Analysis of core life-time and neutronic parameters for HEU and potential LEU/MEU fuels in a typical MNSR

► We model absorbed dose due to b & g -activity of I-131 to thyroid using GEANT4. ► We examine dose for water, ICRP & ICRU soft tissues simulating thyroid tissues. ► The results are validated by comparison with MIRD calculations and experiments. ► Spherical model shows 0.45% increase in dose as compared to the cylindrical model. ► Thyroid dose show good agreement with experiments & with the published results.