“It is not too much to expect that our children will enjoy in their homes electrical energy too cheap to meter.” Lewis Strauss, Chairman, U.S. Atomic Energy Commission, 1954.
[Rear Admiral Lewis Strauss – one of the original members of the Atomic Energy Commission (AEC) – was a leading advocate for the development of nuclear power in the years following World War II.]
Growing up in the 1950s and ’60s, I vividly recall the promise of unlimited, affordable nuclear energy for the baby-boom generation. Nuclear engineers proclaimed they could extract all the energy I would need in my lifetime from a piece of uranium no bigger than a golf ball. America was going to lead the world into a bright and abundant future with nuclear power.
In his 1954 speech to the National Association of Science Writers, Strauss famously predicted that nuclear power plants would, in the span of one generation, deliver electricity to American homes so cheaply that it would cost more to mail out an electric bill than to provide the electricity itself!
So, what happened? Why has civilian nuclear power not lived up to its promise? And today, can we help kick-start a renaissance in the nuclear power industry through production and deployment of safer, more efficient, thorium-powered Molten Salt Reactors (MSRs)?
China believes so and is leading the way. With sufficient thorium reserves to power their electrical grid for 20,000 years, China is building the world’s first commercial-scale Thorium Molten Salt Reactor (TMSR) in the Gobi Desert. European countries such as Denmark, France, Holland, and Switzerland also have ambitious plans for thorium, and to a lesser degree, so does America. More on this in my concluding thoughts.
First, a brief historical background to provide context on how we got to where we are today.
Atomic Energy Commission
After the U.S. dropped nuclear bombs on Japanese cities in the summer of 1945, bringing World War II to an end, Congress established, the following year, the Atomic Energy Commission to promote and to regulate development of atomic science and technology.
President Truman defined AEC’s primary objective to be development and production of evermore powerful atomic weapons.
The mission of the AEC was first and foremost military, and its focus on nuclear weapons profoundly influenced the design and development of civilian nuclear power plants. Plutonium is extremely important in the manufacture of atomic weapons, and plutonium can be readily made from uranium, but not thorium.
For many reasons—technical, political, and economic, but principally because of plutonium—America focused its monetary and intellectual resources on uranium and not thorium. Civilian nuclear plant designers simply followed the already beaten path.
To illustrate the consequences of this path for civilian nuclear power, here is a simplified metaphor in which different models of cars represent uranium and thorium nuclear power plants.
Simplified Analogy
Imagine a sales representative trying to entice you into buying their model of automobile.
Here’s the sales pitch of the first salesperson:
One solid 20-pound uranium fuel rod will power your car for 3 to 5 years before refueling!
But here is the fine print buried in the sales contract. Only one pound (5% of the rod) is used to power the car. The remaining nineteen pounds (95% of the rod) are not used for propulsion. What is worse, driving your car transforms the entire rod into highly toxic, radioactive waste that must be securely stored for tens of thousands of years.
Now the sales pitch of the second car representative:
With our model, you can drive your car for 3 to 5 years on 1/2 pound of thorium dissolved in a liquid salt!
OK, the fuel mileage is better, but what makes this model stand out is that the fine print contains mostly good news. While the car is running, thorium is used to make the nuclear fuel as it is needed.
Consequently, little nuclear fuel is on-board at any one time. If the car gets in an accident, production of nuclear fuel automatically ceases. Almost all the fuel is used to make energy and thus very little is wasted. And, better still, the radioactive waste that is generated is considerably less radioactive; it is not useful for making nuclear weapons; and for the most part it decays away in just a few hundred years.
Now let us take stock of what has transpired in the civilian nuclear industry with uranium and Light Water Reactors (LWRs), and follow by comparing this with what could become a major player in the nuclear renaissance: thorium coupled with Molten Salt Reactors (MSRs)
Uranium and Light Water Reactors (LWRs)
Natural uranium comprises two types (isotopes) of uranium atoms. About 99.3% is uranium-238 (U-238), and the remaining 0.7% is uranium-235 (U-235). Unfortunately, U-238 can’t easily be split apart (it is not fissile), so almost all of natural uranium is not useful for starting and keeping a nuclear reaction going.
All the nearly 100 commercial nuclear reactors operating in the U.S. are Light Water Reactors. LWRs require copious amounts of reactor core cooling water. This cooling water is typically drawn from nearby sources like rivers, lakes, or oceans. LWRs operate at high water pressures necessary for efficient heat transfer and power generation.
For fuel, LWRs use a modified form of uranium called “enriched” uranium. To make natural uranium effective as nuclear fuel for a LWR, the amount of U-235 in the fuel needs to be enriched to about 3-5%. This process, called “enrichment,” is energy-intensive, requires equipment and facilities that are specialized and complex, and requires adherence to strict safety and security measures to prevent accidents and unauthorized access.
As the nuclear reactor “burns” U-235, the concentration of U-235 decreases while radioactive by-products such as fissile plutonium increase. Eventually, the nuclear chain reaction can no longer be sustained, and the reactor must be shut down so the spent nuclear fuel (now a radioactive waste) can be removed and new fuel rods added.
Thorium and Molten Salt Reactors (MSRs)
Thorium is three to five times more abundant than uranium in the Earth’s crust. Almost all thorium found in nature is in the form of thorium-232 (Th-232), which is the desired isotope for nuclear power, and so thorium does not need to be enriched. Unlike U-235, thorium is not fissile. But thorium is fertile. This means that Th-232 can be readily transformed into a nuclear fuel (U-233), which is fissile and can sustain a nuclear reaction.
In the 1960s, America’s Oak Ridge National Laboratory (ORNL) was the first in the world to develop an operational MSR in their groundbreaking Molten Salt Reactor Experiment (MSRE). Known as the “chemist’s reactor” because chemists were deeply involved in its design, the MSR could run on either uranium or thorium. Challenges encountered at the time included corrosion and other difficulties in handling hot molten salts. These remain significant engineering hurdles that are still being addressed today.
Thorium MSRs have many inherently safer design features. Unlike LWRs, they operate at atmospheric pressure. Their liquid nuclear fuel also serves as coolant, obviating the need for large quantities of cooling water. If the reactor core does overheat, the liquid fuel/coolant automatically drains into storage tanks, without human intervention. Liquid fuel also permits refueling while the power plant is operating. This feature eliminates the need for periodic reactor shutdowns to refuel, thus increasing the overall operational time of the reactor.
Continuous removal of unwanted byproducts that accumulate in the liquid fuel is possible, which helps manage nuclear waste more effectively. Additionally, while the radioactive waste generated (plutonium production is approximately 90-95% less than LWRs) does require careful management, most of its radioactivity decays away to background levels within a few hundred years.
Concluding Thoughts
Returning to where we started, in hindsight, Lewis Strauss was overly optimistic that nuclear power would become “too cheap to meter.” Nevertheless, prescient thought upon the future of reliable, safe, carbon-free nuclear power can be found in the insights of his contemporary, Alvin Weinberg, nuclear physicist, and advisor to presidents from Eisenhower to Carter.
Dr. Weinberg was a visionary leader in the field of nuclear energy, advocating for safer and more efficient reactor designs. After working on the first atomic bomb and later designing reactors that convert uranium into plutonium, he became Director of the Oak Ridge National Laboratory from 1955 to 1973.
Weinberg had deep reservations about the civilian use of Light Water Reactors, which produce plutonium. In 1971, he wrote, “We nuclear people have made a Faustian bargain with society.” He believed that Light Water Reactors—originally developed for naval propulsion—were a poor choice for civilian power generation due to their inherent safety risks and the production of long-lived radioactive waste.
Dr. Weinberg forcefully advocated for thorium as a source of nuclear fuel for Molten Salt Reactors, which operate at atmospheric pressure and use nuclear fuel in a liquid form that automatically and without human intervention drains into storage tanks in case of an emergency. Thorium reactors produce minimal plutonium and other weapons-grade materials, reducing the risk of nuclear proliferation. Weinberg’s vision for thorium-based nuclear power was, unfortunately, decades ahead of its time. He hoped that future generations would recognize and develop the potential of this technology.
I am pleased to report this is now happening. Here is but one of several exciting examples happening today. Copenhagen Atomics, based in Denmark (Denmark has banned nuclear power since 1985 because of the high cost and nearly intractable pollution problems associated with conventional LWRs), believes thorium will provide for more than half of the world’s energy needs by 2100 through a localized, distributive network of power generation.
Their mission is to revolutionize the energy sector by developing small, modular thorium molten salt reactors. They plan to finance and build their standardized reactors in shipyard-like factories, with the goal of manufacturing one reactor per day per assembly line. They will own and operate the reactors on customer sites, eliminating the need for tax dollar subsidies or upfront public or private investment.
While this technology holds great promise, it is not yet a solved issue. Further research and development is needed. But I believe, as do a growing number of scientists, engineers, entrepreneurial companies, and a few far-sighted politicians, that thorium and Molten Salt Reactors can and will play a vital role in powering the economy of the future.
To the readers of the Crozet Gazette, I encourage you to learn more about the potential of thorium energy and to support both private and public initiatives that promote its development for the benefit of a more secure energy future and a safer environment for our children and grandchildren!