Three Mile Island epidemiologic radiation dose assessment revisited: 25 years after the accident

Over the past 25 years, public health concerns following the Three Mile Island (TMI) accident prompted several epidemiologic investigations in the vicinity of TMI. One of these studies is ongoing. This commentary suggests that the major source of radiation exposure to the population has been ignored as a potential confounding factor or effect modifying factor in previous and ongoing TMI epidemiologic studies that explore whether or not TMI accidental plant radiation releases caused an increase in lung cancer in the community around TMI. The commentary also documents the observation that the counties around TMI have the highest regional radon potential in the United States and concludes that radon progeny exposure should be included as part of the overall radiation dose assessment in future studies of radiation-induced lung cancer resulting from the TMI accident.     

Metallographic assessment of the thermal exposure to the Three Mile Island Unit 2 reactor lower head

The accident at Three Mile Island Unit No. 2 (TMI-2) on March 28, 1979 was the worst nuclear accident in US history. One of the tasks of the international TMI-2 Vessel Investigation Project (VIP) was to assess the integrity of the vessel. By January 1990, it was possible electrochemically to machine coupons from the lower head by using a specially designed tool. These specimens were taken from regions believed to have experienced the highest temperatures, based on the location of the core debris. The specimens contained the ER308L stainless-steel cladding and the A533 grade-B plate material to a depth of about midwall. The microstructures of these specimens were compared to that of specimens cut from the lower head of the Midland, MI, reactor vessel, made from the same grade and thickness but never placed in service. These specimens were subjected to known thermal treatments between 800 and 1100 °C for periods of 1 to 100 minutes. Because the initial comparison work was qualitative in nature, the writer volunteered to quantify microstructural parameters in the control specimens and in those from TMI-2. Furthermore, selective etchants were utilized to better discriminate desired microstructural features, particularly in the cladding. Hardness traverses were conducted using Vickers microindentations, which have revealed more information than the original bulk hardness traverses. Microprobe analysis that has been conducted on a few specimens has revealed new details about the cladding, interface, and heat-affected zone. This is a progress report on the quantification of changes in both the degree of carbide precipitation and delta-ferrite content and shape in the cladding as a function of temperature and time to refine the estimates of the maximum temperatures experienced.     

Human reliability data, human error and accident models—illustration through the Three Mile Island accident analysis

Our first objective is to provide a panorama of Human Reliability data used in EDF's Safety Probabilistic Studies, and then, since these concepts are at the heart of Human Reliability and its methods, to go over the notion of human error and the understanding of accidents. We are not sure today that it is actually possible to provide in this field a foolproof and productive theoretical framework. Consequently, the aim of this article is to suggest potential paths of action and to provide information on EDF's progress along those paths which enables us to produce the most potentially useful Human Reliability analyses while taking into account current knowledge in Human Sciences.The second part of this article illustrates our point of view as EDF researchers through the analysis of the most famous civil nuclear accident, the Three Mile Island unit accident in 1979. Analysis of this accident allowed us to validate our positions regarding the need to move, in the case of an accident, from the concept of human error to that of systemic failure in the operation of systems such as a nuclear power plant. These concepts rely heavily on the notion of distributed cognition and we will explain how we applied it. These concepts were implemented in the MERMOS Human Reliability Probabilistic Assessment methods used in the latest EDF Probabilistic Human Reliability Assessment. Besides the fact that it is not very productive to focus exclusively on individual psychological error, the design of the MERMOS method and its implementation have confirmed two things: the significance of qualitative data collection for Human Reliability, and the central role held by Human Reliability experts in building knowledge about emergency operation, which in effect consists of Human Reliability data collection. The latest conclusion derived from the implementation of MERMOS is that, considering the difficulty in building ‘generic’ Human Reliability data in the field we are involved in, the best data for the analyst consist of the knowledge built up through already existing probabilistic analyses.     

出租汽车计价器主机计程部分故障分析

本文以ZYJ—B型出租汽车计价器为例介绍出租汽车计价器计程部分故障分析。     

Lessons from Vitruvius

Vitruvius's Ten Books on Architecture was in regular use as a design manual for over 1500 years. This paper argues for a reinterpretation of Vitruvius in terms of design method. On this view, the study of Vitruvius and his historical influence still has important lessons for the theory of types and for the construction of design heuristics.     

空调工程建设中的若干教训

文章对中央空调工程竣工后和使用中常可发现的设备、风管系统和水系统中存在的若干缺陷,分析了它们的成因,提出了可能的防范措施.     

方钢管混凝土柱-H形钢梁螺栓连接节点受力性能试验研究

对适用于装配式钢结构的钢管混凝土L形柱-H型钢梁Z字形节点的抗震性能进行研究。建立并基于节点试验结果验证了ABAQUS有限元模型,通过有限元分析获得了节点的荷载-位移曲线、骨架曲线、破坏模式和性能指标。结果表明：设置腹板拼接板、增加梁高、减小上翼缘最外排螺栓与拼接区中心距离等措施,能够提高节点的屈服荷载和峰值荷载;增加翼缘高强度螺栓数量能够提高节点的滑移荷载,但是会降低延性;增加悬臂梁外伸距离,可以提高滑移荷载、屈服荷载和峰值荷载,减少翼缘连接的高强度螺栓数量需求。基于有限元结果,验证了节点受弯承载力和极限受弯承载力计算公式的可靠性。     

Lessons from the 2004 Sumatra-Andaman earthquake

The 2004 Sumatra-Andaman earthquake (M(w) = 9.0-9.3) is one of the greatest earthquakes ever recorded. In terms of its physical size, it is comparable to the 1960 Chilean (M(w) = 9.5) and the 1965 Alaskan (M(w) = 9.2) earthquakes. However, the damage caused by this earthquake is far greater than that caused by other great earthquakes. The 2004 Sumatra-Andaman earthquake has been studied in great detail over broad time-scales, from a fraction of seconds to hours and months, using the modern seismic data available from global seismic networks and the Global Positioning System data. We summarize the findings obtained mainly from seismic data, and discuss the unique feature of this earthquake, and possible directions of research to minimize the impact of great earthquakes on our society.     

Bhopal: Lessons for technological decision-makers

The accidental release of methyl isocyanate (MIC) on December 2 and 3, 1984, at the Union Carbide India Limited (UCIL) pesticide manufacturing plant in Bhopal, India, killed at least 1,750 people, and probably as many as 2,500,¹ while injuring 50,000 or more. This episode appears likely to mark a watershed in the historical relationships between scientists, corporations, governments and communities. Among the many assumptions that will have to be questioned and reconsidered in the wake of this disaster are the following: that it is possible, in principle, to know enough in advance about a complex chemical process to design a totally safe system; that it is possible, in principle, for human workers to operate such a system safely; that it is possible, in principle, for a public agency to regulate such a system effectively (even if it could be designed); and that “fault” in the legal sense can be meaningfully attributed to one among the various actors in the event of a complex system failure. The above questions all arise prominently in connection with the Bhopal tragedy. This paper recounts the key factors insofar as they are known, commenting on the information available to various parties and the decisions that were made. Some general conclusions are drawn at the end.     

面向经营过程和团队的规划岛──在订单处理过程中顺利实施质量管理的成功因素

在分环节的企业结构内，规划岛对于如何以最佳的方式进行订单处理具有重要的意义。它在几方面对生产过程的质量、绩效制定和资源消耗有较大的影响。规划岛可以通过创造通用而全封闭的生产过程、调节回路及其自身适当的活动空间，来提高生产的满意程度和内在动力。此外，它还可以通过对各种经验和技巧进行跨专业的结合，为产品经营过程和组织机构本身展现出巨大的改进和创新潜力，因而，最终在生产领域中起战略领导的作用。所以，规划岛是在进行订单处理过程中实现通用而全面的质量管理的一个重要因素。     

Diatomaceous Lessons in Nanotechnology and Advanced Materials

Silicon, in its various forms, finds widespread use in electronic, optical, and structural materials. Research on uses of silicon and silica has been intense for decades, raising the question of how much diversity is left for innovation with this element. Shape variation is particularly well examined. Here, we review the principles revealed by diatom frustules, the porous silica shells of diatoms, microscopic, unicellular algae. The frustules have nanometer‐scale detail, and the almost 100 000 species with unique frustule morphologies suggest nuanced structural and optical functions well beyond the current ranges used in advanced materials. The unique frustule morphologies have arisen through tens of millions of years of evolutionary selection, and so are likely to reflect optimized design and function. Performing the structural and optical equivalent of data mining, and understanding and adopting these designs, affords a new paradigm in materials science, an alternative to combinatorial materials synthesis approaches in spurring the development of new material and more nuanced materials.