[en] For the time being two technical solutions have been developed for the interim storage: 1) one is based on forced air cooled pits set out in a concrete structure, as presently provided close to the Vitrification Facilities on reprocessing sites; 2) the other one is based on transportable storage casks standing vertically onto a storage pad, following principles similar to those already experienced with spent fuel storage casks. Considering these two solutions for interim storage, TRANSNUCLEAIRE has developed two main types of transportable casks for vitrified HAW; one is a routine transport cask; the other one is a transportable storage cask. Both are covered by the generic name TN28V and have already been described in previous papers. This paper deals with the safety and operation aspects of the casks under both transport and storage conditions. (J.P.N.)