Related Experiment Video
Updated: May 25, 2026
09:18
Laser-heating and Radiance Spectrometry for the Study of Nuclear Materials in Conditions Simulating a Nuclear Power Plant Accident
Published on: December 14, 2017
Atomistic properties of γ uranium
Benjamin Beeler1, Chaitanya Deo, Michael Baskes
1George W Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
Summary
Atomistic simulations reveal key properties of uranium's high-temperature body-centered cubic (γ) phase. This study provides insights into its mechanical instability, melting point, and defect energies, crucial for understanding uranium behavior.
Area of Science:
- Materials Science
- Computational Physics
- Nuclear Engineering
Background:
- The body-centered cubic γ phase of uranium (U) is stable only at high temperatures.
- This phase is difficult to study experimentally and via first-principles calculations due to its high-temperature stability.
- Understanding γ-U properties is essential for nuclear materials science and engineering.
Purpose of the Study:
- To develop and utilize an atomistic simulation method for calculating the properties of the γ phase of uranium.
- To investigate the mechanical instability of γ-U under pressure.
- To determine thermodynamic and defect properties of γ-U at various temperatures and pressures.
Main Methods:
- Development of a modified embedded-atom method (MEAM) interatomic potential for γ-U.
- Atomistic simulations using the developed MEAM potential.
- Calculation of equilibrium volume, elastic constants, melting point, heat capacity, enthalpy of fusion, thermal expansion, volume change upon melting, vacancy formation energy, and self-defect formation energy.
Main Results:
- The developed MEAM potential accurately reproduces known properties of γ-U, including equilibrium volume and elastic constants.
- Calculated thermodynamic properties (melting point, heat capacity, etc.) show good agreement with experimental data.
- The low-temperature mechanical instability of γ-U was predicted and found to be suppressed above 17.2 GPa.
- Vacancy formation energy exhibits a linear trend with pressure, enabling extrapolation to zero pressure.
- Self-defect formation energy was analyzed as a function of temperature.
Conclusions:
- The study successfully established a reliable atomistic simulation approach for γ-U properties above 0 K.
- The findings provide valuable data on the mechanical and thermodynamic behavior of γ-U, particularly its pressure-dependent instability.
- This work represents the first atomistic investigation of γ-U properties at elevated temperatures using interatomic potentials.
Related Concept Videos
03:20Nuclear Transmutation
Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with another particle. The first manmade nucleus was produced in Ernest Rutherford’s laboratory in 1919 by a transmutation reaction, the bombardment of one type of nuclei with other nuclei or with neutrons. Rutherford bombarded nitrogen-14 atoms with high-speed α particles from a natural radioactive isotope of radium and observed protons being...
03:18Radioactivity and Nuclear Equations
Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The nucleus of an atom is composed of protons and, except for hydrogen, neutrons. The number of protons in the nucleus is called the atomic number (Z) of the element, and the sum of the number of protons and the number of neutrons is the mass number (A). Atoms with the same atomic number but different mass numbers are isotopes of the same element.
A nuclide of an element has a specific number of protons and...
A nuclide of an element has a specific number of protons and...
03:18Nuclear Stability
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively charged protons together in the...
To hold positively charged protons together in the...
03:23Types of Radioactivity
The most common types of radioactivity are α decay, β decay, γ decay, neutron emission, and electron capture.
Alpha (α) decay is the emission of an α particle from the nucleus. For example, polonium-210 undergoes α decay:
Alpha (α) decay is the emission of an α particle from the nucleus. For example, polonium-210 undergoes α decay:
01:03Atomic Nuclei: Nuclear Spin State Overview
NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the absence of a magnetic field, the nuclear magnetic moments are randomly oriented, and the spin states are degenerate. When an external magnetic field is applied, the spin states have only 2 + 1 orientations available to them. A proton with = ½ has two available orientations. Similarly, for a quadrupolar nucleus with a nuclear spin value of one, the...
01:25Microbial Bioremediation of Uranium
Microorganisms play a critical role in the transformation and immobilization of uranium in contaminated environments through four main pathways: bioreduction, biosorption, bioaccumulation, and biomineralization. These mechanisms reduce uranium’s toxicity and prevent its migration through groundwater systems, offering sustainable approaches for in situ bioremediation.Bioreduction of UraniumBioreduction is driven by anaerobic bacteria such as certain strains of Geobacter and Shewanella, which use...