Uranium

Uranium is a naturally occurring heavy metal with significant importance in energy production, industry, and national economies. Recognised for its high atomic weight and radioactive properties, uranium serves as a crucial element in both civilian and military contexts. Its capacity to undergo nuclear fission has made it a central component in electricity generation, while its chemical and physical characteristics have led to diverse applications in other sectors.

Physical and Chemical Characteristics

Uranium is a silvery-grey metallic element belonging to the actinide series, with the atomic number 92 and symbol U. It is weakly radioactive, possessing isotopes that differ in stability and abundance. The most common isotopes are uranium-238 (99.3%) and uranium-235 (0.7%), the latter being the fissile isotope responsible for sustaining nuclear chain reactions.
The metal is dense, about 1.7 times heavier than lead, and reacts slowly with oxygen, water, and acids. When finely divided, it can ignite spontaneously in air. Uranium’s chemical versatility allows it to form numerous compounds, including oxides, fluorides, and nitrates, which are vital in refining and fuel preparation processes.

Occurrence and Extraction

Uranium is widely distributed in the Earth’s crust, found in various minerals such as uraninite, carnotite, and torbernite. Economically viable uranium deposits occur primarily in countries like Kazakhstan, Canada, Australia, and Namibia. Extraction typically involves open-pit mining, underground mining, or in-situ leaching, depending on the geological setting.
Once extracted, uranium ore undergoes crushing, grinding, and chemical treatment to produce yellowcake (U₃O₈), a concentrated uranium oxide. The yellowcake is then refined and converted into gaseous uranium hexafluoride (UF₆) for enrichment, increasing the proportion of uranium-235 for nuclear fuel fabrication.

Nuclear and Energy Applications

The most significant use of uranium lies in nuclear power generation. In nuclear reactors, uranium-235 undergoes controlled fission, releasing vast amounts of heat energy used to produce steam, which drives turbines to generate electricity. A single kilogram of uranium-235 can release energy equivalent to the combustion of roughly three million kilograms of coal.
Uranium fuels various reactor types:

• Light-water reactors (LWRs) – the most common, using low-enriched uranium.
• Heavy-water reactors (CANDU) – capable of using natural uranium.
• Fast breeder reactors – designed to create more fissile material than they consume.

In addition to electricity generation, uranium serves as a power source for naval propulsion systems, particularly in submarines and aircraft carriers, providing extended operational endurance without refuelling.

Industrial and Everyday Uses

Although best known for its nuclear role, uranium and its compounds also find niche industrial and everyday applications. Historically, uranium oxides were used in ceramics and glassmaking, imparting a distinctive yellow to green fluorescence to decorative glassware and glazes. While largely discontinued due to health concerns, some antique “vaseline glass” and tiles still contain trace uranium content.
In modern industry, depleted uranium (DU), a by-product of enrichment with reduced uranium-235 content, has unique physical characteristics. Owing to its high density (about 19 g/cm³) and pyrophoric nature, DU is employed in:

• Radiation shielding in medical and industrial radiography.
• Counterweights in aircraft and spacecraft for stability.
• Armour-penetrating ammunition, as DU rounds can pierce heavily armoured targets.

Its density and self-sharpening behaviour make DU preferable in these contexts, though its use remains controversial due to potential environmental and health implications.

Economic and Strategic Importance

Uranium plays a pivotal role in global energy security and geopolitics. The uranium market is driven by demand from the nuclear power sector, which supplies around 10% of global electricity. Major producers such as Kazakhstan, Canada, and Australia collectively account for over two-thirds of world output. Prices fluctuate with reactor demand, stockpile levels, and policy shifts surrounding nuclear power.
For many nations, uranium mining contributes substantially to national income, employment, and export revenue. In Namibia and Niger, uranium represents a vital export commodity. Additionally, the global transition to low-carbon energy has renewed interest in nuclear power, positioning uranium as a critical mineral in the decarbonisation agenda.
On the strategic front, uranium remains a sensitive resource due to its potential use in nuclear weapons production. The enrichment process required for fuel can, if extended, produce weapons-grade uranium (over 90% U-235), leading to strict international safeguards under the International Atomic Energy Agency (IAEA).

Environmental and Health Considerations

Uranium’s radioactive and toxic properties necessitate careful handling. During mining and milling, workers may be exposed to dust, radon gas, and radioactive waste. Waste management and environmental remediation are therefore integral to modern uranium operations.
Depleted uranium use in munitions has raised environmental concerns in post-conflict regions, where residues can contaminate soil and groundwater. While DU’s radioactivity is low, its chemical toxicity poses potential long-term risks. Governments and agencies continue to study and regulate its safe disposal and cleanup.

Recycling and Future Prospects

Efforts to enhance the sustainability of uranium usage focus on recycling spent nuclear fuel and improving reactor efficiency. Some nations reprocess used fuel to recover uranium and plutonium for reuse, reducing waste and resource demand.
Emerging technologies, including small modular reactors (SMRs) and thorium-based nuclear systems, may further influence uranium’s future role. SMRs promise safer, flexible deployment with optimised uranium fuel utilisation, while thorium cycles could offer complementary alternatives with reduced long-term waste.
As global energy systems evolve, uranium is expected to remain central to achieving reliable and low-carbon electricity supply. Its combination of energy density, availability, and adaptability ensures ongoing relevance, despite the challenges of safety, waste, and proliferation management.