As hydrogen-air mixtures are flammable in a wide range of concentrations and the minimum ignition energy is low compared to hydrocarbon fuels, the safe handling of hydrogen is of utmost importance. Additional hazards may arise with the inadvertent spill of liquid hydrogen. An accidental release of LH2 leads to a formation of a cryogenic pool, a dynamic vaporization process, and consequently a dispersion of gaseous hydrogen into the environment. Several LH2 release experiments as well as modeling approaches address this phenomenology. Different model approaches have been validated in the past against the existing experimental data. These models can be divided into two sections:

1. Models calculating cryogenic pool propagation and vaporization rates,

2. Models calculating gaseous hydrogen dispersion using pre-calculated evaporation rates and pool surface areas as source term.

This leads to uncertainties if LH2 pool models lack relevant processes for vaporization, and in the gas distribution models the source term represents only an approximation of the real source term. At Forschungszentrum Jülich, a transient 3D multicomponent-multiphase model has been developed, using the commercial code ANSYS CFX 15.0 and including the additional sub-models of the rates of vaporization on solid ground, volume vaporization, humidity, and the influence of changing wind conditions. This new modeling approach is capable to simulate the release of LH2, its spreading and vaporization, and the gas distribution in the atmosphere under realistic environmental conditions (e.g. humidity and changing wind conditions). The model has been validated against recent LH2 spill experiments conducted by HSL and the NASA.