New approaches to deriving limits of the release of radioactive material into the environment

During the last few years, new principles have been developed for the limitation of the release of radioactive material into the environment. It is no longer considered appropriate to base the limitation on limits for the concentrations of the various radionuclides in air and water effluents. Such limits would not prevent large amounts of radioactive material from reaching the environment should effluent rates be high. A common practice has been to identify critical radionuclides and critical pathways and to base the limitation on authorized dose limits for local ''critical groups''. If this were the only limitation, however, larger releases could be permitted after installing either higher stacks or equipment to retain the more short-lived radionuclides for decay before release. Continued release at such limits would then lead to considerably higher exposure at a distance than if no such installation had been made. Accordingly there would be no immediate control of overlapping exposures from several sources, nor would the system guarantee control of the future situation. The new principles described in this paper take the future into account by limiting the annual dose commitments rather than the annual doses. They also offer means of controlling the global situation by limiting not only doses in critical groups but also global collective doses. Their objective is not only to ensure that individual dose limits will always be respected but also to meet the requirement that ''all doses be kept as low as reasonably achievable''. The new approach is based on the most recent recommendations by the ICRP and has been described in a report by an IAEA panel (Procedures for establishing limits for the release of radioactive material into the environment). It has been applied in the development of new Swedish release regulations, which illustrate some of the problems which arise in the practical application