Balancing human and technical reliability in the design of advanced nuclear reactors

The strong influence of human factors (HF) on the safety of nuclear facilities is nowadays recognised and the designers are now enforced to consider HF requirements in the design of new facilities. Yet, this consideration of human factors requirements is still more or less restricted to the latest phases of the projects, essentially for the design of human-system interfaces (HSI's) and control rooms, although the design options influencing at most the human performance in operation are indeed fixed during the very early phases of the new reactors projects.The main reason of this late consideration of HF is that there exist few methods and models for anticipating the influence of fundamental design options on the future performance of operation teams.This paper describes a set of new tools permitting (i) determination of the impact of the fundamental process design options on the future activity of the operation teams and (ii) assessment of the influence of these operational constraints on teams performance. These tools are intended to guide the design of future 4th generation (GEN4) reactors, within the frame of a global risk-informed design approach, considering technical and human reliability exigencies in a balanced way.

► Human factors exigencies are often overseen during the early design phases of NPP.
► Optimization of reactors safety is only based on technical reliability considerations.
► The search for more technical reliability often leads to more system complexity.
► System complexity is a major contributor to the operator's poor performance.
► Our method enables to assess plant complexity and it's impact on human performance.