Geomorphologic assessment of areas as sites for high-level nuclear waste repositories

Exposure of high level nuclear waste (HLW) repository as a result of overly ing rock denudation is believed to be extremely dangerous. This possibility should be addressed in the area selected for waste isolation. This paper d eals with tasks, methods, and the problems of prediction of these events bo th for relatively shortterm (up to 10000 yrs) and long-term (up to 20 milli on yrs) periods. The process directly controlling the possibility of reposi tory exposure depending on the geomorphologic setting is represented by den udation, whose qualitative and quantitative parameters change in space and time depending on the topographical environment: (1) altitude and different iation and (2) substrate lithology and landscape-climatic environments. A c omparative analysis of methods of denudation rate calculations aimed at the assessment of the possibility of repository exposure, as well as an analys is of the indefiniteness occurring during these calculations, was performed . It was concluded that, taking into consideration the relief evolution, ca lculation methods applied to the assessment of the possibility the reposito ry exposure are trustworthy only for short-term predictions. In the case of long-term predictions, the geomorphologic assessment should be based on th e probabilistic approach and evolutionary models, which take into account p robable changes of the structural state of the area over the period of time corresponding to major geologic events in the development of the earth's c rust.