Uranium is a silvery-white metal in the actinide series of the periodic table. Uranium is weakly radioactive because all isotopes of uranium are unstable, with half-lives varying between 159,200 years and 4.5 billion years. Uranium has the highest atomic weight of the primordially occurring elements. Its density is about 70% higher than that of lead, and slightly lower than that of gold or tungsten. Uranium is commonly found at low levels (a few ppm – parts per million) in all rocks, soil, water, plants, and animals (including humans). Uranium occurs also in seawater, and can be recovered from the ocean water. Significant concentrations of uranium occur in some substances such as uraninite (the most common uranium ore), phosphate rock deposits, and other minerals.
|Element category||Rare Earth Metal|
|Phase at STP||Solid|
|Ultimate Tensile Strength||390 MPa|
|Yield Strength||190 MPa|
|Young’s Modulus of Elasticity||208 GPa|
|Brinell Hardness||2400 MPa|
|Vickers Hardness||1960 MPa|
|Melting Point||1132 °C|
|Boiling Point||4131 °C|
|Thermal Conductivity||27 W/mK|
|Thermal Expansion Coefficient||13.9 µm/mK|
|Specific Heat||0.12 J/g K|
|Heat of Fusion||8.52 kJ/mol|
|Heat of Vaporization||417 kJ/mol|
|Electrical resistivity [nanoOhm meter]||280|
Applications of Uranium
The main use of uranium in the civilian sector is to fuel nuclear power plants. One kilogram of uranium-235 can theoretically produce about 20 terajoules of energy, assuming complete fission; as much energy as 1.5 million kilograms (1,500 tonnes) of coal. Typical reactor may contain about 100 tonnes of enriched uranium (i.e. about 113 tonnes of uranium dioxide). This fuel is loaded within, for example, 157 fuel assemblies composed of over 45,000 fuel rods. A common fuel assembly contain energy for approximately 4 years of operation at full power. The removed fuel (spent nuclear fuel) still contains about 96% of reusable material (it must be removed due to decreasing kinf of an assembly). Before (and, occasionally, after) the discovery of radioactivity, uranium was primarily used in small amounts for yellow glass and pottery glazes, such as uranium glass. Uranium is also used by the military to power nuclear submarines and in nuclear weapons. Due to its high density, this material is found in inertial guidance systems and in gyroscopic compasses. Depleted uranium is preferred over similarly dense metals due to its ability to be easily machined and cast as well as its relatively low cost. The main risk of exposure to depleted uranium is chemical poisoning by uranium oxide rather than radioactivity (uranium being only a weak alpha emitter). Depleted uranium is uranium that has much less uranium-235 than natural uranium. It is considerably less radioactive than natural uranium. It is a dense metal that can be used as ballast for ships and counterweights for aircraft. It is also used in ammunition and armour. Depleted uranium can be also used to shield radiation. Depleted uranium is much more effective due to its higher Z. Depleted uranium is used for shielding in portable gamma ray sources. Uranium is used in high-speed steels as an alloying agent to improve strength and toughness. Uranium trioxide (also called uranic oxide) with formula UO3, is an orange-yellow powder and is used as a pigment for ceramics. In glasses it produces a beautiful greenish-yellow “uranium glass”.
Production and Price of Uranium
Raw materials prices change daily. They are primarily driven by supply, demand and energy prices. In 2019, prices of pure Uranium were at around N/A $/kg.
Uranium is commonly found at low levels (a few ppm – parts per million) in all rocks, soil, water, plants, and animals (including humans). Uranium occurs also in seawater, and can be recovered from the ocean water. Significant concentrations of uranium occur in some substances such as uraninite (the most common uranium ore), phosphate rock deposits, and other minerals. Uranium is often found with copper, phosphates, and other minerals; thus, it is often a co-product of other mining operations. The worldwide production of uranium in 2015 amounted to 60496 tonnes. Kazakhstan, Canada, and Australia are the top three producers and together account for 70% of world uranium production. Uranium is commonly found at low levels (a few ppm – parts per million) in all rocks, soil, water, plants, and animals (including humans). Uranium occurs also in seawater, and can be recovered from the ocean water. But only a few of the uranium ores known contain sufficient uranium (greater than 0.1%) to extract commercially. Significant concentrations of uranium occur in some substances such as uraninite (the most common uranium ore), phosphate rock deposits, and other minerals.
Mechanical Properties of Uranium
Strength of Uranium
In mechanics of materials, the strength of a material is its ability to withstand an applied load without failure or plastic deformation. Strength of materials basically considers the relationship between the external loads applied to a material and the resulting deformation or change in material dimensions. In designing structures and machines, it is important to consider these factors, in order that the material selected will have adequate strength to resist applied loads or forces and retain its original shape. Strength of a material is its ability to withstand this applied load without failure or plastic deformation.
For tensile stress, the capacity of a material or structure to withstand loads tending to elongate is known as ultimate tensile strength (UTS). Yield strength or yield stress is the material property defined as the stress at which a material begins to deform plastically whereas yield point is the point where nonlinear (elastic + plastic) deformation begins.
See also: Strength of Materials
Ultimate Tensile Strength of Uranium
Ultimate tensile strength of Uranium is 390 MPa.
Yield Strength of Uranium
Yield strength of Uranium is 190 MPa.
Modulus of Elasticity of Uranium
The Young’s modulus of elasticity of Uranium is 190 MPa.
Hardness of Uranium
In materials science, hardness is the ability to withstand surface indentation (localized plastic deformation) and scratching. Brinell hardness test is one of indentation hardness tests, that has been developed for hardness testing. In Brinell tests, a hard, spherical indenter is forced under a specific load into the surface of the metal to be tested.
Brinell hardness of Uranium is approximately 2400 MPa.
The Vickers hardness test method was developed by Robert L. Smith and George E. Sandland at Vickers Ltd as an alternative to the Brinell method to measure the hardness of materials. The Vickers hardness test method can be also used as a microhardness test method, which is mostly used for small parts, thin sections, or case depth work.
Vickers hardness of Uranium is approximately 1960 MPa.
Scratch hardness is the measure of how resistant a sample is to permanent plastic deformation due to friction from a sharp object. The most common scale for this qualitative test is Mohs scale, which is used in mineralogy. The Mohs scale of mineral hardness is based on the ability of one natural sample of mineral to scratch another mineral visibly.
Uranium is has a hardness of approximately 6.
See also: Hardness of Materials
Uranium – Crystal Structure
A possible crystal structure of Uranium is orthorhombic structure.
In metals, and in many other solids, the atoms are arranged in regular arrays called crystals. A crystal lattice is a repeating pattern of mathematical points that extends throughout space. The forces of chemical bonding causes this repetition. It is this repeated pattern which control properties like strength, ductility, density, conductivity (property of conducting or transmitting heat, electricity, etc.), and shape. There are 14 general types of such patterns known as Bravais lattices.
See also: Crystal Structure of Materials
Thermal Properties of Uranium
Uranium – Melting Point and Boiling Point
Melting point of Uranium is 1132°C.
Boiling point of Uranium is 4131°C.
Note that, these points are associated with the standard atmospheric pressure.
Uranium – Thermal Conductivity
Thermal conductivity of Uranium is 27 W/(m·K).
The heat transfer characteristics of a solid material are measured by a property called the thermal conductivity, k (or λ), measured in W/m.K. It is a measure of a substance’s ability to transfer heat through a material by conduction. Note that Fourier’s law applies for all matter, regardless of its state (solid, liquid, or gas), therefore, it is also defined for liquids and gases.
Coefficient of Thermal Expansion of Uranium
Linear thermal expansion coefficient of Uranium is 13.9 µm/(m·K)
Thermal expansion is generally the tendency of matter to change its dimensions in response to a change in temperature. It is usually expressed as a fractional change in length or volume per unit temperature change.
Uranium – Specific Heat, Latent Heat of Fusion, Latent Heat of Vaporization
Specific heat of Uranium is 0.12 J/g K.
Heat capacity is an extensive property of matter, meaning it is proportional to the size of the system. Heat capacity C has the unit of energy per degree or energy per kelvin. When expressing the same phenomenon as an intensive property, the heat capacity is divided by the amount of substance, mass, or volume, thus the quantity is independent of the size or extent of the sample.
Latent Heat of Fusion of Uranium is 8.52 kJ/mol.
Latent Heat of Vaporization of Uranium is 417 kJ/mol.
Latent heat is the amount of heat added to or removed from a substance to produce a change in phase. This energy breaks down the intermolecular attractive forces, and also must provide the energy necessary to expand the gas (the pΔV work). When latent heat is added, no temperature change occurs. The enthalpy of vaporization is a function of the pressure at which that transformation takes place.
Uranium – Electrical Resistivity – Magnetic Susceptibility
Electrical property refers to the response of a material to an applied electric field. One of the principal characteristics of materials is their ability (or lack of ability) to conduct electrical current. Indeed, materials are classified by this property, that is, they are divided into conductors, semiconductors, and nonconductors.
See also: Electrical Properties
Magnetic property refers to the response of a material to an applied magnetic field. The macroscopic magnetic properties of a material are a consequence of interactions between an external magnetic field and the magnetic dipole moments of the constituent atoms. Different materials react to the application of magnetic field differently.
See also: Magnetic Properties
Electrical Resistivity of Uranium
Electrical resistivity of Uranium is 280 nΩ⋅m.
Electrical conductivity and its converse, electrical resistivity, is a fundamental property of a material that quantifies how Uranium conducts the flow of electric current. Electrical conductivity or specific conductance is the reciprocal of electrical resistivity.
Magnetic Susceptibility of Uranium
Magnetic susceptibility of Uranium is N/A.
In electromagnetism, magnetic susceptibility is the measure of the magnetization of a substance. Magnetic susceptibility is a dimensionless proportionality factor that indicates the degree of magnetization of Uranium in response to an applied magnetic field.
Application and prices of other elements