Simulation of melt jet breakup and debris bed formation in water pools with IKEJET/IKEMIX

Large-cell model of radiation heat transfer in multiphase flows typical for fuel–coolant interaction

“…In our case, all the particles and bubbles are much greater than radiation wavelength [2][3][4]. We will assume that thickness of concentric steam layer (steam mantle) separating hot particles from ambient water is also much greater than the wavelength [9].…”

“…The complexity of different stages of interaction of high-temperature core melt with water is one of the reasons of the present-day state of the art when some important physical processes have not been considered in details yet [1]. The efforts of many researchers have been focused on hydrodynamic simulation of melt jet breakup [2][3][4] and specific problems of steam explosion [5][6][7][8]. At the same time, the radiation heat transfer in the multiphase medium containing polydisperse corium particles of temperature of about 2500-3000 K was not a subject of detailed analysis.…”

Steam explosion in nuclear reactors: Droplets of molten steel vs core melt droplets

“…The probability of steam explosion is determined by the so-called premixing stage of FCI when the melt jets are fragmented to numerous small droplets [9,10]. The fragmentation of the melt jets and large droplets is considered as very important process [9][10][11][12][13][14][15][16][17][18][19]. At the same time, many experiments with core melt (corium) jets have failed to produce strong steam explosions.…”

Heat transfer partitioning model of film boiling of particle cluster in a liquid pool: implementation in a CFD code

“…For example, in nuclear reactor safety analysis or in underwater volcano eruption, film boiling occurs around the high temperature particles. In reactor safety analysis, a severe accident scenario is postulated considering core melt-down from excessive heating (may be due to failure of coolant circulation), which releases as molten jet in the coolant and starts to fragment into smaller sized particles (molten droplets) [17,18]. Direct contact of hot particles, following jet breakup, with coolant water creates the background of film-boiling around particle cluster at high temperature.…”