Case Study of Operator Communication and Planned Development in Connection with Computer Control of the Halden Boiling Water Reactor

Abstract

Process computers are increasingly being used for control and supervision of nuclear power reactors as the reactor control become s more complex due to increased plant size and load requirements from the grid. In addition, the operating characteristics are such that one is getting closer to the technical limits of the system. As a consequence, the extended use of computers implies that more emphasis is put on operator-proces s communication.At the OECD Halden Reactor Project, the reactor being an experimental power reactor, an international research and development programme on computer control of nuclear power reactors is being conducted. The programme aims for demonstration and routine operation of plant supervision as well as direct digital control using conventional and advanced methods. For experiments and routine operation the operator communication system is one of the main components in the system. This computer based system is operating in parallel with and is supplementing a conventional control system.The control desk consists of a console, alphanumeric and graphic Cathode Ray Tube display units (CR Ts) journal and report typewriters and plotter. The function of the console is to enable the operators to display process variables, request status, enter constants, change limits, and start and stop control routines. The CR Ts are used for prewarnings and alarm handling, messages, trend and status display, etc.The functions are implemented on a process control computer with about 750 analogue inputs and 224 digital inputs and outputs, 11 analogue outputs, 3 disk drives, 2 tape stations, and a line printer. The computer system has been operational for online applications since the end of 1967, and the scope of computer applications together with the communication system have gradually been extended.The multitude and complexity of computer functions have required a design of an extensive user-developed software to obtain an efficient dataflow and to serve as basis for proper operator - process communication functions. In designing and programming the communication system, emphasis has been put on obtaining sufficiently short response time, clear language with respect to text formats, organization of output, etc. Some efforts have been made to apply human engineering with the purpose of avoiding operator maloperations.The control desk has been easily understood and accepted by the operators, but not all functions introduced were equally much appreciated.Based on this experience which has been followed up by ergonomic studies, further investigations on man - computer - process communication systems will be conducted. This is envisaged due to thedevelopment of new hardware, like advanced minicomputers, and extended use of colour displays. A general purpose communication system, based on modules which can be configurated for the particular purposes can now be realized. The communication system could possibly be adapted to any general process computer. The development of a standard operator communication language is proposed.The paper deals with the experience obtained and the further development plans.