a sealed source, the activity level of which, at the time of its discovery, is above the exemption level referred to in Article 3(2)(a) of Directive 96/29/Euratom, and which is not under regulatory control, either because it has never been under regulatory control or because it has been abandoned, lost, misplaced, stolen or transferred, without proper notification of the competent authority, to a new holder or without informing the recipient;