Stochastic models for individual external dose reconstruction of population evacuated after the Chernobyl accident

As a result of the Chernobyl accident, the residents of Pripjat and other settlements of the 30 km zone were affected by substantial amounts of radiation with the potential of delivering them significant radiation exposures before their evacuation. A reconstruction of individual doses of evacuees, including the determination of the uncertainty of the results, is of interest for epidemiological investigations. Dose rate measurements conducted in the time span between accident and evacuation and individual behavior data obtained by a questionnaire survey involving more than 30,000 evacuees allow for a reconstruction of individual external doses of a large fraction of the evacuated population. A first assessment has already been reported. The results revealed a large variation range for doses of different individuals, showing the importance of performing individual dose reconstructions. This paper reports on developments and results of a second stage of individual external dose reconstruction. In particular, stochastic models based on Monte Carlo methods were developed in order to determine uncertainty distributions of calculated doses from an assessment of the uncertainty of the data. (author)