Thorium Fueled Molten Salt Reactors: A New Era of Renewable Energy

A significant portion of Americans desire cleaner energy options, yet there are doubts about whether solar and wind can fully meet the energy demands of the American Grid. Diversifying energy sources can provide consistent power and ensure clean energy is available during both peak and low-demand periods. Nuclear energy presents a clean, robust power source but often evokes fear due to past disasters. However, there's a safe, cost-effective alternative that remains carbon-neutral, offers substantial energy output, and reduces dependence on foreign fossil fuels. Enter thorium.

The Challenges

#### Uranium

The first challenge is that not all elements can undergo nuclear fission. In the uranium ore used for energy production in nuclear reactors, only 3%-5% is U235, the fissile isotope necessary for fission. To obtain sufficient U235 for the fission process, uranium ore must be enriched. The remaining non-fissile ore can transmute into Plutonium-239, a substance many associate with nuclear weaponry.

Let’s briefly touch on weapons. While producing nuclear weapons from enriched uranium is a complex process, any country capable of enriching uranium to reactor-grade is nearing the threshold for nuclear arms. Enriching uranium from around 5% for reactor use to 90% for weapons-grade is both time-consuming and expensive. Once a nation begins enriching uranium, its "breakout time" for producing weapons-grade material is often just a matter of months.

For context, the U.S. reached this capability at Los Alamos, New Mexico in July 1945, leading to the atomic bombing of Hiroshima in August. The highly enriched uranium for those bombs was developed during the Manhattan Project over 27 months of clandestine work by top scientists.

Moreover, the byproduct of uranium fission in nuclear reactors is plutonium. As plutonium is not found naturally, it forms solely as a byproduct of uranium fission. Once uranium is depleted in a reactor, the spent fuel—which contains plutonium—is removed and replaced. Each reactor generates enough plutonium for roughly 45 atomic bombs, but recovering this plutonium is a job suited only for robots due to high radioactivity. The other atomic bomb dropped on Nagasaki was made from plutonium as well.

To clarify, while the connection between nuclear weapons and nuclear power is complex, it’s not as simple as grabbing plutonium or weapons-grade uranium from a reactor to build a bomb. However, nations with nuclear reactors could eventually produce weapons of mass destruction as a byproduct, given time and expertise.

Additionally, this uranium-based method is inefficient, as traditional fission results in radioactive waste that remains hazardous for up to 10,000 years. To put it in perspective, humans established villages 12,000 years ago and domesticated cattle 10,000 years ago.

While the risk of creating weapons of mass destruction from nuclear waste is low, it still poses health hazards if left improperly stored. The long half-life of radioactive waste necessitates careful management for environmental and public safety. Simply put, we can’t leave this material unattended.

#### Conventional Graphite and Light Water Reactors

Now, let’s discuss light water reactors (LWRs). These reactors utilize water to control and moderate the fission process within the reactor core. Graphite fuel rods heat the water, producing steam that drives a turbine for power generation. In this system, water serves both as an energy source and as a safety mechanism. As water levels decrease, steam production increases, slowing fission.

However, solid nuclear fuel can lead to meltdowns without continuous cooling. Many are familiar with at least one meltdown incident, such as Fukushima, Chernobyl, or Three Mile Island. User error or unforeseen natural events can disrupt the feedback loop, leading to catastrophic failures, even with extensive safety measures, as seen in Fukushima.

It’s understandable why many people fear such occurrences.

Solutions

#### Thorium

One significant advantage of thorium is that most of it found in nature is TH232, the most useful isotope for nuclear reactors. Unlike Uranium-235, thorium isn’t fissile by itself; it requires neutrons to initiate fission. Therefore, when the fission reaction needs to stop, the neutron source can simply be removed, serving as a built-in safety measure.

The usable thorium eventually decays into U233, which can be used in another reactor for additional energy. The best part? This process generates 1,000 to 10,000 times less waste than traditional uranium methods. Thorium doesn’t produce plutonium—a key element that can be used in atomic bombs. Furthermore, its radioactive lifespan is only 500 years, compared to uranium’s 10,000 years. It’s a win-win-win situation.

While any radioactive leftover isn’t ideal, we can plan for the future over a 500-year timeline. A 10,000-year plan? Much less feasible.

#### Molten Salt Reactors

The other crucial element in this discussion is Molten Salt Reactors (MSRs), which originated during the Manhattan Project in the 1960s. Interest waned as funding decreased.

To grasp the concept of an MSR, understand that it utilizes liquid fuel—specifically molten salts—rather than solid fuel rods.

When an MSR reaches 700 degrees Celsius, it stabilizes naturally. As the salts achieve fission stability, they circulate to cool. Since fission cannot occur in this cooling loop, the salts maintain a lower temperature. The key takeaway: molten salts cannot exceed 700 degrees Celsius, making MSRs inherently safe and stable. The likelihood of a meltdown is virtually nonexistent.

In the 1960s, scientists demonstrated that MSRs could operate safely and continuously without manual intervention, even at peak loads—without control rods or operators. These reactors can self-regulate. Unlike traditional reactors, MSRs cannot melt down by their very design. They can also reduce the waste produced from used nuclear fuel, as spent fuel rods can be converted into liquid fuel and recycled.

Finally, MSRs are simpler, requiring fewer components. This compact design makes them cheaper to produce and easier to mass-manufacture.

Imagine a compact nuclear reactor no larger than a human. What potential does that open up?

So, What Will You Choose?

Despite concerns about radioactive waste, all forms of nuclear energy are considered “clean” when compared to carbon-heavy sources like coal and natural gas. While we shouldn’t overlook the radioactive aspect—far from it!—the primary concern for many is safety.

It’s evident that merging these two technologies—molten salt reactors and thorium fuel—offers a significantly safer nuclear option than any existing atomic reactors in the U.S. or globally.

Interest in MSRs is reviving in countries like China, Russia, and Japan. Several prototypes are currently under research and development, including a Molten Salt Fast Neutron Reactor using thorium.

If the U.S. wants to stay competitive in this vital field, policymakers should take three essential steps. First, prioritize the development of Molten Salt Reactors over traditional nuclear options. Second, promote public education regarding MSRs and their safety benefits to alleviate public anxiety. Lastly, allocate funding for the research and development of thorium fuel and molten salt reactors, ensuring the U.S. leads in clean, domestic energy solutions.

Final Thoughts

Nuclear energy tends to polarize the environmental community. You either love it or despise it. Perhaps you, too, once feared it, as I did.

Here are a few points to ponder regarding the future of energy in the U.S.:

• Molten Salt Reactors (MSRs) are fundamentally safe and cost-effective alternatives to conventional nuclear reactors.
• Thorium is more abundant than uranium and does not require enrichment for fission.
• Thorium generates less waste than uranium reactors, with byproducts that are less radioactive and shorter-lived; it does not produce plutonium.
• In emergencies, halting thorium reactions is simpler and quicker than with uranium.
• The combination of MSRs and thorium fuel produces safe, clean, and affordable nuclear energy with no CO2 emissions.

So, which side do you stand on? Are you opposed to nuclear energy, or do you support this technology? Thorium MSRs have genuinely shifted my perspective on the future of nuclear energy—thanks to my Sustainable Energy Policies professor.

Oh, and for what it’s worth: my undergraduate self managed to perform quite well on that policy brief.