Aspects of the Nuclear Power Plant Control Room System Contributing to Safe Operation

Abstract

The performance of a nuclear power plant's operational steering entity, the control room system, has a major impact on operational safety. The construction and modernization of nuclear power plants create a need to evaluate control room systems to assess if they fulfil their purpose to support safe operation. The aim of this study was to identify a foundation for evaluation measures, i.e. to find aspects of the control room system that contribute to safe operation from a human factors perspective. A number of professionals in roles influencing the operation and/or design of Swedish nuclear power plants were interviewed: reactor operators, shift supervisors, instructors, human reliability analysis specialists, human factors specialists, and personnel from the Swedish Radiation Safety Authority. A number of aspects contributing to safe operation were identified and categorised in six overall themes: situations, functions, tasks, structural elements, and characteristics. Situations describe states of and/or events in the surrounding environment that the control room system must be able to handle. Functions are the abilities the control room system must have, and tasks are what operators or technical systems in the control room system must be able to perform. Structural elements are the entities that constitute the control room system, and the characteristics of the structural elements establish conditions for the design of artefacts as well as the behaviours and abilities of personnel. These aspects are examples of what is required for controlled performance of the control room system, a prerequisite for safe operation. Together the themes serve as a structure for defining evaluation measures. The themes can be considered variables or constants when deciding on control room system evaluation measures, a choice that must be made for each evaluation. User experience aspects contribute to safe operation, but the operators’ well-being has a value in its own right and should be considered as an additional goal when designing and evaluating control rooms.