Use of natural analogues to support radionuclide transport models for deep geological repositories for long lived radioactive wastes

Plans to dispose high level and long lived radioactive wastes in deep geological repositories have raised a number of unique problems, mainly due to the very long time-scales which have to be considered. An important way to help to evaluate performance and provide confidence in the assessment of safety in the long term is to carry out natural analogue studies. Natural analogues can be regarded as long term natural experiments the results or outcome of which can be observed, but which, by definition, are uncontrolled by humans. Studies of natural analogues have been carried out for more than two decades, although the application of information from them is only relatively recently becoming scientifically well ordered. This report is part of a the IAEA's programme on radioactive waste management dealing with disposal system technology for high level and long lived radioactive waste. It presents the current status of natural analogue information in evaluating models for radionuclide transport by groundwater. In particular, emphasis is given to the most useful aspects of quantitative applications for model development and testing (geochemistry and coupled transport models). The report provides an overview of various natural analogues as reference for those planning to develop a research programme in this field. Recommendations are given on the use of natural analogues to engender confidence in the safety of disposal systems. This report is a follow up of Technical Reports Series No. 304 on Natural Analogues in Performance Assessments for the Disposal of Long Lived Radioactive Waste (1989)