We perform experiments simulating reactor core melt phenomena in which molten core debris (“corium”) erodes the concrete floor of a containment building. This occurred during the Fukushima nuclear power plant accident though the extent of concrete damage is yet unknown. This video shows the top view of a churning molten pool of uranium oxide at 2000°C (3600°F) seen during an experiment at Argonne. Corium behaves much like lava.

The molten corium is held within a concrete vessel that mimics the floor of a reactor containment building. In a reactor accident, the corium generates large amounts of heat and disintegrates the concrete floor if not cooled. This animation depicts our experiment in which corium disintegrates concrete; corium in red and concrete in blue. The human silhouette is shown to provide scale.

We measure the erosion rate and profile for various concretes used in power plants. This is test data showing temperature and the erosion of 300 mm (12”) of concrete over 7 hours (corium not shown).

Top view of hot corium immersed in water. Quenching of corium with water creates a surface crust in much the same way that seawater freezes lava flows. Concrete disintegration gases propel jets of corium through the crust and into the water, seen here as sparks.