Effect of rainwater on the remobilization and dissolution of 134Cs and 85Sr contained in aerosols similar to those discharged in a nuclear accident and deposited in an urban environment

An accident in a PWR could lead to discharge of radioactive aerosols into the atmosphere. The present study consisted of establishing, under laboratory conditions, how the caesium and strontium contained in such aerosols are remobilized by rainwater after dry deposition in an urban environment. Aerosols representative of those discharged in a PWR accident were generated and deposited on five building materials used in France. A rainfall simulator was used to provide varying intensities of rain. The percentages remobilized, both as particles and dissolved in rainwater, were then measured. Remobilization is dependent on the nature of the material, the radioelement and the intensity of the rain. It varies from 5 to 60% for caesium and from 5 to 30% for strontium. Remobilization increases as rain intensity decreases. Caesium is mainly remobilized in dissolved form while strontium is remobilized in the form of particles.