The release without restrictions of material from nuclear plants

The release of material from nuclear plants, without restrictions from the viewpoint of radiation protection, is currently being discussed in several international organizations as well as by the relevant authorities in many countries. The need for co-ordination can be expected to increase in the future when nuclear plants will be decommissioned and the amount of candidate material for release will therefore be greater. This report gives an overview of current practices and of on-going work. The situation today is that most material release is treated on a case by case basis and, even in countries where there are regulations, the release limits applied vary from country to country: The IAEA and the EU have both produced draft proposals for nuclide specific release limits, based on risk-related calculations. The IAEA draft proposes limits for unconditional clearance, while the EU proposal gives separate values for direct reuse (only surface contamination limits) and for recycling by melting (both surface and mass-specific limits). A group, working within the OECD/NEA Co-operative Programme on Decommissioning, regards the risk criteria used in the IAEA draft as being over-conservative. They also point out that, in the case of contaminated metals, the risks associated with the production of new metals can be several orders of magnitude higher than the risk criteria used to permit recycling of the same metals. The report also discusses exemption, a term applied both by IAEA and the EU to denote the exempting from regulatory control of certain small sources of radioactivity. The report includes a chapter on the practice of exemption as well as the naturally occurring and other sources of exposure to radiation. Short description are given of the techniques considered necessary for recycling material for release, such as melting decontamination and measurement. 82 refs