The European Commission’s Joint Research Centre at Ispra in Italy has announced some of the initial results of its first base-case spreading test involving 230 kg of a reactor corium melt. The experiment, performed mid-1997 in the FARO facility at Ispra, was set up to model the equivalent of a spreading of about 5 t of material in a full geometry.
Tests on core melt slumping and quenching in water and interaction with reactor components are essential for identifying appropriate accident management strategies and procedures to ensure long-term core melt retention within the reactor containment structure.
Videotapes of this experiment showed noticeable differences in comparison to earlier tests performed in several laboratories at lower temperatures or higher flow rates. In particular, the crust, formed at the top surface of the melt due to high radiation heat transfer, had a strong influence on the extent of the melt spreading.
This was the first-of-its-kind large scale test for this melt composition (80% UO2-20% ZrO2), this melt temperature (>2600°C), and this melt delivery rate to the spreading plate (3.2 l/s).
Further tests will be performed with different melt compositions.