After a few days, even the ethnographer ends up stepping into contaminated territory, like anywhere else: surrendering to the beauty of the landscapes. To take into account this tendency not to think, to act or to behave with the invisible, the French nuclear authorities set up strict regulations and established intensive information and training schemes for the atom workers. Residents in areas affected by the Fukushima Daiichi nuclear accident did not receive such training. Faced with the omnipresence of the radioactive threat, they have tended to develop an imaginary of the sub-terrestrial, on the atom’s scale. In this process, technical measurement and scientific knowledge play a major role, but this does not imply that the scale of sensible perception has been relinquished.