Energies | Free Full-Text | Effects of the Aspect Ratio and
The packing characteristics of a pebble bed are essential to understand the heat- and mass-transfer processes occurring within a granular system. Therefore, the packing characteristics of rectangular prismatic pebble beds randomly packed with mono-sized pebbles are analyzed. In terms of the average and local packing fraction …
DEM simulations and experiments of pebble flow with
In this work, a three-dimensional experimental pebble-bed setup was developed to investigate pebble flow behavior in pebble-bed reactors. For the first time, 6.0 cm graphite pebbles were utilized, and features such as one pebble at a time discharge mode and continuous pebble recirculation were incorporated.
Study on the mechanical behaviors and elastic modulus of …
1. Introduction. Due to some of their specific characteristics, granular materials are widely used in various industrial applications. For instance, pebble beds have already been determined as one of the promising form of the tritium breeders (Li-based ceramic, such as Li 4 SiO 4, Li 2 TiO 3, Li 2 O, etc.) and neutron multipliers (such as Be and BeO) …
What's next for Pebble mine, now that the federal …
(Bill Roth / ADN archive) After a decades-long controversy, the Biden administration took a rare step this week to stop the giant Pebble copper and gold mine …
Alaska's Bristol Bay & The Pebble Mine
As proposed, the Pebble Mine project would entail mining a pit over a mile long, a mile wide and 200 meters deep, destroying nearly 3,500 acres of wetlands, lakes, and ponds and 81 miles of salmon streams.
Research on purge gas flow characteristics in different pebble bed …
Lithium ceramics are equipped as pebble beds in the solid-type breeding blanket, with the tritium purge gas flowing through it at a low velocity and pressure to achieve tritium transport. This paper investigated the effects of friction coefficient on the packing and purge gas flow characteristics of the pebble bed. Furthermore, this research …
Bulk porous materials as an alternative to pebble beds in …
Li4SiO4 particles are employed in tritium breeder pebble beds while beryllium particles are selected for neutron multiplier pebble beds. The material properties of Li4SiO4 are listed in Table 1 [20,21]. As explained in Section 2.3, the wall effect on the packing factor could be ignored when the aspect ratio exceeded 30 (α > 30).
A pebble bed modular reactor nuclear power plant reaches …
The fuel is in the form of small spheres (hence the name 'pebble bed'), 60 mm in diameter, each containing 7 g of low (8.5%) enriched uranium fuel, coated with four layers of ceramics and ...
The European DEMO Helium Cooled Pebble Bed Breeding …
Significant design efforts were undertaken during the Pre-Concept Design (PCD) phase of the European DEMO program to optimize the helium cooled pebble bed (HCPB) breeding blanket. A gate review was conducted for the entire European DEMO program at the conclusion of the PCD phase. This article presents a summary of the …
Proof of concept for hyper-fidelity depletion of full-scale pebble bed …
Abstract. Pebble bed reactors, either gas-cooled or fluoride-cooled, are among the most promising advanced reactor concepts with active development worldwide. The relatively small size of the pebbles and the fact that they are continuously recirculated makes the task of simulating fuel burnup particularly challenging.
Optimization of a pebble bed configuration for quasi-direct numerical
The flow configuration used for the present assessment is a defined arrangement of spherical type pebbles. Following the specification of the Pebble Bed Modular Reactor (PBMR)-250MWth design, the diameter of a pebble is kept 60 mm (Lee and Lee, 2008, Lee and Lee, 2010). In reality, the core of PBMR contains a wide range of …
PEA reveals Pebble economics, benefits
By Shane Lasley. Mining News. PEA reveals Pebble economics, benefits. Study outlines economics of 20- and 100-year mining scenarios North of 60 Mining …
Effect of packing structure on mechanical properties of the pebble beds …
It is found that when the thickness of the Li 4 SiO 4 pebble bed (ranging from 15 mm to 25 mm) becomes thinner, or the coefficient of friction (ranging from 0.1 to 0.6) increases, the strain of the pebble bed and the probability of particle crushing increases under the same mechanical load. Pebble beds with different packing structures have the ...
EPA Blocks Pebble Mine with Rare Veto. What …
On January 30, 2023, after over a dozen years of administrative review, the U.S. Environmental Protection Agency ("EPA") vetoed the proposed Pebble Mine, granting petitions filed in 2010 under ...
A pebble bed modular reactor nuclear power plant reaches …
The world's first pebble bed modular reactor (PBMR) nuclear power plant (NPP) achieved full initial power on Friday, World Nuclear News has reported. It is …
What's next for Pebble mine, now that the federal …
It affects a 300-square-mile area of the Pebble deposit, a significantly broader area than Pebble has applied with the Corps to mine over 20 years. EPA officials said the agency wanted to prevent ...
A prediction model for the effective thermal
A model is presented here to predict the effective thermal conductivity of porous medium packed with mono-sized spherical pebbles, and it is valid when pebbles' size is far less than the characteristic length of porous medium just like the fusion pebble beds. In this model, the influences of parameters such as properties of pebble and gas ...
Experimental measurements of gas pressure drop of packed pebble beds …
In 2013, A. Abou-Sena et al. [4] has experimentally measured the helium gas pressure drop across pebble beds and compared them with the prediction of Ergun's correlation. The glass pebbles (diameter: 0.25–1.2 mm) packed in a rectangular canister (dimension: 56 mm × 206 mm × 396 mm) were investigated in their study.
Experimental and computational investigation of flow of …
The Pebble Bed Reactor (PBR) is a 4th generation nuclear reactor which is conceptually similar to moving bed reactors used in the chemical and petrochemical industries. In a PBR core, nuclear fuel in the form of pebbles moves slowly under the influence of gravity. Due to the dynamic nature of the core, a thorough understanding
Both sides dig in as EPA's final decision on Pebble Mine nears
Northern Dynasty Minerals began exploration of the Pebble deposit in 2002, securing mining rights for a project on 186 square miles of Alaska state land, including an open pit spanning 2 to 3 ...
Both sides dig in as EPA's final decision on Pebble …
It would be unusual for the EPA to reverse its preliminary decision to ban mining wastes from Bristol Bay under a provision of the Clean Water Act, but the Pebble …
Effect of friction on pebble flow pattern in pebble bed reactor
Abstract. Friction affects pebble flow pattern in pebble-bed high temperature gas-cooled reactor (HTGR) significantly. Through a series of three dimensional DEM (discrete element method) simulations it is shown that reducing friction can be beneficial and create a uniform and consistent flow field required by nuclear engineering.
Steady-state thermal fluids analysis for the HTR-PM …
In the HTR-PM demonstration plant, there are two standard nuclear steam supply system (NSSS) modules, both of which are connected to a conventional steam turbine generator [8].As shown in Fig. 1, each NSSS module mainly comprises a pebble bed reactor, a steam generator, a helium circulator and a hot gas duct.The reactor …
Numerical investigation of purge gas flow through binary-sized pebble
In general, the thermal conductivity of pebble beds increases as the pebbles are more densely packed. Binary-sized pebble beds can thus be considered to achieve a high packing fraction of pebbles [11,17,18]. Meanwhile, the packing fraction affects the resistance of purge gas flow, which can be expressed as pressure drop in pebble beds.
Pebble Bed
The high-temperature reactor pebble bed module (HTR-PM) is a pebble bed-type high-temperature, helium-cooled reactor. The fuel is UO 2 enriched to 8.5% and contained in TRISO graphite-coated particles that are dispersed in 6-cm-diameter graphite spheres. The 3-m-diameter by 11-m-tall core region represents a tall graphite "hopper ...
Computation | Free Full-Text | Numerical Study on the …
Fuel elements in a high-temperature gas-cooled reactor (HTGR) core may be stacked with a hexagonal close-packed (HCP) structure; therefore, analyzing the temperature distribution and heat transfer efficiency in the HCP pebble bed is of great significance to the design and safety of HTGR cores. In this study, the heat transfer …
Alaska gold, copper mine blocked over environmental worries
FILE - A worker with the Pebble Mine project digs in the Bristol Bay region of Alaska near the village of Iliamma, Alaska, July 13, 2007. The U.S. Environmental Protection Agency announced a decision Tuesday, Jan. 31, 2023, that would block plans for the proposed Pebble Mine, a copper and gold project in southwest Alaska. (AP Photo/Al …
Study on the mechanical behaviors and elastic modulus of …
Considering that the study on the mixed fusion pebble beds has been rarely conducted, in this paper the discrete element method (DEM) was used to report the mechanical behaviors and elastic moduli of mixed pebble beds which contain two kinds of solid materials. Several combinations of two kinds of solid materials were studied …
Pebble bed HTRs
The core of pebble bed type reactor (HTGR) is a packed bed composed of spherical pebbles (fuel element and graphite moderator). ... Mine O. Yilmaz, …, Jens G.M. Andersen. Development and application of a neutronics/thermal-hydraulics coupling optimization code for the CFETR helium cooled solid breeder blanket with mixed pebble …
Shielding Design Optimization of the Helium-Cooled Pebble Bed …
The helium-cooled pebble bed (HCPB) breeding blanket (BB) is one of the two driver-blanket candidates for the European DEMO fusion reactor. Recent design activities were focused, among other objectives, on the achievement of an efficient shielding system to adequately protect the vacuum vessel (VV) and toroidal field coils (TFCs). …
