Analytical Study of Melt Spreading in Shallow Pool Observed in PULiMS-E10 Test Using MSPREAD Implemented With Molten Jet Quench Model

Abstract The subject of this study is a numerical simulation of the melt spreading in a shallow pool using MSPREAD, a two-dimensional high-resolution melt spreading analysis code. The identified influential factors in under-water melt spreading are the heat transfer between the melt and the overlying water, melt-coolant interaction (MCI) caused by water confinement at the time of molten jet impingement, molten jet breakup into melt slugs, disperse of melt slugs and cooling by water recirculating inside the partially solidified debris bed. In particular, the above-mentioned MCI and the subsequent chain of phenomena were named “the molten jet quench” by the authors, and a numerical model was proposed and implemented in MSPREAD. In this model, the diameter of spherical melt slugs and the radius of the floor region where melt continues to be slugs can be given as the user inputs. The three sensitivity analysis cases were performed with varying these two inputs together with no quench cases based on the PULiMS-E10 test conducted by the Royal Institute of Technology. Comparison of the time histories of the spreading area, pool water temperature, 2D spreading shapes and post-test debris cross section indicated that the molten jet quench can explain short spreading distances, thicker solidified debris, and even higher pool water temperatures observed in PULiMS-E10.