- The end product of Deuterium + Tritium is regular, stable Helium, making waste disposal both safe, and cheap
- The input of the process, heavy water, while not safe, is way less dangerous than thorium or uranium
- The whole process is no way involved with nuclear weapons, making security concerns much less relevant
- Since the process produces magnetically charged plasma, steam turbines are not necessary, a solution of directly harvesting energy with electromagnets was proposed.
People, especially mothers were somewhat worried about magic heavy chemical water with different nuclear properties...
That seems a bit dismissive. I would naively assume that there have been exactly zero studies to see if there are any problems with babies drinking heavy water, beyond some LD50 extrapolation.
But there’s tons of inert things that we don’t need to study because it makes no sense.
https://en.wikipedia.org/wiki/Heavy_water#Effect_on_biologic...
From reading that, it seems the mechanisms aren't really understood.
But wouldn't that require aneutronic fusion to be viable? I had thought that the prevalence of neutron radiation otherwise would have made directly tapping the plasma for electricity impractical.
"Side reactions" produce neutrons and gamma rays, and fusion products can get involved in side reactions too, also producing neutrons and gamma rays. If you can keep recirculating the desired reactants, filtering out the products and side products, those reactions can be kept to a low level.
Even better. Helium is a relatively scarce resource, there would be no shortage of people to take it off of your hands.
> If one ton of deuterium were to be consumed through the fusion reaction with tritium, the energy released would be 8.4 × 10^20 joules[1]
That's 0.84 exajoule(233 TWh) per kilo of deuterium or 0.42 exajoule(117 TWh) per kg of helium produced. World energy consumption is 1.6 exajoule per day[2] so less than 4 kg helium will be removed per day if energy extraction is perfect or few 10s of kg assuming imperfection
[1]: https://www.britannica.com/science/nuclear-fusion/Energy-rel... [2]: https://www.statista.com/statistics/265598/consumption-of-pr...
New level of appreciation. Thank you.
Actual fuel fuel estimate: “a 1000 MW coal-fired power plant requires 2.7 million tonnes of coal per year, a fusion plant of the kind envisioned for the second half of this century will only require 250 kilos of fuel per year, half of it deuterium, half of it tritium.” https://www.iter.org/sci/FusionFuels
“Global electricity consumption in 2019 was 22,848 terawatt-hour”
22,848 * 1000 / 365 / 24 = 2608 different 1GW reactors each producing 250kg of helium per year. So 652,000 kg/year if all the worlds electricity was made from fusion or ~3,650,000 cubic meters or ~130,000,000 cubic feet of helium.
PS: Efficiency numbers could wildly change those estimates, but that’s the rough ballpark for electricity let alone stuff like transportation or home heating etc.
The ~300 cubic foot tanks are 9 inches in diameter, 55 inches tall, with about 130 pounds and contain about 1.5kg of helium.
The most important factor.
Helium-3 fusion produces charged particles, which it might be possible to directly harvest as electricity. The He3 fusion reaction has a high activation energy, which is currently unachievable, and there is no Helium-3 on Earth. We'd have to get it from space, somehow. (The movie "Moon" was set on a Helium-3 mining outpost on the Moon.)
D-D fusion does produce neutrons but they're much lower energy than D-T neutrons. Fusion startup Helion is working on a hybrid D-D/D-He3 reactor, saying the combination will produce only 6% of its energy as neutron radiation, low enough so they can do direct conversion.
They've built half a dozen reactors, and now they're working on a seventh that they'll use for a net power attempt around 2025. They recently had a fundraising round led by Sam Altman, and raised $500M with another $1.7 billion of commitments based on milestones.
Surely we are missing something in this discussions?
A couple other fusion companies think they can achieve net power at least, around the same time.
Another choice is fusion of ordinary hydrogen, usually labeled "p" for the proton, with boron, B, thus "pB". But that is even harder to achieve. Still, it is being worked on.
There is no route to commercially viable fusion extracting heat from Tokamak reactors, as any such reactor would need to be enormously bigger and much more expensive to operate than the same-rated fission reactor, which is not today competitive, and gets less so all the time.
Some people hope that something can be learned from Tokamak work that might be applicable to potentially practical designs, but the money is all going to Tokamak, while the others mostly go begging.
Depends on which company you're talking about.
Helion, for a coutner example, is directly harvesting energy out of plasma.
Not the same as "is".
Hellion hopes someday to be extracting more than they put in.
[1] https://en.wikipedia.org/wiki/Heavy_water#Effect_on_animals
(And to point out the obvious, every other liquid apart from drinking water is more toxic when you ingest literal bucketfuls, including harmless household liquids like vinegar, shampoo, ethanol, olive oil.)
In its current form though, the CapEx for fusion projects is huge. Fusion won’t play a big part as an energy source if reactors take 10+ years to come online and cost tens of billions of dollars. Fusion proponents will argue that costs will come down, but if the political and entrepreneurial pressure to reduce cost isn’t there, fusion will end up the same as fission.
Certainly, containing fusing plasma magnetically requires developing a much better understanding than we now have of plasma fluid dynamics under conditions of high pressure and complicated, variable magnetic field geometry, but studying plasma fluid dynamics for itself does not need multi-billion dollar equipment. Nobody wants to give plasma physicists a dime just to learn about plasma, even though it would be fantastically cheaper than what is being done instead.
The chart here shows the energy difference pretty well: https://www.nuclear-power.com/nuclear-power/fission/nuclear-...
More fuel + more energy from fuel = superior for most uses long term. If we pull it off.
Fission is already not competitive, so a technology much more expensive to build and operate is even less so. In ten years, solar and wind will be even cheaper than today, and will be supplying most of our energy needs.
(Not every place is Southern California where there are no clouds and the sun shines all year. Solar is cheap in some places, but not at high latitudes.)
Wind does not confine itself to lower latitudes.
Such reactors would also quickly destroy themselves, so would have no opportunity to pay back the investment.
The only hope for useful fusion is if work on existing designs turns out to be applicable to actually practical, aneutronic forms. Current spending on those is negligible.
Consider that the majority of startup companies with apparently good ideas never get to market. People like to think the hardest problem they know of right now is all that matters, but often it is a boring problem that sinks the company. Maybe it is technically solvable, but costs enough to destroy the value proposition.
So long as solar and wind costs are still falling fast, any prediction about the viability of competing tech is at best provisional.
Solar and wind benefit from the opposite effect: there are known problems, but they have lots of known viable solutions that are just competing for which ones (plural) will end up cheapest, or have the most side benefits, or are easiest to deploy.
It used to be that poor round-trip efficiency would sink a storage technology, but generation has become so cheap that losses matter less than other considerations. 50% loss? Build out more panels!
Hydrogen still has awful efficiency, electrolysers and fuel cells need platinum-group metals, and liquid hydrogen needs really rigorous handling, but H2 is so useful that those don't matter. Efficiency and cost will only improve. Ammonia synthesis is similar: super-useful, but maybe easier to make starting with water. (There will be a lot of waste oxygen soon.)
Iron-air batteries likewise have poor efficiency, and low discharge rate, but the material basis is very, very cheap. You can gang up thousands in parallel to get the rate you need, and stick lithium or lead cells on the front to handle load spikes. Useless for cars, fine for utilities.
Liquifying air is very mature tech, so as the basis for a storage medium it's a safe bet. Storage capacity grows with cheap tankage. And, excess LN2 is valuable, so when your tanks are full you still have revenue.
It turns out there are myriad elevated basins that would be perfect for pumped hydro storage, another very mature technology. Unlike hydro generation, you don't need a whole watershed and river valley, just hills with a dip.
Even if fusion fizzles for utilities, the mostly-aneutronic sort might be perfect for outer solar system propulsion, where a completely different set of constraints apply. And, military deployments will often not be able to lay out much solar where they land. So, even though fission is, relative to solar, super-expensive, places can be found where nothing else will do.
Fission (will?) have the advantage of being able to produce energy whenever we need it. Solar or wind need storage. And as far as I know, there are no viable storage solution as of today.
> It turns out there are myriad elevated basins that would be perfect for pumped hydro storage, another very mature technology. Unlike hydro generation, you don't need a whole watershed and river valley, just hills with a dip.
In some countries, all possible places of hydro generation have already been used. What would be the potential for new hydro solutions in Europe for example, where hydro has been exploited for decades? Again, not an expert, but I don't think that there is an obvious path in countries where population density is pretty high and without large swathe of lands, to build hydro storage to be able to produce enough energy on a sufficient long period of time. Curious to know what you think.
Using any sort of battery, based on a chemical process, will also probably have high impact on the environment. Current battery relies on rare earth material or industrial processes that are very impactful. Creating enough batteries to ensure safe power distribution for billions of people will probably be terrible for the environment.
My point is that there is no silver bullet as of now so putting all you eggs in the same basket does not seem to be a sane strategy. Investigating fusion is worth a shot I think.
And if we worry about money, there's plenty of money to go around. We are talking about the survival of civilization here. 16 billions were poured into the a company providing ways to share pictures of your baby to your high school friends ten years ago (yes Facebook). I am sure we can find the money to finance Fusion AND research on energy storage. It's a question of political will. In the end, we'll get what we deserve...
Where an elevated natural basin can be found, that can radically increase the storage capacity from hours to, potentially, weeks, and for even less expense: just the penstock needs to be built. Elevated basins are much more common than the elevated river valleys needed for pure hydro generation. A hybrid approach is to wall up one end of an elevated box canyon: a dam, technically, but inflow is pumped from below rather than drainage from above. There is some construction cost, but radically less per unit volume of storage than a complete tank. Dams with penstocks are extremely mature tech.
While fusion doesn't need containment for radioactive fuel, a reactor must be much larger than a fission plant because the volumetric energy flux density of fusing plasma is enormously lower than of uranium. And, the heat has to be collected by blasting neutrons right through the magnetic coils and into a "blanket" of thousands of tons of molten, radioactive lithium, in pipes all around, the which does need to be contained. People get testy when that much molten, radioactive lithium runs downhill.
The lithium needs to be confined in plumbing which will be weakened by the neutron blast and need to be replaced frequently, but will be deadly radioactive so need to be replaced using robots. That plumbing is really most of the reactor. Probably it should all be underground, so that when it is seen to cost more to refurbish every couple of years than it is worth, it is already buried.
Meanwhile, the lithium needs to be processed continuously to extract transmuted tritium to use for fuel. It is hard to imagine molten lithium processing being as cheap as managing the water and steam in a fission reactor.
Then, you need to move the heat from the lithium into liquid that will not pick up its radioactivity, thence to water for steam for the turbines. And, you need to maintain the steam turbines frequently, same as in a fission reactor.
Contrast this to negligible upkeep cost for solar and wind, which mostly amounts to unbolting and replacing them as they pass two decades of service. Your storage method might need some upkeep, but you chose it for its low cost.
This potentially creates room for fusion that never existed for fission:
- innovation and entrepreneurial pressure. Best case, we get SpaceX efficiency fusion innovators versus SLS pork barrel subsidy patients.
- insurability. Fusion energy production might become privately insurable.
- political support. If the political buyin required is mainly limited to capex, that's a very big advantage versus fission.
As for short to medium term political motivation, one might hope fusion energy research is to benefit from the tension between Russian and western leadership.
This sounds like a great thing for humanity, but humanity's interests are not properly represented by the existing political power structures.
* compared to fission, the nuclear waste management for fusion looks to be done within a human generation, rather than outlast human civilisation. So how you discount the future has a large impact on the trade-off between fusion and fission.
* the fuel for fission is uranium, a hard to get and limited resource. The fuel for fusion is hydrogen. Initially only the rarer hydrogen isotopes, but we might eventually get fusion to work for the more common isotopes as well.
Nuclear waste is not actually that dangerous that long. Everyone (including the planners) like to hype it up for their own reasons.
Fusion has many fusion pathways, some of which are pretty light on the dangerous radiation, others that are pretty heavy on it. Most advocates don’t know which one they’re advocating for.
The radiation ‘activates’ and damages the interior of the fusion reactor, making it radioactive. This is not a solved problem yet. It may never be.
Can you elaborate? E.g. Plutonium-239 has a half life of 24000 years. That hardly sounds like "not that long"? Leftover uranium-238 even stays radioactive for billions of years (half life of 4.5 billion years).
But there are other long-lived isotopes, as well. Safe disposal is not a difficult technical problem, but is a political football causing limitless distraction.
Some of these elements have pretty high overall energy levels released in their decay chains (so it’s not just one decay) some less - but sources that are more radioactive are decaying and releasing energy faster, have shorter half lives, and are very dangerous for shorter periods of time.
You can literally buy Uranium 238 ore through the mail and handle it with no more special precautions than washing your hands afterwards and not eating it. It’s seriously fine.
Except in a few spots where it was heavily concentrated, most of the legitimately dangerous stuff has decayed to ‘meh, not that bad’ levels already even at Chernobyl.
It’s still not a good idea to lick it, or spend all your time in the main reactor hall, but give it another 50 years and you’ll probably be able pet the elephants foot on a tour.
Hiroshima and Nagasaki has been fine for awhile. People do tours at ground zero of the Trinity test site.
Some of these elements are chemically active in weird ways, and even without the radioactivity, eating plutonium, cesium, or uranium will be a bad time. Same with mercury, lead, cadmium, etc. so I’m not advocating for being careless with them.
But the idea of a big chunk of radioactive waste being a glowing orb in 10k years is fantasy.
All reactors are still at best early scientific experiment level, and have been for some time.
Fission exists now, and we understand the economics. With all the political friction and the like, the west basically builds no new plants.
So we’d be comparing ‘no clue it’s even possible to build a plant’ to ‘expensive and generally not building new ones’
The difference in radioactive danger, is because not all nuclear reactions are treated equally. Tritium decays once, emitting a 0.019MeV beta particle [1]. Uranium creates an avalanche of particles [2] for a total of 51.7 MeV. So it has the leeway to be both more radioactive and to be it for longer. But both the type and energy of the radiation have intricate effects on how they interact with biology and so how dangerous they really are.
That said, exactly how radioactive fusion waste will be is a bit a philosophical problem, as nobody knows what the minimal requirements are for a functional plant.
[0] https://bettermeetsreality.com/how-much-uranium-is-left-in-t... [1] en.m.wikipedia.org/wiki/Tritium [2] https://en.m.wikipedia.org/wiki/Decay_chain
But anyway, those numbers sound about right, here's what wikipedia (and their source, https://doi.org/10.1787/uranium-2018-en) says:
> As of 2017, identified uranium reserves recoverable at US$130/kg were 6.14 million tons (compared to 5.72 million tons in 2015). At the rate of consumption in 2017, these reserves are sufficient for slightly over 130 years of supply. The identified reserves as of 2017 recoverable at US$260/kg are 7.99 million tons (compared to 7.64 million tons in 2015).
I wouldn't be too worried right now though, because Table 1.1 in uranium-2018 shows that the known recoverable uranium sources @ $40/kgU grew 50% between 2015 and 2017, and known recoverable uranium sources @ $80/kgU grew 4.6% over the same time period.
No one's going to go around prospecting unless they think they can make a profit doing it.
This is a really good question, and as someone who knows nothing about this, here's what I've found:
There's 4 kinds of nuclear waste:
- Very low-level waste
- Low-level waste
- Intermediate-level waste
- High-level waste
You just dump very low-level waste into a landfill[1]. This stuff is basically random concrete, etc. that comes from demolishing a nuclear power plant.
Low-level waste is still pretty boring stuff like clothing and rags that got irradiated somehow, and is 90% of the volume and 1% the radioactivity of radioactive waste[1]. The radioactivity in this mostly comes from atoms with a half-life of less than 5 years, although it seems like trace amounts of slightly long-lasting radioactive isotopes are allowed[2].
Intermediate-level waste looks like it's pretty varied things: sludges, fuel cladding, reactor parts from decomissioning. It's 7% of the volume and has 4% of the radioactivity[1]. Looks like this stuff is generally pretty long-lived: takes about 1000 years to become 10x as radioactive as low-level waste, and 100k years to become as radioactive as low-level waste.
High-level waste is basically spent fuel. It's special in that it requires some kind of cooling, at least for a few decades. It's 3% of the volume and 95% of radioactivity[1]. It can often be re-processed into more fuel. After about 200 years, it becomes about as radioactive as intermediate-level waste, and 100k years to become as radioactive as low-level waste.
[1]: https://world-nuclear.org/information-library/nuclear-fuel-c... [2]: https://en.wikipedia.org/wiki/Low-level_waste [3]: https://www.radioactivity.eu.com/site/pages/ML_LLW.htm [4]: https://www.radioactivity.eu.com/site/pages/HLW_Waste.htm
Yes, fusion is considerably more capital intensive than fission power, but the fuel is just water. You don’t need to worry about digging the fuel out of the earth, maintaining a costly disposal scheme for hazardous waste, etc.
If you want some details: check out section 3.2 of the ITER research plan.
https://www.iter.org/doc/www/content/com/Lists/ITER%20Techni...
South Korea built 28 reactors over 36 years and cost fell 1.5% per year, totalling 40% reduction. Even with this South Korean nuclear power is only about as half cheap as solar power locally (as of 2020), and South Korea is a very poor country for solar power considering its latitude and weather.
In terms of cost, 80% of nuclear power is CAPEX. Among OPEX, about 1/3 is fuel, rest is operation and maintenance. So from total cost, about 6% is fuel, and about 1% is waste disposal.
I am not sure if any of the other designs avoid the turbine
No one serious talks about aneutronic fusion because we need to walk 1 mph before we sprint at 500 mph. We'll seriously discuss aneutronic fusion in 200 years when it's relevant.
I.e., a nation that had control of such a fusion plant would have little difficulty attaching an enrichment process without interfering with power output.
Fortunately, no economically practical power generation system can be built using hot-neutron fusion, so it is an idle concern, but almost all the money being spent on fusion pursues that impractical goal.
Maybe because it's the US cold war blueprint and doesn't require any innovation. To be clear: no public program has used magnetic mirrors for enrichment but they are so cheap/small and so hot that they really are a sure thing. Maybe MRI magnets are difficult to source. I feel like the true answer is not rooted in any technical explanation but rather some kind of political explanation.
If I was a warlord trying to make industrial quantities of weapons grade fissile material in 2022 I personally wouldn't go the centrifuge route, but everyone's a critic.
Keeping our copy of the Oak Ridge source operating, and the current world order destabilized, for those 78My seems difficult; and we anyway have made only a Kg. So, this seems like not a practical way to generate a geopolitically effective amount of Pu-239 or U-235.
So the idea is not to use magnetic mirrors for power generation, but as a DD-fusion-powered cheap fast neutron source. I have a hunch that radioisotope companies and government organizations are doing this right now.
0. https://vant.kipt.kharkov.ua/ARTICLE/VANT_2012_6/article_201...
Nuclear fusion emits neutrons.
If you can soak up surplus neutrons in uranium 238 you can breed plutonium 239.
By design intent fusion does not intend making fission happen. A side effect of the nuclear physics makes fission products, if you want to.
You can make weapons grade fission materials, with neutrons from a fusion reactor.
Regardless of this hypothetical: the fact remains that no part of a fusion reactor increases weapons proliferation risks, unlike a fission reactor. You could plop one down anywhere on the planet and locally source fuel.
If you want a neutron source then you can make one in your basement with a fusor or linear magnetic mirror.