Investigation of flow-regime characteristics in a sloshing pool with mixed-size solid particles

Experimental and numerical investigations into molten-pool sloshing motion for severe accident analysis of sodium-cooled fast reactors: A review

“…Figure 6C shows the experimental system employed for investigations with solid particles by utilizing gas injection. Considering the probable situations that might occur in a CDA of an SFR, particle beds with different compositions (such as particles of different density, size (d p , 0.125-8 mm), shape (spherical and non-spherical), components (single size and density, bicomponent mixed-size, bicomponent mixed density), and different initial height (H pb , 5-30 cm) were used and placed on the bottom of pool, and gas-injection duration (0.06-0.1 s) as well as injected gas pressure (2-4 bar) were also treated as experimental parameters to obtain valuable experimental data for further numerical validation (Cheng et al, 2019a(Cheng et al, , 2019b(Cheng et al, , 2019cXu et al, 2022).…”

“…Recognizing that solid particles may also occur in various sizes in the molten pool of an actual CDA of an SFR, a large number of extended experiments using bicomponent mixedsized spherical solid particles at the same densities but with different volumetric mixing ratios were conducted by Cheng et al (2019a) to elucidate the effect of mixed sizes on sloshing motion. From the experiments, although the abovementioned key parametric effects on the flow-regime transitions were in general validated, typically the flow-regime characteristics tended to shift from a higher (e.g., Regime III) to a lower one (e.g., Regime II) if larger weights of smaller particles were employed in the particle mixtures.…”

“…The reason for this incongruity may be that although the overall impact of particle-bed inertia was comparatively somewhat larger than that of the gas-bubble impulsion in cases of Regime III/II or II/III, the impulsion of the rising bubble might still exceed the inertia of smaller particles within the particle mixtures. This can cause the separation of particles of different sizes in the particle mixtures, which could lead to flow-regime deviation from a strict Regime II for instance (Cheng et al, 2019a). This may also explain why the in-between flow regimes were mostly emerged when more particles with small size presented in the particle mixtures.…”

“…In recent decades, it has become clear that an understanding of molten-pool sloshing motion is very important for the improved evaluation of SFR severe accident scenarios, particularly regarding energetic recriticality. A series of experimental investigations was carried out at Karlsruhe Institute of Technology (KIT), Kyushu University, and Sun Yat-Sen University (SYSU) that considered various conditions, such as dam-break, fluid-step, and gas-injection conditions (Maschek et al, 1992a;Maschek et al, 1992b;Morita et al, 2014;Cheng et al, 2018c;Cheng et al, 2018d;Cheng et al, 2019a;Cheng et al, 2019b;Cheng et al, 2019c;Cheng et al, 2020;Xu et al, 2022). Basic mechanisms (e.g., peripheral pushing of molten fuel and gravitation-induced inward centralized sloshing) and important sloshing characteristics (e.g., the maximal inward and outward sloshing liquid heights) were phenomenologically observed via dam-break and fluid-step experiments (Maschek et al, 1992a;Maschek et al, 1992b), in which the outward and inward sloshing motions were both triggered by gravity.…”

“…While observing that it is possible to find the co-existence of molten structural materials and fuel under actual accident conditions, Cheng et al (2020) performed further experimental investigations into sloshing motion in pools with liquid stratification. In addition to experiments in liquid pools without solid phases and considering the fact that, in an actual reactor accident, solid phase materials may be present in the pool as a result of incomplete melting of structural materials and fuel pellets (Liu et al, 2006(Liu et al, , 2007, experiments in liquid pools with solid phases (such as solid particles and solid obstacles with rod-shaped structures) have also been performed under dam-break and gas-injection conditions to accumulate valuable knowledge concerning the effects of solid phases on sloshing characteristics (Maschek et al, 1992a;Maschek et al, 1992b;Cheng et al, 2018d;Cheng et al, 2019a;Cheng et al, 2019b;Cheng et al, 2019c;Xu et al, 2022). These previous experimental investigations into sloshing motion are summarized in Figure 2.…”