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

Abstract

This paper presents numerical simulations using the discrete element method (DEM) to model sedimentation behavior of solid debris particles, which is significant for estimates of the coolability of debris beds. A series of experiments of gravity driven discharge of solid particles into a quiescent water pool was used to validate the DEM simulation method. We evaluated the effects of three crucial factors: particle density, particle diameter, and nozzle diameter on three key quantitative parameters: particle dispersion angle, particle fall time in the pool, and the height of the deposited particle bed to express the particle sedimentation behavior. The three crucial factors play a significant role in the particle sedimentation behavior. We compared the experimental and simulated results of the particle dispersion angle and particle fall time in the pool, and the height and shape of the deposited particle bed. The general trend of the simulation results indicates a reasonable agreement with the experimental observations. The simulations exhibit the potential applicability of the DEM-based simulation technique for the prediction of particle sedimentation behavior.

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

“…For sloshing motion with solid particles, taking into account the past numerical investigations into particle-related phenomena for the assessment of severe accidents in SFRs (Shamsuzzaman et al, 2014;Tagami and Tobita, 2014;Guo et al, 2017;Tagami et al, 2018;Sheikh et al, 2020), in which solid particles played a major role in the multiphase behaviors, microscopic models for inter-particle collisions and contacts or the discrete element method (DEM) may additionally be considered in the simulations to provide appropriate estimates of particle-particle interactions. 6) Further investigations into the effect of coupling between nuclear power deposition as well as recriticality and pool sloshing motion based on the knowledge obtained from thermal-hydraulics studies.…”

Experimental investigation of particulate debris spreading in a pool

“…In recent studies (Kim et al, 2014), the influence of two-phase flow on sedimentation of the different in size particles has been investigated experimentally. Numerical approaches employing discrete element analysis for particle spreading are also under development (Kudinov and Dinh, 2007;Shamsuzzaman et al, 2014).…”

Debris Bed Self-Leveling Mechanism and Characteristics for Core Disruptive Accident of Sodium-Cooled Fast Reactor: Review of Experimental and Modeling Investigations

“…However, different from the SFR, in the case of LWR, the debris bed was formed with an overall several-millimeter debris size in a deep water pool under the reactor vessel (i.e., ex-vessel) over the containment basemat, and attention was generally paid to its ability of cooling and the Molten Core-Concrete Interaction (MCCI) for assessing the response of containment [19][20][21][22][23][24][25][26][27][28]. While regarding the SFR, the debris size is more widely ranged (e.g., from 0.1 millimeters to several millimeters) [11,29], and the aim of studying the self-leveling behavior is to improve the structural designs for the SFR safety devices to ensure IVR (such as core catcher) in case of CDAs with the considerations of not only the ability of cooling of debris bed but also its subcritical neutronic configuration. Nevertheless, thanks to the evaluations of debris bed ability of cooling in the studies for LWR severe accidents, it was understood that the heat-removal capability of debris beds is remarkably dependent on their geometries (such as shapes and heights) [19][20][21][22][23], thereby enlightening the investigations on clarifying the debris bed self-leveling mechanism and characteristics (e.g., leveling tendency and velocity) for SFR, which is of great essence for the improved design of in-vessel safety devices.…”