Thorium as an Alternative Nuclear Fuel: A Strategic Assessment for the United States

Ralph A. Cantafio
Jun 13, 2025
3 min read

Updated: Jun 18, 2025

Thorium-232 (Th-232) is a fertile nuclear material with the potential to serve as an

alternative to uranium-based fuels in nuclear reactors. Despite its advantages—such as

abundance, reduced long-lived radioactive waste, and proliferation resistance—thorium has not been widely adopted in the United States. This paper explores the historical context, current research status, domestic resources, and the comparative advantages and disadvantages of thorium versus uranium as nuclear fuels.

Introduction

The pursuit of sustainable and secure energy sources has reignited interest in thorium-

based nuclear power. Thorium's potential to address concerns related to nuclear waste, safety, and resource availability positions it as a compelling candidate for future nuclear energy strategies.

Historical Context

During the early development of nuclear technology, the United States prioritized

uranium and plutonium fuels due to their applicability in nuclear weapons. Thorium, lacking direct utility for weapons production, was largely sidelined. Notably, the Molten Salt Reactor Experiment (MSRE) at Oak Ridge National Laboratory (1964–1969) demonstrated the feasibility of thorium fuel cycles but did not lead to widespread adoption.

Discontinuance of Thorium Research in the U.S.

Following the MSRE, thorium research lost institutional support. President Nixon's

decision to consolidate the nuclear energy program under the Liquid Metal Fast Breeder Reactor (LMFBR) effectively ended the development of molten salt thorium reactors. The U.S. Atomic Energy Commission and later the Department of Energy focused resources on breeder reactors using plutonium, sidelining thorium. Subsequent energy policy did not prioritize thorium, and the infrastructure, industrial base, and public funding to support it atrophied. In the absence of a weapons connection and with uranium entrenched in civilian power plants, thorium was largely abandoned by federal policymakers.

Current Status of Thorium Research in the U.S.

While thorium research in the U.S. is limited compared to other nations, there are

ongoing efforts: Legislative initiatives such as the Thorium Energy Security Act aim to preserve uranium-233 for future thorium reactor research. Companies like Flibe Energy and research institutions such as Texas A&M University are working on thorium fuel cycle studies and Liquid Fluoride Thorium Reactor (LFTR) designs. However, the U.S. lacks a unified, well-funded national thorium program.

U.S. Thorium Resources

The United States possesses an estimated 595,000 metric tons of thorium, with significant deposits in states like Idaho, Montana, and Florida. Despite the large resource base, there is currently no active thorium mining in the U.S. Advantages of Thorium over Uranium Thorium is more abundant in the Earth's crust, produces less long-lived waste, offers greater proliferation resistance, and can be used in safer reactor designs like LFTRs that operate at atmospheric pressure.

Disadvantages and Challenges

Thorium is not fissile and must be converted to uranium-233; this process produces

uranium-232, which complicates fuel handling due to gamma radiation. Current nuclear

infrastructure is built around uranium, and regulatory hurdles pose barriers to new reactor licensing.

A Coordinated National Program: Proposed Framework

To realize thorium’s potential, the U.S. should implement a coordinated national

program consisting of:

- Establishing a National Thorium Research and Development Initiative under the

Department of Energy

- Preserving uranium-233 stocks and expanding thorium fuel cycle

- Funding academic and national lab partnerships to advance reactor design

- Creating pilot programs for LFTR demonstration reactors

- Developing a regulatory pathway with the NRC for licensing thorium-based

reactors

- Encouraging public-private partnerships and offering incentives for innovation

-Including thorium in federal strategic energy planning & energy security briefings

International Developments

India, China, and several European countries have committed resources to thorium

research. India’s AHWR program and China’s molten salt test reactor signal international

recognition of thorium’s promise.

Conclusion and Recommendations

Thorium presents a promising alternative to traditional uranium-based fuels. By investing in coordinated research, updating regulations, and leveraging domestic resources, the U.S. can regain leadership in next-generation nuclear technologies and improve energy security.

References

International Atomic Energy Agency (IAEA).

https://www.iaea.org/bulletin/thoriums-long-term-potential-in-nuclear-energy

U.S. Congress. 'Thorium Energy Security Act of 2022 (S.4242)

https://www.congress.gov/bill/117th-congress/senate-bill/4242/text

Oak Ridge National Laboratory. 'Molten Salt Reactor Experiment (MSRE).

https://www.ornl.gov/project/msre

U.S. Geological Survey. 'Thorium.' Mineral Commodity Summaries, January 2020.

https://pubs.usgs.gov/periodicals/mcs2020/mcs2020-thorium.pdf

World Nuclear Association. 'Thorium.' https://world-nuclear.org/information-library/current-and-

future-generation/thorium.aspx

Thorium Energy Alliance. https://thoriumenergyalliance.com