A study on the gaseous radionuclide dispersion in the highway across urban blocks: Effects of the urban morphology, roadside vegetation and leakage location

Abstract

Spent fuel is a used nuclear waste that poses a great hazard to human body and the environment. In this work, the dispersion of gaseous radionuclides from the highway to downstream urban is simulated using CFD based on a hypothetical spent fuel transport accident, with focus on the effects of urban morphology, roadside vegetation and leakage location. The velocity field, TKE (turbulent kinetic energy) distribution and radionuclide concentration under different conditions are carefully explored. The results show that the dispersion of radionuclides is greatly influenced by the velocity field and TKE distribution. The health risk to the residents of sparse urban is lowest when the leakage source location is set in the highway where both directly upstream and downstream are empty, due to the strongest flow channeling effect. When the leakage source location is set in the highway where both directly upstream and downstream are buildings, the health risk to the residents of compact urban is lowest, since the flow velocity and TKE at the street canyons are very low. The roadside vegetation can generally decrease the concentration of the radionuclides near the highway. This work provides guidance on assessing the health risk of the population and a reference for emergency response.