The nineties were a period of great innovation in process industries as analogical systems were rapidly replaced with digital systems introducing a higher degree of automation, tighter integration between sub-systems and new levels of man-machine interaction. A lot of attention was put on designing systems that improved overall performance, in terms of safety, reliability and efficiency, without increasing demand on operator workload and attention unnecessarily.
The transition from analogical to digital was so wide reaching that it fundamentally redefined the way process control was carried out. Tasks were reallocated between operators and technical systems; sub-systems were linked up directly; operators’ role in the system shifted from acting on the process to monitoring, verifying systems and managing exceptions.
Work activities themselves had to be redesigned alongside man-machine interfaces. This called for holistic, system-level design. The successful distributed modeling of individual process control tasks led to a series of studies of large systems fulfilling a multiplicity of functions at once. These studies were carried out by multi-disciplinary teams where engineering, mathematics, organisational behaviour and cognitive science, that I represented, perspectives were brought together to build a model of the process-control system as a whole. Distributed cognition provided the framework to analyse and model operations of air-traffic control centers and nuclear power plant control room operations.
In the nuclear energy case, Electricite de France was designing N4, the next generation Nuclear Power plants, with a fully digital control room. I was part of the team (with Pierre Le Bot, Corinne Bieder, Emmanuel Desmares) who defined the model for human reliability in the new digital control room. The model was developed over a period of three years starting with observations in the control rooms, analyses of incidents and accidents, desk research, leading to a series of simulator tests where crews operated under incidental and accidental conditions.
The work led to MERMOS, the reference method used by Electricite de France (EDF) for Human Reliability Assessment (HRA), to assess the emergency operation of nuclear reactors during incidents and accidents for Probabilistic Safety Assessments (PSA). The model is presented and discussed in the following articles writtent with Pierre Le Bot, Corinne Bieder, Emmanuel Desmares and Jean-Luc Bonnet:
MERMOS: an EDF project for updating probabilistic human reliability assessment. Revue Generale Nucleaire, International Edition (1998)
MERMOS: EDF’s new advanced HRA method. Probabilistic Safety Assessment and Management (PSAM 4, 1998)
MERMOS: a second generation HRA method: what it does and doesn’t do. Proceedings of Probabilistic Safety Assessment, Washington (1999)
What are the CICAs? Retrospective analysis of the Three-Mile Island Accident from the MERMOS viewpoint. Proceedings of Probabilistic Safety Assessment, Washington (1999)
MERMOS: New Issues on Human Failure. Probabilistic Safety Assessment and Management, Psam 4: Proceedings of the 4th International Conference on Probabilistic Safety Assessment (Mosleh, Bari eds., Springer Verlag 1998/99)