The CFD Simulation Of Indoor Thoron And It’s Progeny Migrations

In recent decades, the risk of health caused by Radon and its daughters were being focused on with some correlate organizations and populations of the world. The radiation of Radon (including Thoron) and their daughters leading to the average effective radioactive dose per year per adult is1.2milliSevert in the world. But on the contrary with Radon, Thoron and its daughters were often ignored in the dose assessment just like the report of United Nations Scientific Committee on the Effects of Atomic Radiation in1993which pointed out that the effective dose of Thoron and its daughters was just6%to Radon and its daughters. By the increasing acknowledge and the growing investigation about indoor Thoron and its daughters in some countries and regions, the cases that the relative higher indoor Thoron concentration level were founded one after another that provoked people’s attention again.The numerical simulations by computer provide another research method for the indoor Thoron and its daughters cause the limited testing and measuring techniques. Especially, the Computational Fluid Dynamics (CFD) method could solve the indoor air flow problems that should not be neglected in indoor Thoron and its daughters more effectively than the common numerical simulation methods. CFD had more advantages that by solving the Thoron migration in indoor air flow and the progeny’s movement including their settings near the walls so it could provide the accurate results of the indoor Thoron and its daughters’ distributions and the dose assessment.In this paper we apply the turbulent diffusion equation to describe the movement of Thoron and the drift-flux model to represent its progeny’s migration in indoor air by the analysis of Thoron and its daughters’ movement features. We use the value of deposition quantity which was obtained from the settling velocity of Thoron’s daughters near the walls and let it be the boundary conditions, on this basement we design the programming codes and link to the FLUENT solver after compiled the codes and to do the coupling solve with the air flow. We calculate the concentration level of indoor Thoron and its daughters and their characteristics distributions by the different parameters selected as the ventilation rate and the exhalation rate of Thoron from walls, then we investigate the equilibrium factor between Thoron and its daughters and discuss the value of the equilibrium factor at different conditions for providing the reasonable and confidential results of indoor dose assessment about Thoron and its daughters.