US EPA

8323610 

Meetings & Symposia 

Post-accident analysis of hydrogen explosion during Fukushima Daiichi accident 

Kuznetsov, M; Yanez, J; Jordan, T 

2012 

110-116 

English 

Hydrogen mixing and combustion in containment of Nuclear Power Plant (NPP) is one of the important issues of severe accident scenario. Different flame propagation regimes from slow subsonic to relative fast sonic flames and then to the detonations may develop depending on geometry of reactor building and mixture composition. It may lead to different strength of blast wave and effect on surrounding objects. This allows to resolve an inverse problem to evaluate amount of combustible gas knowing strength of blast wave. A post-accident analysis of Fukushima accident was done with respect to evaluate amount of hydrogen released due to reaction of molten core with water. A thermodynamic analysis of high pressure release of steam and hydrogen from reactor vessel was done with respect to evaluate the mixture composition inside the reactor building. It was found that 80 to 200 kg of hydrogen have been involved into the explosion with formation of relative strong shock wave. A fast deflagration was assumed to be the most probable explosion regime with 800 kg of TNT equivalent. The effect of blast wave from such explosion on structures and biological objects was evaluated. The objective of current work was to evaluate amount of hydrogen involved into the explosion process, to define combustion regime and effect of blast wave on environmental objects, structures and humans. The main outcome of the work was to demonstrate how to utilize scaling correlations, experimental data analysis and numerical codes for accident and safety analysis.