Aspects of Risk Tolerability, Manageable vs. Unmanageable Risks in Relation to Critical Decisions, Perpetuity Projects, Public Opposition

ABSTRACT: This paper builds on case studies (major accidents) from prior papers to discuss social acceptability of risk, riskestimates and risk communication. The discussion is of critical importance in view of new projects worldwide and difficultchoices humanity will have to make under demographic and climatic pressure and public opposition. Due to spacelimitation the first part of the paper considers consequences only in terms of casualties. Risks linked to tailings dams,nuclear reactors and a highway tunnel are compared to well known, previously published acceptability criteria. Acomparison of the acceptability of these risks is then carried out from a quantitative risk evaluation point of view showingunexpected results. An additional case from the transportation world is briefly focused on, to show how risk baseddecision-making can be applied to alternative selection. In order to develop the discussion the concepts of socialperception quantification, which could be applied to any accident, in any industry, while developing a holistic riskassessment, are illustrated. The perception gap between societal consequences and factual consequences is explored,as it is a significant source of the pervasive mistrust in technical and scientific opinions. The paper then shows that theselection of the type of consequences and their combination can severely bias the perception of the results of a classicrisk assessment application. A communication strategy is suggested to convey to clients the correct message whendealing with “societal” consequences of private industry risks. The second part of the paper discusses monetary lossesand shows the shape of common tolerability thresholds. The concepts developed for human losses are shown to beapplicable to physical losses. The functional link between tolerability and Manageable vs Unmanageable risks isexposed and then analyzed to describe how governance and leadership can be damaged without proper riskevaluations, prioritization and a deep understanding of tolerability.