Treatment of Radionuclide Transport in Geosphere

Geosphere retention of radionuclides can be an important component of the safety case for deep geological disposal of radioactive wastes. Methods to evaluate and model the migration of radionuclides in the geosphere have been developed intensively over many years. The RETROCK project, "Treatment of Geosphere Retention Phenomena in Safety Assessments", has examined how the retention and transport of radionuclides are dealt with in performance assessment (PA) models for deep geological repositories and how this could be further developed and improved. RETROCK is a part of Euratom's research and training programme and, as a Concerted Action, its work is based on existing background knowledge. The environment considered in RETROCK is saturated, sparsely fractured rock in the socalled far-field (between the repository and the biosphere), where the interconnected fracture network provides flowpaths for groundwater that could transport radionuclides.