What factor is crucial in determining if a system design meets tolerable risk criteria?

The frequency and severity of potential incidents are crucial in determining if a system design meets tolerable risk criteria because these factors directly influence the overall risk assessment of a system. In risk analysis, specifically in the Layer of Protection Analysis (LOPA) methodology, understanding how often incidents may occur (frequency) and the potential consequences of those incidents (severity) allows for a more accurate evaluation of risk.

When assessing whether a risk is tolerable, it is essential to quantify how likely an incident is to happen and what the impact would be if it did occur. If risks are too frequent and/or severe, the system might not meet the organizational or regulatory acceptance criteria for risk. Therefore, this evaluation helps in prioritizing safety measures, designing appropriate layers of protection, and making informed decisions about risk management strategies.

In contrast, while the complexity of the system, the training of personnel, and industry regulations are all important factors in safety and operational effectiveness, they do not directly establish whether a design meets the specified tolerable risk criteria. They contribute to the broader context of safety but do not replace the need for a thorough evaluation of incident frequency and severity.