Monte Carlo implementation of a Gaussian plume model for submersion dose calculation at short downwind distances.

This article focuses on evaluating the limitations of the Gaussian plume model (GPM) for dose assessment from radioactive atmospheric releases, particularly at short downwind distances from low-height emission sources. The study compares two GPM-based software tools, HotSpot and GENII V2.10, with a Monte Carlo radiation transport implementation of GPM in FLUKA, using a scenario involving the release of the radionuclide Argon-41 (41Ar) under different atmospheric stability classes. Results indicate that HotSpot and GENII V2.10 significantly overestimate doses inside the plume due to the semi-infinite cloud approximation and fail to capture dose contributions from photons outside the plume, which FLUKA's Monte Carlo approach can detect. The article suggests that while GPM-based codes remain valuable for rapid and conservative evaluations, more refined Monte Carlo simulations are necessary for accurate dose quantification in scenarios such as medical or industrial facilities with low release heights and complex environments.