Reclamation of natural, seminatural and agricultural environments following radioactive contamination - A Nordic study

A range of methods, from simple cost benefits analyses to sophisticated decision making systems, are available for assessing the net countermeasure benefits to man contamination of different environments. As part of the Nordic Nuclear Safety Research Programme, an attempt was made to develop a strategy for mid- and long-term reclamation of contaminated cultivated agricultural environments, animals, forests, freshwater and fish, and urban environments. The study focused on the long-lived nuclides 137Cs and 90Sr. Also social implications and a sound environmental management should be addressed in the selection of a countermeasure strategy. The considerations of the cultivated agricultural environment included a model of a Nordic environment, with different soil types, land use and crops. When considering countermeasure strategies for animals, both transfer and production rates have to be compared, as the transfer of radiocaesium to animals in cultivated areas is low compared to the transfer in unimproved areas or to wild animals. The countermeasures considered for freshwater were: use of alternative water supply, and ion exchange method, and for freshwater fish: limiting consumption, brining in households, and wet land and lake liming. In urban environments knowledge on the source strengths, relative dose rate at different locations (indoor, outdoor) due to the deposition on different urban surfaces (roofs, walls, paved areas, trees, bushes etc.) is important. For all environments costs and averted doses were estimated for a fallout scenario giving 1 MBq m-2 of 137Cs. The effectiveness of the different countermeasures was then compared and reclamation strategies suggested. (author)