Perceived Risks of Radioactive Waste Transport Through Oregon: Results of a Statewide Survey

Transportation of hazardous materials, and particularly radioactive wastes, on public highways has become an important risk management issue. The unfavorability of public attitudes regarding hazardous and nuclear wastes signals the potential for strong public opposition to programs for transporting these materials. This paper presents the results of a survey conducted to assess public reactions to a long-term nuclear waste transport program planned to follow a route through a portion of rural Oregon. The survey assessed a number of key risk perception issues, including perceived health and safety risks of nuclear waste transport, relative risks of transport vs. storage at an existing site, trust in state officials, and satisfaction with life in communities along the transport route. The survey identified a number of attitudes and concerns that need to be understood and considered by those in charge of designing and implementing the waste-transportation program.     

三峡库区农村生活垃圾现状调查及处理对策分析——以垫江县长大村为例

针对目前我国农村生活垃圾污染生态环境和危害人畜健康的问题,以重庆市垫江县桂溪镇长大村为例,实地调查了村民生活垃圾排放处理现状,并结合当前国内农村生活垃圾处理处置基本模式和当地县城垃圾清运处理方式,提出了“统一收运,集中处理”、“分类收集,分别处理”、“就地减量,定期清运”3种防治处理方案。通过对收运处理量、收运处理成本、填埋库容、资源化、减量化、村民接受程度、政府投入等7个方面的比较,最终确定“就地减量,定期清运”这种方案最有利于农村生活垃圾的管理。     

The Crucial Role of Nomothetic and Idiographic Conceptions of Time: Interdisciplinary Collaboration in Nuclear Waste Management

The disposal of nuclear waste involves extensive time scales. Technical experts consider up to 1 million years for the disposal of spent fuel and high‐level waste in their safety assessment. Yet nuclear waste is not only a technical but also a so‐called sociotechnical problem and, therefore, requires interdisciplinary collaboration between technical, natural, social sciences, and the humanities in its management. Given that these disciplines differ in their language, epistemics, and interests, such collaboration might be problematic. Based on evidence from cognitive psychology, we suggest that, in particular, a concept like time is presumably critical and can be understood differently. This study explores how different scientific disciplines understand extensive time scales in general and then focuses on nuclear waste. Eighteen qualitative exploratory interviews were conducted with experts for time‐related phenomena of different disciplines, among them experts working in nuclear waste management. Analyses revealed two distinct conceptions of time corresponding to idiographic and nomothetic research approaches: scientists from the humanities and social sciences tend to have a more open, undetermined conception of time, whereas natural scientists tend to focus on a more determined conception that includes some undetermined aspects. Our analyses lead to reflections on potential difficulties for interdisciplinary teams in nuclear waste management. We focus on the understanding of the safety assessment, on potential implications for communication between experts from different disciplines (e.g., between experts from the humanities and engineering for risk assessment and risk communication), and we reflect on the roles of different disciplines in nuclear waste management.     

D型水力碎浆机轻杂质排放系统的优化

某纸厂废纸制浆生产线上,45 m3D型水力碎浆机轻渣排放口易被大块杂质堵住,导致轻杂质不能及时排出,为 此对轻杂质排放系统重新优化设计。首先设计了L形结构的挡流板,使未碎解的大块杂质和纸板不能沿着槽体内浆流 的方向直接冲进轻杂质口,而是被轻杂质口内的吸力抽走;其次设计了用于调节轻杂质流量的调节阀,以根据实际情况 调节轻杂质入口的吸力;最后取消轻杂质排放系统内的管道连接弯头,从而减少管道内流体的阻力。改进后的碎浆机系 统运行稳定可靠,轻杂质排放顺畅。     

1.5m2高频振动筛结构改进

针对目前在矿棉板备浆生产线上广泛使用的高频振动筛存在的噪音大、动力消耗大、筛板易堵塞、除渣效果差等 问题,对高频振动筛筛框结构、筛板形状和减震弹簧等进行了优化改进,对振动频率、振幅、筛板的孔径通过理论计算得 出几个基本数值范围,再通过对基本数值范围内的不同数值的实际测试,确定最佳数值。新设计的振动筛经实际使用表 明运行稳定,浆料利用率高,能耗低,噪音小,取得了很好的经济效果。     

Safety Risk Analysis of an Innovative Environmental Technology

The authors describe a decision and risk analysis performed for the cleanup of a large Department of Energy mixed-waste subsurface disposal area governed by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). In a previous study, the authors worked with the site decision makers, state regulators, and U.S. Environmental Protection Agency regional regulators to develop a CERCLA-based multiobjective decision analysis value model and used the model to perform a screening analysis of 28 remedial alternatives. The analysis results identified an innovative technology, in situ vitrification, with high effectiveness versus cost. Since this technology had not been used on this scale before, the major uncertainties were contaminant migration and pressure buildup. Pressure buildup was a safety concern due to the potential risks to worker safety. With the help of environmental technology experts remedial alternative changes were identified to mitigate the concerns about contaminant migration and pressure buildup. The analysis results showed that the probability of an event with a risk to worker safety had been significantly reduced. Based on these results, site decision makers have refocused their test program to examine in situ vitrification and have continued the use of the CERCLA-based decision analysis methodology to analyze remedial alternatives.     

Options in Radioactive Waste Management Revisited: A Proposed Framework for Robust Decision Making

Deregulation, with concurrent pressure on electricity utilities, has fundamentally changed the once-"closed" radioactive waste management system controlled by the so-called "nuclear establishment." Advocacy coalitions may change-who knows in which direction-but policy learning may also take place. This article presents a framework to evaluate the management options for a specified concept of "sustainability." When weighing the different objectives in view of the long-lasting potential danger of radiotoxic substances, the overall goal of a sound waste management system is to demonstrate safety. The first-priority objective of a disposal system, therefore, is its stability so that it can comply with the protection goal, that is, the long-term protection of humans and the environment from ionizing radiation. The complementary objective is flexibility, defined here as intervention potential. Because trade-offs within the "sustainability triangle" of ecology, economy, and society are unavoidable, the concept of "integral robustness"-both technical and societal-is introduced into radioactive waste management. A system is robust if it is not sensitive to significant parameter changes. In the present case, it has to have a conservative, passively stable design with built-in control and intervention mechanisms. With regard to technical implementation, a concept called "monitored long-term geological disposal" is presented. Such an "extended" final disposal concept emphasizes technical robustness, recognizes evaluation demands (for a potential break-off of a project), and enhances process-based transparency. This open approach admittedly sets high challenges with regard to technicalities as well as the institutional setting and the management process. It requires "mutual learning" by and from all stakeholders to achieve a truly sustainable radioactive waste management system.     

Nuclear Waste Management under Approaching Disaster: A Comparison of Decommissioning Strategies for the German Repository Asse II

This article compares different strategies for handling low‐ and medium‐level nuclear waste buried in a retired potassium mine in Germany (Asse II) that faces significant risk of uncontrollable brine intrusion and, hence, long‐term groundwater contamination. We survey the policy process that has resulted in the identification of three possible so‐called decommissioning options: complete backfilling, relocation of the waste to deeper levels in the mine, and retrieval. The selection of a decommissioning strategy must compare expected investment costs with expected social damage costs (economic, environmental, and health damage costs) caused by flooding and subsequent groundwater contamination. We apply a cost minimization approach that accounts for the uncertainty regarding the stability of the rock formation and the risk of an uncontrollable brine intrusion. Since economic and health impacts stretch out into the far future, we examine the impact of different discounting methods and rates. Due to parameter uncertainty, we conduct a sensitivity analysis concerning key assumptions. We find that retrieval, the currently preferred option by policymakers, has the lowest expected social damage costs for low discount rates. However, this advantage is overcompensated by higher expected investment costs. Considering all costs, backfilling is the best option for all discounting scenarios considered.     

Total System Performance Assessment for Waste Disposal Using a Logic Tree Approach

The Electric Power Research Institute (EPRI) has sponsored the development of a model to assess the long-term, overall performance of the candidate spent fuel and high-level radioactive waste (HLW) disposal facility at Yucca Mountain, Nevada. The model simulates the processes that lead to HLW container corrosion, HLW mobilization from the spent fuel, and transport by groundwater, and contaminated groundwater usage by future hypothetical individuals leading to radiation doses to those individuals. The model must incorporate a multitude of complex, coupled processes across a variety of technical disciplines. Furthermore, because of the very long time frames involved in the modeling effort (10⁴ years), the relative lack of directly applicable data, and many uncertainties and variabilities in those data, a probabilistic approach to model development was necessary. The developers of the model chose a logic tree approach to represent uncertainties in both conceptual models and model parameter values. The developers felt the logic tree approach was the most appropriate. This paper discusses the value and use of logic trees applied to assessing the uncertainties in HLW disposal, the components of the model, and a few of the results of that model. The paper concludes with a comparison of logic trees and Monte Carlo approaches.     

Development of a Performance Assessment Capability in the Waste Management Programs of the U.S. Nuclear Regulatory Commission

The U.S. Nuclear Regulatory Commission (NRC) staff has developed a performance assessment capability to address three programmatic areas in nuclear waste management: high-level waste, low-level waste, and decommissioning of licensed facilities (license termination). The NRC capability consists of: (1) methodologies for performance assessment; (2) models and computer codes for estimating system performance; (3) regulatory guidance in various forms, such as regulations, Branch Technical Positions, and Standard Review Plans; and (4) a technical staff experienced in executing and evaluating performance assessments for a variety of waste systems. Although the tools and techniques are refined for each programmatic area, general approaches and similar issues are encountered in all areas.