Abstract: The method for inspecting a nuclear facility comprises the steps consisting of placing a radiation detector (2) in front of a surface of a portion of the facility (1), the radiation detector (2) being collimated to receive radiation from a cylindrical region of the portion of the facility; carrying out a plurality of measurements of radiation received by the radiation detector tar different transmission energies and different distances, along the axis of the cylindrical region, between the radiation detector and surface of the portion of the facility; and analysing the radiation measurements by subdividing the cylindrical region into a plurality of meshes (3) so as to estimate respective levels of radioactivity in the meshes (3).