Operator Decision Strategies in Nuclear Control Centres: A Domain-Specific Information Flow Map

Nuclear power plant control room operators respond to accidents by following detailed emergency procedures. At the same time they ensure the procedures match the accidental situation, especially with unanticipated conditions due to multiple failures, automation disturbances, or unreliable indications. Operator adaptation thus allows the system to respond to unanticipated conditions. The engineering problem with adaptation is how to design and evaluate technology, training and work processes that support the decision strategies people may use when acting adaptively. Designs that do not consider flexible strategy choice will not support operator cognitive demands for the complex tasks that are not automated. Human reliability analyses that do not identify the strategies used in unanticipated conditions will not correctly assess the risks. Operators' strategies can be discovered through cognitive task analysis (CTA), for instance by performing a formative strategy analysis. Yet to date formative strategy analyses have been relatively neglected and are not often applied. Without CTA the task analysis will provide normative support for "the one right way to accomplish the task", instead of tailored support to several viable and effective strategies for context-specific, unanticipated situations. This paper proposes an information flow map for emergency operation in nuclear control centres. This may facilitate the performance of CTA and thereby the ability to design systems capable of supporting operators' adaptation to unanticipated situations.

Keywords: Decision-making, Strategies, Flow-map, Emergency, Procedures, Nuclear, Adaptation.

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