Conversion and modification of the MLSOIL and DFSOIL codes

Research after the Chernobyl nuclear accident has revealed that the greatest contribution to the long-term external dose rates after the accident in both the urban and rural environment comes from radionuclides deposited onto the ground surface. The migration of these radionuclides into soil with time is important for the estimation of the external dose rates from the ground. Two computer code, MLSOIL and DFSOIL, have been originally developed at ORNL in USA for modelling the migration of radionuclides in an undisturbed agricultural land and calculating the resultant external dose rates. It is possible to apply these codes to an open area in the urban environment as well. Therefore, MLSOIL and DFSOIL were converted and modified to make the implementation of the codes easy. Input data files were also prepared for radionuclides important for the assessment of a nuclear accident. Finally the modified versions of both codes were verified to have the intended calculational functions. (author)