A packaging device for the transport and/or storage of a radioactive medium generating flammable gases and/or explosives via radiolysis, comprising a plurality of canisters intended to contain the radioactive medium, each canister defining an inner storage space accessible via an opening for filling the medium, on which plug-forming means are mounted. According to the invention, the device also comprises a structure forming a chamber, and means for placing in communication allowing a fluid communication to be set up between the inner storage space and the chamber.