Estimation of external plume dose for a coastal site

•The developed model estimates external plume photon dose for a coastal site.•The model comprises plume dispersion and point kernel integration modules.•It includes the effect of pollutant dispersion in stable and unstable layers.•A parallel version of the code is also developed for large number of calculations. Estimation of external exposure due to atmospheric releases of photon emitting radionuclides from nuclear facilities is important during normal and emergency conditions since their contribution to the total public dose is relatively significant. Gaussian plume model coupled with either semi-infinite cloud model or finite plume integration method is normally used to estimate this dose component for inland sites. However, for coastal sites, shoreline dispersion model that handles local sea-land breeze circulation should be coupled with the external plume dose-computing module. In the present study, plume external photon dose is calculated for coastal sites considering appropriate combination of these two dispersion models and finite plume integration model. Based on this methodology, a simple and fast calculation tool is developed to estimate external plume doses under normal operating (sector average plume) and accidental conditions (single plume). This numerical program can also be used for source term estimation from field measurements, thereby assisting decision support system during emergency situations.