Risk assessment for chemical pickling of metals contaminated by radioactive materials

In recent years, many cases of contamination of metal scraps by unwanted radioactive materials have occurred. Moreover, international organisations are evaluating the possibility to re-use or to recycle metals coming from nuclear power plants. The metal recycling industry has started to worry about radiation exposure of workers that could be in contact with contaminated metals during each manufacturing phase. Risks are strongly dependent on the radiation source features. The aim of this study is to perform risk assessment for workers involved in chemical pickling of steel coils. Monte Carlo simulations have been performed, using the MCNP package and considering coils contaminated with 60Co, 137Cs, 241Am and 226Ra. Under the most conservative conditions (coil contaminated with 1.0 kBq g-1 of 60Co), the dose assessment results lower than the European dose limit for the population (1 mSv y-1), considering a maximum number of 10 contaminated coils handled per year. The only exception concerns the case of 241Am, for which internal contamination could be nonnegligible and should be verified in the specific cases. In every case, radiation exposure risk for people standing at 50 m from the coil is widely <1 mSv y-1. © The Author 2006. Published by Oxford University Press. All rights reserved.