Thorium (chemical symbol Th, atomic number 90) is one of the lesser-known elements on the periodic table, but its potential as an energy source could reshape the future of nuclear power. Named after Thor, the Norse god of thunder, thorium is a naturally occurring radioactive element that has fascinated scientists for over a century. While thorium was once overshadowed by uranium and plutonium in nuclear power, it is gaining attention today as a safer and more abundant alternative to traditional nuclear fuels.
In this blog post, we’ll explore the history, properties, and modern-day uses of thorium, with a particular focus on its potential to revolutionize the nuclear energy industry.

The Discovery of Thorium
Thorium was discovered in 1828 by Swedish chemist Jöns Jakob Berzelius, one of the founders of modern chemistry. Berzelius identified thorium while analyzing a mineral sample provided by the amateur geologist Morten Thrane Esmark. The mineral, later named thorite, contained the new element, which Berzelius named thorium after Thor, the Norse god of thunder and strength.
Thorium remained relatively obscure for several decades after its discovery, mostly of interest to mineralogists and chemists. However, in the early 20th century, the radioactive properties of thorium began to be understood, especially following the work of scientists like Marie Curie and Ernest Rutherford, who studied radioactivity and nuclear physics.

Properties of Thorium
Thorium is a soft, silvery metal that is about as common in the Earth’s crust as lead. It is primarily found in thorite, monazite, and thorianite minerals. While thorium itself is not fissile (it cannot directly sustain a nuclear chain reaction), it is fertile, meaning it can absorb neutrons and be converted into uranium-233 (U-233), a fissile material that can be used in nuclear reactors.
Key properties of thorium include:
Abundance: Thorium is estimated to be three to four times more abundant than uranium, making it an attractive option for countries with limited uranium reserves.
Low Radioactivity: Although thorium is radioactive, its radioactivity is relatively low compared to other radioactive elements like uranium and plutonium.
Stability: Thorium has a half-life of about 14 billion years, which means it decays extremely slowly and is relatively stable.

The Potential of Thorium as a Nuclear Fuel
One of the most exciting modern applications of thorium is in nuclear energy. Thorium has long been considered a promising alternative to uranium and plutonium for several reasons:
1. Safer Nuclear Reactors
Thorium-based reactors are considered inherently safer than traditional uranium reactors. In a thorium reactor, the process of converting thorium-232 to uranium-233 occurs more slowly and requires a continuous supply of neutrons, which means that if something goes wrong, the reaction can stop more easily. This reduces the risk of meltdowns like the ones that occurred at Chernobyl and Fukushima.
In addition, thorium reactors produce much less long-lived radioactive waste than uranium reactors, meaning they don’t create as many environmental hazards for future generations.
2. Abundance and Availability
Thorium is found in large quantities in several countries, including the United States, India, Australia, and Norway. Because thorium is more abundant than uranium, it offers the potential for a long-term, sustainable source of nuclear fuel.
India, for example, has the world’s largest thorium reserves and has been actively developing thorium-based nuclear energy as part of its energy security strategy. India’s Advanced Heavy Water Reactor (AHWR) is designed to use thorium as a primary fuel source, aiming to reduce reliance on uranium imports.
3. Proliferation Resistance
One of the major concerns with uranium and plutonium-based nuclear power is the potential for nuclear weapons proliferation. Uranium-233, the fissile material produced from thorium, is more difficult to weaponize than plutonium-239, which is produced in uranium reactors. This makes thorium a more proliferation-resistant nuclear fuel, reducing the risk that civilian nuclear programs could be diverted to weapons production.
4. Reduced Nuclear Waste
Thorium reactors produce far less long-lived nuclear waste compared to traditional uranium reactors. The waste from thorium reactors decays faster and is less hazardous in the long term. While uranium reactors produce plutonium, which has a half-life of 24,000 years, thorium reactors produce less plutonium and other long-lived transuranic elements, making waste management easier and safer.

The Challenges of Thorium
Despite its potential, thorium has faced several challenges that have slowed its adoption as a primary nuclear fuel.
1. Lack of Infrastructure
Most of the world’s nuclear infrastructure is built around uranium. Developing the reactors and facilities needed to support thorium fuel cycles would require significant investment, and countries that have already invested heavily in uranium-based nuclear programs may be reluctant to switch.
2. Technical Hurdles
Although thorium has been tested in nuclear reactors since the mid-20th century, developing thorium reactors on a large scale is still an ongoing challenge. One of the main technical challenges is the need to safely handle uranium-233, the fissile material produced in thorium reactors. U-233 is highly radioactive, and any reactor using thorium must be able to safely manage the production and reprocessing of U-233.
3. Economic Barriers
Thorium may be abundant, but the cost of building new reactors, upgrading existing ones, and developing thorium fuel technology can be high. Many governments and energy companies are hesitant to invest in thorium when uranium is already well-established and widely available.

Other Modern Uses of Thorium
Beyond nuclear energy, thorium has other applications in modern technology, although these are more limited due to its radioactivity:
Lighting: Thorium was once used in gas mantles for portable lamps because of its ability to produce a bright, white light. This use has largely been phased out due to the availability of safer alternatives and concerns about radioactivity.
Aerospace and Electronics: Thorium is occasionally used in magnesium alloys to make materials stronger and more heat-resistant. These alloys are sometimes used in the aerospace industry and in high-performance electronics.
Scientific Research: Thorium is used as a source of neutrons in certain scientific experiments, including research into nuclear fusion, which could eventually provide clean, unlimited energy.

The Future of Thorium
While thorium has not yet reached its full potential as a nuclear fuel, many scientists believe it could play a key role in the future of clean, sustainable energy. Countries like India and China are continuing to explore thorium reactors, and advancements in nuclear technology could make thorium a more viable option in the coming decades.
One promising development is the Liquid Fluoride Thorium Reactor (LFTR), a type of molten salt reactor that uses thorium fuel dissolved in liquid salt. LFTRs offer the potential for safer, more efficient nuclear power, and several research programs around the world are working to bring this technology to fruition.
As the world continues to search for reliable, low-carbon energy sources, thorium’s abundance, safety, and sustainability make it an attractive candidate for next-generation nuclear energy.

Conclusion
Thorium may have been overlooked in favor of uranium during the early days of nuclear power, but its potential as a safer, more abundant, and environmentally friendly nuclear fuel cannot be ignored. As the world grapples with the need for sustainable energy solutions, thorium could offer a promising path forward for clean, reliable nuclear power.
While there are still challenges to overcome, advances in nuclear technology, along with growing interest in thorium’s benefits, suggest that this often-overlooked element could play a vital role in the future of energy production. With its potential to reduce nuclear waste, lower the risk of weapons proliferation, and provide energy for centuries to come, thorium is truly an element to watch as we seek to power the world more sustainably.