Development of nuclear power plant operator simulator for man-machine interface evaluation

The operational safety in nuclear power plants depends strongly on man machine interfaces (MMI), such as assignment of equipment on control boards and operation procedures in emergency situations. Therefore, the evaluation and analysis methods for the MMI are important. In order for the methods to be practical, the methods should be executed in each step of design and be easy for designers to use. We aim to develop SEAMAID system: a computer supported system for evaluating and analyzing the MMI by simulating the interaction between the operator and the machine. In this paper, we discuss problems of the conventional methods and the required functions of the operator simulator for the SEAMAID. The operator simulator executes not human errors but correct behavior which follows the operational procedure. The SEAMAID evaluates the MMI by finding potential human errors which could occur in the simulated interactions and points out the problematic interaction parts which could induce human errors. We construct the operator simulator by combining the human model which was proposed by Prof. Reason, and the knowledge base model based on the Petri net model. This simulator can treat frequency parameter which represents the degree of frequency of using a certain knowledge. We conduct two sample simulations in different frequency parameters in the same scenario. These simulation results show that even if the operator behaves correctly following the procedure, there are alternative task sequences. We verify that the simulated interactions are in good agreement with the actual one. Also, we propose the method to point out the problematic parts in the interactions based on the working memory consumption. (author)