Acceptable Residual Risk – Principles, Philosophies and Practicalities

Safety is typically demonstrated by identifying hazards, mitigating those hazards, and then by showing that the remaining risk is acceptable. This paper begins by setting out some principles for assessing tests of risk acceptability. It then categorises and examines existing methods of testing for risk acceptability against those principles, and finds that they fall short. A new measure of risk acceptability is proposed, the Minimum Industry Safety Return on Investment (MISRI). MISRI is an industry-specific measure, which complies with ALARP and with the principles espoused in the early part of this paper.