Study on the formation processes of air concentration of a radioactive material and dose rate distributions over hilly-terrains by LHADDAS

Nakayama, Hiromasa   ; Satoh, Daiki   ; Kadowaki, Masanao   

In local-scale atmospheric dispersion problems, an important issue is the accurate analysis of airborne radioactive materials released from nuclear facilities for safety and consequence assessment. At distances of up to several kilometers from the emission source, inhomogeneous distributions of air concentration and surface deposition around the evaluation point should be investigated considering the turbulent effects induced by individual buildings and local terrain variability. In this study, we perform a numerical simulation of unsteady behaviors of turbulent flow and plume dispersion over a 2-dimensional hill by a local-scale high-resolution atmospheric dispersion and dose assessment system (LHADDAS). Then, we investigate the formation processes of air concentration and dose rate distributions over the hill from the viewpoint of the turbulent structures.