This article examines a set of public controversies surrounding the role of nuclear power and the threat of radioactive contamination in a post-Fukushima Japan. The empirical case study focuses on the Ministry of Economy, Trade and Industry (METI), Japan most influential ministry and, more importantly, the former regulator of nuclear energy before the 2011 Fukushima nuclear disaster. Through participant observation of METI’s public conferences, as well as interviews with state and non-state actors, I examine how particular visions of nuclear power continue to affect the basis of expert authority through which state actors handle post-Fukushima controversies and their subsequent uncertainties. In its post-Fukushima representations, METI frames nuclear power as an apolitical necessity for the well-being of the Japanese nation-state and the common humanity. It does so by mobilizing categories of uncertainty around specific political scenes, such as global warming. For METI, the potential uncertainties linked with the abandonment of nuclear power have the power to trigger political turmoil of a higher scale than those linked with Fukushima’s radioactive contamination. A form of double depoliticization takes place, in which the issue of Fukushima’s radioactive contamination gets depoliticized through perceived priorities that are paradoxically depicted as ‘post-political’ – that is, in an urgent need for immediate action and not open to in-depth deliberation. I refer to this process as establishing ‘post-political uncertainties’. This kind of depoliticization raises ethical questions surrounding meaningful public participation in decisions that happen at the intersection of politics and science and technology study.