Mining and milling of uranium ores has been undertaken in many places around the world, resulting in large volumes of mining/milling residues with low activity concentrations of long lived nuclides that often have been disposed of in a haphazard fashion. This report summarizes the current state of the art of uranium mill tailings disposal and the results from an IAEA Coordinated Research Project (CRP) on technologies and strategies for their long term stabilization. The aim of the CRP was to develop conceptual and technical solutions that render tailings more inert over prolonged time spans, that render impounded materials and engineered structures stable over prolonged time spans, that minimize the need for active maintenance, and that are technically and economically feasible. The emphasis was on solutions that can be applied retrospectively, i.e. in a restoration/remediation context. It was recognized, however, that these objectives cannot be met by engineering design only, but must also involve appropriate management and planning procedures.
