Experimental and Numerical Study of the Movement Mechanism and Characteristics of the Quasi-Static Pebble Flow

2013 ◽  
Author(s):  
Xinlong Jia ◽  
Nan Gui ◽  
Xingtuan Yang ◽  
Jiyuan Tu ◽  
Shengyao Jiang
Keyword(s):  
Numerical Study ◽  
Mixing Zone ◽  
Force Analysis ◽  
Particle Movement ◽  
Pebble Bed ◽  
Dem Simulation ◽  
Pebble Bed Reactor ◽  
Pebble Bed Reactors ◽  
Movement Mechanism ◽  
Pebble Flow

Quasi-static pebble flow, or so-called the very slow pebble flow, in a pebble bed reactor, with evident randomicity and dispersibility, is extremely complex. Improving the knowledge of the movement mechanism of quasi-static pebble flow can be beneficial to the safety of the pebble bed reactor. This study utilizes a phenomenological method and a discrete element method to investigate the interface features of two regions composed of differently colored pebbles. A pseudo-two dimensional experimental setup is established to facilitate the observation of movement of pebble. Then, the DEM simulation is carried out to analyze the further details of particle movement mechanism. To some extent, the two methods are closely related and mutually confirmed. In this study, some special phenomena are observed, such as the non-uniformity, mixing zone, stagnant zones, the propagation of voids, slow flow zone, etc. Moreover, some basic issues on the movement mechanism and characteristics of quasi-static pebble flow are discussed, e.g. the interpretation of force analysis inside the pebble packing, propagation and distribution of voids, formation of equilibrium arches, the effects of stagnant zone on the flow field, and so on. These characteristics of the quasi-static pebble flow are very different from the continuous flow, and the understanding of these characteristics is very helpful for the design and analysis of pebble bed reactors.

Effect of bed configuration on pebble flow uniformity and stagnation in the pebble bed reactor

2014 ◽  
Vol 270 ◽  
pp. 295-301 ◽  
Author(s):  
Nan Gui ◽  
Xingtuan Yang ◽  
Jiyuan Tu ◽  
Shengyao Jiang
Keyword(s):  
Flow Uniformity ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Pebble Flow

scholarly journals Physical Analysis of the Initial Core and Running-In Phase for Pebble-Bed Reactor HTR-PM

2017 ◽  
Vol 2017 ◽  
pp. 1-6
Author(s):  
Jingyu Zhang ◽  
Fu Li ◽  
Yuliang Sun
Keyword(s):  
Physical Parameters ◽  
Physical Analysis ◽  
Fuel Management ◽  
Fuel Temperature ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Pebble Bed Reactors ◽  
Management Scheme ◽  
Typical Scheme ◽  
Scheme Evaluation

The pebble-bed reactor HTR-PM is being built in China and is planned to be critical in one or two years. At present, one emphasis of engineering design is to determine the fuel management scheme of the initial core and running-in phase. There are many possible schemes, and many factors need to be considered in the process of scheme evaluation and analysis. Based on the experience from the constructed or designed pebble-bed reactors, the fuel enrichment and the ratio of fuel spheres to graphite spheres are important. In this paper, some relevant physical considerations of the initial core and running-in phase of HTR-PM are given. Then a typical scheme of the initial core and running-in phase is proposed and simulated with VSOP code, and some key physical parameters, such as the maximum power per fuel sphere, the maximum fuel temperature, the refueling rate, and the discharge burnup, are calculated. Results of the physical parameters all satisfy the relevant design requirements, which means the proposed scheme is safe and reliable and can provide support for the fuel management of HTR-PM in the future.

Effect of friction on pebble flow pattern in pebble bed reactor

2016 ◽  
Vol 94 ◽  
pp. 32-43 ◽  
Author(s):  
Yu Li ◽  
Nan Gui ◽  
Xingtuan Yang ◽  
Jiyuan Tu ◽  
Shengyao Jiang
Keyword(s):  
Flow Pattern ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Pebble Flow

Spectral Zones Determination for Pebble Bed Reactor Cores Using Diffusion Theory Spectral Indices

2008 ◽  
Author(s):  
Ramatsemela Mphahlele ◽  
Abderrafi M. Ougouag ◽  
Kostadin N. Ivanov ◽  
Hans D. Gougar
Keyword(s):  
Diffusion Theory ◽  
Surface Fluxes ◽  
Spectral Indices ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Absolute Value ◽  
Pebble Bed Reactors ◽  
Spectral Changes ◽  
Diffusion Constants

A practical methodology is developed for the determination of spectral zones in Pebble Bed Reactors (PBR). The methodology involves the use of spectral indices based on few-group diffusion theory whole core calculations. In this work a spectral zone is defined as made up of a number of nodes whose characteristics are collectively similar and that are assigned the same few-group diffusion constants. Therefore, spectral indices that reflect the physical behaviors of interest can be used to characterize said behaviors within each zone and thus to identify and distinguish the spectral zones. Several plausible spectral indices have been investigated in this work. Special emphasis and focus was placed on the trend or behavior of the spectral index at various positions along the radial and axial dimensions in the core. The ratio of group-wise surface currents to total surface fluxes, has been used to successfully identify spectral zone boundaries. A plot of the absolute value of this ratio versus position in the reactor exhibits a series of minima and maxima points. These extrema correlate with regions of significant spectral changes, and therefore are identified as plausible spectral zone boundaries.

Gas-Cooled Modular Reactors With Spherical Fuel Elements — Their Inherent Safety and Applications Not Just for Power Generation

2014 ◽  
Author(s):  
Walter Jaeger ◽  
H. J. Hamel ◽  
Heinz Termuehlen
Keyword(s):  
Power Generation ◽  
High Temperature ◽  
Reactor Design ◽  
Inherent Safety ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Pebble Bed Reactors ◽  
Fuel Elements ◽  
High Temperature Gas

The gas-cooled reactor design with spherical fuel elements, referred to as high-temperature gas-cooled reactors (HTGR or HTR reactors) or pebble bed reactors has been already suggested by Farrington Daniels in the late 1940s; also referred to as Daniels’ pile reactor design. Under Rudolf Schulten the first pebble bed reactor, the 46MWth AVR Juelich reactor (Atom Versuchs-Reactor Jülich) was built in the late 1960s. It was in operation for 22 years and extensive testing confirmed its inherent safety.

scholarly journals Experimental and Numerical Study of Stagnant Zones in Pebble Bed

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Xinlong Jia ◽  
Xingtuan Yang ◽  
Nan Gui ◽  
Yu Li ◽  
Jiyuan Tu ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Numerical Study ◽  
Reactor Core ◽  
Stagnant Zone ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Area Method ◽  
Base Angle ◽  
Bed Height ◽  
Tracking Time

The experimental method (side area method) and DEM simulation have been carried out to analyse the stagnant zone in the quasi-two-dimensional silos. The side area method is a phenomenological method by means of investigating the interface features of different areas composed of different coloured pebbles. Two methods have been discussed to define the stagnant zone. In particular, the area of the stagnant zone has been calculated with the mean-streamline method, and the tracking time of different marking pebbles has been investigated with the stagnant time method to explore the kinematics characteristics of the pebbles. The stagnant zone is crucial for the safety of the pebble-bed reactor, and the practical reactor core must avoid the existence of the stagnant zone. Furthermore, this paper also analyses the effects of bed configuration (the bed height, the base angle, and the friction coefficient) on stagnant zone with the two methods mentioned above. In detail, the bed height shows little impact on the stagnant zones when the bed height exceeds a certain limit, while the base angle has negative prominent correlation with the stagnant zone. The friction coefficient effect seems complicated and presents the great nonlinearity, which deserves to be deeply investigated.

A study on evaluation of pebble flow velocity with modification of the kinematic model for pebble bed reactor

2013 ◽  
Vol 55 ◽  
pp. 322-330 ◽  
Author(s):  
Song Hyun Kim ◽  
Hong-Chul Kim ◽  
Jong Kyung Kim ◽  
Jea Man Noh
Keyword(s):  
Flow Velocity ◽  
Kinematic Model ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Pebble Flow

scholarly journals The implication of Thorium fraction on neutronic parameters of pebble bed reactor

2021 ◽  
Vol 48 (3) ◽  
Author(s):  
Zuhair Zuhair ◽  
◽  
R. Andika Putra Dwijayanto ◽  
Suwoto Suwoto ◽  
Topan Setiadipura ◽  
...  
Keyword(s):  
Neutron Transport ◽  
Neutron Generation ◽  
Neutron Lifetime ◽  
Reactor Model ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Pebble Bed Reactors ◽  
Fuel Burn ◽  
Neutronic Parameters ◽  
High Level

Thorium abundance in the Earth's crust is estimated to be three to four times higher than uranium. This is one potential advantage of Thorium as a provider of attractive fuel to produce nuclear energy. Fewer transuranics produced by Thorium during the fuel burn up in the reactor may also be another advantage for reducing the long-term burden of high-level long-lived waste. The scope of this paper is to study the implication of Thorium fraction on neutronic parameters of pebble bed reactor. The reactor model of HTR-10 was selected, and the (Th, 235U)O2 fuel was used in this study. The MCNP6 code was applied to solve a series of neutron transport calculations with various Thorium fractions in (Th,235U)O2 fuel based on the ENDF/BVII library. The calculation results show that the total temperature coefficient of reactivity of Thorium-added pebble bed reactors is generally more negative than those of LEU-fuelled one, except for 10% Thorium fraction. The kinetic parameters, especially prompt neutron lifetime and neutron generation time of pebble bed reactors, are higher, which means the addition of Thorium in the fuel makes the reactor more easily controlled. However, the burn-up calculations show that the introduction of Thorium in the same fuel kernel as LEU within the pebble bed reactor is unable to lengthen the fuel residence time, except for a minimum of 40% Thorium fraction.

Sign in / Sign up

Export Citation Format

Share Document