Process Control

There are many control rooms across different industries that present the operators with highly complex, stressful cognitive work environments. Over the last few years we have started to work with our colleagues at the Idaho National Laboratory in Idaho Falls on issues regarding the workload of nuclear power plant control room operators and the possible redesign of the control room displays and control interfaces. The following description stems from a recent paper abstract written by Tom Ulrich (together with Ron Boring and myself) that illustrates our research in this area.

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Traditional nuclear power plant control room operations involve an operating crew interacting with control boards containing analog indicators and controls. In a typical plant, a senior reactor operator (SRO) uses paper procedures to direct a crew of operators to verify indicator values and manipulate hard controls. Digital technology has begun to permeate the control room in the form of digital soft control systems embedded within the control boards and desktop monitoring computer displays. As plants continue to extend their operation beyond their original 40 year licenses, the analog components continue to degrade and require replacement. These analog components are costly to replace, which increasingly leads to replacement of analog components with digital soft control interfaces. These new digital soft controls alter the available interaction methods for the operators, which will meaningfully impact operator situation awareness.

Current implementations of digital soft control systems have created a fundamental shift in the interaction methods used by operators within plant monitoring and control. Plant parameters are no longer represented in a continuous analog form across the control boards. Instead they are represented within discrete digital systems across multiple screens and displays. To access information and controls, the operator can no longer rely on visual scanning to locate the target indicator or control. Instead, the operator often must navigate multiple screens to reach the one containing the desired indicator or control. This leads to a number of related situation awareness issues that require consideration.

To achieve situation awareness, the operator must build a mental model of the interface’s screen organization and each screen’s content for navigation purposes. As more digital soft controls are added to the control room, the operator must also track multiple mental models of the various digital interfaces. Additionally, information is no longer commonly displayed for the crew since individual operators can independently toggle between screens within digital displays based on their current task.