Alpha particle energy spectra were measured at femoral endosteal surfaces of Canadian Arctic caribou (Rangifer tarandus) to assess the profile of concentration with depth of 210Po supported by 210Pb. Femur samples from five caribou all showed a pronounced superficial concentration of 210Po, in a layer 1.9 - 6.4 microns thick. Within this layer 210Po was concentrated 1.5 - 10 times with respect to diffuse volume-distributed 210Po. This result is consistent with an earlier study of 210Po at human cranial bone surfaces, which showed 210Po to be concentrated about four times in a surface layer <3 microns thick. However, the present results have higher precision than the human bone data due to the much greater concentration of 210Pb and 210Po in caribou bone. The validity of using 210Po as a marker of 210Pb, and the in vivo 210Po/210Pb ratio are discussed. As a result of the measured endosteal superficial concentration of 210Po in caribou, the alpha particle dose was calculated to be enhanced by a factor of 1.06 - 1.96 (mean 1.48) for bone lining cells, and of 1.08 - 2.39 (mean 1.69) for soft tissue above the bone surface, assuming equilibrium between 210Pb and 210Po. It is suggested that an additional longer-lived compartment for bone surface lead could be incorporated into bio-kinetic models for lead.
Results of the aerosol sampling inside the Object Shelter at the Chornobyl nuclear reactor site are considered in the work. The results show a consistent and significant contribution of submicron fraction to the total aerosol activity. Different methods of interpretation of impactor data series are compared in order to indicate and detect in the most effective way the submicron fraction as a separate component of the distribution. The methods used are as follows-method of probabilistic-logarithmic scale, method of likelihood function, non-linear approximation by sum of several log-normal distributions, and restoration of the initial distribution using passage functions of impactor cascades. Practically all the collected data on aerosol distribution inside the Shelter show a distinct submicron component. The contribution of the submicron component into the total aerosol activity is about 35%. Influence of the actual aerosol distribution on the dose coefficients is analyzed.
Modern state and approach regarding organisation of individual internal dose monitoring of the personnel of industrial complex for radioactive waste management at the Chornobyl exclusion zone (CEZ) is presented. Sensitivity and adequacy of the acknowledged instrumental methods is considered taking into account the features of interpretation using indirect methods in the specific working conditions of industrial complex for radioactive waste management at the CEZ. The performed analysis enables clear recommendations to be made with regard to optimum design of an internal monitoring program for personnel, including application of specific techniques.
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