Abstract: The present invention relates to a dynamic containment device, outside and in the vicinity of an orifice of an opening cavity for example an opening of a valve. A device according to the invention comprises a hub for collecting by aspiration, comprising a plurality of unitary elements, the overall profile of which corresponds substantially to the contour of the border of the orifice of the said cavity, as well as a plurality of flexible conduits communicating, on the one hand, with each unitary element and, on the other hand, with an aspiration conduit. The invention is applied, in particular, to the partial decontamination of primary circuits of a nuclear power station.