Risk Management and Decision Rules for Light Water Reactors

A quantitative approach to risk management for accidents in light water nuclear power reactors is proposed to serve as one focus for discussion. In this proposal risk management is divided into two major tasks: the predominantly social and political task of setting the safety goals and the technical task of estimating the risks and deciding whether the safety goals have been met. The proposed safety goals include limits on the following: risk to the individual of early death or delayed cancer death; overall societal risk of early or delayed death; and the frequency of core melt accidents as well as the frequency of containment failure, given a core melt. Also included are a small element of risk aversion and an "as low as reasonably achievable" (ALARA) approach with a cost-effectviness criterion which includes both economic and health effects.     

Applications of probabilistic risk assessments: the selection of appropriate tools

Probabilistic risk assessment (PRA) is an important methodology for assessing the risks of complex technologies. This paper discusses the strengths and weaknesses of PRA. Its application is explored in three different settings: adversarial policy processes, regulatory/licensing procedures, and plant safety audits. It is concluded that PRA is a valuable tool for auditing safety precautions of existing or planned technologies, especially when it is carried out as an interactive process involving designers and plant personnel who are familiar with actual, everyday operations. PRA has not proven to be as well-suited in providing absolute risk estimates in public-policy debates concerning the acceptability of a technology, or for the licensing and regulatory procedures. The reasons for this are discussed.     

Perceived Nuclear Risk, Organizational Commitment, and Appraisals of Management: A Study of Nuclear Power Plant Personnel

This study examined to what extent nuclear risk perceptions, organizational commitment (OC), and appraisals of management are associated with each other among nuclear power plant personnel. The sample consisted of 428 nuclear power plant workers who completed a questionnaire at their workplace. Perceived nuclear risk and OC were most closely related to the appraisals of the top management of the organization. As the trust in and satisfaction with the top management increased, perceived nuclear safety and acceptance of the organizational goals and values heightened. This result is discussed in the context of industrial safety management.     

Safety Management and Public Spaces: Restoring Balance

Since 2000, the reputation of health and safety in the United Kingdom has been tarnished, so much so that it has become the subject of both a media circus and a government inquiry. This not only threatens the worthy goals of health and safety, but also impacts upon the associated tool of risk assessment itself such that "risk assessment" is increasingly seen by the public at large as a term inviting ridicule, even abuse. The main thrust of the government's examination of health and safety has been its concern that safety requirements were placing a disproportionate burden on business. However, there is another source of discontent, which is public chagrin over the impact of injury control measures upon life beyond the conventional workplace, in particular upon the public spaces that people frequent in their leisure time and on the activities they engage in there. This article provides a perspective on this second dimension of the crisis in confidence. It describes how many U.K. agencies with responsibilities for a wide portfolio of public amenities ranging from the provision of play spaces for the young to the management of publicly accessible countryside, the maintenance of urban and rural trees, the stewardship of sites of cultural heritage, and the pursuit of outdoor educational activities have responded to some conflicts posed to their services by the new safety culture. It concludes with a discussion of implications for the management of public space and for risk assessment itself.     

The Risk Criteria for Assessment of Temporary Changes in a Nuclear Power Plant

Risk criterion is a term that may distinguish between what is considered as an acceptable level of safety and what is not. One of the ways of determining quantitative risk criteria for temporary changes in a nuclear power plant considering probabilistic safety assessment is presented. Risk criteria are based on timing and on time duration of the change. Several examples of temporary changes in a nuclear power plant were examined to evaluate the criteria. Results show that it is possible to determine a set of risk criteria for temporary changes. Risk criteria can represent a standpoint for risk-informed decision making.     

Nuclear Safety in Ontario: A Critical Review of Quantitative Analyses

In this article quantitative analyses of CANDU nuclear generating stations are evaluated using an explicit set of criteria derived from a decision-analytic framework. A systematic search was made for relevant analyses, including both risk assessments and economic analyses. Only a small number of scientifically sound quantitative analyses that are being used to make decisions about specific safety measures or projects were located. The availability of scientifically sound quantitative data for making major energy policy decisions is even more limited, and what is available has major shortcomings. The province of Ontario is now heavily dependent on nuclear energy. Given the uncertainties surrounding the health, environmental, economic, and social consequences of nuclear energy, there is a need to assemble the information that is available within a comprehensive decision-making framework, and to decide future energy policies for the province in a public forum from a societal perspective.     

Perceived Risks of Conventional and Organic Produce: Pesticides, Pathogens, and Natural Toxins

Public risk perceptions and demand for safer food are important factors shaping agricultural production practices in the United States. Despite documented food safety concerns, little attempt has been made to elicit consumers' subjective risk judgments for a range of food safety hazards or to identify factors most predictive of perceived food safety risks. In this study, over 700 conventional and organic fresh produce buyers in the Boston area were surveyed for their perceived food safety risks. Survey results showed that consumers perceived relatively high risks associated with the consumption and production of conventionally grown produce compared with other public health hazards. For example, conventional and organic food buyers estimated the median annual fatality rate due to pesticide residues on conventionally grown food to be about 50 per million and 200 per million, respectively, which is similar in magnitude to the annual mortality risk from motor vehicle accidents in the United States. Over 90% of survey respondents also perceived a reduction in pesticide residue risk associated with substituting organically grown produce for conventionally grown produce, and nearly 50% perceived a risk reduction due to natural toxins and microbial pathogens. Multiple regression analyses indicate that only a few factors are consistently predictive of higher risk perceptions, including feelings of distrust toward regulatory agencies and the safety of the food supply. A variety of factors were found to be significant predictors of specific categories of food hazards, suggesting that consumers may view food safety risks as dissimilar from one another. Based on study findings, it is recommended that future agricultural policies and risk communication efforts utilize a comparative risk approach that targets a range of food safety hazards.     

Risk‐Informed Regulation and Safety Management of Nuclear Power Plants—On the Prevention of Severe Accidents

There are four operating nuclear power plant (NPP) units in Finland. The Teollisuuden Voima (TVO) power company has two 840 MWe BWR units supplied by Asea‐Atom at the Olkiluoto site. The Fortum corporation (formerly IVO) has two 500 MWe VVER 440/213 units at the Loviisa site. In addition, a 1600 MWe European Pressurized Water Reactor supplied by AREVA NP (formerly the Framatome ANP—Siemens AG Consortium) is under construction at the Olkiluoto site. Recently, the Finnish Parliament ratified the government Decision in Principle that the utilities' applications to build two new NPP units are in line with the total good of the society. The Finnish utilities, Fenno power company, and TVO company are in progress of qualifying the type of the new nuclear builds. In Finland, risk‐informed applications are formally integrated in the regulatory process of NPPs that are already in the early design phase and these are to run through the construction and operation phases all through the entire plant service time. A plant‐specific full‐scope probabilistic risk assessment (PRA) is required for each NPP. PRAs shall cover internal events, area events (fires, floods), and external events such as harsh weather conditions and seismic events in all operating modes. Special attention is devoted to the use of various risk‐informed PRA applications in the licensing of Olkiluoto 3 NPP.     

Insights into the Societal Risk of Nuclear Power Plant Accidents

The elements of societal risk from a nuclear power plant accident are clearly illustrated by the Fukushima accident: land contamination, long‐term relocation of large numbers of people, loss of productive farm area, loss of industrial production, and significant loss of electric capacity. NUREG‐1150 and other studies have provided compelling evidence that the individual health risk of nuclear power plant accidents is effectively negligible relative to other comparable risks, even for people living in close proximity to a plant. The objective of this study is to compare the societal risk of nuclear power plant accidents to that of other events to which the public is exposed. We have characterized the monetized societal risk in the United States from major societally disruptive events, such as hurricanes, in the form of a complementary cumulative distribution function. These risks are compared with nuclear power plant risks, based on NUREG‐1150 analyses and new MACCS code calculations to account for differences in source terms determined in the more recent SOARCA study. A candidate quantitative societal objective is discussed for potential adoption by the NRC. The results are also interpreted with regard to the acceptability of nuclear power as a major source of future energy supply.     

Precautionary Regulation in Europe and the United States: A Quantitative Comparison

Much attention has been addressed to the question of whether Europe or the United States adopts a more precautionary stance to the regulation of potential environmental, health, and safety risks. Some commentators suggest that Europe is more risk-averse and precautionary, whereas the United States is seen as more risk-taking and optimistic about the prospects for new technology. Others suggest that the United States is more precautionary because its regulatory process is more legalistic and adversarial, while Europe is more lax and corporatist in its regulations. The flip-flop hypothesis claims that the United States was more precautionary than Europe in the 1970s and early 1980s, and that Europe has become more precautionary since then. We examine the levels and trends in regulation of environmental, health, and safety risks since 1970. Unlike previous research, which has studied only a small set of prominent cases selected nonrandomly, we develop a comprehensive list of almost 3,000 risks and code the relative stringency of regulation in Europe and the United States for each of 100 risks randomly selected from that list for each year from 1970 through 2004. Our results suggest that: (a) averaging over risks, there is no significant difference in relative precaution over the period, (b) weakly consistent with the flip-flop hypothesis, there is some evidence of a modest shift toward greater relative precaution of European regulation since about 1990, although (c) there is a diversity of trends across risks, of which the most common is no change in relative precaution (including cases where Europe and the United States are equally precautionary and where Europe or the United States has been consistently more precautionary). The overall finding is of a mixed and diverse pattern of relative transatlantic precaution over the period.     

Managing Safety‐Related Disruptions: Evidence from the U.S. Nuclear Power Industry

Low‐probability, high‐impact events are difficult to manage. Firms may underinvest in risk assessments for low‐probability, high‐impact events because it is not easy to link the direct and indirect benefits of doing so. Scholarly research on the effectiveness of programs aimed at reducing such events faces the same challenge. In this article, we draw on comprehensive industry‐wide data from the U.S. nuclear power industry to explore the impact of conducting probabilistic risk assessment (PRA) on preventing safety‐related disruptions. We examine this using data from over 25,000 monthly event reports across 101 U.S. nuclear reactors from 1985 to 1998. Using Poisson fixed effects models with time trends, we find that the number of safety‐related disruptions reduced between 8% and 27% per month in periods after operators submitted their PRA in response to the Nuclear Regulatory Commission's Generic Letter 88‐20, which required all operators to conduct a PRA. One possible mechanism for this is that the adoption of PRA may have increased learning rates, lowering the rate of recurring events by 42%. We find that operators that completed their PRA before Generic Letter 88‐20 continued to experience safety improvements during 1990–1995. This suggests that revisiting PRA or conducting it again can be beneficial. Our results suggest that even in a highly safety‐conscious industry as nuclear utilities, a more formal approach to quantifying risk has its benefits.     

Fuzzy‐Logic‐Based Safety Verification Framework for Nuclear Power Plants

This article presents a practical implementation of a safety verification framework for nuclear power plants (NPPs) based on fuzzy logic where hazard scenarios are identified in view of safety and control limits in different plant process values. Risk is estimated quantitatively and compared with safety limits in real time so that safety verification can be achieved. Fuzzy logic is used to define safety rules that map hazard condition with required safety protection in view of risk estimate. Case studies are analyzed from NPP to realize the proposed real‐time safety verification framework. An automated system is developed to demonstrate the safety limit for different hazard scenarios.     

Toward an Application Guide for Safety Integrity Level Allocation in Railway Systems

The work in the article presents the development of an application guide based on feedback and comments stemming from various railway actors on their practices of SIL allocation to railway safety‐related functions. The initial generic methodology for SIL allocation has been updated to be applied to railway rolling stock safety‐related functions in order to solve the SIL concept application issues. Various actors dealing with railway SIL allocation problems are the intended target of the methodology; its principles will be summarized in this article with a focus on modifications and precisions made in order to establish a practical guide for railway safety authorities. The methodology is based on the flowchart formalism used in CSM (common safety method) European regulation. It starts with the use of quantitative safety requirements, particularly tolerable hazard rates (THR). THR apportioning rules are applied. On the one hand, the rules are related to classical logical combinations of safety‐related functions preventing hazard occurrence. On the other hand, to take into account technical conditions (last safety weak link, functional dependencies, technological complexity, etc.), specific rules implicitly used in existing practices are defined for readjusting some THR values. SIL allocation process based on apportioned and validated THR values is finally illustrated through the example of “emergency brake” subsystems. Some specific SIL allocation rules are also defined and illustrated.     

Task Design,Team Context,and Psychological Safety: An Empirical Analysis of R&D Projects in High Technology Organizations

High technology organizations need to develop new products or processes that address the dual goals of exploration and exploitation. The competing viewpoints and the asymmetric nature of market returns associated with these goals in R&D projects can heighten stress levels among project team members and reduce their psychological safety. While current research calls for greater focus on task design for improving psychological safety, we know little about how team contextual factors affect this relationship. This study develops and tests a conceptual framework that examines the moderating role of R&D team contextual factors, namely, relative exploration and project‐organization metric alignment on the relationship between a key task design variable, namely, team autonomy, and psychological safety. Relative exploration captures the extent to which exploration goals are emphasized over exploitation goals in an R&D project, while project‐organization metric alignment measures the extent to which project metrics are aligned with broader organizational metrics. Furthermore, we examine the performance consequences of psychological safety in R&D projects. The empirical analysis is conducted using primary data collected from multiple informants across 110 R&D projects in 34 high technology business units. Our results indicate that relative exploration and project‐organization metric alignment have contrasting moderating effects. Furthermore, the effect of psychological safety on project performance is found to be indirect and mediated through team turnover. Implications of the study findings, limitations, and directions for future research are discussed.     

The Risks of Licensing Persons with Diabetes to Drive Trucks

The 1990 Americans with Disabilities Act forbids employers to bar disabled persons from jobs unless employers can show the disabled person cannot perform the tasks. The Federal Highway Administration will not license persons with diabetes mellitus to drive commercial motor vehicles in interstate commerce. These individuals may experience severe hypoglycemia, greatly increasing their risk of losing control of the truck. This prohibition is currently being reexamined. We describe the disease process leading to severe hypoglycemia and its physical manifestations. To quantify the risks of licensing persons with diabetes to use insulin, we first estimate the number of potential insulin-using drivers. We estimate that 1420 insulin-using persons would seek licenses in the United States if they were permitted to do so (920 noninuslin dependent and 500 insulin dependent). Next, we estimate the annual incidence of mild and severe hypoglycemia in these populations. The third step is to estimate the number of hypoglycemic episodes while driving. Estimating the likelihood of a crash due to a mild or severe hypoglycemic episode is the fourth step. We estimate that an additional 42 crashes each year would occur if insulin using persons were licensed to drive commercial motor vehicles in interstate commerce (20 from insulin dependent and 22 from non-insulin dependent drivers).     

Specifying Risk Goals: Inherent Problems with Democratic Institutions

Many risks have the property that large numbers of people are exposed and have little or no individual control over the risks they face. Dams, nuclear power plants, and recombinant DNA research have proven controversial not simply because there is vast uncertainty about the true level of risk associated with each, but because a fundamental issue is that in each case social risks can be lessened by spending more on safety: dams can be designed to withstand larger earthquakes, nuclear plants can have additional safety equipment, and DNA research could be done in yet more carefully isolated laboratories. Since each person will have preferences regarding the proper trade-off between increased cost and increased safety, there is little possibility of consensus. More importantly, we show that a voting process for expressing individual preferences can be manipulated and is seriously flawed in the sense that it does not lead to an "efficient" outcome. In addition, we show that virtually all people are unhappy with the safety decision, in the sense that each would prefer either a safer or a cheaper outcome. Thus, making safety decisions that affect a large group of people who will not be able to control the outcome is even more difficult than has been appreciated. We suggest some ways of handling some of the difficulties.     

A Review of Risk Matrices Used in Acute Hospitals in England

In healthcare, patient safety has received substantial attention and, in turn, a number of approaches to managing safety have been adopted from other high‐risk industries. One of these has been risk assessment, predominantly through the use of risk matrices. However, while other industries have criticized the design and use of these risk matrices, the applicability of such criticism has not been investigated formally in healthcare. This study examines risk matrices as used in acute hospitals in England and the guidance provided for their use. It investigates the applicability of criticisms of risk matrices from outside healthcare through a document analysis of the risk assessment policies, procedures, and strategies used in English hospitals. The findings reveal that there is a large variety of risk matrices used, where the design of some might increase the chance of risk misprioritization. Additionally, findings show that hospitals may provide insufficient guidance on how to use risk matrices as well as what to do in response to the existing criticisms of risk matrices. Consequently, this is likely to lead to variation in the quality of risk assessment and in the subsequent deployment of resources to manage the assessed risk. Finally, the article outlines ways in which hospitals could use risk matrices more effectively.     

Trust‐Level Risk Evaluation and Risk Control Guidance in the NHS East of England

In recent years, the healthcare sector has adopted the use of operational risk assessment tools to help understand the systems issues that lead to patient safety incidents. But although these problem‐focused tools have improved the ability of healthcare organizations to identify hazards, they have not translated into measurable improvements in patient safety. One possible reason for this is a lack of support for the solution‐focused process of risk control. This article describes a content analysis of the risk management strategies, policies, and procedures at all acute (i.e., hospital), mental health, and ambulance trusts (health service organizations) in the East of England area of the British National Health Service. The primary goal was to determine what organizational‐level guidance exists to support risk control practice. A secondary goal was to examine the risk evaluation guidance provided by these trusts. With regard to risk control, we found an almost complete lack of useful guidance to promote good practice. With regard to risk evaluation, the trusts relied exclusively on risk matrices. A number of weaknesses were found in the use of this tool, especially related to the guidance for scoring an event's likelihood. We make a number of recommendations to address these concerns. The guidance assessed provides insufficient support for risk control and risk evaluation. This may present a significant barrier to the success of risk management approaches in improving patient safety.     

A Comparison of Organic and Conventional Fresh Produce Buyers in the Boston Area

Food safety concerns and the demand for organically grown produce have increased significantly in the United States over the last decade. Key differences in lifestyle characteristics, food safety attitudes and beliefs, perceived food safety risks, and valuation of health risk reductions between organic and conventional food buyers remain largely unknown, however. To better characterize how buyers of organic fresh produce differ from their conventional counterparts, over 700 food shoppers were sampled from ten major retail stores in the Boston area. Survey results show that self-reported organic buyers are more likely than conventional buyers to engage in a variety of health-promoting and environmentally friendly behaviors. Organic buyers are less trusting of federal food safety agencies than are conventional buyers, and perceive greater benefits associated with organically grown produce than do their conventional counterparts. Further, organic buyers have significantly higher risk perceptions than do conventional buyers for food safety hazards associated with conventionally grown produce. Compared to conventional buyers, organic produce buyers also perceive significant risk reductions associated with switching to organically grown produce and are willing to pay a higher price to reduce perceived food safety risks. Few sociodemographic differences between buyer types were observed, possibly due to how organic and conventional food stores were matched. Survey findings highlight the need for greater public education about a range of food safety issues and farming practices to ensure that consumers are making informed decisions in the marketplace.