Abstract
The experience from ITER (International Thermonuclear Experimental Reactor), highlights the importance of addressing fire and explosion risks involving hydrogen in future fusion plants, where hydrogen isotope inventories will be even larger, especially in DEMO (DEMOnstration power plant) and other fusion reactors. The study reviews safety cases related to hydrogen–oxygen reactions that could lead to explosions, analysing the chemical, thermodynamic and gas dynamic aspects influencing such events. A literature review revealed significant inconsistencies in available data, due to differences in standards, experimental geometries, ignition energies and criteria. To overcome these gaps, various test rigs were compared, leading to the selection of a 20 liter spherical apparatus for a focused experimental campaign. The work evaluated LEL (Lower Explosion Limits) and UEL (Upper Explosion Limits) of hydrogen–air mixtures at sub atmospheric condition between 5 and 100 kPa, also studying the temperature effect. Results were analysed using ASTM E918 to determine explosive limits under these conditions and to assess explosion severity through the Kst index.
