Hydrogen Deflagration Analysis in THAI Experiments Using MELCOR Code

Abstract

The Research Center Řež (CVŘ) is developing a methodology to simulate nuclear power plants under accidental conditions. A particular effort is focused in the severe accident phenomenology where hydrogen deflagration carries a critical issue for the containment integrity, such as Fukushima Daiichi accident. For this purpose, the Thermal-hydraulics, hydrogen, aerosol and iodine (THAI) experimental campaigns are chosen due to the several tests involved in different conditions. THAI containment test facility is used to open questions concerning the behavior of hydrogen, iodine, and aerosols in the containment of water-cooled reactors during severe accidents.The Fukushima Daiichi Accident demonstrates that the hydrogen deflagration could lead to a significant containment damage. For this reason, a particular attention is given to the hydrogen deflagration scenario. All simulations are prepared and modeled in melcor 2.1. The results obtained showed a strong influence related to some factors such as: the nodalization pattern, control volumes (CVs) number, flow paths (FPs) number, and time-step. In order to assess the THAI model with the THAI final reports, a sensitivity analysis focused on those parameters was performed, which developed four different models with different nodalization.