Post Farmer Modeling, Measuring and Comparing risks for Industry

F. In 1967, F. R. Farmer proposed a model for assessing the safety of a nuclear reactor, using a global approach that inaugurated the probabilistic approach to nuclear safety. The proposed method for calculating the probability of failure of a complex system is still valid today, as is its probability-consequence diagram. This is what is often summarized in the literature.

Nevertheless, two aspects of F.R. Farmer's work have received less attention. The first is the study of the context and motivations that led to this approach, making it a pioneer in the study of technical systems through the management of their safety. Its approach has become the benchmark in the debate between designers and evaluators on the societal acceptability of risky technologies. The second is the decision-making process used to arrive at an assessment of the total risk in order to decide on its acceptability.

If we agree that the risk representation tools and the quantitative safety criterion proposed in the article have had a considerable influence in the field of operational safety and risk control, particularly in large-scale technical systems at risk (nuclear, aeronautical, space, rail, defense, etc.), we can see that the main current practices, beyond those of experts and specialists in these fields, on the one hand remove key stages in the resolution of the problem and, on the other hand, have led to the development of a new approach to risk management.), we can see that the main current practices, beyond those of experts and specialists in these fields, on the one hand remove key stages in the resolution of the problem to be solved and, on the other, have led to an amalgam between the concepts of random event, consequences, probability measurement, risk, risk from the point of view of its management, risk measurement, risk estimation and risk assessment.

In order to identify the gaps between current practices and F. R. Farmer's initial approach, the first section reviews the proposed approach.

Then, following a review of the state of the art, the second section identifies the key legacy points in terms of the decision-making process for solving a complex risk acceptability problem.

The third section, after identifying current practices, notes the differences in the way risk is taken into account in relation to F. R. Farmer's initial proposal.

Finally, in the fourth section, we discuss a risk model compatible with F.R. Farmer's and four proposed risk measures for operational safety, risk control and risk management in industry, including a statement of the main mathematical properties of these measures. These measures are a first step in comparing risks taking into account losses,...