Time-Spatial Peculiarities of Dose Formation after Inhalation of Alpha Emitters

A detailed study of the time dynamics of radiation dose formation after inhalation of alpha-emitting aerosols has been carried out, using the Internal Dosimetry Support System (IDSS) computer code. The deformation of the primary aerosol size distribution has been calculated for all respiratory tract regions. The role of endogenous short-range radiation sources (body fluids) in the irradiation of lung tissues had been studied. The ICRP 66 Respiratory Tract model takes no account of energy self-absorption within aerosol particles so non-standard calculations of alpha particle energy transport were performed to investigate this effect. For UO2 particles of 20 and 100 μm AMAD containing uniformly distributed 239 Pu the committed equivalent dose to the extrathoracic tissues is reduced by factors of 1.1 and 3.9, respectively. The corresponding factors for committed effective dose are 1.1 and 3.2, respectively.