A new method to account for the depth distribution of 137Cs in soils in the calculation of external radiation dose-rate

This work reports a new method for calculating the external dose-rate as a function of height above land that has been contaminated with a surface deposition of 137Cs. Unlike previous work this method accounts for vertical migration of 137Cs using the Advection Dispersion Equation (ADE) with appropriate parameters. The results have been successfully verified with field measurements from the 137Cs contaminated regions within the Republic of Belarus. The method also correctly predicts the observed variation of dose-rate with elevation above the soil surface and it is shown how this method can be used to predict the reduction in surface dose-rate after remediation measures such as deep ploughing have taken place.