Physical Analysis of LBE Spallation Target Coupled With the Reactor for CIADS

2014 ◽  
Author(s):  
Lu Zhang ◽  
Yongwei Yang ◽  
Yucui Gao
Keyword(s):  
Density Distribution ◽  
Energy Deposition ◽  
Amplification Factor ◽  
Spallation Target ◽  
The Core ◽  
Beam Pipe ◽  
Power Amplification ◽  
Deposition Density ◽  
Neutronic Parameters ◽  
Critical Reactor

For the project of the Chinese Initiative Accelerator Driven Sub-critical system (CIADS), the Lead-Bismuth-Eutectic (LBE) spallation target is one of the two alternatives, which has high good thermal performance, mature technology, and other advantages. The physical design of the spallation target determines the neutron yield and the utilization of the neuron source, as well as the performance of the sub-critical reactor and other key issues. Based on the Monte Carlo program MCNPX, we did the preliminary design of spallation target coupled with the reactor with a keff about 0.95. The energy deposition density distribution of the target and the window were calculated. In the mean time, the neutron flux density, the neutron energy spectrum, and the power amplification factors were calculated. By changing the positions of the target, the radii of the beam pipe and the thickness of target, we studied the variation of the neutronic parameters mainly mentioned above. The energy deposition density distribution was used as the heat source of the thermal-hydraulics analyses. From the neutronic parameters, we found that to get the maximum power amplification factor, the target window should be put at the positions 11.4 cm above the center of the core. Actually, when the target was put above the center of the core, from 0cm to 22cm, the maximum differences of the power amplification factor is less than 4.0%, which means the position will have little influences in this range. When the target window was put at the center, increasing of the window’s thickness will lead the decreasing of the power amplification factor. The enlargement of the beam pipe radii will decrease the maximum that the amplification factors can reach. Meanwhile, the increasing of the beam radii will enlarge the power amplification factor slightly. The physics analysis of the LBE target coupled with the reactor can give more information to the optimization of the target structure and the sub-critical reactor for CIADS.

Jumping, Climbing and Suspensory Locomotion

2018 ◽  
Keyword(s):  
Energy Storage ◽  
Elastic Energy ◽  
The Core ◽  
Power Amplification ◽  
Core Concepts

Jumping, climbing and suspensory locomotion are specialized locomotor mechanisms used on land and in the air. Jumping is used for rapid launches from substrates. Climbing and suspensory movements enable locomotion up, under and through vertically-structured habitats, such as forests. Elastic energy storage is particularly important for jumping and catapult systems and we address the core concepts of power amplification that are exemplified in nature’s extreme jumpers. We examine the diverse mechanisms of attachment that characterize animals that can grasp and adhere to a diversity of structures. We conclude the chapter by examining the integration of biological capabilities with engineering innovations in these systems.

Density functional theory is straying from the path toward the exact functional

Science ◽  
2017 ◽  
Vol 355 (6320) ◽  
pp. 49-52 ◽  
Author(s):  
Michael G. Medvedev ◽  
Ivan S. Bushmarinov ◽  
Jianwei Sun ◽  
John P. Perdew ◽  
Konstantin A. Lyssenko
Keyword(s):  
Density Functional Theory ◽  
Density Distribution ◽  
Ground State ◽  
Electron Density Distribution ◽  
Density Functional ◽  
Electron System ◽  
The Other ◽  
Functional Theory ◽  
The Core ◽  
Exact Density

The theorems at the core of density functional theory (DFT) state that the energy of a many-electron system in its ground state is fully defined by its electron density distribution. This connection is made via the exact functional for the energy, which minimizes at the exact density. For years, DFT development focused on energies, implicitly assuming that functionals producing better energies become better approximations of the exact functional. We examined the other side of the coin: the energy-minimizing electron densities for atomic species, as produced by 128 historical and modern DFT functionals. We found that these densities became closer to the exact ones, reflecting theoretical advances, until the early 2000s, when this trend was reversed by unconstrained functionals sacrificing physical rigor for the flexibility of empirical fitting.

scholarly journals DESIGN OF NEUTRONIC PARAMETERS OF MTR REACTOR USING WIMSD-5B/BATAN-FUEL CODES

2020 ◽  
Vol 5 (3) ◽  
pp. 239-248
Author(s):  
Tukiran Surbakti ◽  
Surian Pinem ◽  
Lily Suparlina
Keyword(s):  
Neutron Flux ◽  
Thermal Neutron ◽  
Cycle Length ◽  
Thermal Neutron Flux ◽  
Diffusion Method ◽  
Irradiation Position ◽  
Research Reactors ◽  
The Core ◽  
Neutronic Parameters ◽  
Control Rods

BATAN has three aging research reactors, so it is necessary to design a new, more modern MTR type reactor using high-density, low enrichment uranium molybdenum fuel. The thermal neutron flux at the irradiation position is an important concern in the design of research reactors. This analysis is performed using standard computer codes WIMSD-5B and Batan-FUEL. The purpose of this study is to analyze the effect of the core configuration with safety control rods and neutronic parameters using the diffusion method calculation. The reactor core consists of 16 fuel elements and four control rods placed in the 5 x 5 position of the grid plate and is loaded the reflector elements outside the core. The cycle length is also a concern, not less than 20 days, and the reactor can be operated safely with a power of 50 MW. The calculation results show that for the highest fuel loading, which is 450 grams of U7Mo/Al fuel with D2O as a reflector, it will provide the lowest thermal neutron flux at the center of the core irradiation position, namely 1.0 x1015 n/cm2s. The core fuel cycle length will be up to 39 days, meeting the expected acceptance and safety criteria.

scholarly journals Relativistic Hirshfeld atom refinement of an organo-gold(I) compound

IUCrJ ◽  
2021 ◽  
Vol 8 (4) ◽  
Author(s):  
Sylwia Pawlędzio ◽  
Maura Malinska ◽  
Magdalena Woińska ◽  
Jakub Wojciechowski ◽  
Lorraine Andrade Malaspina ◽  
...  
Keyword(s):  
Density Distribution ◽  
Electron Density ◽  
Electron Correlation ◽  
Electron Density Distribution ◽  
Gold Atom ◽  
Relativistic Effects ◽  
Model Parameters ◽  
Statistical Parameters ◽  
Mercury Compounds ◽  
The Core

The main goal of this study is the validation of relativistic Hirshfeld atom refinement (HAR) as implemented in Tonto for high-resolution X-ray diffraction datasets of an organo-gold(I) compound. The influence of the relativistic effects on statistical parameters, geometries and electron density properties was analyzed and compared with the influence of electron correlation and anharmonic atomic motions. Recent work in this field has indicated the importance of relativistic effects in the static electron density distribution of organo-mercury compounds. This study confirms that differences in electron density due to relativistic effects are also of significant magnitude for organo-gold compounds. Relativistic effects dominate not only the core region of the gold atom, but also influence the electron density in the valence and bonding region, which has measurable consequences for the HAR refinement model parameters. To study the effects of anharmonic motion on the electron density distribution, dynamic electron density difference maps were constructed. Unlike relativistic and electron correlation effects, the effects of anharmonic nuclear motion are mostly observed in the core area of the gold atom.

scholarly journals Simultaneous formation of Jupiter and Saturn

2010 ◽  
Vol 6 (S276) ◽  
pp. 428-429
Author(s):  
Octavio M. Guilera ◽  
Adrián Brunini ◽  
Omar G. Benvenuto
Keyword(s):  
Density Distribution ◽  
Solar Nebula ◽  
Classical Model ◽  
Protoplanetary Disk ◽  
Instability Mechanism ◽  
Simultaneous Formation ◽  
The Core ◽  
Growth Regime ◽  
Significant Change

AbstractWe calculate the simultaneous in situ formation of Jupiter and Saturn by the core instability mechanism considering the oligarchic growth regime for the accretion of planetesimals. We consider a density distribution for the size of planetesimals and planetesimals migration. The planets are immersed in a realistic protoplanetary disk that evolves with time. We find that, within the classical model of solar nebula, the isolated formation of Jupiter and Saturn undergoes significant change when it occurs simultaneously.

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