America’s reliance on carbon-based fossil fuels cannot last forever. It’s not that steps haven’t been made to wean us off our addiction to oil, gas and coal-based fuels — between 2008 and 2018, the total amount of renewable electricity like wind and solar power produced in the U.S. has doubled, according to the Energy Information Administration (EIA).
Yet in its 2019 Annual Energy Outlook report, that same organization pours cold water on the idea that we’re just a few years — or even a few decades — away from total reliance on non-carbon energy. By their projections, natural gas and coal together will account for 56 percent of electricity generated in the United States in 2050, a relatively small downgrade from the 62 percent it represented in 2018. This is a bad sign for the environment: CO2 emissions rose by 3.4 percent in 2018, the largest increase in 20 years. Scientists have been warning for years that current levels of carbon emissions cannot increase without seriously damaging our planet.
The EIA has its fair share of criticism in the mainstream, to say nothing of the snowball-toting, Luke Skywalker argument against climate change currently being employed by Republicans. But those of us who wouldn’t use a picture of Ronald Reagan riding a dinosaur in a serious presentation (read: normal people) acknowledge that something needs to be done about our dependence on carbon-based sources for energy.
Is Nuclear the Answer?
As the search for a solution to our carbon-fuel dependence continues, some propose that nuclear energy could provide an answer. Normally, nuclear power is generated by nuclear fission, the splitting of uranium atoms, which generates steam that powers turbines to create electricity. This doesn’t require burning coal or gas, making nuclear power a carbon-free source of energy. Nuclear power plants are also highly efficient compared to emerging renewable energy sources like wind and solar.
So we should be building nuclear plants as fast as we can to create new sources of efficient, clean energy — right?
It’s not so cut and dried. The high cost of establishing a nuclear power plant continues to rise — the Union of Concerned Scientists reports that between 2002 and 2008, the cost estimates to build a new nuclear power plant jumped from between $2 and $4 billion up to $9 billion. In the late 2000s, the Westinghouse Electric Company launched a project to design and build a new type of nuclear reactor, the AP1000, with the goal of reducing the cost and time required to establish a plant. It failed spectacularly, running an estimated $13 billion over its allotted budget and forcing Westinghouse into bankruptcy in 2017.
Besides the high cost in comparison to traditional fossil fuels, nuclear energy also has a PR problem, thanks to high-profile disasters in places like Chernobyl (Pripyat), Fukushima and Three Mile Island. In 2016, Gallup reported that more Americans (54 percent) opposed nuclear energy than supported it (44 percent) for the first time since the poll began in 1994.
But what if there was a safer nuclear option, one that didn’t pose as big of a threat in the event of an accident? One that could provide carbon-free power so cheaply and efficiently that consumers would be forced to follow their wallets into a world of clean energy?
“But what if there was a safer nuclear option, one that didn’t pose as big of a threat in the event of an accident? One that could provide carbon-free power so cheaply and efficiently that consumers would be forced to follow their wallets into a world of clean energy?”
Molten Salt and Thorium-Fueled Reactors: Climate Savior or Naive Pipe Dream?
Enter the molten salt nuclear reactor (MSR). Advocates for the technology believe it could help lift the nuclear sector out of its slow decline and provide the world with an important source of clean energy.
It’s important to note before diving in that two distinct concepts are being discussed when molten salt reactors are brought up. The first is a type of nuclear reactor that is cooled by molten fluoride salts instead of water; the second is a molten salt-fueled reactor, where nuclear fuel is dissolved into the salt. Many people also lump both types of MSRs into the same category as thorium-fueled reactors, which are powered by an element called thorium. Proponents believe that thorium is more abundant, safer and more efficient as a nuclear fuel than uranium-238.
DOPE, unfortunately, doesn’t have a nuclear scientist working on staff — yet — so to find out more about MSRs and their potential, we spoke to Nicholas Brown, Ph.D., a professor in the Nuclear Engineering department at the University of Tennessee. From 2015 through 2016, Brown worked on the research and development team at the Oak Ridge National Laboratory in Tennessee, a federally-funded research lab that operated the only active molten salt reactor between 1966 and 1969.
Digging into Claims Made by MSR Advocates
One of the big claims made by those who support molten salt reactors is that they are more efficient than uranium-fueled reactors. On this count, fans of molten salt-cooled reactors are technically correct, says Brown.
“When you have a water-cooled reactor, the outlet temperature is 300 degrees C. If you have a salt-cooled reactor, the outlet is 700 degrees C,” he tells me. “When you have heat at a higher temperature, you can use it to drive not just the more efficient production of electricity, but a variety of other processes, such as the desalination of water.” In practical terms, this means that people can do more with the same amount of nuclear fission.
MSR supporters also claim their preferred reactors are much safer than conventional light-water reactors (LWRs) since water being used to cool the fission process is kept at a much higher level of pressure than molten salt. This is also correct, but there’s an important caveat.
“In a pressurized water reactor, the water is at [around] 2000 PSI (pounds per square inch) — because at a higher pressure level, you increase the boiling point. When it’s under that high of a pressure, if you get a break … imagine a balloon. When a balloon pops, everything that was in that balloon, because it’s at higher pressure than everything outside of it … that coolant is going to very rapidly evacuate from the system,” Brown says.
“Molten salt reactors can achieve a 700 degree temperature at almost ambient pressures. So there isn’t a driving force to evacuate the coolant the way there is with a high-pressure coolant like water.”
That difference in pressure can help prevent the spread of radioactive material in the event of an accident, which is important when you consider that most nuclear plants are built on lakes, rivers or oceans.
Practical Power versus “Paper Reactors”
What many pro-MSR folks forget, however, is that existing water-cooled nuclear reactors are already pretty safe.
“Water-cooled reactors have been demonstrated to be very safe, and there’s a lot more experience with them,” Brown says.
It’s true — in six decades of over 17,000 cumulative reactor-years of commercial nuclear power generated in 33 different countries, there have only been three major accidents in the world. The safety difference between MSRs and LWRs could be compared to the difference between going for an evening walk wearing normal clothes, versus wearing a helmet and protective padding: yes, you’re safer in padding if an accident happens, but you were probably already pretty safe to begin with.
The pro-MSR crowd also likes to claim that these reactors are a better global solution because MSRs that use thorium cannot be used to make nuclear weapons. In theory, this means that countries could develop robust systems for nuclear power generation without the rest of the world worrying about a dictator using the technology to drop bombs.
This, however, is a sheer myth. A technical paper sponsored by the Department of Energy and published in the 2012 Nuclear Technology journal states:
All fissile material must be rigorously safeguarded to detect diversion by a state and must be provided the highest levels of physical protection to prevent theft. … No “silver bullet” fuel cycle has been found that will permit the relaxation of current international safeguards or national physical security protection levels.
Julian Kelly, chief technical officer at a Norwegian company researching and testing nuclear fuel based on thorium, stated: “Conspiracy theories about funding denials for thorium work are for the entertainment sector.”
Still, all of this doesn’t mean that there’s no potential for thorium or molten salt reactors. The main problem with them right now, as Brown explained it to me, is that these reactors are largely theoretical. The Oak Ridge reactor of the late 1960s is still the only molten salt reactor ever to operate, and it was largely conceived as a test to prove the viability of the idea.
Admiral Hyman G. Rickover, who helped pioneer the development of nuclear energy for the U.S. Navy in the 1940s and ‘50s, called these untested ideas about nuclear plants “paper reactors,” because the only place they exist is on the pages of academic papers.
As Brown summarizes: “Molten salt reactors are a potentially promising reactor technology to enhance the efficiency of nuclear electricity production and make it more competitive with natural gas … but those that study this field seriously recognize that there are a number of challenges to tackle before MSRs can be deployed commercially.”
For now, the jury is still out on molten salt reactors. But there’s one thing that proponents of all types of nuclear energy can agree on — the world needs to shift away from carbon-intensive fuels sooner, rather than later.