Modelling steam explosions for the Savannah River Site reactor probabilistic risk assessment

As part of the probabilistic risk assessment (PRA) for the Savannah River Site (SRS) reactors, a theoretical model has been used to evaluate the magnitude of steam explosions that could occur during postulated severe accidents at the plant. The model predicts pressure, steam generation and mechanical work during the explosion phase of the interaction. The model is applied to two hypothetical events illustrating typical small-scale and large-scale explosions found in the PRA. These two examples show that yield predictions may range from megajoules to gigajoules for kinetic energy, 10 to 1000 kg for steam generated, and 10 to 1000 atm for peak explosion-zone pressures. A brief study is made to characterize the sensitivity of kinetic energy yield to initial fuel mass and fuel temperature. Explosion kinetic energy increases linearly in proportion to fuel mass, but displays a non-linear dependence on fuel temperature over parameter values of interest