Experimental study on debris bed characteristics for the sedimentation behavior of solid particles used as simulant debris

Shamsuzzaman, Mohammad; Horie, Tatsuro; Fuke, F.; Kamiyama, Motoki; Morioka, Tohru; Matsumoto, Tatsuya; Morita, Koji; Tagami, Hirotaka; Suzuki, Tsuneo; Tobita, Yoshiharu

doi:10.1016/j.anucene.2017.09.011

Cited by 20 publications

(16 citation statements)

References 8 publications

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“…(1) Further experimental investigations and modeling verifications (or developments) in the case of other initial bed shapes. According to the recent visualization experimental and modeling research on debris bed formation behavior [8,12,[56][57][58], it was clarified that under different parametric conditions with considerations of a typical CDA of SFR, not only the convex bed, but also the flat, concave and trapezoid beds would possibly form due to the different interparticle and particle-fluid interactions. However, in the past self-leveling investigations, it was assumed that the particle bed was initially convex, which was inadequate to take all possible initial debris bed shapes into account.…”

Section: Future Prospectsmentioning

confidence: 99%

“…Subsequently, as shown in Figure 1, along with the fast quenching and fragmentation, the molten materials will become solid debris and accumulate on the core-support structure in the lower part of the reactor vessel to form the debris bed [10,11]. To achieve In-Vessel Retention (IVR), which is primely essential for SFR, it is necessary to ensure the adequate cooling of the debris beds and their neutronically subcritical conguration [12,13]. Nevertheless, it was recognized that the sodium coolant is probably heated and boiled by the hightemperature accumulated debris with decay heat, causing the interactions between bubbles and solid debris within debris beds [10,14].…”

Section: Introductionmentioning

confidence: 99%

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

Xu¹,

Cheng²

2022

Science and Technology of Nuclear Installations

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Evaluations of the Core Disruptive Accident (CDA) are significantly important for safety analysis of Sodium-cooled Fast Reactor (SFR) despite the very low probability of occurrence for CDA. During the material-relocation phase in CDA of SFR, the molten materials are possibly released from the core region into subcooled sodium, subsequently forming the debris bed on the lower part of the reactor vessel after being quenched and fragmented. The accumulated high-temperature debris with decay heat can cause sodium coolant boiling, leading to the so-called “debris bed self-leveling behavior” during which the shape of the debris bed becomes flattered (leveling). It is important to investigate the debris bed self-leveling behavior due to its potential capacity to induce the transfer of debris and affect the ability of cooling and criticality of the debris bed. Thus, in recent years, valuable knowledge concerning the mechanism and characteristics of this behavior was accumulated through lots of experimental results and modeling developments. Aimed at providing a valuable guideline for future investigations on this issue, in this study, the past experimental and modeling investigations on debris bed self-leveling mechanism and characteristics are systematically summarized and reviewed, and some future remarks are also proposed to promote the progression of further research for SFR severe accident analysis.

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Section: Future Prospectsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Xu¹,

Cheng²

2022

Science and Technology of Nuclear Installations

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“…Considering that the debris bed configurations are of great essence to neutr criticality and self-sustainable long-term coolability, adequate comprehensive eva for debris relocation in the CDA of an SFR are necessary to realize the In-Vessel R (IVR) for fuel debris [28][29][30]. On the other hand, focusing on the IVR of SFRs, safety equipment (e.g., core catchers) is also recommended for employment below actor vessel to enlarge the safety margin [26,31].…”

Section: Introductionmentioning

confidence: 99%

“…Based on these in tions, the self-leveling mechanisms (e.g., bubble-particle interactions within partic and characteristics (e.g., parametric influence on the leveling rate) were clarifie ever, it should be noted that the complex multiphase flows, including solid debri coolant, and sodium vapor, involved in the DBF process can result in varyin shapes of the debris bed, which in turn can influence the progression of severe a in SFRs. Hence, it Is of great importance to understand the characteristics and mec Considering that the debris bed configurations are of great essence to neutronic recriticality and self-sustainable long-term coolability, adequate comprehensive evaluations for debris relocation in the CDA of an SFR are necessary to realize the In-Vessel Retention (IVR) for fuel debris [28][29][30]. On the other hand, focusing on the IVR of SFRs, relevant safety equipment (e.g., core catchers) is also recommended for employment below the reactor vessel to enlarge the safety margin [26,31].…”

Section: Introductionmentioning

confidence: 99%

Characteristics and Mechanisms of Debris Bed Formation Behavior in Severe Accidents of Sodium-Cooled Fast Reactors: Experimental and Modeling Studies

Cheng

2023

Applied Sciences

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A Sodium-cooled Fast Reactor (SFR) is one of the optimized candidates in Generation IV nuclear reactor systems, but safety is an essential issue for SFR development and application. Most knowledge was accumulated through SFR safety investigations, especially for Core Disruptive Accidents (CDAs). During the CDA of SFRs, the molten materials in the core region are likely to discharge into subcooled sodium and form a debris bed on the lower region of the reactor vessel. Noticing that elaboration on the characteristics and mechanisms of Debris Bed Formation (DBF) behavior should be essential for the subsequent analysis of debris bed coolability and accident progression through various experimental and modeling studies, much knowledge was obtained during the past decades. Motivated to promote future investigations on CDAs of SFRs, the previous experiments and modeling studies on DBF behavior are systematically reviewed and discussed in this paper. The experimental results showed that the flow-regime and accumulated-bed characteristics during DBF were influenced by varying parameters and realistic conditions. Through the modeling studies, several empirical models were proposed for predicting the flow regime and accumulated-bed characteristics in DBF. In addition, to promote further development of research, the future prospects concerning DBF behavior are also described.

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“…Experimental investigations with simulant materials composed of homogeneous solid particles were conducted recently [12,13] and, in connection with this study, an exploration was performed in our previous studies for mixtures of particles with different properties [14,15]. These experimental analyses discovered the nature of the shape characteristics of the particle bed and its dependence on some important factors, such as particle density and diameter as well as the diameter and length of the nozzle, which is used to discharge solid particles into the water pool [12][13][14][15]. As the experimental process consumes a high cost and long duration, the evaluation of such sedimentation behaviors is performed knowing the limited scope of reproducibility.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of the Solid Particle Sedimentation and Bed Formation Behaviors Using a Hybrid Method

et al. 2020

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In the safety analysis of sodium-cooled fast reactors, numerical simulations of various thermal-hydraulic phenomena with multicomponent and multiphase flows in core disruptive accidents (CDAs) are regarded as particularly difficult. In the material relocation phase of CDAs, core debris settle down on a core support structure and/or an in-vessel retention device and form a debris bed. The bed’s shape is crucial for the subsequent relocation of the molten core and heat removal capability as well as re-criticality. In this study, a hybrid numerical simulation method, coupling the multi-fluid model of the three-dimensional fast reactor safety analysis code SIMMER-IV with the discrete element method (DEM), was applied to analyze the sedimentation and bed formation behaviors of core debris. Three-dimensional simulations were performed and compared with results obtained in a series of particle sedimentation experiments. The present simulation predicts the sedimentation behavior of mixed particles with different properties as well as homogeneous particles. The simulation results on bed shapes and particle distribution in the bed agree well with experimental measurements. They demonstrate the practicality of the present hybrid method to solid particle sedimentation and bed formation behaviors of mixed as well as homogeneous particles.

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Experimental study on debris bed characteristics for the sedimentation behavior of solid particles used as simulant debris

Cited by 20 publications

References 8 publications

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

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

Characteristics and Mechanisms of Debris Bed Formation Behavior in Severe Accidents of Sodium-Cooled Fast Reactors: Experimental and Modeling Studies

Numerical Simulation of the Solid Particle Sedimentation and Bed Formation Behaviors Using a Hybrid Method

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