Stefan Hirschberg

A Comparative Analysis of Accident Risks in Fossil, Hydro, and Nuclear Energy Chains

ABSTRACT This study presents a comparative assessment of severe accident risks in the energy sector, based on the historical experience of fossil (coal, oil, natural gas, and LPG [Liquefied Petroleum Gas]) and hydro chains contained in the comprehensive Energy-related Severe Accident Database (ENSAD), as well as Probabilistic Safety Assessment (PSA) for the nuclear chain. Full energy chains were considered because accidents can take place at every stage of the chain. Comparative analyses for the years 1969–2000 included a total of 1870 severe (≥ 5 fatalities) accidents, amounting to 81,258 fatalities. Although 79.1% of all accidents and 88.9% of associated fatalities occurred in less developed, non-OECD countries, industrialized OECD countries dominated insured losses (78.0%), reflecting their substantially higher insurance density and stricter safety regulations. Aggregated indicators and frequency-consequence (F-N) curves showed that energy-related accident risks in non-OECD countries are distinctly higher than in OECD countries. Hydropower in non-OECD countries and upstream stages within fossil energy chains are most accident-prone. Expected fatality rates are lowest for Western hydropower and nuclear power plants; however, the maximum credible consequences can be very large. Total economic damages due to severe accidents are substantial, but small when compared with natural disasters. Similarly, external costs associated with severe accidents are generally much smaller than monetized damages caused by air pollution.

The CESA method and its application in a plant-specific pilot study on errors of commission

Abstract A pilot study on errors of commission (EOCs) was performed for a Swiss nuclear power plant, with the goals of (a) evaluating PSIs Commission Errors Search and Assessment (CESA) method for identifying potential EOC situations, and (b) obtaining an estimate of the potential risk significance of the analyzed EOCs. The EOC search and screening process of the method proceeds from a given action to scenarios in which the action is inappropriate. A catalog of key actions required in the responses to the plant events is first compiled. This catalog is then used in a systematic search of context-action combinations, to obtain a set of situations with EOC opportunities to be examined in detail. The results show that the CESA identification process is feasible and effective: it is able to identify plausible situations in which EOCs may occur. A preliminary quantification of four of these has been performed; the analyses so far show that the situations identified in the pilot study deserve careful consideration. Although the identification approach in CESA covers a subset of EOC types, the demonstration of the CESA method in the pilot study and the resulting identification of EOC cases is encouraging in terms of progress on the issue of EOCs.

Comparative assessment of severe accident risks in the coal, oil and natural gas chains

This study compared severe accident risks of fossil energy chains (coal, oil and natural gas), based on the historical experience contained in the comprehensive database ENSAD. Considered risk indicators focused on human health impacts, i.e., fatality rates and maximum consequences were calculated for a broad range of country groups. Generally, expected fatality rates were lowest for natural gas, intermediate for oil and highest for coal. Concerning maximum consequences of a single accident, natural gas also performed best, followed by coal, whereas accidents in the oil chain can claim significantly more fatalities. In general, OECD and EU 27 ranked top, while non-OECD countries and China in the case of coal were worst. The consideration of numerous additional country groups enabled a more detailed differentiation within the main bounding groups. Furthermore, differences among country groups are distinctly decreasing from coal to oil and natural gas, both for fatality rates and maximum consequences. The use of import adjusted-fatality rates indicates that fatality risks in supply countries are an essential aspect to understand how specific risk reduction strategies may affect other components of energy security, and thus tradeoffs and compromises are necessary. Finally, the proposed fatality risk score for fossil chains (FRSF) allows a comparison of the combined accident risk for the considered fossil energy chains across individual countries, which can be visualized using risk mapping.

Human reliability analysis in probabilistic safety assessment for nuclear power plants

This technical opinion paper represents the consensus of risk analysts in the NEA member countries on the current state of the art of human reliability analysis (HRA) within probabilistic safety assessment (PSA) for nuclear power plants. The objective is to present to decision makers in the nuclear community a clear technical opinion of HRA status as implemented in industrial PSAs. The intended audience is primarily nuclear safety regulators, senior researchers and industry leaders. Government authorities, nuclear power plant operators and the general public may also be interested.

Assessment of severe accident risks in the Chinese coal chain

Severe accident risks in Chinas coal chain were investigated in detail based on extensive statistics using Chinese sources that were not open until recently. Every year about 6000 fatalities occur in Chinese coal mines; about one third due to severe (≥ five fatalities) accidents. The Chinese severe accident fatality rate for the coal chain is 6.17 per GWeyr, which is about 10 times higher than in other non-OECD countries and about 40 times higher than in OECD countries. At the province level lower fatality rates were associated with higher mechanised levels of coal mining. Severe accidents are about five times more frequent in small mines than large mines because many small mines lack even basic safety standards, whereas large mines invest up to 15?20% of total costs in safety. This study contributed to the evaluation of energy policy strategies for China, based on an inter-disciplinary assessment including comprehensive risk analysis.

Assessment of Severe Accident Risks

This chapter deals with the Risk Assessment Task within CETP. This task addressed the comparative assessment of accidents risks associated with the various electricity supply options. The full account of the work carried out within this task is provided in the technical report (Hirschberg et al., 2003a).

Environmental Impact and External Cost Assessment

Aside from tremendous benefits the conversion of energy can be harmful to the human health and environment. Assessment of public health effects associated with air pollution caused by various means of electricity generation was one of the central goals of CETP. Currently, China is experiencing rapid economic growth, and this trend is expected to continue. But the damage to air, soil and water quality backfires on the rate of growth. Economic growth is accompanied by increasing electricity demand, with coal as the dominant energy source. This development implies that, along with the dominant health effects, sulfur deposition (and the resulting acidification) stand out as the primary environmental issues to be addressed. Examples of the impacts include effects such as chronic bronchitis, reduction in lifetime expectancy, or adverse effects on the environment, such as loss of crops.

Health effects of technologies for power generation: Contributions from normal operation, severe accidents and terrorist threat

As a part of comprehensive analysis of current and future energy systems we carried out numerous analyses of health effects of a wide spectrum of electricity supply technologies including advanced ones, operating in various countries under different conditions. The scope of the analysis covers full energy chains, i.e. fossil, nuclear and renewable power plants and the various stages of fuel cycles. State-of-the-art methods are used for the estimation of health effects. This paper addresses health effects in terms of reduced life expectancy in the context of normal operation as well as fatalities resulting from severe accidents and potential terrorist attacks. Based on the numerical results and identified patterns a comparative perspective on health effects associated with various electricity generation technologies and fuel cycles is provided. In particular the estimates of health risks from normal operation can be compared with those resulting from severe accidents and hypothetical terrorist attacks. A novel approach to the analysis of terrorist threat against energy infrastructure was developed, implemented and applied to selected energy facilities in various locations. Finally, major limitations of the current approach are identified and recommendations for further work are given.

Comparative Assessment of Accident Risks in the Energy Sector

This chapter is structured in five parts. The introduction discusses the relevance of accidents in the energy sector and puts them into the broader perspective of sustainability, energy security, and critical infrastructure protection. Furthermore, an overview of various risk assessment concepts is given. The second part provides a detailed overview of the comprehensive framework for comparative risk assessment developed by the Paul Scherrer Institut (PSI), at the core of which is the energy-related severe accident database (ENSAD). Third, a broad range of risk indicators and other measures are described and calculated allow for an objective, fair, and quantitative comparison of accident risks across a broad range of fossil, nuclear, and renewable technologies. This evaluation is complemented by a compilation of additional risk factors that can play a key role in decision processes and stakeholder interaction. However, for the time being they are often not amenable to full quantification because they cannot be described and analyzed by traditional risk metrics mainly focusing on consequences or because only limited historical experience is available. The chapter ends with a summary of the main findings and conclusions that can be drawn from comparative risk assessment as well as their potential implications for policy making.

Probabilitically based decision support

Abstract Probabilistic Safety Assessment, usually referred to by the acronym PSA, has by now become a recognized tool for safety analysis of nuclear power plants. In recent years, an increasing number of plants have been analysed, and as the technique has matured, the area of application of PSA based analyses has been expanded. Thus, probabilistic methods are now used increasingly in the day-to-day work concerning the safety, maintenance and operation of plants. In this context, the question of interpretation and application of analysis results in various decision situations has become crucial. This paper gives some comments concerning the basis for decision making involving probabilistic analyses.