国际辐射单位与测量委员会（ICRU）发布第92号报告《放射性核素向环境释放后公众防护的辐射监测》

国际辐射单位与测量委员会(ICRU)发布第92号报告《放射性核素向环境释放后公众防护的辐射监测》。核设施含有大量的放射性物质,在事故情况下,可能有大量的放射性物质释放到环境中去。切尔诺贝利核电站事故和福岛第一核电站事故就是这种情况下的两个特例。     

放射性物质运输事故分析及后果评价方法

主要介绍国内外近年来在放射性物质运输事故后果评价方法方面的研究成果，描述了铁路运输和公路运输的事故景象、放射性物质运输事故的严重程度和类别，列出了运输事故情况下不同照射途径的剂量计算方法，并介绍了事故可能引起的健康效应和经济影响。     

秦山核电二期工程事故源项分析

针对核电厂可能发生的设计基准事故,分析了事故发生后放射性物质的产生、迁移和释放途径,从而得出放射性物质向环境中的释放量,用于剂量后果计算.文中介绍了秦山核电二期工程事故源项分析的范围、假设、方法以及所采用的程序,并对事故源项分析的结果进行了讨论.     

核电站事故情况下气载放射性致厂址周围公众集体剂量当量的估算方法

对核电站潜在的放射性物质外泄事故可能导致后果的严重程度给出一个合理保守的评价方法是十分必要的。本文给出一个厂址周围８０ｋｍ范围内集体剂量当量的估算方法，该方法借鉴Ｕ．Ｓ．ＮＲＣ．１．１４５事故后果的概率处理方法，将大气弥散情况下人口分布相结合，计算给出的集体剂量当量的超越概率不大于５％。     

放射性物质运输与环境安全

本文用实际事例说明:只要包装的设计和试验符合《放射性物质安全运输规程》的要求,则放射性物质运输事故不会对工作人员、公众和环境产生显著的影响。     

乏燃料运输事故中放射性物质的释放机制及途径

符合国际原子能机构《放射性物质安全运输规定》要求的乏燃料运输容器,具有相当高的抗事故能力。但在运输过程中,仍有可能出现超过容器设计基准的冲撞(撞车、撞击山体或其它构筑物)、翻车、火灾等事故,导致乏燃料组件及其运输容器受损,向环境释放出放射性物质;或者导致运输容器屏蔽能力减弱乃至丧失,使意外接近容器的人员或公众受到较高水平的外照射。     

放射性物质公路运输事故率初探

放射性物质运输是核能和核技术应用中的一项活动,放射性物质运输事故的发生概率以及事故对工作人员、公众及环境的放射性影响是现实存在的。本文分析了放射性物质运输单位行驶量的事故率和装运单位货包的事故率,结果表明我国与美国、英国、德国等国的放射性物质运输事故率基本相当;另外,将我国放射性物质运输事故率与国道、高速公路事故率进行了比较。     

关于编写放射性物质运输环境影响报告书需要注意的问题

本文提出了编写放射性物质运输环境影响报告书时应该注意的问题。着重对运输线路优化分析、事故源项、事故的防范措施和应急准备,以及运输质量保证等方面进行了讨论。     

模型库技术在核化事故危害预测中的应用研究

针对核化事故危害预测模型多环节、多模型、模型间具有继承性的特点,以核化事故中放射性物质及有害化学品大气扩散模型为重点,应用面向对象方法建立模型基本体系,并在此基础上论述了基于决策支持的核化事故危害预测模型库系统的设计和实现技术。     

核电厂事故厂外后果早期评价中碘和惰性气体等效量的应用

本文介绍核电厂事故厂外后果早期评价中碘和惰性气体等效量应用的主要依据、计算的方法和实例。等效量应用的主要依据是反应堆内放射性物质达到平衡后的事故释放。事故早期碘和惰性气体对公众剂量的贡献是主要的。由于碘和惰性气体各自的释放、输运和转相同,因此可以应用碘和惰性气体的等效释放量计算核电厂事故早期对场外环境的辐射影响移特性采用等效量计算方法可以简化计算模式、缩短计算时间,特别适用于手工计算方法,故在事故早期的后果评价中具有较高的实用价值。     

Analyses of historical rail accidents to identify accident parameters impacting transport of spent nuclear fuel

Abstract

As a regulatory authority for the transportation of spent nuclear fuel (SNF) in the USA, the Nuclear Regulatory Commission requires that SNF transportation packages be designed to endure a fully engulfing fire with an average temperature of 800°C (1475°F) for 30 min, as prescribed in Title 10 of the Code of Federal Regulations Part 71. The work described in this paper was performed to support the Nuclear Regulatory Commission in determining the types of accident parameters that could produce a severe fire with the potential to fully engulf an SNF transportation package. This paper describes the process that was used to characterise the important features of rail accidents that would potentially lead to an SNF transport package being involved in a severe fire. Historical rail accidents involving all hazardous material (i.e. all nine classes of hazardous material) and long duration fires in the USA have been analysed using data from the Federal Railroad Administration and the Pipeline and Hazardous Materials Safety Administration. Parameters that were evaluated from these data include, but were not limited to, class of track where the accident occurred, class of hazardous material that was being transported and number of railcars involved in the fire. The data analysis revealed that in the past 34 years of rail transport, roughly 1800 accidents have led to the release of hazardous materials, resulting in a frequency of roughly one accident per 10 million freight train miles (Because all of the data were obtained in the USA, which still uses distance measured in miles, and the primary source is an extensive database from the Federal Railroad Administration that is also in reported in miles, the data in this paper are reported in miles rather than kilometres. Conversion of miles to kilometres is by multiplication of 1·61.). In the last 12 years, there have only been 20 accidents involving multiple car hazardous material releases that led to a fire. This results in an accident rate of 0·003 accidents per million freight train miles that involved multiple car releases and a fire. Out of all the accidents analysed, only one involved a railcar carrying class 7 (i.e. radioactive) hazardous material.     

Spent fuel transportation risk assessment: conclusions

Abstract

The US Nuclear Regulatory Commission (NRC) has recently completed an updated Spent Fuel Transportation Risk Assessment, NUREG-2125. The study reached the following findings. First, the collective dose risks from routine transportation are vanishingly small. These doses are about four to five orders of magnitude less than collective background radiation doses. Second, the routes selected for this study adequately represent the routes for spent nuclear fuel transport, and there was relatively little variation in the risks per kilometre over these routes. Third, radioactive material would not be released in an accident if the fuel is contained in an inner welded canister inside the cask. Fourth, only rail casks without inner welded canisters would release radioactive material, and only then in exceptionally severe accidents. Fifth, if there were an accident during a spent fuel shipment, there is less than one in a billion chance the accident would result in a release of radioactive material. Sixth, if there were a release of radioactive material in a spent fuel shipment accident, the dose to the maximally exposed individual would be <2 Sv (200 rem) and would not cause an acute fatality. Seventh, the collective dose risks for the two types of extraregulatory accidents (accidents involving a release of radioactive material and loss of lead shielding) are negligible compared to the risk from a no release, no loss of shielding accident. Eight, the risk of loss of shielding from a fire is negligible. Ninth, none of the fire accidents investigated in this study resulted in a release of radioactive material. Based on these findings, this study reconfirms that radiological impacts from spent fuel transportation conducted in compliance with NRC regulations are low. In fact, this study’s radiological impact estimates are generally less than the already low estimates reported in earlier studies. Accordingly, with respect to spent fuel transportation, this study reconfirms the previous NRC conclusion that the regulations for transportation of radioactive material are adequate to protect the public against unreasonable risk.     

几起近期发生的放射源事故原因分析及管理对策建议

本文通过介绍我国发生的一些放射源事故情况,分析事故发生的原因,总结了《放射性同位素与射线装置安全和防护条例》颁布后在实施过程中还存在的一些关键问题,提出了加强放射源管理的对策与建议.     

放射性物品运输辐射监测数据管理软件的设计及应用

为了协助委托人做好放射性物品运输辐射监测数据管理,我们开发设计了用于委托人办理放射性物品运输辐射监测报告的数据管理终端软件,使用该软件可实现对办理报告相关文件资料的集中管理,辐射监测机构也可方便地收集有关放射性物品信息,实现信息共享,提高工作效率。相关信息提供给辐射管理部门后,还可方便辐射管理部门掌握放射性物品运输情况,为放射性物品运输过程中对环境和人员造成的潜在风险和事故评价提供支持,可探索实现对放射性物品运输进行动态管理。     

概率截断值对先进轻水堆核电厂应急计划区划分的影响

1997年,美国核管会（NRC）在对被动与改进型先进轻水堆的应急计划进行评估后指出,在现有的技术框架下先进轻水堆的应急计划应当保持不变,但也表明如果考虑到严重事故发生概率更低,事故的延迟时间更长,则有可能简化对先进轻水堆的应急计划要求,减小应急计划区。这意味着,如果在事故选择时不考虑低于某一概率截断值的事故,则有可能对先进轻水堆核电厂应急计划区的划分产生较大的影响。本文以AP1000核电机组为例,参考美国NUREG-0396的方法,使用MACCS程序对选取不同事故概率截断值可能产生的影响进行研究。研究结果表明,只有当概率截断值高于某些相对概率较大、而后果较为严重的事故的发生概率时,才会对先进轻水堆应急计划区的划分产生较大影响。     

放射性物质运输线路优化方法的研究

在放射性物质运输的活动中,为了使所选取的放射性物质运输线路相对最优,本文在给定的运输起点和终点并且具有时间窗约束的情况下,对运输活动的运输时间、运输成本和运输风险3个关键因素进行综合考虑,将其确立为3个目标向量。根据实际的运输任务,利用灰色关联度分析方法,从3个目标量中确定一个理想化的最优样本,以此为参考样本,通过计算各样本序列与该参考序列的关联度,对被评价对象做出综合比较和排序,选取最优的运输线路。本文为放射性物质运输线路的选择提供了一种分析方法。     

A dynamic neural network based accident diagnosis advisory system for nuclear power plants

In this work, an accident diagnosis advisory system (ADAS) using neural networks is developed. In order to help the plant operators quickly identify the problem, perform diagnosis and initiate recovery actions ensuring the safety of the plant, many operator support systems and accident diagnosis systems have been developed. The ADAS is a kind of such accident diagnosis system, which makes the task of accident diagnosis easier, reduces errors, and eases the workload of operators by quickly suggesting likely accidents based on the highest probability of their occurrence. In order to perform better than other accident diagnosis systems, the ADAS has three main objectives. To satisfy these three objectives, two kinds of neural networks that consider time factors are used in this work. A simple accident diagnosis system is implemented in order to validate the ADAS. After training the prototype, several accident diagnoses were performed. The results show that the prototype can detect the accidents correctly with good performance.     

Transport of radioactive materials: the need for radiation protection programmes

Abstract

The increase in the use of radioactive materials worldwide requires that these materials be moved from production sites to the end user, or in the case of radioactive waste, from the waste generator to the repository. Tens of millions of packages containing radioactive material are consigned for transport each year throughout the world. The amount of radioactive material in these packages varies from negligible quantities in shipments of consumer products to very large quantities in shipments of irradiated nuclear fuel. Transport is the main way in which the radioactive materials being moved get into the public domain. The public is generally unaware of the lurking danger when transporting these hazardous goods. Thus radiation protection programmes are important to assure the public of the certainty of their safety during conveyance of these materials. Radioactive material is transported by land (road and rail), inland waterways, sea/ocean and air. These modes of transport are regulated by international 'modal' regulations. The international community has formulated controls to reduce the number of accidents and mitigate their consequences should they happen. When accidents involving the transport of radioactive material occur, it could result in injury, loss of life and pollution of the environment. In order to ensure the safety of people, property and the environment, national and international transport regulations have been developed. The appropriate authorities in each state utilise them to control the transport of radioactive material. Stringent measures are required in these regulations to ensure adequate containment, shielding and the prevention of criticality in all spheres of transport, i.e.routine, minor incidents and accident conditions. Despite the extensive application of these stringent safety controls, transport accidents involving packages containing radioactive material have occurred and will continue to occur. When a transport accident occurs, it is unlikely to result in a significant release of radioactive material, loss of shielding or loss of criticality control.     

快堆MOX元件运输容器的缓冲器研究

快堆MOX元件运输容器的缓冲器是决定其放射性包容边界安全的重要部件。某型号MOX元件运输容器的缓冲器材料首次选择泡沫铝,通过自由下落试验的标准姿态进行吸能原理分析,设计出了适用于缓冲器材料的型号、结构及关键参数。对选定的材料进行了拉伸、压缩、剪切3种准静态和动态力学性能试验,获得了用于数值模拟计算的材料本构关系参数,并对模型参数进行了测试,用弯曲试验进行了验证。有限元分析和试验结果对比显示：运输容器缓冲器材料的本构关系具有适用性,可用于快堆某型号MOX元件运输容器的自由下落分析计算。