Predicting contamination levels in foodstuffs in the longer-term after a nuclear accident. Prof. Nick Beresford

Following the 1986 Chernobyl accident restrictions were placed on the movement and slaughter of sheep in upland areas of the United Kingdom because of high 134,137Cs activity concentrations in their meat. It was stated that the restrictions would be in place for a matter of weeks, but, in actual fact restrictions were in place until 2012. Why were the original predictions so wrong? The answer is, models which were not fit for purpose.

The Chernobyl accident highlighted that some areas may be more ‘sensitive’ or ‘vulnerable’ (e.g. have comparatively high transfers to foodstuffs or contribute relatively high fluxes of radionuclides to the public via contaminated foodstuffs) to radiological contamination than other areas. Commonly used models to predict radionuclide activity concentrations in human foodstuffs tend to use empirical soil-to-plant transfer factors (or soil-plant concentration ratios) to describe the transfer of radionuclides from soil to crops. Such models cannot easily cope with variation in root uptake caused by variation in soil properties. In the late 1990’s – 2000’s, process-based soil-plant transfer models were developed that could be implemented spatially and predict radiocaesium transfer based upon relatively readily available soil properties (e.g. pH, soil organic matter content, clay content, exchangeable potassium).

The Fukushima accident renewed interest in process-based soil-plant models leading to their re-evaluation and the development of similar models for radiostrontium.

An overview, including potential future developments, of process-based soil-plant models will be given, with consideration about when such models are useful following an accidental release.

Prof. Nick Beresford leads the Environmental Contaminants Group at the UK Centre for Ecology & Hydrology’s Lancaster site. He has been a radioecologist for over 30 years and has an Honorary Professorship at the University of Salford. He is the Vice-President of the European Radioecology ALLIANCE (http://www.er-alliance.eu/) and an Associate Editor of the Journal of Environmental Radioactivity. In the 2000’s Nick was one of the developers of the ERICA Tool for the radiological assessment of wildlife and is now one of the group who maintains the tool and its under-pinning databases, as well as providing training on its use.

Current/recent projects include: investigations of wildlife in the Chernobyl Exclusion Zone; development of alternative approaches to model radionuclide transfer to wildlife and crops; application/development of process-based soil-plant models; working with local communities and government agencies to consider future management options for areas of the Ukraine abandoned after the Chernobyl accident. Nick is also contributing to the development of the ICRPs environmental protection framework and the IAEAs modelling approach for planned releases.

Nick has published around 190 referred papers and, with Prof. Jim Smith, wrote the book Chernobyl Catastrophe and Consequences. He currently co-supervises PhD-students at the universities if Salford and Stirling.

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