An analysis of the sensitivity of non-urban environments to radioactive contamination under the IAEA EMRAS-II Program

Since the early 1980s the International Atomic Energy Agency (IAEA) has led a succession of international programs to improve environmental transfer models for the assessment of radiological impacts on humans and non-human biota arising from radionuclides in the environment. These programs have included VAMPS (Validation of Model Predictions), BIOMASS (BIOsphere Modelling and ASSessment), and EMRAS (Environmental Modelling for RAdiation Safety). The current EMRAS-II program (2009-2011) includes both routine and accidental emissions of artificial and natural radionuclides .This paper reports on the activities of Working Group 8 dealing with sensitive non-urban environments. In addition to conventional agricultural settings in the temperate zones, the group is considering special environments such as Alpine, Arctic, temperate forests, freshwater aquatic, and coastal marine environments.Initial modelling exercisesare being carried out for depositions of the long-lived radionuclides 137Cs and 90Sr and the short-lived radionuclide 131I. Radionuclides concentrations are calculated in several environmental compartments, especially those leading to human exposures. Short term and long term radiations doses are calculated to the most exposed human populations. The goal of these exercises is not just to compare different models but also to use these models as tools to investigate which environments and which components of each environment would be most sensitive to a major release of radionuclides. The results will aid in the planning and implementation of emergency countermeasures following a nuclear accident.