Reconstruction of doses from radionuclide inhalation for nuclear power plant workers using air concentration measurements and associated uncertainties

This paper presents a case study to illustrate the influence of parameter u ncertainties on calculating an internal radiation dose of one actual nuclea r plant worker, alias Mr. X, as well as the utility of air sampling for int ernal dose reconstruction. Input probability distributions for air concentr ations of radionuclides were derived from empirical air measurements taken by fixed area air samplers. The total internal dose was calculated by multi plying radionuclide intake by dose conversion factors in Monte-Carlo simula tions. There is significant variability in dose conversion factors and unce rtainty in the estimated concentrations of radionuclides in the air to whic h Mr. X was exposed. The high variability and uncertainty of the model para meters contributed to large ranges of predicted internal doses for Mr. X, T wo-dimensional Monte-Carlo simulations were conducted to separate contribut ions of the uncertainty and variability. Sensitivity analysis was conducted to determine which of the input parameters contributed most to uncertainty in internal dose estimates. Our analysis suggests that the uncertainty res ulting from use of general air surveys contributes more to the internal dos e ranges than the variability from DCFs and other population-derived parame ters, Reduction of the uncertainty in reconstructed internal dose can be ac hieved by using personal air sampling and/or individual bioassays and regul ar whole-body counting.