In this article, we propose a set of models and a prototype to capitalize and share knowledge of expert tutors using training simulators. This is a particularly important issue in contexts with strong stakes such as training of operators of nuclear power plants, where operators’ accreditation strongly depends on skills of tutors and tolerate no errors. In such a context, observation, analysis and debriefing of interactions of trainees’ operators are complex activities especially for the young tutors who do not have the expertise of confirmed tutors. Based on digital traces, our approach consists in providing a visual synthesis of trainees’ activities by using the knowledge of experts. Such a synthesis, showing the relationships between lowlevel traces and high-level behaviors, enables tutors to enhance their understanding and better analyze the activity in order to prepare the debriefing. Our approach has been implemented in a prototype, called D3KODE, which was evaluated according to a comparative protocol conducted with a team of tutors from EDF Group (Electricity Of France). The result demonstrated that the visual synthesis and the higher informations provided by D3KODE helped the intructors to confirm/validate more easily realizations and no-realizations of educational objectives trainees and facilitated the exchanges between tutors and trainees.