Enhancement of the ERMIN urban dose and remediation model to account for physicochemical properties of contamination

The European Model for Inhabited Areas (ERMIN) predicts long-term doses and other consequences following contamination of built-up areas by airborne radioactivity. Central to ERMIN are empirical models of the long-term contamination on urban surfaces taking into account weathering and clean-up. Previous versions were largely based on the behaviour of caesium following the Chernobyl accident. Recommendations from a review on the physicochemical properties of particles have allowed enhancement of ERMIN to make it appropriate to a wider range of situations, in particular those where there may be a large proportion of insoluble fuel particles. Weathering experiments in which building materials were contaminated and weathered outdoors have reinforced some of the retention assumptions made by ERMIN but also suggest ways in which future versions of the model might be developed. This paper describes the changes made to ERMIN while maintaining its operational utility within decision support systems and it gives an example of how different assumptions regarding the physicochemical make up of particles can affect results.