An analysis of hydrogen dispersion from leakage in nuclear containment using large eddy simulation

Hydrogen leaking inside a nuclear power plant poses a critical safety issue and accurate prediction of the dispersion process of hydrogen has become an important topic of research. In the present study, temporal evolution of hydrogen dispersion in a test facility (called PANDA) for nuclear safety is analyzed using high-fidelity simulation techniques such as large eddy simulation (LES), high-order discretization methods, immersed boundary (IB) method, etc. An important topic in this study is how a turbulent buoyant jet of a hydrogen-vapor mixture interacts with a hydrogen layer accumulated near the ceiling of a container. It plays some role a biased shift of the jet trajectory which is different from a regular buoyant jet. Also, we observe more realistic representation of turbulent dispersion and coherent structures compared to conventional RANS simulations. The present data such as the depth of jet penetration and the velocities of fountain propagation in horizontal and vertical directions are compared with the theoretical scaling laws. Furthermore, the dispersion process is analyzed using evolution of the flammable region and profiles of the mass fraction of hydrogen.