HEAT TRANSFER CHARACTERISTICS OF TWO-LAYER CORIUM POOLS UNDER ROLLING CONDITIONS

Heat transfer characteristics of two-layer corium pools under rolling conditions were studied experimentally and numerically in this paper. In the experiments, the test section was designed as a semi-ellipsoidal slice, measuring a span of 1.2m, a total pool depth of 0.32m and a thickness of 0.2m. Two immiscible fluids, water and fluorinert liquid FC-40, were selected as simulant materials for metal layer and molten oxide layer, respectively. The experiments found that under rolling conditions, thermal stratification is weakened in general, while the sideward heat transfer is enhanced. The ratio of Grashof number Gr to Taylor number Ta, i.e., Gr/Ta, can be used to quantify the effects of rolling motions. When the ratio is less than 2, rolling motions can exert strong influences on the temperature field and the maximum sideward heat transfer capacity and the two parameters will vary rapidly with the increase of Gr/Ta. On base of the experiments, large eddy simulations were performed. Through the numerical results, it was found that despite a mostly homogeneous temperature field under rolling conditions, obvious temperature gradient still exists at bottom of the corium pool, which may be explained by the better cooling capacity and the weaker convection intensity at this region. This research can provide valuable references for the safety analysis of in-vessel retention (IVR) strategy applied in the ocean floating reactors.