Boiling and fragmentation behaviour during fuel-sodium interactions

Fragmentation of a Single Molten Metal Droplet Penetrating Sodium Pool II Stainless Steel and the Relationship with Copper Droplet

“…The molten 304SS droplet with an initial mass from 1.50 to 5.20 g penetrated a sodium pool at an initial temperature from 295 to 337 C in a range of superheat from 43 to 393 C, which corresponds to T i from 901 to 1,086 C, and in a narrow range of ambient Weber number (56 < We a < 95). The present results of a single molten droplet are found to be in fair agreement with those of streamlets and droplets (9.1-29.1 g) reported by Armstrong et al 6) and those of jets (2.5 and 4 kg) conducted by Schins' group 7,8) in the molten stainless steel experiments. Moreover, the authors also report that at T i > 1;000 C, the fragmentations of the single molten stainless steel and copper droplets 5) possessing the different thermophysical properties have almost the same D m =D 0 values.…”

“…Figure 2 shows the size distributions of D m against T i for the present stainless steel droplet, which are compared with the D m data of streamlets and droplets reported by Armstrong et al 6) and the D m data of jet reported by Schins' group. 7,8) The D m distributions obviously have a turning point near T i ¼ 1;000 C (hereafter referred to as T tp ). When T i > T tp , not only the stainless steel droplets are fragmented finely with their increasing T i values, but also the D m values of droplets with different masses have small differences.…”

“…Schins and Gunnerson 7) released about 4 kg of molten stainless steel jet into a sodium pool of 400 C at an initial temperature of 1,627 C (T i ¼ 1;041 C < T ss;mp ) through a 12-mm-diameter hole in the crucible bottom. The D m value of the fragments was about 1.2 mm.…”

Fragmentation of a Single Molten Metal Droplet Penetrating Sodium Pool I Copper Droplet and the Relationship with Copper Jet

“…The experiments using the single molten copper droplet with a fivefold difference in mass (1, 3, and 5 g) were carried out in a wide range of temperatures for superheating from 1 to 635 C, which corresponds to instantaneous contact interface temperatures from 995 C (below its melting point of 1,083 C) to 1,342 C, and in a narrow range of ambient Weber numbers (52 < We a < 114) as well as a narrow range of sodium pool temperatures from 249 to 314 C. In addition to the correlation of the fragment sizes of a single molten copper droplet, the authors also reported the relationship of the present results of a single molten copper droplet with the previous results of a single molten copper jet (from 20 g to 4 kg) reported by Nishimura et al 7,8) and Schins' group. 9,10) The relationship shows that the present D m =D 0 data give a distribution with larger values than those of molten copper jets under the lower T i condition because of the limited amount of heat of the droplet while the present D m =D 0 data under the higher T i condition give more effective fragmentation than those of molten copper jets with a large mass of 4 kg.…”

“…This is useful information for safety evaluation. The data of Schins' group 9,10) were obtained in the experiment using a molten copper jet of about 4 kg released into a sodium pool of 400 C in the T i range higher than 1,480 C (T h ) T Cu,melting ). The D m =D 0 data normalized by the nozzle diameter of 12 mm were somewhat higher than the present datum obtained at T i ¼ 1;342 C. The comparison in the higher T i range indicates that the fragment sizes of copper jets even with 1,000-fold difference in mass show little difference from those of copper droplets.…”