Abstract: As stated in 10CFR § 50.34（f）, containment integrity will be maintained during an accident that releases hydrogen generated from 100％ fuel clad metal-water reaction accompanied by hydrogen burning. This paper presents the method to calculate the combustion pressure load post accidents assuming the combustion process is adiabatic, complete and at constant volume, based on the energy balance equation and ideal gas equation before and after hydrogen Combustion. Then, based on this method, this paper calculates the pressure loads of 300MWe and 1000MWe Nuclear Power Plants designed in China from hydrogen combustion generated 100％ fuel clad metal-water reaction, and demonstrates the containment design of these two types meet the requirements of 10CFR § 50.34（f）.