A human factors methodology for safety assessment based on the DYLAM approach

This paper discusses how the problem of human factors can appropriately be included in a probabilistic safety study. During incidents, the effect of the plant dynamic evolution and the failures of components can lead to non-intuitive configuration of the system and, when the interaction of the operator and the control and protection system is accounted for, the overall scenario of the safety study becomes particularly complex. These problems demand the use of a dynamic reliability methodology technique and the development of an appropriate model of human behavior to be coupled to a taxonomy of erroneous actions. At JRC these two endeavors have been carried out by the DYLAM approach and by a number of modeling architectures of operator simulation, which have been coupled for the development of a dynamic methodology for human factors analysis. In the paper, a simple application case is shown by the study of the control of an Auxiliary Feedwater System during incidental conditions.