Calculation of Fission-Product Gas Pressures in Operating UO₂ Fuel Elements

A method has been evolved for the calculation of the fission-product gas pressure inside operating UO₂ fuel elements. The calculations are based on a model in which the hot center of the UO₂ pellet is assumed to flow plastically under stress, and the outer annulus is cracked. The calculated pressures are shown to be in reasonable agreement with experimental measurements of the gas pressure inside fuel elements.