Sustained uranium dioxide/concrete interactions tests: The SURC test series

The SURC-1 and SURC-2 tests were large-scale tests of the interactions of molten UO2-ZrO2-Zr mixtures with limestone and siliceous concretes. Each of the tests included in the melt charge a selection of fission product elements. Releases of these elements provide data for development and validation of fission product release models. The tests show that heat transfer models developed for the CORCON code can predict the erosion of concrete by oxidic as well as metallic melts. Zirconium chemistry drastically affects the interactions of melts with concrete and must be included in the models of ex-vessel core debris interactions to predict loads on reactor containments early in the ex-vessel phase of a severe accident. Aerosols produced during the interactions are predominantly composed of concrete constituents, but also contain significant amounts of barium, cerium, and uranium. The results of the SURC tests provide a vehicle for substantial validation of models such as CORCON and indicate that an adequate understanding now exists concerning core debris interactions with concrete when liquid water is not present. (orig./HP)