Numerical Simulation of the Self-Leveling Phenomenon by Modified SIMMER-III

2012 ◽  
Author(s):  
Bin Zhang ◽  
Tatsuya Matsumoto ◽  
Koji Morita ◽  
Hidemasa Yamano ◽  
Hirotaka Tagami ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Heat Removal ◽  
Transient Behavior ◽  
Rapid Quenching ◽  
Solid Particles ◽  
The Self ◽  
Core Material ◽  
The Core ◽  
Model Improvement ◽  
Regulation Model

During a hypothetical core-disruptive accident in a sodium-cooled FBR, degraded core material can form debris beds on the core-support structure and/or in the lower inlet plenum of the reactor vessel, due to the rapid quenching and fragmentation of the core material melt. Heat convection and vaporization of the sodium will lead ultimately to leveling the debris bed that is of crucial importance to the relocation of the molten core, the recriticality evaluation and the heat removal capability of the debris bed. There is, therefore, a great need for more studies focusing on this topic, especially the much needed numerical simulation. The widely-used fast reactor safety analysis code, SIMMER-III, has difficulties in this simulation because of the lack of modeling for mechanistic interactions among particles in the current version. However, the extensive experimental analysis and the previously-proposed analytical model provide SIMMER-III the possibility of taking consideration of the extra influence of solid particles in this phenomenon. Thus, the debris fluidization model and the boiling regulation model are proposed and introduced into SIMMER-III. Calculations, by the modified SIMMER-III, against several representative experiments with typical self-leveling behavior have been performed and compared with the evaluated items recorded in experiments. The good agreements on these items suggest the modified SIMMER-III can simulate the self-leveling behavior with reasonable precision, especially on the onset of self-leveling, although further model improvement is necessary to represent the transient behavior of bed leveling more reasonably.

Numerical Simulation of Self-Leveling Behavior in Debris Bed by a Hybrid Method

2013 ◽  
Author(s):  
Liancheng Guo ◽  
Koji Morita ◽  
Hirotaka Tagami ◽  
Yoshiharu Tobita
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Hybrid Method ◽  
Fluid Model ◽  
Splitting Method ◽  
Heat Removal ◽  
Safety Analysis ◽  
Contact Forces ◽  
Solid Particles ◽  
Strong Interactions

The postulated core disruptive accidents (CDAs) are regarded as particular difficulties in the safety analysis of liquid-metal fast reactors (LMFRs). In the CDAs, the self-leveling behavior of debris bed is a crucial issue to the relocation of molten core and heat-removal capability of the debris bed. The fast reactor safety analysis code, SIMMER-III, which is a 2D, multi-velocity-field, multiphase, multicomponent, Eulerian, fluid dynamics code coupled with a fuel-pin model and a space- and energy-dependent neutron kinetics model, was successfully applied to a series of CDA assessments. However, strong interactions among rich solid particles as well as particle characteristics in multiphase flows were not taken into consideration for fluid-dynamics models of SIMMER-III. In this article, a developed hybrid method, by coupling the discrete element method (DEM) with the multi-fluid model of SIMMER-III, is applied in the numerical simulation of self-leveling behavior in debris bed. In the coupling algorithm the motions of gas and liquid phases are solved by a time-factorization (time-splitting) method. For particles, contact forces among particles and interactions between particles and fluid phases are considered through DEM. The applicability of the method in such complicate three phase flow is validated by taking the simulation of a simplified self-leveling experiment in literature. Reasonable agreement between simulation results and corresponding experimental data shows that the present method could provide a promising means for the analysis of self-leveling behavior of debris bed in CDAs.

The Process of Co-Extrusion – An Analysis

2011 ◽  
Vol 491 ◽  
pp. 81-88 ◽  
Author(s):  
Kai Kittner ◽  
Birgit Awiszus
Keyword(s):  
Numerical Simulation ◽  
Axial Strain ◽  
Strain Difference ◽  
Stable Process ◽  
Quality Criterion ◽  
Extrusion Process ◽  
Core Material ◽  
Process Window ◽  
The Core ◽  
Adequate Quality

This paper provides an analysis of a co-extrusion process. The compound consists of the sleeve material, aluminum, and the core material, magnesium. It is imperative to produce impeccable compounds without cracks in the interface. Therefore, a simple indicating value for damaging effects during the process is necessary. In the numerical simulation the compound quality is noticeable by the current macro mechanical criterion of axial strain difference. A statistical analysis verifies this criterion as an adequate quality criterion. By means of this criterion it is possible to define a stable process window for the co-extrusion process.

Analysis of Accident Progression of Fukushima Daiichi NPP by the SAMPSON Code

2014 ◽  
Author(s):  
Masanori Naitoh ◽  
Marco Pellegrini ◽  
Hiroaki Suzuki ◽  
Hideo Mizouchi ◽  
Hidetoshi Okada
Keyword(s):  
Nuclear Power ◽  
Water Injection ◽  
Heat Removal ◽  
Fission Products ◽  
Severe Accident ◽  
Core Material ◽  
Decay Heat ◽  
The Core ◽  
Fukushima Daiichi ◽  
Fire Engine

This paper describes analysis results of the early phase accident progression of the Fukushima Daiichi Nuclear Power Plant (NPP) Unit 1 by the severe accident analysis code SAMPSON. The isolation condensers were the only devices for decay heat removal at Unit 1, but they stopped after the loss of AC and DC powers. Since there were no decay heat removal for about 14 hours after their termination until the start of alternative water injection into the core by the fire engine, the core melt and the reactor pressure vessel (RPV) bottom failure occurred resulting in large amount of fission products release into the environment. The original SAMPSON was improved by adding new modellings for the phenomena which have been deemed specific to the Fukushima Daiichi NPP: (1) deterioration of SRV gaskets and (2) buckling of in-core-monitor housings which caused the early steam leakage from the core into the drywell, and (3) melt of the in-core-monitor housings in the lower plenum of the RPV. The analysis results showed that (1) 55.3% of UO2 of the initial loading and 66.1% of the core material including UO2, zircaloy, steel and control materials had melted down into the pedestal of the drywell, (2) the amount of Hydrogen generated by Zr-H2O reaction was 686 kg, (3) amount of Cs element released from fuels was 61 kg which was 72% of the total Cs element which was included in fuels at the initiation of the accident, and (4) 18.3% of the corium which fell into the pedestal was one large lump and the 81.7% was particulate corium.

Pathways to Success Through Identity-Based Motivation

2015 ◽  
Author(s):  
Daphna Oyserman
Keyword(s):  
The Self ◽  
The Core ◽  
Very Young Children ◽  
The Future ◽  
Identity Based ◽  
Future Self ◽  
Fidelity Measures ◽  
The Individual ◽  
Taking Action ◽  
Minimal Effort

Everyone can imagine their future self, even very young children, and this future self is usually positive and education-linked. To make progress toward an aspired future or away from a feared future requires people to plan and take action. Unfortunately, most people often start too late and commit minimal effort to ineffective strategies that lead their attention elsewhere. As a result, their high hopes and earnest resolutions often fall short. In Pathways to Success Through Identity-Based Motivation Daphna Oyserman focuses on situational constraints and affordances that trigger or impede taking action. Focusing on when the future-self matters and how to reduce the shortfall between the self that one aspires to become and the outcomes that one actually attains, Oyserman introduces the reader to the core theoretical framework of identity-based motivation (IBM) theory. IBM theory is the prediction that people prefer to act in identity-congruent ways but that the identity-to-behavior link is opaque for a number of reasons (the future feels far away, difficulty of working on goals is misinterpreted, and strategies for attaining goals do not feel identity-congruent). Oyserman's book goes on to also include the stakes and how the importance of education comes into play as it improves the lives of the individual, their family, and their society. The framework of IBM theory and how to achieve it is broken down into three parts: how to translate identity-based motivation into a practical intervention, an outline of the intervention, and empirical evidence that it works. In addition, the book also includes an implementation manual and fidelity measures for educators utilizing this book to intervene for the improvement of academic outcomes.

scholarly journals Acoustic Panels Made of Paper Sludge and Clay Composites

2021 ◽  
Vol 13 (2) ◽  
pp. 637
Author(s):  
Tomas Astrauskas ◽  
Tomas Januševičius ◽  
Raimondas Grubliauskas
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Composite Panel ◽  
Sound Absorption Coefficient ◽  
Core Material ◽  
Paper Sludge ◽  
Frequency Range ◽  
Absorption Properties ◽  
Air Gaps ◽  
The Core

Studies on recycled materials emerged during recent years. This paper investigates samples’ sound absorption properties for panels fabricated of a mixture of paper sludge (PS) and clay mixture. PS was the core material. The sound absorption was measured. We also consider the influence of an air gap between panels and rigid backing. Different air gaps (50, 100, 150, 200 mm) simulate existing acoustic panel systems. Finally, the PS and clay composite panel sound absorption coefficients are compared to those for a typical commercial absorptive ceiling panel. The average sound absorption coefficient of PS-clay composite panels (αavg. in the frequency range from 250 to 1600 Hz) was up to 0.55. The resulting average sound absorption coefficient of panels made of recycled (but unfinished) materials is even somewhat higher than for the finished commercial (finished) acoustic panel (αavg. = 0.51).

scholarly journals Iron Based Core-Shell Structures as Versatile Materials: Magnetic Support and Solid Catalyst

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 72
Author(s):  
Christian Zambrzycki ◽  
Runbang Shao ◽  
Archismita Misra ◽  
Carsten Streb ◽  
Ulrich Herr ◽  
...  
Keyword(s):  
Water Purification ◽  
Functional Materials ◽  
Core Material ◽  
Solid Catalyst ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
The Core ◽  
Shell Nanostructures ◽  
Sio2 Shell ◽  
Iron Based

Core-shell materials are promising functional materials for fundamental research and industrial application, as their properties can be adapted for specific applications. In particular, particles featuring iron or iron oxide as core material are relevant since they combine magnetic and catalytic properties. The addition of an SiO2 shell around the core particles introduces additional design aspects, such as a pore structure and surface functionalization. Herein, we describe the synthesis and application of iron-based core-shell nanoparticles for two different fields of research that is heterogeneous catalysis and water purification. The iron-based core shell materials were characterized by transmission electron microscopy, as well as N2-physisorption, X-ray diffraction, and vibrating-sample magnetometer measurements in order to correlate their properties with the performance in the target applications. Investigations of these materials in CO2 hydrogenation and water purification show their versatility and applicability in different fields of research and application, after suitable individual functionalization of the core-shell precursor. For design and application of magnetically separable particles, the SiO2 shell is surface-functionalized with an ionic liquid in order to bind water pollutants selectively. The core requires no functionalization, as it provides suitable magnetic properties in the as-made state. For catalytic application in synthesis gas reactions, the SiO2-stabilized core nanoparticles are reductively functionalized to provide the catalytically active metallic iron sites. Therefore, Fe@SiO2 core-shell nanostructures are shown to provide platform materials for various fields of application, after a specific functionalization.

scholarly journals Influence of Salt on the Self-Organization in Solutions of Star-Shaped Poly-2-alkyl-2-oxazoline and Poly-2-alkyl-2-oxazine on Heating

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1152
Author(s):  
Tatyana Kirila ◽  
Anna Smirnova ◽  
Alla Razina ◽  
Andrey Tenkovtsev ◽  
Alexander Filippov
Keyword(s):  
Phase Separation ◽  
Salt Concentration ◽  
Monomer Unit ◽  
Salt Content ◽  
The Self ◽  
Self Organization ◽  
Phase Separation Temperature ◽  
The Core ◽  
Separation Temperature ◽  
Water Salt

The water–salt solutions of star-shaped six-arm poly-2-alkyl-2-oxazines and poly-2-alkyl-2-oxazolines were studied by light scattering and turbidimetry. The core was hexaaza[26]orthoparacyclophane and the arms were poly-2-ethyl-2-oxazine, poly-2-isopropyl-2-oxazine, poly-2-ethyl-2-oxazoline, and poly-2-isopropyl-2-oxazoline. NaCl and N-methylpyridinium p-toluenesulfonate were used as salts. Their concentration varied from 0–0.154 M. On heating, a phase transition was observed in all studied solutions. It was found that the effect of salt on the thermosensitivity of the investigated stars depends on the structure of the salt and polymer and on the salt content in the solution. The phase separation temperature decreased with an increase in the hydrophobicity of the polymers, which is caused by both a growth of the side radical size and an elongation of the monomer unit. For NaCl solutions, the phase separation temperature monotonically decreased with growth of salt concentration. In solutions with methylpyridinium p-toluenesulfonate, the dependence of the phase separation temperature on the salt concentration was non-monotonic with minimum at salt concentration corresponding to one salt molecule per one arm of a polymer star. Poly-2-alkyl-2-oxazine and poly-2-alkyl-2-oxazoline stars with a hexaaza[26]orthoparacyclophane core are more sensitive to the presence of salt in solution than the similar stars with a calix[n]arene branching center.

scholarly journals nanocrystals (0 ≤ x ≤ 1): growth, size control and shell formation on β-NaCeF4:Tb core particles

CrystEngComm ◽  
2020 ◽  
Vol 22 (46) ◽  
pp. 8036-8044
Author(s):  
Jannis Wehmeier ◽  
Markus Haase
Keyword(s):  
Size Control ◽  
Lattice Parameters ◽  
Core Material ◽  
Shell Formation ◽  
Shell Material ◽  
Strontium Content ◽  
The Core ◽  
Lighter Lanthanides ◽  
Core Particles

is an interesting shell material for β-NaREF4 particles of the lighter lanthanides (RE = Ce, Pr, Nd), as variation of its strontium content x allows to vary its lattice parameters and match those of the core material.

Kierkegaard, Metaphysics, and Love

2013 ◽  
Vol 2013 (1) ◽  
Author(s):  
George Pattison
Keyword(s):  
Sense Of Self ◽  
The Self ◽  
The Other ◽  
Gabriel Marcel ◽  
The Core ◽  
The Dead ◽  
Alternative Reading ◽  
The Way

AbstractNoting Heidegger’s critique of Kierkegaard’s way of relating time and eternity, the paper offers an alternative reading of Kierkegaard that suggests Heidegger has overlooked crucial elements in the Kierkegaardian account. Gabriel Marcel and Sharon Krishek are used to counter Heidegger’s minimizing of the deaths of others and to show how the deaths of others may become integral to our sense of self. This prepares the way for revisiting Kierkegaard’s discourse on the work of love in remembering the dead. Against the criticism that this reveals the absence of the other in Kierkegaardian love, the paper argues that, on the contrary, it shows how Kierkegaard conceives the self as inseparable from the core relationships of love that, despite of death, constitute it as the self that it is.

SHELL MATERIAL'S PERFORMANCE OF THE MICROCAPSULE FOR ELECTROLYTIC CO-DEPOSITION

2010 ◽  
Vol 24 (15n16) ◽  
pp. 3124-3130 ◽  
Author(s):  
HUI CONG LIU ◽  
XIU QING XU ◽  
WEI PING LI ◽  
YAN HONG GUO ◽  
LI-QUN ZHU
Keyword(s):  
Composite Coating ◽  
Methyl Cellulose ◽  
Water Vapor Permeability ◽  
Core Material ◽  
Vapor Permeability ◽  
Shell Material ◽  
The Core ◽  
Surface Performance ◽  
The Stability ◽  
Positive Effect

The shell material of microcapsules has an important effect on the electrolytic co-deposition behavior, the release of core material and the surface performance of composite coating. This paper discussed the tensile property and the stability of three shell materials including polyvinyl alcohol (PVA), gelatin and methyl cellulose (MC). It is found that these three shell materials have good mechanical strength and flexibility which are favorable to electrolytic co-deposition and stability of microcapsules in composite coating and that MC has well permeability and porosity which has a positive effect on the release of the core material in composite coating. Moreover, the study of the thermal properties and water vapor permeability of the three shell materials showed that their permeability improved with increase of temperature and humidity. In addition, the composite copper coating containing microcapsules with PVA, gelatin or MC as shell material was prepared respectively.

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