量率均值分别为(120.1±16.1) nSv/h和(124.4±16.7) nSv/h,与氡浓度无相关性。研究发现夏季室内氡浓度较高;低层建筑室内氡浓度受周围环境影响较大,高于高层建筑,并且随着楼层的增高室内氡浓度降低;墙体建筑材料和墙体装修材料对室内浓度有显著影响。     

关于在建材放射性含量标准中增加氡析出率控制指标的建议

采用高纯锗γ谱仪和活性碳盒法对选取的26个来自不同产地的建筑材料样品中的放射性核素比活度和氡析出率进行了测量。结果表明,建筑材料中镭含量与氡析出率之间并不完全相关。我国现行国家标准"建筑材料放射性核素限量"(GB 6566-2001)中仅以内外照射指数作为控制指标,没有对氡析出率进行控制,而建筑材料中氡析出率与室内氡浓度密切相关。因此建议国家建筑材料放射性核素限量标准中增加氡析出率控制指标。     

建筑材料和土壤中氡的析出

土壤和建筑材料的氡析出是使环境空气遭受氡污染的主要原因。就室内空气中的氡而言,建筑材料和建筑物下面土壤的贡献达80%左右。土壤和建材的氡析出能力直接与其镭含量相关,镭经放射性衰变生成的氡,一部分进入颗粒间隙的流体中,成为可以自由扩散的氡。本文根据 Fick定律和 Darcy 定律对几种情况下的氡传输进行了计算,建立了氡析出率与有关参数的定量关系。这些计算将告诉和启示我们,在估计或测量建材和土壤的氡析出率时应该考虑哪些因素;对需要采取防护措施的地方,哪些措施是可供选择的。     

包头市建筑主体材料天然放射性水平

采用低本底多道NaIγ能谱仪测定了建筑主体材料天然放射性核素40K、232Th和226Ra的比活度,并根据国家标准和欧盟放射卫生防护原则进行分析评价。结果表明,建筑主体材料中40K、232Th和226Ra的放射性比活度分别为218.82 1145.92、19.75 132.50和11.46 82.66 Bq/kg;其内照射指数IRa为0.06 0.41,外照射指数Iγ为0.28 0.70;年有效剂量率为0.41 0.97 mSv/y,内、外照射指数均小于1,本文所采集和测定的建筑主体材料的天然放射性水平都在允许范围内,故可销售和使用。然而,灰渣砖所致的居民的年有效计量率(0.97mSv/y)接近最大允许限值1 mSv/y。因此,应有效地监管建筑材料中工业废渣的用量,避免给居民带来不必要的照射。     

工业废渣及建筑材料的天然放射性水平

报道了粉煤灰、煤渣、铝钒土和花岗岩等工业废渣和建筑材料中的天然放射性水平,包括原料和成品堆场表面γ辐射量率和样品中的天然放射性核素比活度;对部分建材测量了建筑物室内的γ辐射剂量率。结果表明,除个别地区的样品外,基本上低于国家限制标准。     

建筑材料放射性检测的国际惯例

建筑物，无论是民用建筑，还是工业建筑，所用建筑材料(建筑主体材料、装饰材料)都不同程度地含有天然放射性物质。因此，关注各种建筑材料的放射性是人类生存、发展的必然。我国是WTO成员国的一员，建筑材料的放射性检测方法，包括建筑材料中核素限量、危害评估体系等理应按国际标准进行检测，使用国际上惯用的技术规则，还应与国际上惯用的建筑材料放射性核素限量及危害评估体系保持同步。     

关于工业废渣的分类处理标准

本文介绍了一些国家或组织提出的关于放射性固体废物的标准,结合我国实际情况,通过代价-利益分析,初步提出了工业废渣的分类处理标准。     

环境放射性测评工作--以蒙古和罗马尼亚为例

由于人类非常态活动，导致环境放射性异常变化。蒙古是世界第二大内陆国，铀资源殷实，煤电是主要能源；罗马尼亚为欧洲内陆国家，平均每1万平方公里的国土面积里就拥有一个铀矿床。由于历史原因，两国铀工业活动较活跃。近年来，两国十分关注环境问题，先后对建筑材料的放射性、室内外空气中的氡等实施调查和研究。本文介绍了蒙古和罗马尼亚两国环境放射性的基本态势，以及环境放射性调查方法等。两国环境放射性调查的结果表明：由于蒙古特殊的地理、政治、工业环境。导致其少数地区河水中的铀偏高(61～985μg／L)，部分土壤中的^137Cs也有增高现象，少量花岗岩石材的放射性核素含量较高。罗马尼亚工业废渣制成的建材放射性核素含量也很高(与其欧洲邻国相比较)，今后拟慎用。蒙古和罗马尼亚两国环境放射性调查的实践与经验对我国类似的工作具有借鉴意义。     

The evolution of the structure and application of U.S. NRC regulations and standards

NRC regulations and standards and their implementation have evolved from early adaptations of conventional engineering practices to a mature, cohesive set of regulations that govern NRC regulation of nuclear power plant safety in the United States.From a simple set of rules and design criteria and from the standards of the professional engineering societies, a hierarchy of practices, standards, guides, rules and goals has developed. Resting on a foundation of industrial practices, this hierarchy rises through levels of national standards, regulatory guides and standard review plans, policy statements and NRC regulations.The licensing process is evolving today toward one that permits both site approval and standard design certification before the plant is constructed. At the present time, NRC is reviewing five standard designs for certification for a period of 15 years. NRC focuses its regulation of operating nuclear plants on inspections conducted from five regional offices. Resident inspectors, specialist inspectors, and multi-disciplinary inspection teams examine specific plant situations. The results of all these inspections are used to develop a complete understanding of a plant's physical condition, its operation, maintenance and management.To improve safe operation of nuclear plants in the U.S., a most important program, the Systematic Assessment of Licensee Performance, measures operational performance, using a broad spectrum of functional areas.     

The Industry Commitment to Global Transport Safety Standards

Abstract

Standards and regulations have no intrinsic practical effect without taking into account those who are the object of such standards and regulations. Standards and regulations do not become operationally effective until they are implemented by the entities which are subject to them. Accordingly, there is a necessary synergy between the regulator and the regulated— the regulators whose task it is to make and enforce the rules for safe, efficient and reliable transport, and those whose job it is to transport within the rules. One has no full meaning without the other. Harmonisation issues which can impede efficient and timely implementation of regulations can occur at any stage of the process, starting with the timely publication of the IAEA regulations, incorporation by the modal organisations, adoption by national competent authorities and finally, rendered operational by industrial transport organisations. Both the regulator and the transporter can be more effective in achieving their purposes when they co-operate in the interest of mutual understanding. PATRAM provides one excellent opportunity for such exchange between the regulator and the regulated—there are other important opportunities within the IAEA and international modal organisations. It is suggested, however, that more could be done between the regulators and the regulated collectively to share real-life experiences with actually implementing the regulations and operating within them, and to draw appropriate lessons.

In the case of the international transport safety regulatory regime, it is the nuclear transport industry, such as represented by the World Nuclear Transport Institute (WNTI), which is, of course, the object of transport safety standards and regulations. And as such, the nuclear transport industry is a principal stakeholder in the regime.

Regulatory compliance is a cornerstone of the nuclear transport industry. The international nature of the fuel cycle mandates transnational movement of radioactive materials on a regular basis; this means that a single shipment may fall under the jurisdiction of numerous regional, national and local regulatory schemes as well as the overarching international system. That is why, in the interest of safe and efficient transport, it is important to strive for maximum harmonisation.     

关于建筑材料防护标准的探讨

本文简要综述了各类主要建筑材料中的放射性水平,讨论了室内γ辐射剂量的计算方法和人在室内受到的附加剂量的计算方法。还讨论了在年全身附加剂量为1和1.5 mSv时建筑材料放射性的控制标准。     

Movements of radioactive material on nuclear licensed sites

Abstract

The regulations governing the transport of radioactive materials are prepared by the International Atomic Energy Agency (IAEA) and then introduced into modal regulations and national legislation. These regulations are based on a graded approach to contents limits for packages and conveyances and to performance standards applied to package designs depending upon the hazard of the radioactive contents.

They apply to the transport of radioactive material in the public domain in which the packages can be conveyed by road, rail, sea, inland waterways or air transport modes and may share transport routes with movements of people and cargoes in close proximity.

In contrast, the movement of radioactive materials on nuclear sites is a much more controlled operation. Normally, only road or rail transport is involved, there are much lower volumes of other traffic and any hazards during the movement are generally less severe than the test conditions in the IAEA transport regulations representing accident conditions of transport.

Furthermore, there is no internationally accepted set of design standards applicable to packages intended purely for onsite movements.

In the UK, suitable safety cases need to be prepared to demonstrate the acceptability of the onsite movement of radioactive material to the regulator, the Nuclear Installations Inspectorate (NII). The safety case includes engineering substantiation against appropriate design standards. However, the criteria in the design standards do not need to be as demanding as those in the IAEA transport regulations because of the controlled environment within which onsite movements take place.

The principles of the graded approach in the IAEA transport regulations can be applied to onsite movements of radioactive material. However, the high level of safety resulting from compliance with these regulations can be achieved for movements of radioactive material packages on a nuclear licensed site by amending limits and test criteria to take account of the stringent onsite controls and environment. Examples of this are increasing the package contents limits for a particular package type, reducing the package test requirements or a combination of the two.

There are also general requirements in the IAEA transport regulations for all packagings and packages, and aspects of these can be applicable for packages used for onsite movements of radioactive material. However, there are aspects of these where the detailed implementation can be relaxed for onsite movements, such as the acceleration values experienced at the typically low speeds of onsite movements and the limited ambient temperature and pressure ranges for a specific site.

The present paper discusses various differences between transport of radioactive material in the public domain and on nuclear licensed sites.