scholarly journals B205 Engineering study of gas flow in breeder pebble bed for fusion blanket

2012 ◽  
Vol 2012.17 (0) ◽  
pp. 265-266
Author(s):  
Yohji SEKI ◽  
Akira YOSHIKAWA ◽  
Hisashi TANIGAWA ◽  
Takanori HIROSE ◽  
Koichiro EZATO ◽  
...  
Keyword(s):  
Gas Flow ◽  
Pebble Bed ◽  
Engineering Study

CFD Investigation of helium gas flow in sphere packed (Pebble bed) in a rectangular canister using OpenFOAM

2021 ◽  
Vol 172 ◽  
pp. 112858
Author(s):  
Pratyush Kumar ◽  
Abhishek Thakur ◽  
Sandip K. Saha ◽  
Atul Sharma ◽  
Deepak Sharma ◽  
...  
Keyword(s):  
Gas Flow ◽  
Pebble Bed ◽  
Helium Gas

The Re-Evaluation of the AVR Melt-Wire Experiment Using Modern Methods With Specific Focus on Bounding the Bypass Flow Effects

2008 ◽  
Author(s):  
Carel F. Viljoen ◽  
Sonat Sen ◽  
Frederik Reitsma ◽  
Onno Ubbink ◽  
Peter Pohl ◽  
...  
Keyword(s):  
Gas Flow ◽  
Coupled System ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Control Rod ◽  
Melting Temperatures ◽  
The Core ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Effects ◽  
The Many

The AVR (Arbeitsgemeinschaft Versuchsreaktor) is a pebble bed type helium cooled graphite moderated high temperature reactor that operated in Germany for 21 years and was closed down in December 1988 [1]. The AVR melt-wire experiments [2], where graphite spheres with melt-wires of different melting temperatures were introduced into the core, indicate that measured pebble temperatures significantly exceeded temperatures calculated with the models used at the time [3]. These discrepancies are often attributed to the special design features of the AVR, in particular the control rod noses protruding into the core, and to inherent features of the pebble bed reactor. In order to reduce the uncertainty in design and safety calculations the PBMR Company is re-evaluating the AVR melt-wire experiments with updated models and tools. 3-D neutronics thermal-hydraulics analyses are performed utilizing a coupled VSOP99-STAR-CD calculation. In the coupled system VSOP99 [4] provides power profiles on a geometrical mesh to STAR-CD [5] while STAR-CD provides the fuel, moderator and solid structure temperatures to VSOP99. The different fuel histories and flow variations can be modelled with VSOP99 (although this is not yet included in the model) while the computational fluid dynamics (CFD) code, STAR-CD, adds higher-order thermal and gas flow modelling capabilities. This coupling therefore ensures that the correct thermal feedback to the neutronics is included. Of the many possible explanations for the higher-than-expected melt-wire temperatures, flow bypassing the pebble core was identified as potentially the largest contributor and was thus selected as the first topic to study. This paper reports the bounding effects of bypass flows on the gas temperatures in the top of the reactor. It also presents preliminary comparisons between measured temperatures above the core ceiling structure and calculated temperatures. Results to date confirm the importance of correctly modelling the bypass flows. Plans on future model improvements and other effects to be studied with the coupled VSOP99-STAR-CD tool are also included.

DEM-CFD simulation of purge gas flow in a solid breeder pebble bed

2016 ◽  
Vol 113 ◽  
pp. 288-292 ◽  
Author(s):  
Hao Zhang ◽  
Zhenghong Li ◽  
Haibing Guo ◽  
Minyou Ye ◽  
Hongwen Huang
Keyword(s):  
Gas Flow ◽  
Cfd Simulation ◽  
Pebble Bed ◽  
Purge Gas

DEM-CFD Study of Purge Gas Flow in Pebble Bed of WCCB for CFETR

2017 ◽  
Author(s):  
Youhua Chen ◽  
Lei Chen ◽  
Songlin Liu
Keyword(s):  
Pressure Drop ◽  
Gas Flow ◽  
Flow Characteristics ◽  
Diameter Ratio ◽  
Pebble Bed ◽  
Ratio Requirement ◽  
Packing Factor ◽  
Test Reactor ◽  
Purge Gas ◽  
Cfd Method

As one of the breeding blanket candidates for China Fusion Engineering Test Reactor (CFETR), the water-cooled ceramic blanket (WCCB) was proposed to use mono-sized beryllium pebble bed and binary mixed Li2TiO3/Be12Ti pebble bed in order to increase the packing factor and meet the tritium breeding ratio requirement. Helium (mixed with 0.1% content of H2) is used as the purge gas to sweep tritium out when it flows through the pebble beds. Purge gas flow characteristics are of great importance to tritium recovery system design and will dominate the tritium sweep capability. In this study, DEM-CFD method was used to study the flow characteristics including porosity distribution, velocity distribution and pressure drop in the pebble beds. Mono-sized pebble bed with a packing factor of 0.61 and binary mixed pebble beds with the diameter ratio of 6:1, packing factor of 0.755, and diameter ratio of 7:1, packing factor of 0.7513 were simulated. This method can be used to study the detailed flow characteristics in pebble beds and optimize the pebble bed packing parameters to obtain an appropriate pressure drop, and could be extended to study tritium sweep capability for the design of fusion blanket.

Experimental Investigations and Analytical Improvements for HTR Pebble Bed Cores

2012 ◽  
Author(s):  
H.-J. Allelein ◽  
B. Schloegl ◽  
J. Baggemann ◽  
S. Juehe ◽  
S. Kasselmann
Keyword(s):  
Fluid Mechanics ◽  
Gas Flow ◽  
Experimental Investigations ◽  
Reactor Safety ◽  
Pebble Bed ◽  
Cfd Validation ◽  
Main Research ◽  
Cfd Models ◽  
Experimental Facilities ◽  
Air Ingress

One of the main research topics of the Chair for Reactor Safety and Technology at RWTH Aachen University and the Institute for Nuclear Waste Management and Reactor Safety (IEK-6) deals with accident scenarios of gas-cooled High-Temperature Reactors, especially the air ingress scenario. Two experimental facilities have just started operation providing experimental data for the validation and improvement of fluid mechanics codes being developed and applied at IEK-6. The INDEX (INDuction EXperiment) facility is able to heat up single spheres inductively up to 1200°C while exposed to defined gas atmospheres and gas flow conditions. This experimental setup is well suited to study pebble / gas flow interactions as well as graphite corrosion phenomena in detail. The NACOK II (NAturzug im COre mit Korrosion) facility is an integral experiment for fluid mechanics and graphite corrosion processes under natural convection effects. It will examine spherical fuel element samples as well as prismatic blocks. In addition the instrumentation is suitable for CFD validation calculations, for example because PIV (particle image velocity) is applied. The data obtained are used to validate and improve computational fluid dynamics (CFD) models for pebble bed reactors or reactor dynamics code like MGT-3D, which are able to simulate air ingress scenarios. The CFD model shall be able to simulate the fluid mechanics as well as the corrosion processes of after a total pressure release. In this paper we report on the status of the experimental facilities as well as on advances in modelling the fluid mechanics of HTR pebble cores.

Simulation and experimental analysis of purge gas flow characteristic for pebble bed

2021 ◽  
Vol 172 ◽  
pp. 112778
Author(s):  
Chirag Sedani ◽  
Maulik Panchal ◽  
Paritosh Chaudhuri
Keyword(s):  
Experimental Analysis ◽  
Gas Flow ◽  
Flow Characteristic ◽  
Pebble Bed ◽  
Purge Gas

TEM evaluation of graded SixGe1-x heterolayers

1991 ◽  
Vol 49 ◽  
pp. 894-895
Author(s):  
N. David Theodore ◽  
Mamoru Tomozane ◽  
Ming Liaw
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
Gas Flow ◽  
Field Effect Transistors ◽  
Chemical Vapor ◽  
Dark Field ◽  
Bipolar Transistors ◽  
Structural Quality ◽  
Weak Beam ◽  
Transmission Electron ◽  
And Behavior

There is extensive interest in SiGe for use in heterojunction bipolar transistors. SiGe/Si superlattices are also of interest because of their potential for use in infrared detectors and field-effect transistors. The processing required for these materials is quite compatible with existing silicon technology. However, before SiGe can be used extensively for devices, there is a need to understand and then control the origin and behavior of defects in the materials. The present study was aimed at investigating the structural quality of, and the behavior of defects in, graded SiGe layers grown by chemical vapor deposition (CVD).The structures investigated in this study consisted of Si1-xGex[x=0.16]/Si1-xGex[x= 0.14, 0.13, 0.12, 0.10, 0.09, 0.07, 0.05, 0.04, 0.005, 0]/epi-Si/substrate heterolayers grown by CVD. The Si1-xGex layers were isochronally grown [t = 0.4 minutes per layer], with gas-flow rates being adjusted to control composition. Cross-section TEM specimens were prepared in the 110 geometry. These were then analyzed using two-beam bright-field, dark-field and weak-beam images. A JEOL JEM 200CX transmission electron microscope was used, operating at 200 kV.

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