Hydrogen is not more dangerous than current fossil energy carriers, but it behaves differently. Therefore hydrogen specific analyses and countermeasures will be needed to support the development of safe hydrogen technologies. A systematic step-by-step procedure for the mechanistic analysis of hydrogen behaviour and mitigation in accidents is presented. The procedure can be subdivided into four main parts:

1. 3D modelling of the H2-air mixture generation
2. hazard evaluation for this mixture based on specifically developed criteria for flammability, flame acceleration and detonation on-set
3. numerical simulation of the appropriate combustion regime using verified 3D-CFD codes
4. consequence analysis based on the calculated pressure and temperature loads.