Numerical simulations on the leakage and diffusion of tritium

Abstract

Based on the knowledge that the surroundings of tritium leakage and diffusion in hydrogen storage vessels can be either open space or closed space, the subsonic jet flow of a slow tritium leak from a hydrogen storage bed under open and closed spatial conditions is simulated by Fluent finite element software. Furthermore, the quantitative relationship between mass flow rate and time is established by using the user defined function (UDF) to compile interface codes. The subsonic tritium jet, velocity profiles, tritium diffusion distance, and the tritium concentration along the jet trajectory are obtained in two different scenarios (open space and closed space). The results show that the closed space inhibits the vertical convection diffusion of tritium and has a favorable improving effect on the horizontal convection diffusion of tritium, whereas the open space has the opposite influence on the convection diffusion of tritium. In addition, an eddy current whirlpool develops under the closed space condition. The concentration distribution along the jet center line can be significantly influenced by the spatial boundary condition and leak aperture. An increase of leak aperture facilitates vertical diffusion of tritium and the velocity near the leakage hole. The oblique downward wind and horizontal wind lead to an enhancement of tritium cloud horizontal drifting. The oblique upward wind can be considered as a method to effectively dilute leaked tritium concentration.