This report (HPA-RPD-032) describes the Gamma Radiation Above Nuclides In Soil (GRANIS) model for calculating external photon dose.
GRANIS is a model developed by the Health Protection Agency (HPA) to calculate the external photon dose from layers of contaminated material which have finite thickness yet are effectively infinite in horizontal extent. The model allows different vertical activity profiles to be considered, so has particular application for the prediction of external gamma irradiation following the deposition of radionuclides to ground following short or continuous releases to the environment. GRANIS calculates effective dose and equivalent dose for 4 tissues.
This report describes the theory behind the GRANIS version 3 model and includes results calculated for a set of typical cases.