VULCANO VB-U7 experiment on interaction between oxidic corium and hematite-containing concrete

•Oxidic corium was poured into a concrete crucible.•EPR sacrificial concrete type, containing hematite, was used.•Concrete ablation was measured.•Sidewall ablation was much faster than basemat ablation.

In a severe accident, the core of a reactor melts and forms corium, a mixture that includes molten UO2 and ZrO2. If the reactor pressure vessel fails, corium can interact with concrete.This paper describes the VB-U7 experiment, which was performed in the VULCANO facility in Cadarache, France, in co-operation between CEA and VTT. This test aims at studying the interaction of more than 50 kg of prototypic oxidic corium with EPR sacrificial ferro-siliceous concrete. The experimental configuration, the measured data and post examination and analysis results are presented.This test showed that EPR-type ferro-siliceous sacrificial concrete was anisotropically ablated by oxidic corium. This behavior is similar to that of other silica-rich concretes previously tested in CCI and VULCANO facilities. The corium temperature decreased to the value corresponding to about 50 vol% solid fraction when the concrete test section broke, leading to significant spreading.