Résumé : The ethical matrix is a participatory tool designed to structure ethical reflection about the design, the introduction, the development or the use of technologies. Its collective implementation, in the context of participatory decision-making, has shown its potential usefulness. On the contrary, its implementation by a single researcher has not been thoroughly analyzed. The aim of this paper is precisely to assess the strength of ethical matrixes implemented by a single researcher as a tool for conceptual normative analysis related to technological choices. Therefore, the ethical matrix framework is applied to the management of high-level radioactive waste, more specifically to retrievable and non-retrievable geological disposal. The results of this analysis show that the usefulness of ethical matrixes is twofold and that they provide a valuable input for further decision-making. Indeed, by using ethical matrixes, implicit ethically relevant issues were revealed—namely issues of equity associated with health impacts and differences between close and remote future generations regarding ethical impacts. Moreover, the ethical matrix framework was helpful in synthesizing and comparing systematically the ethical impacts of the technologies under scrutiny, and hence in highlighting the potential ethical conflicts.