What is the acceptable criterion for risk if the estimated fatalities per year from a cooling pump failure is 0.00000012?

The scenario discusses acceptable risk criteria in the context of Layer of Protection Analysis (LOPA). When evaluating risks, particularly in safety-critical systems, the goal is typically to maintain risk levels as far below an established baseline as possible, rather than allowing them to match that baseline exactly.

The value of 0.00000012 fatalities per year represents a calculated risk threshold associated with a cooling pump failure. Acceptability is based on the principle that risk levels should ideally be kept lower than the threshold to account for uncertainties and ensure safety margins. It reflects a baseline of risk that could be viewed as the maximum tolerable risk from a regulatory or safety perspective.

Thus, indicating that a risk greater than this baseline is acceptable contradicts the fundamental principle of risk management, which seeks to minimize risk wherever feasible. Allowing risks to meet or exceed the known threshold without implementing additional protective measures could lead to unacceptable safety outcomes.

This way of understanding indicates that maintaining a risk level below this figure is not only the ideal scenario but is also the expected practice in risk management frameworks like LOPA, which aim for higher safety assurance levels through layers of protection.