Short abstract:

This article demonstrates how nuclear experts produce incommensurable knowledge on nuclear accidents, which provides "epistemic leeway" to cope with crises. It results from the preservation of alternative knowledge claims in separate spaces of comparison within the same field of expertise.

Long abstract:

How does knowledge production during crises contribute to challenge contemporary institutions or, on the contrary, to maintain them? This article investigates this question in the case of expert knowledge on nuclear accidents in France in the aftermath of the Fukushima Dai-ich accident in March 2011. The article draws on a study of the French and European “lessons from Fukushima” learning exercise, based on document analysis, interviews and ethnographic observation of nuclear experts’ working practices. The article demonstrates how, while setting up a learning exercise that requires making Fukushima and nuclear installations elsewhere comparable, nuclear experts use their “epistemic leeway ”, the ability to define what can be compared and how in a crisis, to avoid different approaches and methods of safety analysis from dialoguing with each other. This especially preserves the boundaries between prescriptive and empirical safety analysis, protecting theoretical assumptions from being questioned in the face of a new event. Experts thereby progressively (re)construct the incommensurability of nuclear safety and render accidents ultimately unknowable. The article contributes to better understanding the understudied mechanisms of the production of incommensurability through expert knowledge and opens more general questions about the limits of knowledge on crises .