Research on simulation of hydrogen diffusion behavior based on CONTHAC-3D code

Abstract

An in-house code called CONTHAC-3D was developed to investigate the fundamental thermal–hydraulic phenomena occurred in the containment under severe accidents for NPPs. The code included specific models to simulate the special systems of HPR1000 and ACP100. The classical backward-facing step flow benchmark and BMC HYJET helium jet experiments were selected to investigate the code’s capability of simulating hydrogen diffusion process. The results showed that the difference between the calculated and experimental results could be negligible. The code was then applied to investigate hydrogen diffusion and distribution for HPR1000. The results showed that the hydrogen released from the break rises vertically and rapidly to the containment dome, then the gas diffused into the dome and lower compartments. As the time went by, the hydrogen concentration in lower compartments seemed to be higher than that in the containment dome. The results could provide foundation for the arrangement of hydrogen risk mitigation measures.