[en] An experiment was performed in order to evaluate the additional effects of zirconium metal oxidation on core debris interactions using molten stainless steel as the core debris simulant. The SURC-4 experiment eroded a total of 25 cm of basalatic concrete during 62 minutes of sustained interaction. The meltpool temperatures during the test ranged from 1500/degree/C before zirconium addition to 1650/degree/C during the zirconium-steel-concrete phase of the test which lasted 42 minutes. Large increases in erosion rate, gas production, and aerosol release were also measured shortly after Zr metal was added to the melt. The data return from the test was outstanding and these results were subsequently used as input to an OECD code comparison exercise. 19 refs., 86 figs., 32 tabs