Modeling the dispersion of radionuclides released during reactor accidentsaboard nuclear-powered vessels

A radioactive aerosol and vapor dispersion model, RADiM, has been developed to predict the distribution of acquired doses from radionuclides escaping into the atmosphere following a marine reactor accident. Designed as a deci sion aid for emergency response teams, RADiM is based on a Gaussian plume m odel, which considers decay and transmutation, as well as meteorological an d terrain effects. An initially estimated source term can be adjusted for s trength and composition, based on subsequent field survey measurements and gamma-spectroscopy. RADiM was validated using field release data and was co mpared to predictions from established codes. Possible accident scenarios w ere also examined.