All technological controversies are socially and culturally framed. Studying those moments of “expertise in crisis” has become increasingly crucial since they structure scientific communities at a landmark moment when scientists are compelled to justify their decisions, often before a community of laypeople. Using the example of the Sellafield nuclear site and the controversies it gave birth to, we shall analyze the way technological controversies provide a valuable analytical framework on the forms of expertise related to nuclear risks. Then focussing on technological facts, the present study shall assess how the transformations triggered by those controversies have embodied a shift from a technocratic model, related to an information deficit among the laypeople, to a more nuanced model in which laypeople to a certain extent succeeded in entering the scientific sphere. Even though mastering the sheer technical facts remains the prerogative of the scientists, laypeople are thus trying to legitimize their own discourses. We shall demonstrate how the traditional divide between experts and laypeople has somehow been abolished and replaced by a continuum of expertise ranging from the most inexperimented to the most specialized actors, depending on their involvement. Laypeople have questioned the monopoly of the institutional expertise and asserted their wish to participate in the debate – in spite of its technical nature. Ultimately, the previous controversies also helped reconstruct the role laypeople are playing in the decision-making process, as the State – theoretically at least – is increasingly favouring an improved form of public participation.