[en] The large scale sodium test facility in use at Sandia Laboratories was designed to be used for a wide range of sodium interaction experiments. Of initial concern is the interaction of hot sodium with concrete under conditions similar to accident conditions in any sodium cooled reactor. The tests to be run cover the cases of sodium spills and sprays on bare concrete and on cells with defective steel liners. The initial series of tests in progress at the facility involves rapidly dropping from 20 kg to 225 kg of sodium at temperatures from 550⁰C to 850⁰C into concrete crucibles that are representative of the concrete to be used at the Clinch River Breeder Reactor Plant (CRBRP). Specific objectives are to obtain sufficient information to completely describe the sodium/concrete interaction including: reaction rate, heat of reaction, gas evolution and flow, movement of the reaction front, reaction product formation, and the effects of variation of drop temperature and reaction area geometries