Abstract The international DOPAS Project (Demonstration Of Plugs And Seals), which involves the participation of 14 European organizations (Posiva, ANDRA, DBE-TEC, GRS, NAGRA, RWA, SÚRAO, SKB, CTU, NRG, GSL, BTECH, VTT and ÚJV Řež), is concerned with the structural solution for sealing plugs to be used in deep geological radioactive waste repositories. The project is funded by the 7th Framework Programme – EURATOM. The Czech contribution to the DOPAS project (the EPSP experiment – Experimental Pressure and Sealing Plug) consists of an experiment that is being conducted at the Josef Regional Underground Research Centre (Josef URC, Čelina-Mokrsko). The aims of the EPSP experiment are to develop, monitor and verify the functionality of such plugs, and to determine a detailed characterization of the materials from which the plug is constructed. The EPSP experiment is being conducted by a Czech consortium made up of SÚRAO, CTU and ÚJV Řež, a. s.