The cooling capability of a newly engineered corium cooling system, that is, an ex-vessel core catcher system, was quantified experimentally. The scaling analysis was applied to design the test facility compared with the prototypic core catcher cooling system. The natural circulation flow rates were measured experimentally, and the flow characteristics in the inclined channel were investigated. As the coolant temperature and heat flux increase, the circulation mass flow rate also increases. The experimental results show that the cooling capability of the real core catcher system is sufficient at the given thermal load imposed on the real core catcher body from the corium pool. The boiling-induced natural circulation flow in a real-scaled experimental cooling channel was also modeled and solved by considering the conservation of mass, momentum and energy in the two-phase mixture to estimate the natural circulation flow rate. The circulation mass flow rates were calculated along with the coolant temperature and wall heat flux. The calculated mass flux depended on the void fraction correlation, and it was expected that the Wallis separate cylinder model was more feasible than the homogeneous model. However, a more accurate void fraction model should be required to apply to the rectangular flow channel with a downward facing heated surface.
展开▼
