1.4. Research into the geological disposal of radioactive waste has been under way for several decades [5]. At present, practical experience gained in the disposal of radioactive waste in geological formations is limited. For high level waste, characterization of sites for proposed geological disposal facilities has been carried out in a number of States, and a few States have constructed underground laboratories or facilities for characterization of the host rocks. There are only a few operating geological disposal facilities for intermediate level waste. Experience in closing of geological disposal facilities is very limited.