Evaluation of dose conversion coefficients for external exposure to radionuclides in the environment; Exposure to contaminated soil

Satoh, Daiki   ; Endo, Akira   ; Bolch, W.*; Lee, C.*

In order to make a remediation strategy for the contaminated environment, it is important to assess the radiation dose from external exposure to radionuclides distributed in the environment. To meet the demand, we evaluate the dose conversion coefficients for environmental radionuclides with latest knowledge of radiation protection, and the data are prepared for typical ages from newborn to adult. In this work, the evaluation of the dose conversion coefficients is performed as follows: (1) Determination of radiation field in the environment by means of particle transport simulations in a huge geometry considering the nuclear interactions. (2) Calculation of organ absorbed doses using voxel phantoms put in the radiation field determined above. (3) Derivation of dose conversion coefficients for each radionuclide from the analysis of the absorbed doses using decay data library employed in the ICRP Publication 107. (4) Preparation of the data for dose assessment at typical age from newborn to adult. From the calculations, it was found that the effective dose increases with decreasing the body size of the phantoms.