Diverse challenges associated with legacy near-surface waste disposal sites

Full text: Numerous countries around the world are currently managing various types of sites contaminated with radioactive materials derived from past nuclear activities and accidents. Many of these sites consist of a shallow excavation in the ground (with or without engineered containment) into which radioactive waste materials were placed - these are sometimes referred to as "legacy trench sites". Many of these sites were operational in the decades following the Second World War, when research into nuclear power and related activities was rapidly expanding in many countries worldwide. During this period, there was no international consensus on disposal of radioactive waste, and shallow burial was a commonly used method for disposing of low-level wastes. It is now recognized that some of these sites may pose immediate or future unacceptable radiological risks to members of the public and/or the environment, and therefore require the consideration of management options and evaluation of remedial actions. Problems associated with managing these sites include the lack of site-specific information (including characteristics of buried wastes), unclear responsibility and ownership, limited availability of technical expertise, scientific uncertainty, societal issues, and various constraints and limitations. The future management of these sites would be improved by international cooperation aimed at encouraging IAEA Member States to take relevant measures in management of legacy sites. The Legacy Trench ("abdou") initiative, within the IAEA Environet network, aims to address the needs identified above. The activities of this working group will include: developing a global inventory of legacy sites, encouraging preservation of relevant information, identifying and addressing common issues, developing methods of disseminating knowledge, provision of technical assistance or advice, and maintaining relevant expertise. (author)