Nothing in this life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less.

– Marie Curie, radiation pioneer

Around 55 years ago, Molten Salt Reactor (MSR) and liquid thorium-fueled nuclear technologies found their beginnings from among the minds of Alvin Weinberg, Eugene Wigner, and Glenn Seaborg – and yet only after realizing the potential behind their discoveries had the door been slammed shut by just a few ill-informed, politically motivated decisions made by some people in positions of power. This science was then revisited and further pioneered by Kirk Sorensen and various others – half a century later.

Thorium is undoubtedly the future fuel of nuclear energy, and MSRs – particularly Liquid-Fluoride Thorium Reactors (LFTRs) – are quite likely to be the best way to take it forward.

Come for the thorium, stay for the reactor.

– David LeBlanc, CTO of Terrestrial Energy

As the human population exponentially grows, so too, does the necessity for better, cleaner, and more reliable sources of energy production. With a global population of approximately 7.36 billion people today, and a projected increase of about 22% by 2040 – bringing the estimated total to about 9 billion people – there is certainly a strong sense of urgency associated with this prospect.

Global warming and air pollution from the burning of fossil fuels have been responsible for far more deaths and damage to the environment than nuclear industry ever has, and while some might opt to look towards solar, wind, geothermal, or hydraulic for alternative sources of energy – these are intermittent, inefficient, and unfortunately unreliable on a grid-scale level. There are many cities and regions in the world that rarely experience proper conditions to take advantage of these sources of energy – and none at all that could rely solely on them – demonstrating the need to pursue nuclear technology.

As it is, just about 20% of all of the electricity production in the United States is provided by Generation II nuclear power plants predominantly fueled by uranium-235, but with incredibly poor efficiency in regards to energy conservation.

For a frame of reference on this, consider that current nuclear technologies can extract only 0.5% of their potential fuel energy, whereas the use of a thorium-based liquid fuel (e.g. thorium tetrafluoride salts) in an MSR could result in an extraction of ~90% of its latent energy – consistently, and with fail-safe, ‘walk-away’ inherent safety during continuous operation.

One ton of thorium-232 can end up producing a gigawatt of energy (enough to power a middle-sized city), which is a magnitude of 250 times greater than what the same amount of uranium-235 can accomplish. Another big factor to consider is that the form of uranium utilized in today’s reactors is among the rarest of elements found in the Earth’s crust. Uranium naturally exists in the crust as a mixture predominantly of two isotopes; uranium-238 (~99.3%) and uranium-235 (~0.7%), while thorium is three times more abundant than uranium altogether. Thorium can also be found in many various regions of the Earth, rather than a select few locations, and can be adjusted to not so easily be abused for uranium enrichment and weapons proliferation – factors that would more readily allow for the global propagation and implementation of LFTR technology.

aaauranium-238-235-atoms

MSRs work by dissolving thorium fuel pellets inside a molten salt coolant mixture of lithium and beryllium fluorides (FLiBe), which then very safely incubate the fuel while the mixture flows throughout the system of appropriated reduction and fluorination columns in order to selectively remove fission and decay products. Using a neutron source to first initiate the reaction will then result in a beta decay chain, yielding fissile uranium-233 and the production of additional neutrons – causing a sustainable chain of fission reactions so long as additional fuel is added as needed, and xenon is removed (both of which can easily be done during standard reactor operation). The fission of uranium-233 will release nearly a million times more energy per unit mass than the burning of fossil fuels. This heat energy then gets transferred to the coolant salt through a primary heat exchanger, which then in turn transfers its heat into steam in order to drive a closed-cycle gas turbine – generating electricity. So in other words, it’s a really fancy teapot.

There are numerous advantages to this technology:

  • The use of a liquid fuel instead of solid oxides means that online chemical processing and extraction of decay and fission products become possible
  • MSRs operate at atmospheric pressure, but very high temperatures (around 700°C), which could allow for various important industrial applications such as desalination & ethanol, ammonia and hydrogen production from harnessing the heat waste
  • Various measures of passive, inherent safety; high volumetric heat capacity, incredible stability of fluoride salts due to their powerful ionic bonds that make them impervious to radiation damage from neutrons or gamma rays – and in the event of an accident, a frozen salt plug positioned at the bottom of the core would melt, and drain the fuel salt safely into a storage tank
  • Anti-proliferation strategy / regulatory perspective; ‘spiking’ the fuel with thorium-230 (a natural decay product from abundant uranium-238 that is also referred to as ionium) would thwart any attempts to isolate and extract the protactinium-233 before it decays into uranium-233
Thorium Passive Reactor_Kirk Sorensen

The half-life length of a particular element is inversely proportional to its overall radioactive decay. Uranium-238 has a half-life of about 4.5 billion years, implying next to no radioactive decay (less than various other isotopes commonly found in rocks and sand), with very little basis for any fear of danger posed at all to the environment and society due to its radioactivity – while the more utilized and readily fissionable form, uranium-235, has a half-life of 700 million years (more active, but still quite safe). This being said, if the U.S. transitioned to utilizing thorium-232 as the initial source of the excellent fissile fuel, uranium-233, we would be carrying around material with a half-life of 14.05 billion years – in other words, an even less actively decaying element than the currently used alternatives.

Thorium-232 itself is not a fissile fuel, but is ‘fertile’, and therefore upon the absorption of a neutron after bombardment, will undergo a series of transformations that end up transmuting the material into uranium-233. This was Glenn Seaborg’s self-described ’50-quadrillion dollar discovery’ back in 1940 at UC-Berkeley with his graduate student, John Gofman. The magic concept behind the thorium fuel cycle was its incredible potential for sustainable self-perpetuation. Seaborg and his contemporaries discovered that thorium-232 could absorb a neutron and transmute into thorium-233, an unstable isotope with a half-life of 22 minutes, after which the extra neutron would undergo beta decay and turn into a proton – transmuting the element into protactinium-233, which would subsequently beta decay over 27 days into uranium-233, which could then finally be used as a fissile fuel. The bombardment of uranium-233 was found not only to produce 198 MeV of energy, but also the splitting of the nucleus into two new isolable and extractable elements of unequal size, along with the release of 2-3 additional neutrons (hence the sustainable perpetuation).

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At this same time, Glenn Seaborg had also realized that uranium-238 was a fertile isotope, but that the resulting fissionable product, plutonium-239, produced less than two neutrons when struck by a neutron – which made this process unsustainable and far less attractive. That is, until fast-breeder reactors were regrettably prioritized over thermal breeders by the United States in the late 1960s, subsequently to be followed by much of the developed world.

Countries that began nuclear arms programs did so well before intentionally developing their nuclear energy capabilities, and for various different reasons. So instead of simply dismissing nuclear energy technologies based solely on the fear of widespread weapons proliferation, all the while trying to find safe places to hide and store the radioactive material that we have already accumulated from irreversible historical events – such as decommissioned warheads – these could instead feasibly be used as a fuel source for MSRs, thus reducing stockpiles of existing plutonium waste. While in turn, fissile byproducts from this process could then be used to initially power LFTRs without the need for uranium enrichment.

In addition to this, several other highly valuable byproducts from the LFTR could then also be chemically isolated, extracted and re-purposed for industry and sold; such as helium-3, xenon, neodymium, molybdenum-99, radio-strontium, zirconium, rhodium, ruthenium, palladium – as well as bismuth-213 and non-fissile plutonium-238 – critical materials for precise targeted alpha particle emission treatment of cancers, and NASA’s deep space exploration vehicle batteries, respectively – both of which have otherwise been entirely depleted, and have no other means of synthesis.

As outlined in the Nuclear Energy Research and Development Roadmap report to Congress from April of 2010, the U.S. Department of Energy fully expects private industry to lead the future of nuclear energy.

“In the United States, it is the responsibility of industry to design, construct, and operate commercial nuclear powerplants.” (pg 22)

“It is ultimately industry’s decision which commercial technologies will be deployed. The federal role falls more squarely in the realm of research and development.” (pg 16)

“The decision to deploy nuclear energy systems is made by industry and the private sector in market-based economies.” (pg 45)

This is really important to note, because this marks a stark change from how nuclear energy technologies were formerly developed and operated in the United States.

There is no better time than now to help pioneer this technology. I have spent a lot of time looking into who is actively working on and providing funding for these future generation reactor technologies – and thanks to Gordon McDowell, whose videos are absolutely worth your time, a comprehensive list is available:

Countries that have initiated coordinated private efforts to pursue the research and development of this technology include: Australia, Canada, China, Czech Republic, Denmark, India, Indonesia, Italy, Japan, Russia, Switzerland, Turkey, United Kingdom and the United States. However, government involvement is largely focused in China and India specifically, with a third and fourth likely to emerge soon within Canada and the UK.

Three future paths for nuclear energy are:

  • To continue burning uranium-235; the least naturally-occurring, as well as the least efficient of the potential fuels
  • To prioritize uranium-238 fast breeder reactors; a somewhat better choice in regards to efficiency and quantity of material
  • Or to proceed with molten salt/thermal breeder reactors using thorium; a vastly more abundant and clean fuel

Using a thorium fuel cycle, the amount of long-lived ‘waste’ that is produced can be reduced to 1-1.5% of the initial input mass – a drastic improvement to current nuclear reactors. While the extracted and reprocessed fission and decay products are highly valuable and can be sold to help cover initial costs for construction of these reactors and/or return investments.

Some near-term future challenges that need to be addressed are:

“During my life I have witnessed extraordinary feats of human ingenuity. I believe that this struggling ingenuity will be equal to the task of creating the Second Nuclear Era.”

“My only regret is that I will not be here to witness its success.”

– Alvin Weinberg (1915-2006)