Modelling of a large-scale urban contamination situation and remediation alternatives.

The Urban Remediation Working Group of the International Atomic Energy Agency's EMRAS (Environmental Modelling for Radiation Safety) program was organized to address issues of remediation assessment modelling for urban areas contaminated with dispersed radionuclides. The present paper describes the first of two modelling exercises, which was based on Chernobyl fallout data in the town of Pripyat, Ukraine. Modelling endpoints for the exercise included radionuclide concentrations and external dose rates at specified locations, contributions to the dose rates from individual surfaces and radionuclides, and annual and cumulative external doses to specified reference individuals.

Improvement of modelling capabilities for assessing urban contamination: the EMRAS Urban Remediation Working Group.

The Urban Remediation Working Group of the International Atomic Energy Agency's Environmental Modelling for Radiation Safety (EMRAS) programme was established to improve modelling and assessment capabilities for radioactively contaminated urban situations, including the effects of countermeasures. An example of the Working Group's activities is an exercise based on Chernobyl fallout data in Ukraine, which has provided an opportunity to compare predictions among several models and with available measurements, to discuss reasons for discrepancies, and to identify areas where additional information would be helpful.

[Colonization and destruction of concrete by mitosporic fungi in model experiment].

When investigating the action of microscopic fungi of genera Aspergillus, Alternaria, Cladosporium and Paecilomyces on concrete specimens in the model system, it was shown that the fungi can colonize successfully the concrete surface during 1 year and cause its destructive changes. However the fungi did not colonize those sections of concrete surface which were filled with granite. The fungi leached chemical elements of concrete into nutrition medium, accumulated them in their biomass and caused their transformation into newly-formed crystals of calcium oxalates on the surface of concrete.