By John Krzyzaniak, Nicholas R. Brown | December 18, 2019
Andrew Yang, like many of the 2020 Democratic presidential hopefuls, has an ambitious plan to wean America off of fossil fuels. Unlike many of the other candidates, however, a key piece of his plan to address climate change involves harnessing nuclear power—in particular thorium. According to Yang, thorium is “superior to uranium on many levels.” But Yang isn’t alone; thorium boosters have been extolling its supposed virtues for years.
Do the claims about thorium actually hold up? The Bulletin reached out to Nicholas R. Brown, an associate professor in the department of Nuclear Engineering at the University of Tennessee, to examine five common claims about thorium and next-generation nuclear reactors. Brown’s responses are below.
Overall, although existing and new nuclear reactors may indeed be part of a long-term carbon-free energy mix in the United States, the public has good reason to be skeptical that thorium can or should play any role in the future.
Claim: Thorium reactors would be more economical than traditional uranium reactors, particularly because thorium is more abundant than uranium, has more energy potential than uranium, and doesn’t have to be enriched.
False. Although thorium is more abundant than uranium, the cost of uranium is a small fraction of the overall cost of nuclear energy. Nuclear energy economics are driven by the capital cost of the plant, and building a power plant with a thorium reactor is no cheaper than building a power plant with a uranium reactor. Further, using thorium in existing reactors is technically possible, but it would not provide any clear commercial benefit and would require other new infrastructure.
Additionally, there is technically no such thing as a thorium reactor. Thorium has no isotopes that readily fission to produce energy. So thorium is not usable as a fuel directly, but is instead a fertile nucleus that can be converted to uranium in a reactor. Only after conversion to uranium does thorium become useful as a nuclear fuel. So, even for a reactor that would use thorium within its fuel cycle, most energy produced would actually come from uranium fissions.
Claim: Next generation thorium reactors would be safer than current reactors.
True but misleading. Nuclear energy is already very safe, and Yang is correct about that. The current US nuclear fleet generates about 20 percent of all electricity in the United States and has an excellent safety record—despite accidents such as Three Mile Island. When it comes to new reactors, although some next-generation designs offer potential safety benefits relative to current reactors, they could be operated in either thorium-uranium or uranium-plutonium fuel cycles. Consequently, the benefits are a function of the inherent safety in the next-generation designs, not the utilization of thorium.
Claim: The waste from thorium reactors would be easier to deal with than waste from today’s uranium reactors.
False. A comprehensive study from the US Energy Department in 2014 found that waste from thorium-uranium fuel cycles has similar radioactivity at 100 years to uranium-plutonium fuel cycles, and actually has higher waste radioactivity at 100,000 years.
Claim: Thorium would be more proliferation-resistant than current reactors—you can’t make nuclear weapons out of it.
False. A 2012 study funded by the National Nuclear Security Administration found that the byproducts of a thorium fuel cycle, in particular uranium 233, can potentially be attractive material for making nuclear weapons. A 2012 study published in Nature from the University of Cambridge also concluded that thorium fuel cycles pose significant proliferation risks.
Claim: Building new nuclear reactors will likely be necessary if the United States wants to achieve net-zero emissions by 2049.
True. Nuclear energy is already the primary ultra-low carbon energy source for base-load electricity generation. Although solar and wind have their place in the energy mix, the primary benefit of nuclear energy is that it is not intermittent, as solar and wind are, so it is almost always available without needing energy storage. So new nuclear reactors will be necessary to both replace aging ones and to meet a net-zero carbon emissions goal. But thorium-uranium fuel cycles provide no inherent benefits relative to uranium-plutonium fuel cycles, so the new reactors need not be thorium-powered.
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The statement about weapons proliferation needs more detail. Commercial LWR power plants are not proliferant. Their spent fuel does contain plutonium, but the isotopic composition of spent fuel is not suitable for military weapons. The statement does not take account of the specific design of a power plant using thorium. In the case of the ThorCon liquid fission plant, the proliferation resistance is better than that of a standard LWR. I recommend the authors review the document at http://thorconpower.com/docs/docs_safeguards_pub.pdf and explore others on the website ThorConPower.com.
True that LWRs are not a major proliferation problem, as long as the spent fuel is not reprocessed. That is because you can’t steal spent fuel and separate the plutonium. It is too radioactive, at least for the next several hundred years. The isotopic composition has nothing to do with it. If LWR fuel is reprocessed, however, the plutonium can be used for bombs by governments or terrorists, irrespective of isotopic composition. This is publicly known since the 1970’s. See for example https://fas.org/rlg/980826-pu.htm Thorium needs reprocessing in any case. For that reason it does not solve the (not-so-severe) problem of… Read more »
Yes. You can make a bomb from Pu240 and Pu 242, extracted from LWR waste but spontaneous fissioning makes the yield terrible, and risks a fizzle.
Its possible, but barely plausible. LWR reactor waste diversion, for weapons, is senseless.
These arguments are in reference to solid-fuel thorium reactors, when the design being most discussed for the past decade is a liquid-fueled thorium reactor (LFTR). The latter is greatly superior regarding resistance to weaponization. There are two options with conventional solid-uranium fueled LWR waste: store or re-process. Neither of these is an issue with an LFTR. If the waste is stored, it eventually cools (by radioactive decay) to the point it could be conveniently and safely handled. Eventually the heavier plutonium isotopes eventually decay, leaving the much longer-lived, weaponizable isotope Pu-239. It may be thousands of years in the future,… Read more »
There are a lot of flaws in this analysis of Andrew Yang’s claims. Admittedly Yang does not clarify what type of thorium reactor he is referring to, but from his comments it is likely that he is referring to the liquid flouride throrium reactor (LFTR) or some similar variant, which uses liquid fluoride as the coolant rather than water, and does not use solid fuel, but rather adds the fuel (unanium 233) to the liquid coolant that runs through the system. COST: The first claim from Andrew Yang is that a thorium reactor would be cheaper. The article indicates that… Read more »
I think the claim that thorium reactors are more proliferation resistant has to do with the fact that the process of converting thorium to uranium 233 also results in generating uranium 232. Uranium 232 is quite easy to detect from large distances, which makes it undesirable for nuclear weapons (i.e., it is too easy to find them). Purifying uranium 233 by removing uranium 232 is very difficult (expensive) and is not 100% effective, which makes uranium 233 a poor choice for building weapons.
You wouldn’t let U232 accumulate in the U233, in the first place. U233 can be sorted very cleanly.
The proliferation risk is not zero.
On the other hand, neutron efficiency in a Th MSR is so tight, extracting U233 out of the system would have you loading in new Th at a relatively fast clip. Simple accounting input methods would be enough to spot a weapons grade U233 plant.
Loading in…? Are you talking about a solid-fueled reactor?
In an LFTR, fuel is loaded and re-processed continuously.
We do not need it, and we cannot afford more nuclear power adventures. The VC Summer plant was cancelled after the waste of $8,000,000,000, and the Vogtle plants in Georgia have such high construction costs their cost of power will be over 15 cents/kWh. By contrast, the City of Los Angeles just contracted for PV power at under 2 cents/kWh daytime and 3.3 cents/kWh at night from utility-scale battery storage. My own household and at least one of our two electric cars are powered by the PV system on our roof, which lets us put power into the grid in… Read more »
Except thorium reactors *will* cost a lot less to build than a standard Light Water Reactor. There’s no need for that kind of investment in the first place. They don’t need containment dome and all kinds of scram features. Molten thorium is both the coolant and a fuel source. It is kept circulating by a pump and held inside the reactor by a freeze plug. It’s walk away safe. Power goes down, the freeze plug melts, the thorium drains out simply by gravity. If you took every battery in the US, even the ones in cars and trucks, they could… Read more »
That analysis isn’t quite honest, is it? MSRs may not need certain expensive features of conventional LWR plants but they will need other expensive features instead such as a chemical processing plant for their fuel salt for recycling of the salt and removal of fission products. Corrosion and how to control is still not fully solved. Heck, it’s not even clear yet what chemical composition the salt should be – but we do know that if your salt contains Lithium, you’d have to use enriched Li-7 which is another expensive feature over LWRs. At this early stage I find such… Read more »
Speaking of honesty… In a comparison of conventional LWRs with LFTRs, both of them require extensive chemical facilities. One of the huge advantages of MSRs over solid-fuel reactors is that chemical processing can be performed on the fly in MSRs — your tone is that this was somehow a bad thing… As to expense — all power generation solutions have their costs. For example, you have simply chosen disregard the cost of the presence of tens of thousands of windmills, or square miles of solar cells, and huge battery installations. The point being made was that LFTR reduces both capital… Read more »
MSRs can be used to make U233/U232, which is easily fashioned into low-yield nuclear weapons. Bomb experts from Los Alamos and Lawrence LIvermore have already described how easy it is to do this.
I ask that amateurs should stop pumping Thorium molten salt reactors. Let the experts and the scientists, who understand the science, handle this. Please.
The last claim, that nuclear is necessary for zero emissions, is open to doubt. Wind and solar power will soon overtake nuclear, in annual terawatt-hours, in the world. It has already done so in China, India, the UK, Germany, Italy, Indonesia, Brazil, Mexico, Spain and in fact most nations of the world, according to data for 2018 in the BP statistical review of world energy. It has been done, it can be done. There is no reason why wind, photovoltaics, thermal solar, geothermal, existing hydro and biomass could not supply 100 per cent of the global electricity, together with demand… Read more »
The problem with your statement is not in the actual production of the energy, but in the space required to produce energy from those sources, the toxicity of the materials used, versus the after effects of placement. Hydroelectric Dams while close to carbon neutral after production requires large bodies of water to generate minimal amounts of electricity. To produce said dams, a large area has to be flooded before energy production can take place. While this method does not release carbon into the atmosphere, it still causes large area scale environment destruction. Wind turbines are not as clean as one… Read more »
Regarding your last remark about fusion: it is false that fusion has been ignored. It has been heavily funded for many decades. There are U.S. congresspersons currently pushing it. And for fifty years, we have been told of fusion break-throughs, and solutions around the corner. The truth is, more break-throughs will be required to make it practical; there must be a solution, but it would be naive to believe it’s around the next corner or the one after. Fusion is indeed the dream energy source. We must continue to pursue it — but it would be irrational to rely on… Read more »
It appears the fact checking was only for solid fuel reactors. In that sense they are correct. But Wang has also noted that GenIV reactors including Molten Salt Reactors (for thorium as well as uranium) which are much cheaper to build since, at least at one level, the reactor vessel and balance of plant, has only to be built for atmospheric pressure, unlike in today’s GenIII pressurized water reactors. The only area where the fact checking is quite wrong is in acquiring thorium. Thorium only has to be milled to purity using existing industrial technology. There is no enrichment. Many… Read more »
You are right that Thorium is 4 times more abundant than Uranium. But note that the Uranium 235, which is directly usable in reactors, is less than 1% of the uranium that is mined. So Thorium is really much easier to access by a factor of hundreds than the typical uranium used in reactors.
Lance, I think you are comparing the claims of LFTR reactors with conventional uranium LWR reactors. Liquid salt uranium reactors have some of the same efficiency advantages as LFTR — in particular, they can be designed to operate with different neutron energy spectrums, so that they could in principle burn more of the input fuel than a slow-neutron LWR. It is clear that conventional uranium LWRs are very inefficient in converting the input fuel to energy, compared to a LFTR. Breeder reactors can burn U-238, however, so this isn’t so much a distinction between uranium and thorium as fuel, but… Read more »
This article completely overlooks the current outstanding issues presented by thorium reactors. First among many issues is the lack of metal alloys that can resist the extremely corrosive molten salt fuel mixtures.
Having materials that can withstand the corrosive salts is indeed a challenge. This was considered one of the great challenges to solve by the engineers and scientists that built the molten salt reactor experiment at Oak Ridge National Laboratories and ran it in the 60s. Significant progress was made at the time to find materials that could withstand the corrosive salts. Hastelloy-N was found to do a reasonable job. It is unfortunate that the research was halted by lack of support from the Nixon administration since this issue might have been resolved by now. The chinese appear to be spending… Read more »
The Fact Check’s refutation of the claim that one can’t make nuclear weapons from the thorium fuel cycle, can be strengthened by noting that the US has successfully tested nuclear weapons using U-233 from thorium — see U.S. Congress Office of Technology Assessment 1994. Technical Options for the Advanced Liquid Metal Reactor—Background Paper. OTA-BP-ENV-126. Washington, DC: U.S. Government Printing Office, May.
Yes, Yang was incorrect to state that Thorium (or at least Uranium 233 is part of the Thorium decay chain) can’t be used to to make nuclear weapons. It can. However, the decay chain also include Uranium 232, so you always get a mix of Uranium 233 and 232 when using thorium to generate fuel. Uranium 232 is a gamma emitter, and gamma radiation is easy to detect from long distances. Uranium 232 is also very difficult to handle because it is a gamma emitter. Separating the two completely is not practical. This makes uranium 233 much less desirable for… Read more »
Not true. By extracting the Pa233 as quickly as it’s made, the U233 that decays from it is very clean.
Any reactor can produce pretty much any isotope — that’s kind of what they do. The questions here are: who is doing it, and would it be practical for them? Let’s run through some scenarios. Could a country misuse an LFTR to produce weapons-grade plutonium? I know of no reason why they couldn’t, in principle. But would they go to the trouble and expense to use an LFTR to do something it wasn’t designed to do, when there are well-known reactor designs that can produce plutonium very efficiently? If a country wants plutonium, it is not that hard to make,… Read more »
The Molten Salt Reactor, which does not have to be thorium fuelled does not need expensive steam containment structure, therefore, it is mass producible. It is based on molten salts and there are a variety of designs that MUST be approved FOR TESTING (see the best one). One uses molten salt in tubes surrounded by non fissionable fuel salts. Others are just like the old MSRE that Nixon nixed for reasons of??? Still others are like LFTR, using thorium.
This article totally forgot the heart of “thorium”, the MSR!
These points are not helpful to the larger discussion. The type of reactor Yang references, a molten salt reactor, is still very much worth pursuing because 1: It is not water-cooled, and 2: It does not operate under pressure. This means that the reactors can be deployed anywhere, not just near a body of water, and that in the event of an emergency they shut down on their own without human guidance. This isn’t USA warming, it’s GLOBAL warming. We need an energy-dense technology that can be deployed in remote regions of the world without a massive team of nuclear… Read more »
Frederik Lundberg and George Kamburoff are correct in stating that we do not need nuclear power. Indeed, any type of base-load power station is unnecessary. Regions with good wind and/or solar resources can have 100% renewable electricity with high penetrations of variable renewables providing bulk electricity firmed up with relatively small contributions from dispatchable renewables and other forms of storage. This is demonstrated by both practical experience and simulation modelling. The electricity grid of South Australia has operated reliably for the past two years with about 50% of annual electricity provided by wind and solar PV, which have displaced coal… Read more »
I lack your ability to see into the future. Let me describe what I see with my handicap. Without perfect forsight, we perceive huge catastrophy looming, and several proposed energy production solutions. Each solution has its cost, each has its place. Some regions have lots of hydroelectric possibilities — but hydroelectric power involves big environmental changes, which many would find objectionable. Some regions have lots of sun and lots of cloudless days — but even there, solar is available only in daytime. In a few regions, the wind blows hard most of the time — but even there, tens of… Read more »
The whole discussion of the danger of proliferation is predicated on bomb-grade fissile materials as the object of terrorist or unauthorized proliferation and military use. It is not necessary to create an explosive nuclear device to create a lot of harm and havoc. Even a “fizzle bomb” would be capable of making large parts of a city the size of Manhattan inhabitable, and damaging telecomm equipment, automobile computers and other solid-state electronic infrastructure. The advantage of the thorium/liquid salt reactor design is that it neither accepts nor produces materials and wastes of any interest to such actors. It uses its… Read more »
Dwain, Your point is well taken, that efficient nuclear bombs are only one danger of nuclear waste. For instance, it would be very bad for a substantial quantity of plutonium, even contaminated with its 240-isotope, to fall into the wrong hands. And yes, one of the advantages of MSRs (including LFTRs) is that they can burn plutonium for energy. I think you’re being overly-optimistic about no radioactive waste coming out of an LFTR. Besides, some radioactive elements are very useful to have — mostly short-lived isotopes. We don’t want large quantities of dangerous, long-lived, useless stuff coming out of reactors.… Read more »
There are dozens of companies working through the regulatory maze of the United States, Canada, Europe and other jurisdictions. The Chinese government is building MSRs today and will be operating them very soon. I think when Andrew Yang talks about “thorium reactors” he is actually referring to molten salt reactors. And yes the US government did work on these at Oak Ridge National Lab’s in the 1960s. The original researchers concluded that the next rounds of reactor development would solve the minor issues found the first MSRE test. The program got cancelled, however. There is a lot of excitement and… Read more »
What you did not mention is the cost of manufacturing the solid fuel pebbles to precise measurements and replacement after 2-3 years, adding it to the radio-active waste storage at high cost. The fuel rods must be replaced while the reactor is idle in a LWR while it (the Thorium or depleted fuel of a LWR) can be added when needed in the LFTR online. The radio-active waste of molten salt reactors is also MUCH less than the solid fuel reactors because of better utilising of the fuel in a LFTR (98%) against the fuel utilisation in a LWR (2%).… Read more »
I would rate the claim of nuclear reactors being necessary for meeting the zero carbon goal as mostly false. While we can easily deploy enough wind energy in the time period. We could even do 100% wind for our electrical needs in 2 years, but ramping up production that high would be extremely costly, and create more carbon emissions in the short term. There is a limit to solar deploment in short-term due to the more advanced infrastructure required for solar, but with proper subsidies we could increase rooftop solar drastically in under 8 years. This could be enough to… Read more »
This is what I hear you saying:
We have an environmental disaster looming, but we should not try all the options, because you know that certain options prefered by you will suffice to avert the disaster.
Have I misunderstood?
Yes but the uranium thorium gets converted into is uranium 233 which is alot more efficient than traditional uranium
Andrew Yang has no background in nuclear engineering so his views are a product of what he has heard from others. He, like most thorium reactor promoters, has never bothered to examine the criticisms of the technology. Here is some background. There are a couple of U.S. engineers that have launched a major campaign, using a variety of media outlets, to engage others in promoting their molten salt thorium reactor concept. Their aim is to get the federal government, and other investors, to finance the development their project. They present a slanted story that tends to appeal to large numbers… Read more »
I looked at all the links (the ones that still work anyway) that you mention. None of them mentions the primary thorium reactor design being discussed, LFTR. They all completely miss this crucial point. I cannot imagine how anybody could miss this point at this time, unless they had blinkered themselves — every web search on the topic of thorium reactor turns up LFTR. Thorium alone as a fuel is attractive in several ways, but it is LFTR’s combination of thorium fuel with molten-salt reactor (MSR) designs that has spectacular promise. But the worse flaw in your reasoning is that… Read more »
Give it up. We cannot afford nuclear power when we can put up solar PV with battery storage right now quickly and for 1.9 cents/kWh daytime and 3.3 cents/kWh at night. No new nuclear plant can do that. The new designs are doing us no good. The V.C. Summer reactors were cancelled after squandering $8,000,000,000 of the People’s Money. Their twins, the Vogtle units in Georgia are so far over budget the cost of their power is projected to be over 15 cents/kWh, and it has to run for 50 years to pay back at that cost. Whose power do… Read more »
Your argument denies off-hand (“does no good”) the fact that different nuclear reactors have different characteristics. And you mention a uranium-based, water-cooled reactor projects, although the topic here is thorium-based reactors, whose preferred design uses a molten salt. I’m afraid you missed the point of the discussion. I recommend that you do some research into it — you might change your mind. Your argument ignores the fact that each means of energy production has its strengths and weaknesses, and its own costs, and each is objectionable. Your argument ignores the fact that all renewable methods have limitations in availability. In… Read more »
This is an unfortunate mess, the “fact check” on pretty much every point. As other posters have pointed out, the technology under discussion is liquid fluroide thorium reactor (LFTR), not just thorium fission reactor. It is the combination of liquid-salt and thorium that provides a substantial sweet spot, in safety and, waste, and in efficiency and economy. Thorium as a fuel by itself has the advantage that vastly less plutonium-239 is produced, than in commercial uranium reactors. Besides this, are the advantages that it is much more plentiful than Uranium and more evenly distributed over the earth, and it requires… Read more »
The one thing no one ever talks about when it comes to nuclear power is the mining and first level processing to refine the materials needed. I used to live in Grand Junction, CO (the Grand Valley area) where much of the uranium was given its first refining before being sent on for further refining so it could be used. One of the dirty side effect we in the Valley had to live with was the mill tailings, of which was used as fill dirt all around the valley. Eventually the hazard was discovered in a 1962 article in the… Read more »
This is a pretty biased article. Take cost: “Nuclear energy economics are driven by the capital cost of the plant, and building a power plant with a thorium reactor is no cheaper than building a power plant with a uranium reactor. ” That is utterly, completely false. LFTRs operate at atmospheric pressure, vs 70 to 160 atmospheres in PWRs. Hence building PWRs is very expensive, because reactor has to be able to withstand this pressure very, very reliably. Also with PWRs you have to build extensive active safety systems that are not needed with LFTRs, because they have passive safety… Read more »