About This Post
During December 2022 I began reading about nuclear fusion - I mean controlled fusion for electric power production. I've discovered that we've all been told a Big Lie. It's the kind of deep, structural lie that becomes the consensus story of a group of experts in their communication with the public and goes on for decades, making it difficult for any single expert or small group to correct.
The big lie is simple: that the fuel for nuclear fusion is cheap and limitless. The truth is different, so different it's almost impossible to believe: the fuel for nuclear fusion here on Earth is fantastically expensive and desperately constrained - so desperately that it's unclear how we can bootstrap a fusion power industry at all.
If you are curious about this and want to know more, I hope you'll read on. I'm confident that everything I write here is on a solid technical foundation; there are references at the end, including references to original scientific papers published by the world's leading experts on this topic.
Just a Little Physics
Hydrogen is the most plentiful element in the universe, and the Sun fuses ordinary hydrogen to make heat; this much is true. But no fusion reactor ever seriously contemplated on Earth has even considered using this process. The required temperatures are far too high to achieve in "magnetic bottles" or by "laser confinement" or any of the other techniques that have been investigated during the past 75 years, even in the cores of our weapons. Equivalently, we can say the reaction rate is much too low to be useful.
Fusion reactions that occur here on Earth - and this includes our weapons - rely on the fusion of unusual variant forms ("isotopes") of hydrogen. There are two, deuterium and tritium, so the reaction is often called "D-T fusion." Deuterium is naturally occurring, common enough, and not radioactive; it can reasonably be characterized as "cheap, safe, and limitless".
Tritium is a different story.
Tritium doesn't exist naturally on Earth except in trace quantities. It's radioactive, and has a fairly short half life (12.33 years) so stocks of it simply disappear over time. It can be made, but only in particle accelerators and nuclear reactors, at great cost; its current retail price is around $30,000 / gram. The world's entire inventory is much less than 100 pounds. Existing stocks were created by an aging fleet of nuclear (uranium fission!) reactors of a specific design, mostly in Canada, at the rate that exceeds the inevitable radioactive decay by maybe half a kilogram (about a pound) a year.
Fusion power reactors will require kilogram quantities. The first large fusion facility, ITER, now under construction in southern France, is scheduled to consume most of the world's inventory. ITER does not make electricity (it's a science experiment). It will severely deplete the world supply, leaving essentially no tritium for follow-on projects. There are no clear plans in place to create any tritium to bootstrap follow-on reactors.
Tritium doesn't exist naturally on Earth except in trace quantities. It's radioactive, and has a fairly short half life (12.33 years) so stocks of it simply disappear over time. It can be made, but only in particle accelerators and nuclear reactors, at great cost; its current retail price is around $30,000 / gram. The world's entire inventory is much less than 100 pounds. Existing stocks were created by an aging fleet of nuclear (uranium fission!) reactors of a specific design, mostly in Canada, at the rate that exceeds the inevitable radioactive decay by maybe half a kilogram (about a pound) a year.
Fusion power reactors will require kilogram quantities. The first large fusion facility, ITER, now under construction in southern France, is scheduled to consume most of the world's inventory. ITER does not make electricity (it's a science experiment). It will severely deplete the world supply, leaving essentially no tritium for follow-on projects. There are no clear plans in place to create any tritium to bootstrap follow-on reactors.
I know this may be difficult to believe. It sounds like the world's fusion scientists are impossibly stupid. There are many reasons for this, and the full story is too long for this blog post. But there is a candle of hope, and it's bound to be mentioned by any defender of the fusion power industry.
Tritium Breeding
In the previous section I said tritium could be made "...in particle accelerators and nuclear reactors." This includes nuclear fusion reactors; they can, in theory, "breed" their own tritium. They can do this by splitting atoms of another element, lithium, into atoms of tritium. In theory, again, this can be done continuously, in a lithium "breeder blanket" surrounding the reaction chamber, making them self-sufficient.
This "continuous tritium breeding" concept is the only solution to the worldwide tritium shortfall that has been widely discussed. Unfortunately, it has many issues. First and most obviously, it doesn't begin to address the startup problem, which I've called "bootstrapping." Large D-T reactors will require a lot of tritium to start up, and they can't breed any tritium until they're operating. It's currently unclear how the world will get past the tritium shortfall in the late 2020s and 2030s, as the unique Canadian reactors reach their design lifetimes and ITER consumes most of the world's existing stockpile.
Second, the breeding ratios are not very high. The "doubling time", the time required to breed enough fuel to start a second reactor, is probably measured in years (yes, years). See the Notes for references on this.
This leads to the third issue: the difficulty of breeding sufficient tritium places a challenging set of constraints on the design of fusion reactors, which were already some of the most complicated things that people have ever tried to build. Tritium is extremely difficult to handle. It's radioactive--every part of the tritium handling system will become low-level radioactive waste. It gets into everything--it even diffuses through steel plates! The design of the tritium recycling system will affect every part of the reactor design.
Perhaps worst of all, fusion reactors will have to operate almost all the time to create the fuel required for their next restart plus a small surplus. They'll have to achieve extremely high availability numbers. And I mean they will have to - there will not ever be sufficient tritium to restart them again and again without long periods of operation between the restarts to breed the necessary tritium surplus.
Perhaps worst of all, fusion reactors will have to operate almost all the time to create the fuel required for their next restart plus a small surplus. They'll have to achieve extremely high availability numbers. And I mean they will have to - there will not ever be sufficient tritium to restart them again and again without long periods of operation between the restarts to breed the necessary tritium surplus.
This is an incredibly high barrier for a new technology that was extremely challenging to begin with.
The Bottom Line
After carefully reviewing the facts (see my notes below), I've come to believe that ITER, which has a design lifetime measured in days and is not designed to produce electricity, will not be the prototype of a new generation of power plants. Rather, ITER will be the last D-T fusion plant ever constructed. The bootstrapping problem seems insurmountable to me: in practice, governments would need to invest billions of dollars in specialized nuclear reactors designed to make the tritium required to bootstrap the next generation of fusion reactors. And they'd need to start now, because building up our tritium stocks will require decades.
But to argue for these facilities, fusion's community of experts would need to unwind their decades of lies about "clean and limitless" fuel. They'd need to appeal to governments and investors for billions of dollars to build specialized facilities to breed fuel.
This is not going to happen. Rather, what we can expect over the next several years will be more like the popping of a large, decades-long bubble. Funding for D-T fusion will dry up, leaving only minimal funding for more exotic concepts (see notes). These exotic alternatives require much higher temperatures and/or compressions, making them likely to become power alternatives in the 22nd century rather than the 21st.
Notes
The best overall writeup I've found about this topic is on the web site of the highly-respected journal of the American Association for the Advancement of Science (AAAS), Science, posted June 2022.
The best current example of history of lies about "cheap and limitless" fusion is the on the home page of Commonwealth Fusion Systems, a well-funded D-T fusion startup spun off from MIT. It says "One glass of water will provide enough fusion fuel for one person's lifetime." This is a flat-out lie - a glass of water won't fuel any fusion at all, here on Earth. There's no tritium in a glass of water other than the trace amounts that are occasionally created by cosmic rays.
This entire story, along with other debunking of the fusion lies I haven't even mentioned, was substantially driven by Steven Krivit and his web site, New Energy Times. Mr. Krivit is an interesting fellow; his site was formerly dedicated to coverage of "Low Energy Nuclear Reactions" (LENR), the topic previously known as "cold fusion". But when the latest surge of interest in "cold fusion/LENR" began to die out during the 20-teens, he turned to debunking the "conventional" fusion industry. He began by debunking the false power production claims of ITER and more recently moved on to this topic, fusion fuel.
Mr. Krivit has done more than any other single individual to raise the world's awareness of these issues. His site contains quotes and videos documenting the enormous extent and duration of the Big Lie. You can also watch this excellent video, linked from Mr. Krivit's site, which makes most of the points I've made here.
Next, there are some Wikipedia links. You can read about the unique Canadian reactor design which has serendipitously created the world's entire tritium inventory. And you can read about the ITER project, an ongoing multinational effort to build a "tokamak-" (donut-shaped) D-T fusion reactor in southern France. I'm engaged in trying to get a false statement about "fusion processes of the Sun" removed from the first paragraph; you can see my comment on the Talk page. You can also read about ITER on their own site.
And what about our weapons? A surprising amount is publicly known - because it has leaked, or is deducible from the physics, or has been declassified. Weapons do use small quantities of tritium for a "fusion boosting". The Department of Defense contracts with the Tennessee Valley Authority to place lithium rods in a couple of the TVA's uranium fission power reactors, periodically collects the rods, and reprocesses them to gather the generated tritium for its needs (which are small, a few grams per weapon, refreshed every few years). You can read about fusion boosting.
Large "hydrogen" (really "thermonuclear") weapons do perform D-T fusion, but don't package tritium. Instead, they package lithium and deuterium in the form of "lithium deuteride" with an atomic bomb as the trigger. During the detonation, the immense neutron flux creates tritium from the lithium and D-T fusion follows. This option obviously isn't available for power reactors since they don't have such a large neutron flux - they're not triggered by atomic bombs.
So the Defense Department avoids the need for an inventory of large quantities of tritium. All the nations that have thermonuclear weapons seem to have hit on lithium deuteride as the fuel. You can read about this too.
From this design and other knowledge of the US nuclear weapons program, we can take away an important fact. Lithium, like hydrogen, has two stable isotopes. Only one is useful for breeding tritium, and it's the less common of the two. It's necessary to perform isotopic enrichment of natural lithium to create the stuff that ends up in the breeding blanket, and isotopic enrichment is inherently difficult - both variants are "lithium", so it's necessary to exploit their subtle differences to change their proportions. The US used the environmentally nightmarish COLEX process during the 1950s to create the stockpile of isotopically-enriched lithium that (when mixed with deuterium) has provided the fuel for our thermonuclear weapons ever since.
From this design and other knowledge of the US nuclear weapons program, we can take away an important fact. Lithium, like hydrogen, has two stable isotopes. Only one is useful for breeding tritium, and it's the less common of the two. It's necessary to perform isotopic enrichment of natural lithium to create the stuff that ends up in the breeding blanket, and isotopic enrichment is inherently difficult - both variants are "lithium", so it's necessary to exploit their subtle differences to change their proportions. The US used the environmentally nightmarish COLEX process during the 1950s to create the stockpile of isotopically-enriched lithium that (when mixed with deuterium) has provided the fuel for our thermonuclear weapons ever since.
Which brings us to the scientific papers, the first of which is about lithium isotope enhancement. You can read the abstract and the introduction to confirm several of the points I've made here. A description of the fusion process used by the Sun (but nowhere on Earth) is on the Hyperphysics site.
But the most important scientific paper by far is the work of M. Abdou, a physics professor at UCLA. Prof. Abdou is without doubt the world's leading expert on the topics I've discussed with nearly 40 years of experience. For this paper he assembled a diverse team of experts from many disciplines. The paper is really an engineering feasibility study, not a physics paper; it's difficult because the engineering concepts are very involved, but it doesn't demand extensive knowledge of physics.
But the most important scientific paper by far is the work of M. Abdou, a physics professor at UCLA. Prof. Abdou is without doubt the world's leading expert on the topics I've discussed with nearly 40 years of experience. For this paper he assembled a diverse team of experts from many disciplines. The paper is really an engineering feasibility study, not a physics paper; it's difficult because the engineering concepts are very involved, but it doesn't demand extensive knowledge of physics.
You can also read conference presentations by Prof. Abdou. [Update: due to link issues, visit this page https://www.fusion.ucla.edu/presentations/ and click on the second of the three presentations for 2022.] Skip directly to his "concluding remarks" on slides 30 and 31. For a person of Prof. Abdou's stature, these conclusions are apocalyptic: he's saying, bluntly and directly, that the worldwide community's present path (i.e. the "DEMO" production scale fusion reactor currently planned to follow ITER) is impossible; that the community must realign around production of tritium. As I mentioned above, I don't think this is likely. Rather, I think the effect will be more like the popping of a bubble, and progress toward workable fusion reactors will be set back by 30 years, if not forever.
Finally, there are a few fusion companies doing research on fusion that doesn't use tritium. Every one of the alternative fusion reactions requires higher temperatures and/or pressures than D-T fusion, so these approaches are all more speculative (in the main text, I used the term "exotic"). One example is Helion, a privately funded company that proposes to fuse deuterium with helium-3 (which has to be bred in the reactor because it's also not found on Earth in substantial quantities). [Update: here is a video about Helion.] TAE Technologies proposes a different set of alternative physics.
I hope one of these startups succeeds, because I don't think D-T fusion will.
