Hydrogen is seen as an ideal energy carrier for stationary and mobile applications. However, the use of high energy density condensed hydrogen storage materials, such as NH3BH3, comes with risks associated with their high reactivity with water exposure and their decomposition products reactivity in air. To predict their behavior under these circumstances, idealized finite element models of hypothetical accident scenarios have been developed. Empirical thermodynamic calculations based on precise thermal gravimetric analysis (TGA) and calorimetric experiments have been performed in order to quantify the energy and hydrogen release rates and to quantify the reaction products resulting from water and air exposure.