Modeling for water penetration into narrow gap in CAMP code

An analytical code, CAMP, is being developed at JAERI for thermo-fluiddynamics of a molten core in the lower plenum of the reactor pressure vessel (RPV). Models for the water penetration into narrow gaps based on the flooding of a two-phase flow have been recently incorporated in CAMP code. The in-vessel debris coolability experiments performed at Japan Atomic Energy Research Institute (JAERI), where an Al2O3 melt was poured into a water-filled lower head experimental vessel and the interfacial gap between the solidified Al2O3 and the vessel was supposed to form, were analyzed with CAMP code. It was found that temperature histories at the vessel outer surface were qualitatively reproduced using the water penetration model. The analysis also implied that an appropriate flooding correlation are needed to increase the predictability of CAMP code and that the steam generation in the interfacial gap, which largely influences on the flooding, was dominated by thermal radiation from the surface of the solidified Al2O3 to the penetrating water. (author)