Experimental Study of Melt Jet Breakup in Water

Abstract

In the present study, the jet breakup characteristics of molten material is experimentally investigated in nonboiling condition using Wood's metal to isolate the key features of jet breakup phenomenon from the conjugated nature of melt breakup and steam generation. The experimental apparatus consists mainly of melt generating furnace and melt crucible equipped with variable nozzle diameter, a rectangular water tank of 350×350×800 mm equipped with temperature controlling heater and thermocouples. The jet diameters were 10 and 20 mm and the jet velocity was varied by pressurizing the melt container. Wood's metal of 70 • C melting temperature was used. Visualization of jet breakup provided characteristics of jet breakup in water. The range of jet velocity was 2.2-5.5 m/s. The debris were collected and sieved and it was shown that the debris sizes of 1.0-2.8 mm had the largest mass fraction, up to 50%. In the present experimental conditions, the Kelvin-Helmholtz instability is considered the most probable cause of jet breakup.

Flow transition criteria of a liquid jet into a liquid pool

“…According to previous work, the fragment size is affected by classical instabilities (Abe et al, 2004(Abe et al, , 2005(Abe et al, , 2006Bang et al, 2003;Matsuo et al, 2008). The relationship between the evaluated droplet size and the critical wavelength of each instability is compared here.…”

“…Instead, a scoping study of the fundamental process is an effective approach to understanding the actual situation. To date, there have been many experimental efforts under various conditions that have been aimed at clarifying the melt-coolant interaction, including UO2 into sodium (Magallon et al, 1992;Schins and Gunnerson, 1986), molten oxide into sodium (Kaiser et al, 1998;Matsuba et al, 2015;Schins and Gunnerson, 1986), molten metal into sodium (Kaiser et al, 1998;Matsuba et al, 2016a;Nishimura et al, 2010;Schins and Gunnerson, 1986), corium into water (Huhtiniemi and Magallon, 2001;Magallon, 2006;Magallon and Huhtiniemi, 2001;Spencer et al, 1994), molten oxide into water (Kaiser et al, 2001;Karbojian et al, 2009;Kudinov et al, 2013;Manickam et al, 2014Manickam et al, , 2016Moriyama et al, 2005) and molten metal into water (Abe et al, 2006;Bang et al, 2003;Bang and Kim, 2014;Bürger et al, 1995;Cho et al, 1991;Dinh et al, 1999;Iwasawa et al, 2015bIwasawa et al, , 2015cKondo et al, 1995;Mathai et al, 2015;Matsuo et al, 2008;Pillai et al, 2016;Spencer et al, 1986;Wei et al, 2016). The aim of all these experiments and tests was not limited to understanding a CDA in an SFR; a severe accident in a light-water reactor was also included as a possible scenario.…”

A numerical simulation of jet breakup in melt coolant interactions

“…Melt jet fragmentation, modes of breakup and jet-breakup length has been studied previously by many investigators, experimentally and numerically (Bürger et al, 1995;Wang et al, 1989;Berg et al, 1993;Nishimura et al, 1999;Bang et al, 2003). Despite of many experiments and numerical work done on liquid-liquid systems, it has not yielded to a sufficient understanding of the fragmentation process.…”

Numerical study on sedimentation behavior of solid particles used as simulant fuel debris

“…After the melt discharge to the plenum, FCIs lead to solidification and fragmentation of the melt with very small particles. To investigate FCI phenomena, in fact, a lot of out-of-pile experiments have been performed by discharging the melt into the coolant as a jet through a circular nozzle with a diameter of several centimeters [3,5]. The fragmented core materials into fine debris will relocate to the bottom of the reactor vessel or to the core-catcher (debris tray) finally.…”

“…Over the past decades, many researchers have studied the interactions between molten fuel and coolant. They mostly focused on the jet breakup characteristics [2][3][4] jet fragmentation and premixing -and on the debris formation processes [5]. However, there are very little exper- * Corresponding author.…”