November 2017
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55 Reads
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14 Citations
Annals of Nuclear Energy
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November 2017
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55 Reads
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14 Citations
Annals of Nuclear Energy
November 2017
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27 Reads
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12 Citations
Annals of Nuclear Energy
Studies on debris bed formation behavior are important for the improved evaluation of Core Disruptive Accident (CDA) of Sodium-cooled Fast Reactors (SFR). To clarify the flow-regime characteristics underlying this behavior, in recent years a series of simulated experiments was performed at the Sun Yat-sen University by discharging various solid particles into Two-Dimensional (2D) water pools. Based on the experimental observation, it is found that, due to the different interaction mechanisms between solid particles and water pool, four kinds of regimes, termed respectively as the particle-suspension regime, the pool-convection dominant regime, the transitional regime and the particle-inertia dominant regime, are identifiable. In this work, aimed at providing some evidence for understanding the effect of coolant boiling on the regime transition, a number of new experiments are performed by percolating nitrogen gas uniformly through the water pool during the particle sedimentation. It is recognized that, possibly caused by the enhanced pool convection as well as the weakened role of particle inertia, increasing the gas velocity are confirmable to have an evident impact on the regime transition. On the other hand, even for the cases without regime transition, the gas flow injected is also verifiable to have a great influence on the particle-bed properties (e.g. specific geometric angles), regardless what regime it is. Knowledge and evidence from our work might be utilized for future development of a general model directly applicable for reactor safety analyses as well as the verifications of SFR severe accident analysis codes in China.
October 2017
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167 Reads
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31 Citations
Nuclear Engineering and Technology
It is important to clarify the characteristics of flow regimes underlying the debris bed formation behavior that might be encountered in core disruptive accidents of sodium-cooled fast reactors. Although in our previous publications, by applying dimensional analysis technique, an empirical model, with its reasonability confirmed over a variety of parametric conditions, has been successfully developed to predict the regime transition and final bed geometry formed, so far this model is restricted to predictions of debris mixtures composed of spherical particles. Focusing on this aspect, in this study a new series of experiments using nonspherical particles have been conducted. Based on the knowledge and data obtained, an extension scheme is suggested with the purpose of extending the base model to cover the particle-shape influence. Through detailed analyses and given our current range of experimental conditions, it is found that, by coupling the base model with this scheme, respectable agreement between experiments and model predictions for the regime transition can be achieved for both spherical and nonspherical particles. Knowledge and evidence from our work might be utilized for the future improvement of design of an in-vessel core catcher as well as the development and verification of sodium-cooled fast reactor severe accident analysis codes in China.
July 2017
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14 Reads
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2 Citations
Studies on debris bed formation behavior are of crucial importance for the improved evaluation of core relocation and debris bed coolability that might be encountered in a Core Disruptive Accident (CDA) of Sodium-cooled Fast Reactors (SFR). Motivated to clarify the characteristics of flow regimes underlying this behavior, both experimental investigations and empirical-model development are being performed at the Sun Yat-sen University. As for the experimental study, several series of simulated experiments are being conducted by discharging various solid particles into water pools. To obtain a comprehensive understanding, a variety of experimental parameters, including particle size (0.256∼8mm), particle density (glass, alumina, zirconia, steel and lead), particle shape (spherical and irregularly-shaped), water depth (0∼60cm), particle release pipe diameter (10∼30mm) as well as the particle release height (110∼130cm) were varied. It is found that due to the different interaction mechanisms between solid particles and water pool, four kinds of flow regimes, termed respectively as the particle-suspension regime, the pool-convection dominant regime, the transitional regime and the particle-inertial dominant regime, were identifiable. As for the empirical-model development, by using dimensional analysis technique, a regime map (base map), which is restricted to predictions of spherical particles up until now, was recently suggested. It is shown that a respectable agreement between experiments and the regime-map predictions could be obtained. This work, which gives a large palette of favorable data and insight for a better understanding and an improved estimation of CDAs in SFRs, is expected to benefit future analyses and verifications of SFR severe accident analysis codes in China.
April 2017
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24 Reads
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20 Citations
Progress in Nuclear Energy
Studies on debris bed formation behavior are of crucial importance for the improved evaluation of Core Disruptive Accidents (CDA) that could occur for Sodium-cooled Fast Reactors (SFR). In this work, to clarify the mechanisms underlying this behavior, a series of experiments was performed by discharging solid particles into two-dimensional rectangular water pools. To obtain a comprehensive understanding, various experimental parameters, including particle size (0.256∼8 mm), particle density (glass, alumina, zirconia, steel and lead), particle shape (spherical and irregularly-shaped), water depth (0–60 cm), particle release pipe diameter (10–30 mm), particle release height (110–130 cm) as well as the gap thickness of water tank (30–60 mm), were varied. It is found that due to the different interaction mechanisms between solid particles and water pool, four kinds of regimes, termed respectively as the particle-suspension regime, the pool-convection dominant regime, the transitional regime and the particle-inertial dominant regime, are identified. The performed analyses in this work also suggest that under present experimental conditions, the particle size, particle density, particle shape, particle release pipe diameter and water depth are observable to have remarkable impact on the above regimes, while the role of particle release height and gap thickness of water tank seems to be less prominent. Knowledge and data from this work might be utilized for the improved design of core catcher as well as analyses and verifications of SFR severe accident analysis codes in China in the future.
... For clarifying the DBF mechanisms and characteristics in CDAs of SFR, in the previous decade, lots of experimental, modeling and numerical outcomes were achieved in the studies conducted at Kyushu University and Japan Atomic Energy Agency (JAEA) (Shamsuzzaman et al., 2012(Shamsuzzaman et al., , 2013(Shamsuzzaman et al., , 2014a(Shamsuzzaman et al., ,b, 2018Sheikh et al., 2016Sheikh et al., , 2018Sheikh et al., , 2020Kawata et al., 2017), Indira Gandhi Centre for Atomic Research (IGCAR) (Jasmin Sudha et al., 2015), Sun Yat-Sen University (SYSU) (Cheng et al., , 2018a(Cheng et al., ,b, 2019aLin et al., 2017;Xu et al., , 2023a, Pohang University of Science and Technology (POSTECH) (Hwang et al., 2019) and Xi'an Jiao Tong University (XJTU) (Ding et al., 2023). Table 1 provides a summary of the previous DBF investigations. ...
November 2017
Annals of Nuclear Energy
... As can be seen in Fig. 2, our research on the current subject, including both experimental study and predictive-model development, mainly contains two steps: step 1dunderstanding the mechanisms of flow regimes and performing modeling studies for various parameters within two-dimensional (2D) conditions and step 2dvalidating of the 2D experimental results at larger-scale three-dimensional (3D) conditions and developing a general model (or regime map) directly applicable for reactor safety analyses. In our recent publications [21,22], a series of 2D experiments involving various parameters, such as particle size (0.125~8 mm), particle density (beads of glass, alumina, zirconia, steel and lead), water depth (0e60 cm), particle release pipe diameter (10e30 mm), particle release height (110e130 cm), and gap thickness of the water tanks (30e60 mm), have been conducted. Based on experimental observations and parametric analyses, it is recognized that, because of the different interaction mechanisms between solid particles and the water pool, four kinds of regimes, termed respectively the particle-suspension regime, the pool-convection dominant regime, the transitional regime, and the particle-inertia dominant regime, were identifiable. ...
July 2017
... Table 2 compares the material proprieties in experimental and accidental conditions. The experiments were initially performed at room temperature with varying parameters (e.g., particle size, density, component and shape; water depth; discharging nozzle configurations) to study the fundamental DBF characteristics, mainly including the flow-regime transitions during DBF and formed-bed geometries after DBF (Shamsuzzaman et al., 2012(Shamsuzzaman et al., , 2013(Shamsuzzaman et al., , 2014a(Shamsuzzaman et al., , 2018Jasmin Sudha et al., 2015;Sheikh et al., 2016Sheikh et al., , 2018Cheng et al., 2017Cheng et al., , 2018bCheng et al., , 2019bLin et al., 2017). Further, considering the possible coolant boiling triggered by the high-temperature falling debris and the accumulated debris beds, extended experimental investigations were carried out to further elaborate the effect of coolant boiling on DBF characteristics (Cheng et al., 2018a(Cheng et al., , 2019aXu et al., , 2023a. ...
October 2017
Nuclear Engineering and Technology
... Table 2 compares the material proprieties in experimental and accidental conditions. The experiments were initially performed at room temperature with varying parameters (e.g., particle size, density, component and shape; water depth; discharging nozzle configurations) to study the fundamental DBF characteristics, mainly including the flow-regime transitions during DBF and formed-bed geometries after DBF (Shamsuzzaman et al., 2012(Shamsuzzaman et al., , 2013(Shamsuzzaman et al., , 2014a(Shamsuzzaman et al., , 2018Jasmin Sudha et al., 2015;Sheikh et al., 2016Sheikh et al., , 2018Cheng et al., 2017Cheng et al., , 2018bCheng et al., , 2019bLin et al., 2017). Further, considering the possible coolant boiling triggered by the high-temperature falling debris and the accumulated debris beds, extended experimental investigations were carried out to further elaborate the effect of coolant boiling on DBF characteristics (Cheng et al., 2018a(Cheng et al., , 2019aXu et al., , 2023a. ...
November 2017
Annals of Nuclear Energy
... The characteristics of the criticality of the fuel debris are expected to vary during its dispersion and sedimentation in DBF process (Muramoto et al., 2019(Muramoto et al., , 2021Shiba et al., 2023). It was also found that the formed debris beds may perform different geometrical characteristics at different hypothetical accident conditions (e.g., debris properties, coolant boiling) due to the varying multi-phase interactions (Lin et al., 2017;Cheng et al., 2018c; σ surface tension (N⋅m − 1 ) ϕ particle sphericity (-) ψ quantity characterizing the bubbling effect on restraining the particle-flow induced pool convection (-) Ω convergence degree of mixed-sized particle mixture (-) Subscripts a area mean term B boiling b particle bed c critical value convection pool convection cr cross section dim dimple eff effective ev equivalent f fluid g gas in inner container inertia particle inertia ip initial value of particle L left l liquid level fully leveled off m particle mound n nozzle p particle pr particle releasing R right r repose re relative quantity tank water tank top topmost particle tp two-phase fluid v stands for a volume mean term w water (Cheng et al., 2013c;Suzuki et al., 2014;Lin et al., 2017). ...
April 2017
Progress in Nuclear Energy