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> nuclear proliferation problems with fusion

We already have fusion bombs. Building fusion reactors wouldn't impact nuclear proliferation at all. I really can't think of a single fusion reactor design that produces "nuclear weapons material." If fusion designs made nuclear material, then we'd probably already have nuclear-material-producing fusion reactors.

I find it strange that you think breeder reactors are the way to go. Fusion's challenges are rooted in engineering - creating magnetic fields, heating plasma, breeding tritium. Fission's challenges are in public sentiment, exuberant costs, and dealing with extremely toxic metals.

> it's not better or cleaner technology than modern fission reactor designs

The "nasty ingredients" in fusion are deuterium, tritium, lithium, and irradiated confinement metal (think eutectic materials like stainless steel). The "nasty ingredients" for fission are much, much worse - both in products and required inputs.

Fusion promises energy generation without the high atomic count; this makes the inputs easier to acquire, the risk of catastrophe much lower, and allows more flexibility in design (scale, cost, efficiency targets).

> Fission's challenges are in public sentiment, exuberant costs, and dealing with extremely toxic metals.

I'd argue that a lot of the public sentiment problems with nuclear were PR'd into existence by the insanely powerful and wealthy fossil fuel industry to which fission is a very real existential threat. If we're talking about exuberant costs, fusion beats fusion hands down and has yet to deliver a single net watt of power. The waste disposal is more of a political problem than a technical one.

Overall, the problems with fusion are hard technical problems, and the problems with fission are self-imposed political ones pushed by the fossil fuel extraction industry that fission could very realistically replace.

Unfortunately, we live in a world where public opinion (skewed by fossil fuel companies or otherwise) is a huge driving force. We can lament what the world would be like if only people were more knowledgeable, but at the end of the day it's the ecosystem we have to operate in.

Fusion power has indeed had high R&D costs, but so has any significant project before the ROI starts to kick in. Fusion power (especially the types that don't generate a neutron flux) is safer and more productive in principle compared to fission, and I have high confidence I will live to see a commercial fusion reactor come online in my lifetime.

While it would last a long time at current levels, the supply of fission materials is quite limited when you’re looking into interstellar travel etc. That’s really the promise of fusion it’s an unimaginably vast energy source for the future.

As to more sort term concerns, fission has a lot of very expensive requirements like 24/7/365 security which make it difficult to integrate with vastly cheaper renewables. Baseline power sources like nuclear and coal wind are at a massive disadvantage when integrating with significantly cheaper wind and solar. They lose significant amounts of money during part of the day and need much higher premiums the rest of the day to make up for it.

In today’s energy market there is definitely a place for fission. However, with a 50 year payback period you need to project into future energy markers with even cheaper solar, wind, and batteries. That’s why electricity companies generally view it as a dead end. Fusion is a larger unknown, it’s probably not going to be cost effective but it’s also the kind of long shot that might just pay off.

> the supply of fission materials is quite limited when you’re looking into interstellar travel etc

Yeah, sure, if we're gonna get a big spaceship to even a small fraction of light speed, that would require absolutely stupendous amounts of energy.

But lets worry about that after we avoid cooking ourselves with GHG emissions? We might or might not have enough fission fuel for large-scale interstellar travel, but certainly more than enough to get rid of fossil fuels.

> fission has a lot of very expensive requirements like 24/7/365 security

So will fusion, unfortunately, unless someone figures out aneutronic fusion, which is a much longer shot than D-T fusion most efforts are concentrating on.

I'm all for spending a lot more on fusion R&D though; the potential win is just so enormously large that it makes sense to bet some amount of resources on it, just in case it works out.

> Building fusion reactors wouldn't impact nuclear proliferation at all. I really can't think of a single fusion reactor design that produces "nuclear weapons material."

Since a fusion reactor would produce an intense neutron field, it doesn't take a genius to figure out that if you line the reactor vessel with natural uranium, you have a device for producing plutonium. That is by no means a showstopper, but it means fusion plants will need 24/7 security, IAEA inspections, worries when/if suspicious tinpot dictator states decide that they will need their own fusion power plants, etc. etc. Even if we'd magically solve the technical challenges in fusion, we won't be seeing things like dinky fusion-powered ships sailing around the oceans (for larger ships, one could envision some kind of IAEA monitoring system for those).

Of course, if someone figures out aneutronic fusion (pB11 or such), these proliferation concerns would evaporate. That's a pretty big if, though.

> dealing with extremely toxic metals.

Spent fuel, in particular, is certainly radiotoxic, but chemically, no, not that big of a worry. Society routinely deals with other toxic heavy metals like lead as well, not to mention all kinds of other extremely toxic compounds.

Fusion power plants are certainly not the only thing we have that makes neutrons. You can buy neutron sources suitable for irradiating fissile material without having to build a fusion power plant.

Fusion power plants would also be a terrible place to irradiate uranium. Getting material in and out would be a total hassle and you wouldn't necessarily be able to control the reaction.

It's a pretty big logical jump to say fusion has proliferation problem because it creates a neutron stream. It will be as if they build the Hadron collider to warm up soup. It's unrelated to the plant operation, unlike fission.

I think this highlights the bias in the article you shared. Moreover, it solely focuses on ITER which is not a great example any more.

Fusion doesn't really have the problems of fission. Because fusion has been extremely underfunded, the money is being spent extra carefully on ITER. But MIT SPARC is using new super conductors to get much smaller reactors.

Reactors will produce some low level waste, but once we get a handle of the confinement, that issue can be eliminated with hydrogen isotope mixes. Also, Tokamak is only one fusion design, there may be better ways to capture the neutron stream.

These are all valid points, and I'm not saying we shouldn't do research on fusion. It certainly has promise. However, I don't think it has a serious chance of pulling a deus ex machina move and saving us from climate change in our lifetimes. A solid energy source a century from now? Sure. Fission on the other hand has a good chance of uprooting the fossil fuel industry, and combined with other renewables is our best chance of getting carbon emissions to a place where civilization might not go into a bronze age-style collapse from climate change.

As an industry insider: everyone knows this. Fusion isn't the technology that saves mankind in this century, but it is the technology that mankind needs to have working by the next century if we want to stay on our current industrial track. The march of progress might halt if we run out of ever-increasing access to free energy.

> still produces nuclear waste,

Yes but you only have to worry about radioactive reactor parts and other structural materials, not spent fuel.

> still capable of producing nuclear weapons material,

I don't get this argument at all. A fusion reactor does not generate heavy elements such as uranium or plutonium. However, the fusion reaction can be a neutron source which could be used to convert heavy elements such as thorium or uranium into fissile material. But by no means would this be part of any power generation station. This leads us to...

> We'd be better off just coming up with good fast breeder reactor designs

So this neutron source is somehow more clean and secure than the other one you just dismissed?

Working on fusion doesn't mean we're not working on better fission. We should do both. I think both fusion/fission are great but your comment is misleading at best.

- Fusion produces much less radioactive waste byproducts then fission. It's not zero, but it's a significant difference.

- The problems with nuclear weapons proliferation are much easier to handle with fusion. For starters, you're not transporting enriched uranium fuel around. Also you don't end up with fun transuranics like plutonium which can be readily used to make weapons, unlike any key byproducts of fusion. Hell, the main byproduct of our fusion reactors is gonna be Helium, which we actually need more of because it is a very useful element that experiences shortages due to not being contained in the atmosphere and not being super prevalent in the earth's crust.

- "Extremely fussy" is a selling point. Extremely fussy means that if something goes wrong you don't have a runaway chain reaction that makes everything go boom. It's impossible to design a fusion reactor that can melt down. Meanwhile, melting down is the default mode for fission reactors and needs to be carefully designed around.

- Fusion is the only viable energy source for long-term space travel/colonization.

- The point about net energy surplus is kinda nonsensical. Of course we're not there yet, that's why it's a problem we're actively working on and not something we've already solved. Your point is literally "we shouldn't develop this technology because we haven't developed this technology yet".

Also not sure how we can simultaneously need to "come up" with a good fast breeder reactor design while at the same time it's apparently "tried and true technology".

> - "Extremely fussy" is a selling point. Extremely fussy means that if something goes wrong you don't have a runaway chain reaction that makes everything go boom.

Sorry, I should've elaborated a bit on this point. I'm talking about the expensive containment system which will be subject to extreme conditions and have a short lifetime[1].

> Under reactor-relevant conditions, the following are the most serious damaging mechanisms: thermally induced defects such as cracking and melting of the plasma-facing material (PFM); thermal fatigue damage of the joints between the PFM and the heat sink; hydrogen-induced blistering; helium-generated formation of nanosized clusters; and neutron-induced degradation of the wall armor via reduction of the thermal conductivity, embrittlement, transmutation, and activation.

> Further serious lifetime-limiting PWI processes are caused by material irradiation with hydrogen isotope ions (D+ and T+) and impurities that—depending on their impact energy—will sputter the wall material. The eroded species will be deposited elsewhere, for example, on unshielded parts of the vacuum vessel, on blanket modules, or on less severely exposed divertor targets (outside the separatrix strike zone). Implantation of hydrogen isotopes into the surface of the PFM will result in severe embrittlement of the wall. This also has a strong impact on its cracking resistance, in particular during short transient thermal loads (i.e., ELMs). Helium will also be implanted into the surface of the wall armor or buried in redeposited surface layers. Implanted helium tends to migrate (depending on the prevailing temperature) and to form tiny bubbles that again can interact with implanted hydrogen. In several fusion-relevant PFMs (e.g., tungsten) helium can initiate rather substantial changes in surface morphology, such as the growth of tiny tendrils or “fuzz” on the surface of the PFM.12 These layers can easily reach several micrometers in thickness. These effects need to be considered as a potential source for the release of dust particles and contamination of the burning fusion plasma.

So I'm not talking about the fail-safe nature but rather the extreme cost and technical difficulty of containing the reaction for the amount of time that would be needed for fusion to be a viable commercial energy source.

[1] https://aip.scitation.org/doi/10.1063/1.5090100

I think one of the advantages of the General Fusion approach is that both what the heat gets transferred to and what bears most of the neutron flux (and hence gets irradiated) is the liquid metal, which is presumably easily replaced (and could presumably even be done incrementally while the reactor is live, since it's going to be flowing through a heat exchanger anyway)?

Shouldn't (at least) the USA have enough sub tropical geography for solar panels?

We definitely do! However the rate that solar can be added is nowhere near fast enough to replace fossil fuels in a timeframe that meets our climate goals and prevents environmental catastrophe[1].

> Solar and wind power alone can’t scale up fast enough to generate the vast amounts of electricity that will be needed by midcentury, especially as we convert car engines and the like from fossil fuels to carbon-free energy sources. Even Germany’s concerted recent effort to add renewables—the most ambitious national effort so far—was nowhere near fast enough. A global increase in renewables at a rate matching Germany’s peak success would add about 0.7 trillion kilowatt-hours of clean electricity every year. That’s just over a fifth of the necessary 3.3 trillion annual target.

> To put it another way, even if the world were as enthusiastic and technically capable as Germany at the height of its renewables buildup—and neither of these is even close to true in the great majority of countries—decarbonizing the world at that rate would take nearly 150 years.

[1] https://www.wsj.com/articles/only-nuclear-energy-can-save-th...

> However the rate that solar can be added is nowhere near fast enough ...

Any idea what the bottleneck(s) is/are?

In the UK substation capacity is a constraint. Rural connection points tend to have limited capacity to export to the wider grid.

It seems unfair to compare a hypothetical nuclear build rate to a real one in renewables. We just don't know if a nuclear industry could get anywhere near the deployment rate required.

You're right, and I'm not saying we should slow down on solar, but based on the numbers, solar alone is not going to get us where we need to be, so we should be pushing the nuclear industry to find out how fast they can deploy and bulldozing a path for them while we also push for faster deployment of solar.

Between 2010 and 2019 the UK added 10GW of onshore wind generating capacity, 8.5GW of offshore wind generating capacity, roughly 13GW of solar capacity, and 0 nuclear plants.

The UK has not brought a new (commercial/public power) nuclear reactor online since the nineties, or finished building a completely new site since the eighties.

It has started building one, which is over budget and delayed and has been described as “the most expensive power station in the world”.

It has had three recent plans cancelled, four more go nowhere in years, had two developers (EON and nPower) pull out of UK nuclear, and the Scottish parliament had backed no new nuclear plants in Scotland.

If nuclear is our saviour, it’s not looking very likely that we’ll be saved.

You don't even need sub tropical.

Massachusetts, in the Northeast, is showing a real-world strategy for solar.

Massachusetts incentivizes homeowners to have their own solar installs. My house, for example, has solar, as do many houses in my town. Yesterday it produced about 50 kWh, meaning I was sending energy into the grid.

You might ask, what's the point of solar if there's no storage? Going 100% renewable would be amazing, but reducing CO2 is a win. If electric load declines because more and more homes can produce their own electric, that's a huge reduction in total CO2 that needs to be produced at the power plants. It doesn't mean we can throw away the gas plants, but they can be run at lower capacity. Storage isn't really discussed yet, but maybe one day we'll get there.

We're also investing in a huge offshore wind farm.