scholarly journals Computational Modeling Towards Accelerating Accident Tolerant Fuel Concepts and Determining In-Pile Fuel Behavior

2021 ◽  
Author(s):  
Ember Sikorski
Keyword(s):  
Density Functional ◽  
National Laboratory ◽  
The United States ◽  
Corrosion Properties ◽  
Functional Theory ◽  
Surface Stability ◽  
Reactor Coolant ◽  
Safety Margins ◽  
Uranium Nitride ◽  
Increasing Temperature

To mitigate global warming, we need to develop carbon-free ways to generate power. Nuclear energy currently generates more carbon-free power in the United States than all other sources combined at 55%. To make nuclear as viable a power source as possible, we need to maximize power density and safety. Both of these can be improved with Accident Tolerant Fuel (ATF) materials. Uranium nitride (UN), a candidate ATF material, offers high fuel economy due to its uranium density and improved safety margins from thermal properties. However, its instability in the presence of water, a reactor coolant, must be addressed. This dissertation employs Density Functional Theory-based methods to investigate the atomistic and electronic mechanisms in UN corrosion initiation. To ensure accuracy in future UN models, the effects of magnetic treatments on UN surface stability and corrosion properties are also determined. The performance of advanced nuclear materials must be tested in research reactors before they can be implemented in power reactors. To get real-time temperature data from these tests, sensors are required that can survive the high temperatures and irradiation. To meet these needs, Idaho National Laboratory has been developing High Temperature Irradiation Resistant Thermocouples (HTIR-TCs). Towards increasing temperature resolution and in-pile lifetime, an ab initio method has been developed to predict HTIR-TC performance. The method considers the effects of composition and temperature on performance and has been validated against experiment. To predict the interaction of HTIR-TCs with research reactor coolant, corrosion and oxidation mechanisms have been investigated. By examining the diffusion behaviors of water and oxygen, recommendations are made for which thermoelement materials may be the most resistant to corrosion and/or oxidation.

scholarly journals First-principles study of organic molecule for corrosion inhibition

2019 ◽  
Vol 116 ◽  
pp. 00007
Author(s):  
Rachid Belkada ◽  
Dalila Hammoutène ◽  
Rahma Tibigui ◽  
Ikram Hadj-Said
Keyword(s):  
First Principles ◽  
Global Economy ◽  
Density Functional ◽  
Corrosion Inhibitors ◽  
Computational Techniques ◽  
Corrosion Properties ◽  
Functional Theory ◽  
Fundamental Level ◽  
Organic Inhibitors ◽  
The Relationship

The widespread use of steel in various industries, especially in the transportation of hydrocarbons and gas, has recently gained a potential interest to explore eco-friendly solutions against corrosion. In fact, the highly aggressive environment generates considerable losses that affect global economy of countries that are mainly depending on the production and transport of energy. In the field of corrosion inhibitors, most common method so far available for protection against corrosion relies on synthetic one. These are unfortunately harmful to the environment as well to the human health, however they remain the most popular and the most effective due to their cost, and their ease of application. One of the most challenging issues in this area is the accurate understanding and measure of the degree of the passivation of corrosion inhibitors, which is complex and depend on many factors such as the nature of the metal, the fluid, the electronic structure of the inhibitor, the temperature, the exposure time, and so on. Recently, organic inhibitors have become increasingly attractive due to their competitive character as compared to the synthetic ones. With the use of advanced computational techniques enhanced by the development of density functional theory (DFT), it becomes possible to identify and design at the fundamental level, novel corrosion inhibitor molecules as complementary well established tool beside to the experimental techniques, which are often very expensive and time-consuming. In this work, we explore by mean of DFT, the anti-corrosion effect of the Lawsone molecule (2-hydroxy-1,4-naphthoquinone) and some of its derivatives to clarify and understand the relationship at the fundamental level between the anti-corrosion properties and the structure of the molecule in contact with the iron.

scholarly journals Crystal Structures, Surface Stability, and Water Adsorption Energies of La-Bastnäsite via Density Functional Theory and Experimental Studies

2016 ◽  
Vol 120 (30) ◽  
pp. 16767-16781 ◽  
Author(s):  
Sriram Goverapet Srinivasan ◽  
Radha Shivaramaiah ◽  
Paul R. C. Kent ◽  
Andrew G. Stack ◽  
Alexandra Navrotsky ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Crystal Structures ◽  
Density Functional ◽  
Water Adsorption ◽  
Experimental Studies ◽  
Functional Theory ◽  
Surface Stability ◽  
Adsorption Energies

scholarly journals First-principles investigations of the electronic and magnetic structures and the bonding properties of uranium nitride fluoride (UNF)

2017 ◽  
Vol 72 (10) ◽  
pp. 725-730
Author(s):  
Samir F. Matar
Keyword(s):  
Magnetic Structure ◽  
Density Functional ◽  
Geometry Optimization ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Magnetic Structures ◽  
Overlap Population ◽  
Bonding Properties ◽  
Uranium Nitride ◽  
Structure Investigations

AbstractBased on geometry optimization and magnetic structure investigations within density functional theory, a unique uranium nitride fluoride, isoelectronic with UO2, is shown to present peculiar differentiated physical properties. These specificities versus the oxide are related to the mixed anionic substructure and the layered-like tetragonal structure characterized by covalent-like [U2N2]2+ motifs interlayered by ionic-like [F2]2− ones and illustrated herein with electron localization function projections. Particularly, the ionocovalent chemical picture shows, based on overlap population analyses, stronger U–N bonding versus U–F and d(U–N)<d(U–F) distances. Further generalized gradient approximation+U calculations provide the ground state magnetic structure as insulating antiferromagnet with ±2 μB magnetization per magnetic sub-cell and ~2 eV band gap.

Surface stability of potassium nitrate (KNO3) from density functional theory

2010 ◽  
Vol 50 (2) ◽  
pp. 356-362 ◽  
Author(s):  
O.M. Løvvik ◽  
T.L. Jensen ◽  
J.F. Moxnes ◽  
O. Swang ◽  
E. Unneberg
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Potassium Nitrate ◽  
Functional Theory ◽  
Surface Stability

scholarly journals Temperature-Dependent Generalized Planar Fault Energy and Twinnability of Mg Microalloyed with Er, Ho, Dy, Tb, and Gd: First-Principles Study

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Lili Liu ◽  
Yelu He ◽  
Dingxing Liu ◽  
Xiaozhi Wu ◽  
Rui Wang
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Density Functional ◽  
Atomic Radius ◽  
Temperature Dependent ◽  
Functional Theory ◽  
Planar Fault ◽  
Change Trend ◽  
Underlying Mechanisms ◽  
Increasing Temperature

The generalized planar fault energies, Rice criterion ductility, and twinnability of pure Mg and Mg-RE (RE = Er, Ho, Dy, Tb, and Gd) alloys at different temperature have been investigated using density functional theory. It is shown that all the fault energies and twinnability in the same materials decrease with increasing temperature. However, the ductility has the opposite change trend. On the other hand, alloying rare earth elements will generally decrease the fault energies and increase the ductility and twinnability of Mg at different temperature. It is interesting to note that alloying larger atomic radius will enhance the ductility of Mg more easily and alloying smaller radius will make twinning tendency of Mg more easily. Finally, the electron structure further reveals the underlying mechanisms for the reduction of fault energies with the addition of rare earth elements.

scholarly journals Origin of the multiple configurations that drive the response of δ-plutonium’s elastic moduli to temperature

2016 ◽  
Vol 113 (40) ◽  
pp. 11158-11161 ◽  
Author(s):  
Albert Migliori ◽  
Per Söderlind ◽  
Alexander Landa ◽  
Franz J. Freibert ◽  
Boris Maiorov ◽  
...  
Keyword(s):  
Density Functional ◽  
Recent Observation ◽  
Continuous Distribution ◽  
Spin Fluctuations ◽  
Functional Theory ◽  
Thermally Activated ◽  
Invar Alloys ◽  
Bonding Properties ◽  
Increasing Temperature ◽  
Magnetic States

The electronic and thermodynamic complexity of plutonium has resisted a fundamental understanding for this important elemental metal. A critical test of any theory is the unusual softening of the bulk modulus with increasing temperature, a result that is counterintuitive because no or very little change in the atomic volume is observed upon heating. This unexpected behavior has in the past been attributed to competing but never-observed electronic states with different bonding properties similar to the scenario with magnetic states in Invar alloys. Using the recent observation of plutonium dynamic magnetism, we construct a theory for plutonium that agrees with relevant measurements by using density-functional-theory (DFT) calculations with no free parameters to compute the effect of longitudinal spin fluctuations on the temperature dependence of the bulk moduli in δ-Pu. We show that the softening with temperature can be understood in terms of a continuous distribution of thermally activated spin fluctuations.

scholarly journals Inhibition of Aluminium Corrosion in 1M HCl by Pyridoxine Hydrochloride: Thermodynamic and Quantum Chemical Studies

2020 ◽  
pp. 20-38
Author(s):  
Mamadou Yeo ◽  
Mougo André Tigori ◽  
Amadou Kouyaté ◽  
Paulin Marius Niamien ◽  
Albert Trokourey
Keyword(s):  
Density Functional ◽  
Activation Parameters ◽  
Structure Property ◽  
Pyridoxine Hydrochloride ◽  
Functional Theory ◽  
Structure Property Relationship ◽  
Chemical Studies ◽  
Quantum Chemical Studies ◽  
Increasing Temperature ◽  
Green Corrosion Inhibitors

Currently, research in the area of corrosion inhibition is focussed on the development of green corrosion inhibitors. It is with this in mind that pyridoxine hydrochloride, which is vitamin B6, has been tested as a corrosion inhibitor of aluminium in 1M HCl by mass loss, Density Functional Theory (DFT) and Quantitative Structure-Property Relationship (QSPR) methods. The results obtained show that the inhibition efficiency increases with concentration but decreases with increasing temperature. This vitamin is adsorbed on aluminium according to the modified Langmuir isotherm and occurs in two modes: physisorption and chemisorption. Thermodynamic adsorption and activation parameters have been determined and discussed. Finally, QSPR approach was used to find the best set of parameters in order to determine the theoretical inhibition efficiencies from the experimental data. Experimental measurements were found in good collaboration with the theoretical results.

Electronic Properties of Thermoelectric PbSe2 Compound by Density Functional Theory Method

2020 ◽  
Vol 999 ◽  
pp. 136-141
Author(s):  
Man Man Han ◽  
Jia Fu ◽  
Xing Liu ◽  
Tao Jiang
Keyword(s):  
Density Functional Theory ◽  
Debye Temperature ◽  
Density Functional ◽  
Density Functional Theory Method ◽  
Elevated Pressure ◽  
Debye Model ◽  
First Principles Calculation ◽  
Functional Theory ◽  
Increasing Temperature ◽  
The Given

Based on the first-principles calculation and the quasi-harmonic Debye model, the electronic and thermodynamic properties of CuCl2-type PbSe2 compound of a promising thermoelectric (TE) material are studied. According to the analysis of the density of states (DOS) and the Mulliken electron population, it is found that the PbSe2 compound possesses weak metallic characterization, where the covalent bonding exists in PbSe2 compound and the ionic bonding exists between Pb and Se atoms. Besides, the Debye temperature decreases with increasing temperature at certain pressures, and it shows the increasing tendency under the elevated pressure at certain temperatures. The Grüneisen parameter increases with increasing temperature at the given pressures, and it also decreases with increasing pressure at the given temperatures. The density functional theory (DFT) is used to obtain the parameters of the Debye temperature, the Grüneisen constant and thermal expansion coefficient, which are about 319.76 K, 2.42, and 8.41×10-5K-1 at 0 GPa, which provides useful parameters and contributes to explore new potential TE materials in future.

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