Numerical Simulation of Graphite Dust Deposition in Pebble Bed Reactor Core of HTGR

2017 ◽  
Author(s):  
Tao Chen ◽  
Jie Wang ◽  
Wei Peng ◽  
Xiaokai Sun
Keyword(s):  
Surface Temperature ◽  
Reactor Core ◽  
Particle Diameter ◽  
Deposition Efficiency ◽  
Shielding Effect ◽  
Discrete Phase Model ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Inlet Velocity ◽  
Fuel Elements

The deposition of graphite dust produced by the collision between graphite components would cause the security issue in HTGR and need to be analyzed. In this paper, a numerical calculation about the graphite dust’s deposition in the pebble bed reactor core of high-temperature gas cooled reactor was conducted. The three-dimensional steady-state solver was employed for the calculation of flow field and temperature field during simulation. The discrete phase model (DPM) and Lagrange method were applied for the simulation of graphite dust. Effects of parameters such as particle diameter, pebble bed layer numbers, inlet velocity and surface temperature of fuel elements on deposition of graphite dust are analyzed. The results indicated that a majority of particles deposit on the first layer pebble because of first layer’s shielding effect on nether layers. Moreover, deposition efficiency of graphite dust increases with increasing particles diameter and increasing inlet velocity due to greater motion inertia of particles. Compared with fewer layers, more layers structure would lead to larger deposition efficiency because of more opportunities for collision between graphite dust and pebbles, but the difference is not obvious. In addition, the higher surface temperature of fuel elements would cause lower deposition efficiency due to larger thermophoretic force which would drive particles to deviate from pebbles.

scholarly journals Modeling of Fuel Elements Cycling System in Pebble Bed Reactor Based on Timed Places Control Petri Nets

2013 ◽  
Vol 05 (04) ◽  
pp. 510-516
Author(s):  
Hongbing Liu ◽  
Peng Shen ◽  
Dong Du ◽  
Xin Wang ◽  
Haiquan Zhang
Keyword(s):  
Petri Nets ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Cycling System ◽  
Fuel Elements

Combined CFD and DEM Simulations of Fluid Flow and Heat Transfer in a Pebble Bed Reactor

2011 ◽  
Author(s):  
Xiang Zhao ◽  
Trent Montgomery ◽  
Sijun Zhang
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Discrete Element Method ◽  
Reactor Core ◽  
Turbulence Models ◽  
Discrete Element ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Packing Structure ◽  
Dem Simulations

This paper presents combined computational fluid dynamics (CFD) and discrete element method (DEM) simulations of fluid flow and relevant heat transfer in the pebble bed reactor core. In the pebble bed reactor core, the coolant passes highly complicated flow channels, which are formed by thousands of pebbles in a random way. The random packing structure of pebbles is crucial to CFD simulations results. The realistic packing structure in an entire pebble bed reactor (PBR) is generated by discrete element method (DEM). While in CFD calculations, selection of the turbulence models have great importance in accuracy and capturing the details of the flow features, in our numerical simulations both large eddy simulation (LES) and Reynolds-averaged Navier-Stokes (RANS) models are employed to investigate the effects of different turbulence models on gas flow field and relevant heat transfer. The calculations indicate the complex flow structure within the voids between the pebbles.

Fuel elements of the high temperature pebble bed reactor

1975 ◽  
Vol 34 (1) ◽  
pp. 93-108 ◽  
Author(s):  
L. Wolf ◽  
G. Ballensiefen ◽  
W. Fröhling
Keyword(s):  
High Temperature ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Fuel Elements

scholarly journals Study on the effect of various burnable poisons on pebble bed reactor with OTTO fuelling schemes using Serpent 2 Monte Carlo code

2021 ◽  
Vol 927 (1) ◽  
pp. 012018
Author(s):  
Nicholas Sidharta ◽  
Almanzo Arjuna
Keyword(s):  
Power Density ◽  
Power Distribution ◽  
Reactor Core ◽  
Monte Carlo Code ◽  
Volumetric Fraction ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Burnable Poison ◽  
Discrete Element Method Simulation ◽  
Upper Level

Abstract Pebble bed reactor with a once-through-then-out fuelling scheme has the advantage of simplifying the refueling system. However, the core upper-level power density is relatively higher than the bottom, producing an asymmetric core axial power distribution. Several burnable poison (BP) configurations are used to flatten the peak power density and improve power distribution while suppressing the excess core reactivity at the beginning of the burnup cycle. This study uses HTR-PM, China’s pebble bed reactor core, to simulate several burnable poison (BP) configurations. Serpent 2 coupled with Octave and a discrete element method simulation is used to model and simulate the pebble bed reactor core. It is found that erbium needs a large volumetric fraction in either QUADRISO or distributed BP to perform well. On the other hand, gadolinium and boron need a smaller volumetric fraction but perform worse in radial power distribution criteria in the fuel sphere. This study aims to verify the effect of BP added fuel pebbles on an OTTO refueling scheme HTR-PM core axial power distribution and excess reactivity.

Analysis of Graphite Dust Deposition in Steam Generator of HTR

2012 ◽  
Author(s):  
Wei Peng ◽  
Xiao-yong Yang ◽  
Su-yuan Yu ◽  
Jie Wang
Keyword(s):  
Steam Generator ◽  
Particle Diameter ◽  
Deposition Efficiency ◽  
Dust Particles ◽  
Dust Deposition ◽  
Inlet Velocity ◽  
Transfer Tube ◽  
Diffusion Characteristics ◽  
High Turbulence ◽  
And Diffusion

The behavior of the graphite dust in the steam generator is important to the safety of High Temperature gas-cooled Reactor (HTR). The present study numerically investigates the effect of steam generator structure on deposition and diffusion of graphite dust particles in HTR, then the effect of helium velocity, tube spacing and graphite dust particle diameter on the deposition and diffusion characteristics of graphite dust are analyzed. The results showed that the flow field around the heat transfer tube is complex and high turbulence intensity; the deposition efficiency of the graphite dust will increase as the tube spacing increases, while the deposition efficiency of the graphite dust will decrease with the inlet velocity increases.

A Numerical Study of Particle Deposition Through Fuel Pebble Bed in HTGR

2018 ◽  
Author(s):  
Qi Sun ◽  
Gang Zhao ◽  
Wei Peng ◽  
Suyuan Yu
Keyword(s):  
Particle Deposition ◽  
Numerical Study ◽  
Three Dimensional ◽  
Intensity Change ◽  
Discrete Phase Model ◽  
Pebble Bed ◽  
Deposition Fraction ◽  
Discrete Phase ◽  
Face Centered ◽  
Fuel Elements

The study on the deposition of graphite dust is significant to the safety of High-Temperature Gas-cooled Reactor (HTGR) due to potential accident such as localized hot-spots and intensity change which is caused by the graphite dust generated by abrasion of fuel elements. Based on the steady flow and three-dimensional face centered structures of fuel pebble bed, the discrete phase model (DPM) were applied to simulate trajectory of graphite dust in conditions of HTGR. To determinate the deposition of particle, the present study introduces a rebound condition with critical velocity by a user defined function. The particle trajectories show most of particle deposition can be summed up as the effect of backflow region, turbulent diffusion and inertial impact. The original trap condition overestimates the deposition fraction especially for large particles compared with involving rebound condition. In addition, the trend of deposition fraction shows as the dimeter of particle increases, deposition fraction decreases first and then increases.

Investigations on the Movement of Fuel Elements in the Core of a Pebble Bed Reactor

1969 ◽  
Vol 91 (2) ◽  
pp. 390-394
Author(s):  
D. Bedenig ◽  
C. B. v. d. Decken ◽  
W. Rausch
Keyword(s):  
Theoretical Model ◽  
Flow Behavior ◽  
Experimental Studies ◽  
Experimental Equipment ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
The Core ◽  
Method Of Measurement ◽  
Fuel Elements ◽  
Type Fuel

For several years gas-cooled high temperature reactors have been developed in Germany, the main feature of which are their pebble-type fuel elements. The pebble bed is in the state of a continuous circulation process which is the reason for a series of nuclear and technical advantages. To make use of these advantages, comprehensive experimental studies on the flow behavior of a pebble bed were carried out. First, experimental equipment and the most successful method of measurement are described. Then typical results of parameter studies are reported as well as a theoretical model to calculate the pebble bed flow behavior. At last typical functions describing the flow behavior in the core of the THTR 300 MWe Prototype Reactor are reported.

scholarly journals Pore Scale Thermal Hydraulics Investigations of Molten Salt Cooled Pebble Bed High Temperature Reactor with BCC and FCC Configurations

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Shixiong Song ◽  
Xiangzhou Cai ◽  
Yafen Liu ◽  
Quan Wei ◽  
Wei Guo
Keyword(s):  
Fluid Dynamics ◽  
High Temperature ◽  
Pressure Drop ◽  
Surface Temperature ◽  
Molten Salt ◽  
Thermal Hydraulics ◽  
Pore Scale ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Body Center Cubic

The present paper systematically investigated pore scale thermal hydraulics characteristics of molten salt cooled high temperature pebble bed reactor. By using computational fluid dynamics (CFD) methods and employing simplified body center cubic (BCC) and face center cubic (FCC) model, pressure drop and local mean Nusselt number are calculated. The simulation result shows that the high Prandtl number molten salt in packed bed has unique fluid-dynamics and thermodynamic properties. There are divergences between CFD results and empirical correlations’ predictions of pressure drop and local Nusselt numbers. Local pebble surface temperature distributions in several default conditions are investigated. Thermal removal capacities of molten salt are confirmed in the case of nominal condition; the pebble surface temperature under the condition of local power distortion shows the tolerance of pebble in extreme neutron dose exposure. The numerical experiments of local pebble insufficient cooling indicate that in the molten salt cooled pebble bed reactor, the pebble surface temperature is not very sensitive to loss of partial coolant. The methods and results of this paper would be useful for optimum designs and safety analysis of molten salt cooled pebble bed reactors.

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