Why Has Thorium Not Yet Seen Widespread Use in Commercial Reactors?

The push for clean and sustainable energy has led to renewed interest in thorium as a potential nuclear fuel. While uranium currently dominates the commercial nuclear industry, thorium presents several advantages. Despite these benefits, thorium has not yet been widely adopted in commercial reactors. This article will explore the reasons behind this situation.

The Benefits of Thorium

Thorium is significantly more abundant than uranium and is longer-lasting due to its ability to generate more fissionable material. Moreover, thorium produces less waste compared to uranium and plutonium. However, thorium requires uranium to initiate its nuclear fuel reaction, which has yet to be studied and refined for commercial reactors.

Thorium's Abundance and Safety

According to estimates, the earth has a much greater supply of thorium compared to uranium, particularly urains-235, which is essential for producing plutonium. Thorium converts to uranium-233 under neutron bombardment and is much less likely to be used in nuclear proliferation, leading to its potential use in peaceful nuclear power.

Technology and Safety

The safety benefits of thorium come from the reactor design rather than the material itself. Thorium can be used in Molten Salt Reactors (MSRs), which are purported to be safer than traditional Light Water Reactors (LWRs) and Pressurized Water Reactors (PWRs). The technology behind thorium-based reactors is progressing, but significant challenges remain.

Challenges and Limitations

Thorium is not well-suited for direct nuclear fission. It requires irradiation with neutrons from a standard fission process to convert into uranium-233, which can then be used to drive a reaction. This process is more complex than using uranium in standard reactors. New technologies are needed, and although the principle has been demonstrated, some ideas have faced practical challenges.

The Thorium Breeding Cycle

The concept of thorium as a sustainable fuel involves breeding new uranium from thorium. This process requires a reactor designed for the thorium cycle, where uranium is used to create fissionable material from thorium. However, this approach is more challenging than using uranium directly, and several technological issues have arisen.

Technical Challenges

One proposed design involves forming spherical fuel elements composed of a thorium compound, uranium compound, and moderator graphite. While this method could allow for continuous fuel circulation, the brittleness of the spheres has posed a problem. Another design proposes the flow of molten salts through the reactor, but the corrosive nature of molten salts poses challenges for maintaining reactor integrity.

Despite these challenges, thorium has shown potential in test reactors and pilot plants. However, the high cost of developing and implementing new technologies has deterred many companies from investing extensively in thorium-based reactors. Additionally, the rapid advancements in fusion technology may make traditional fission reactors, including those based on thorium, less attractive in the long term.

Conclusion

While thorium offers numerous advantages over uranium, its widespread adoption in commercial reactors faces several technical, economic, and practical hurdles. As technology and safety measures continue to evolve, the future of thorium in the nuclear industry remains promising, but much work remains to be done.

You can learn more about thorium and its advancements by exploring Flibe Energy and Sorenson's videos on the thorium cycle and Molten Salt Reactors. These resources provide valuable insights into the ongoing research and development efforts.