Analysis of control room computers at nuclear power plants

The following problems are analyzed: - the developing of a system - hardware and software - data - the aquisition of the system - operation and service. The findings are: - most reliability problems can be solved by doubling critical units - reliability in software has a quality that can only be created through development - reliability in computer systems in extremely unusual situations can not be quantified or verified, except possibly for very small and functionally simple systems - to attain the highest possible reliability by such simple systems these have to: - contian one or very few functions - be functionally simple - be application-transparent, viz. the internal function of the system should be independent of the status of the process - a computer system will compete succesfully with other possible systems regarding reliability for the following reasons: - if the function is simple enough for other systems, the dator system would be small - if the functions cannot be realized by other systems - the computer system would complement the human effort - and the man-machine system would be a better solution than no system, possibly better than human function only. (Aa)