Comment by perrygeo | Hacker News Reader

Comment by perrygeo | Hacker News Reader

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There are three main hurdles here

First, actually getting fusion to positive energy ROI. That's step zero and we're not even close.

Second, scaling the production of fusion in an safe and economical way. Given the utter economic failure of fission nuclear power (there has never been a profitable one), my priors are that the fusion advocates are vastly underestimating, if not willfully ignoring, this part.

Finally, even if we do get to "too cheap to meter" energy, what then? Limitless electricity is not the same thing as limitless stored energy. Only 20% of our energy needs are supplied by electricity. To wit, the crucial industrial processes required to build the nuclear power plant in the first place can only be accomplished with combustible carbon. A power plant cannot generate the energy to build another power plant. Please let that sink in.

We're already seeing countries with photovoltaic and wind hitting $0/kW on sunny windy days - the grid is nearly saturated for daytime load. There isn't enough demand! This makes the economic feasibility of fusion even less attractive. No one is going to make money from it.

Where did you get the data that there has never been a profitable one? Not calling you out, but curious of where you are getting this data.

I would expect that there have been multiple nuclear power plants that provide a net positive return, specially on countries like France where 70% of their energy is nuclear.

France lost an incredible amount of money on nuclear through capacity factor issues. The numbers are so bad they don’t want to admit what they are.

However a reasonable argument can be made the public benefited from externalities like lower pollution and subsidized electricity prices even if it was a money pit and much of the benefit was exported to other countries via cheap off peak prices while France was forced to import at peak rates.

Regulatory burdens on fission account for negative externalities to an arguably overzealous degree, whereas fossil fuel energy has been until recently allowed to completely ignore them. Doesn't seem like a fair comparison.

Regulatory burdens on fission result from the inherent risks and negative externalities. You’re never going to see huge long term exclusion zones with coal, but nuclear has two of them right now (Ed: Overkill though the current size may be) which also have massive government funded cleanup efforts.

So while regulations may be overkill it’s not arbitrary only hydro is really comparable but hydro also stores water and reduces flood risks most years. Fusion sill had real risks, but there’s no concern around $500+ Billion cleanup efforts.

I wonder how bad the property value damage would be from widespread tritium contamination of ground water.

Depends on if anyone uses wells in the area. Probably not that much outside of some sci-fi movie extreme as piping water from in contaminated regions wouldn’t be particularly expensive, but the question is assuming something I’m not sure is possible.

How exactly would you get meaningful widespread tritium contamination of groundwater? IE not just the trace amounts you see from existing nuclear reactors.

Groundwater doesn’t flow quickly from a point source and tritium has a fairly short half-life. 60 years later you might be looking at a larger though still small area, but 97% of the stuff will have decayed and what remains is now diluted and doesn’t bioaccumulate.

It’s not going to concentrate around some site after entering the atmosphere the way heavier than air particulate pollution would.

The flow of tritium through a DT reactor is five orders of magnitude higher than tritium production in a fission reactor of the same thermal output. To put a number on it: the tritium produced and consumed in one year by a 1 GW(e) DT power plant would, if released as tritium oxide, contaminate two months of the average flow of the Mississippi River above the legal limit for drinking water.

Fusion power plants aren’t like nuclear reactors where you keep years worth DT in the reactor. DT only works if you’re actively recycling a breeder blanket. They are also going to be working with gasses as unlike fission reactors it’s not produced in fuel submerged in water thus contaminating the water.

Nearly pure tritium is extremely valuable so we aren’t going to be dealing with some long term leak. You hypothetically might have a large tank with say 1 month of T2 fuel but that would be really expensive directly and waste quite a bit of fuel through nuclear decay over time. Having that much fuel across multiple different systems is more plausible but then requires a wide range of different failures. But let’s assume such an improbable tank catastrophically fails, outside of containment, and then completely burns so the tritium will eventually fall back to earth.

It then has to rain over land, though even then storms don’t release all the moisture in the air, that water must be absorbed into the soil rather than running off or evaporating, where it’s further mixed with groundwater as it slowly seeps deep enough to be collected in some well. Thus even if conditions are perfect you’d have trouble reaching above the legal limit for drinking water.

I mean maybe if you intentionally selected the perfect moment with the perfect weather pattern and the perfect local geography and geology perhaps you’d be over the legal limits for a few wells for a little while until it rapidly decays.

My point is: even small leaks (in percentage terms) will result in much larger releases from LWRs. And tritium promises to be very difficult to contain, as it diffuses through a wide variety of materials. For example, it diffuses through polymer seals. Materials of a reactor will become saturated with it, providing a substantial source term in accidents.

Lurking over all this is the issue that loss of property value doesn't require anyone to actually prove tangible harm. The mere fact that property values were affected is enough for a tort.

The kind of releases you’re talking about is 8+ orders of magnitude smaller than in your prior example and again without burning it’s lighter than air and just going strait up. Right now T2 is ~$30,000 / gram hell even D is ~13,000x as much as hydrogen. This just isn’t the kind of thing you’d let escape in meaningful quantities in day to day operations.

When people talk about how safe fusion is they aren’t kidding, even breathing in a significant amount of T2 isn’t particularly dangerous radiologically as density is really low and you will quickly exhale it. Huge quantities would be a larger suffocation risks but then you’re talking multi million dollar accidents simply from lost fuel.

Not really in the sense that the owning company has managed to survive without the state stepping in and give them money.

Most reactors are old and in need of repair, most of these earlier than planned afaik.

There is also the bigger issue that some reactors are shut down in the summer because cooling water would leave the reactor so hot that it would be a danger to the animals living in the river.

Not a single one of the ~700 nuclear power plants has been built without significant government subsidies [1][2].

Additionally, the industry as a whole is shielded from the liability that would otherwise have bankrupted it multiple times. Notably, the clean up from Fukushima will likely take over 100 years, requires tech not yet invented and will likely cost as much as a trillion dollars [3]. In the US, there is a self-insurance fund paid into by the industry, which would've been exhausted 10-20 times over from a Fukushima level disaster. Plus, Congress severely limits liability from nuclear accidents, both on a per-plant and total basis ie the Price-Anderson Act [4].

Next, it seems like it's the taxpayer who is paying to process and store spent nuclear waste, a problem that will persist for centuries.

Even with all this the levellized-cost-of-energy ("LCOE") of fission power is incredibly expensive and seemingly going up [5].

Some want to reduce costs by using more off-the-shelf tech and replicating it for scale, most notably with small modular reactors ("SMRs") but this actually makes no sense because larger fission reactors are simply more efficient.

[1]: https://theecologist.org/2016/jan/04/after-60-years-nuclear-...

[2]: https://www.ucs.org/resources/nuclear-power-still-not-viable...

[3]: https://cleantechnica.com/2019/04/16/fukushimas-final-costs-...

[4]: https://www.yuccamountain.org/price_anderson.htm

[5]: https://en.wikipedia.org/wiki/Cost_of_electricity_by_source

I won't dispute that fission power has enormous capital costs. But how much of its alleged "failure" has been the utter FUD that's been pushed for the past 50+ years about how we'd all be glowing if nuclear power was widespread?

I mean sure, waste disposal is a serious issue that deserves serious consideration. But fission waste contaminates a discrete area. Fossil fuels at scale cause climate change that contaminates the entire freaking planet. It's a travesty we haven't had a nuclearized grid for 20-30 years at this point.

That's not quite right: 20% of our energy supply comes from electricity. But over 50% of the energy we consume gets wasted as heat, and fossil fuel energy wastes a lot more of its energy as heat.

So the real number is closer to 40%. If we switch ground transport to EV's and heating to heat pumps we can get up to ~75%.

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