An inherent safety-based incident investigation methodology

A methodology is being developed to enable the explicit use of the principles of inherent safety in an incident investigation protocol.; Incident investigation is a well-recognized and vital component of a Process Safety Management (PSM) system. Investigation enables the PSM system to ensure that process safety lessons learned in the past can be utilized in day-to-day operations and when planning for new projects and construction. Incident investigation reports therefore provide an important link between the lessons of past incidents and safer design and operation in the future. The rewards of a successful investigation are the prevention of accidents and better protection of employees, equipment and other physical assets, and the environment.; Process chemists and engineers of today are increasingly considering inherently safer options in their design decisions, but the authors of incident reports do so less often. Explicit attention to inherent safety principles---minimize, substitute, moderate and simplify---during incident investigation can, however, be effective in preventing incidents with similar root causes in the future. In this manner, workplaces may be made safer by removing hazards rather than attempting to keep them under control with engineered and procedural measures.; The usefulness of the technique developed in the current work is demonstrated by application to the Westray coal mine explosion that occurred in Nova Scotia in 1992. This process-related disaster resulted in the deaths of 26 workers, destruction of the underground workings, and bankruptcy of the parent company. The purpose in presenting this case study is twofold---to validate the methodology, and to identify the inherent safety considerations that could have prevented the incident. These findings have application beyond the realm of coal mining and extending well into the world of the chemical process industries.