Detection and removal of a large area Cs-137 contamination at a scrap processing plant

Radioactive contaminations of larger quantities of scrap have been detected in several cases. One incident of this kind, which occurred in an aluminium factory, is presented in some detail. 7000 tons of aluminium scrap material had to be scanned for Cs-137. A portal monitor was used to scan the material, which had been loaded into railway wagons, automatically. It was proved that the specific activity limit of 100 Bq/kg was not exceeded. However, the asphalt and gravel in front of the storage hall had to be removed and decontaminated