This paper explains several experiences in inherent safety where, despite substantial progress in the reduction of risk, the public or regulators were not satisfied with the outcome. The key reason for this is the lack of any accepted methodology, set of criteria, and requirement for ‘tolerable risk' decision-making. This, combined with public outrage on the issue if there is an extreme aversion to risk or possibly a threat or perceived threat, such as from a past accident or the fear of terrorism, results in an environment where irrational decisions can be made. The author believes will occur more frequently in the future as the degree of risk tolerance is diminishing.
Inherent safety as a regulatory concept has known complicating issues, such as the lack of metrics to judge the adequacy of the efforts employed. More so, experience has shown that the public and regulators may not be satisfied with inherent safety improvements even if they are substantial reductions in risk. The key expectation with most persons exposed to a potential release is that the reduction of risk results in zero exposure to them. The final expectation is the reduction of consequences v. the reduction of risk in total. Inherent safety (substitution or minimization) becomes the preferred mechanism in the eyes of the public for achieving that reduction.
The paper will show how these decisions are both challenging technically as well as emotional and go beyond technical ‘precision'. The current system lacks incentives for industry to use IST if the investments will not be fairly judged. Given the lack of specific guidance on decision-making in this situation, the benefits and impacts of intended changes, and the lack of specific guidance on how regulatory burdens may be reduced and safety and security risks improved, industry is uncertain on the value of IST investments.