Safety culture as an element of plant design for the reduction of risk from unsafe operator actions

Safety culture is mainly the result of anticipating effort in hazard identification and prevention, i.e. hypothetical event sequences have to be considered with special emphasis. This paper deals with plant designing activities aiming at the reduction of risk from unsafe operator actions. To support forecasting expert knowledge, event tree and fault tree methods are recommended. It is demonstrated by cases from incident reports that the effectiveness of a plant feature designed for the prevention of a given error depends on the psychological cause of this error. The development and assessment of such design features require additional research concerning cognitive ergonomics. Concluding from empirical evidence is a useful completion of forecasting expert knowledge supported by fault tree and event tree methods. such conclusions should be based on the Gestalt tradition of psychology meaning that operator errors indicate design deficiencies. Therefore, plant design should consider three feedback concepts: (i) history feedback, i.e. incorporation of lessons learned from past operator errors in comparable plants, (ii) living feedback, i.e. incorporation of actual plant-specific human performance data, and (iii) artificial feedback, i.e. incorporation of lessons learned from simulator experience. The main conclusion is that methods from probabilistic safety assessment (PSA) have the power to assess and improve safety culture. Therefore investigation on PSA method improvements should be continued , especially in the field of human reliability analysis. (author)