Heat transfer during molten corium-concrete interactions

Severe accidents in light water-cooled nuclear power plants involved heat transfer from molten reactor core materials or “corium” penetrating the reactor pressure vessel and coming to rest upon the containment building concrete floor covered by water. This paper discusses the difficulties of getting good information about the properties of the components and the flow structure during molten corium-concrete-water interactions. Also, potential heat transfer mechanisms are described and available prototypical tests are utilized to show that the enhancement in heat transfer by rising gas bubbles is the most likely mechanism, particularly if heat transfer by iradiation across the gas bubbles is included.