Beta dosimetry of airborne hot particles from Chernobyl fallout

A technique for beta dosimetry of hot particles from Chernobyl fallout has been developed. It allows the dose distribution around a hot particle in biological tissue to be evaluated. The experimental technique is based on measurement of individual electron tracks in a hot particle autoradiogram in a nuclear emulsion: as a result, the beta dose distribution in the emulsion is measured. It is shown that the dose distribution in emulsion and in biological tissue is generally the same with uncertainties not worse than 20%. This was proved by calculation of the beta electron transport in tissue and in emulsion. The nuclear fuel beta spectra at different times after the accident were used in calculation. Calculated results are in good agreement with autoradiography experimental data. It was found that the dose curve alteration with time, after the accident, depends mainly on nuclide disintegration rather than spectral shape deformation. Thus, simple evaluation of dose distribution in tissue is available using only either beta activity data or experimental optical density curves from the autoradiogram. Activities, specific activities and sizes of airborne particles, accumulated in lung tissue near the Chernobyl NPP were measured by autoradiography methods.