• FSI
• Hydrogen
• Detonation
• SSEXHY

In industry sectors handling hydrogen, explosions are feared because of their harm for on people and property. In the nuclear industry, hydrogen explosions, which are possible during severe accidents, can challenge the containment and potentially release radioactive materials into the environment. The Three Mile Island accident in the United States in 1979 and more recently the Fukushima accident in Japan have highlighted the importance of this phenomenon for a safe operation of nuclear installations and during accident management.

In 2013, the French Research Agency (ANR) launched the MITHYGENE project with the main aim of improving knowledge on hydrogen risk for the benefit of reactor safety. In this project, one of the areas of work concerned the effect of hydrogen explosions. In this context, CEA carried out a test program with its SSEXHY facility and CFD computational analysis with the EUROPLEXUS code to build a database on deformations of simple structures following an internal hydrogen explosion. Different regimes of explosion propagation have been studied from detonation to slow deflagration. Different targets were tested such as plates of variable thickness and cylinders. Detailed instrumentation was used to obtain data for the validation of coupled CFD models of combustion and structural dynamics.

In this work, a validation of the models addressing Fluid Structure Interaction (FSI) implemented in EUROPLEXUS code was performed. In the validation procedure a step-by-step approach was adopted. Three main steps were involved starting by validating the target boundary conditions with quasi-static tests. Then, in a second step, the dynamics of the structure was studied in a decoupled manner using the verified boundary conditions obtained from the first step; this resulted in obtaining reasonable results compared to the experimental ones. Eventually, the third step was devoted to study the dynamics of the structures in a coupled manner with the treatment of the propagation of the explosion in the tube.