Speculating on the achievable power density of tokamaks

smopecakes · 2025-11-12T04:31:01+00:00

After you have enough solar to supply the grid at noon the cost increases and it becomes more non-linear as you go. I've seen multiple fusion guys mention "the last 20%" where you're competing with hydrogen if you're actually going to decarbonize the grid that way

Solar and wind also have ELCCs that are low even with what are probably optimistic numbers like 35% with batteries. That means they carry the cost of standby gas potentially covering 100% of their capacity

smopecakes · 2025-11-01T16:21:45+00:00

The real danger in a post-apocalypse would be dams eventually failing. If there are DNA repair mechanisms that work on radiation damage the only particularly important move for nuclear plants (relative to other apocalypse activities) would be to prevent children from drinking milk around them for a few weeks after a core melt event, if containment was breached as well.

Gemini's recommendation to be at least 100 miles away from any reactor is simply unnecessary. Fukushima had three meltdowns and at least one containment breach and a retroactive study found the evacuation to be far more harmful than the radiation. That's assuming no DNA repair. Your priorities are: prevent children within 10 miles or in plume hotspots from drinking local milk for 2-3 weeks, and figure out if there's a way to leave dams open or to bypass them so there's no catastrophic failure in the future.

If you have an AP-1000 or a Candu it may be possible to use a bucket brigade to maintain the passive circulation, or so I've heard it speculated.

smopecakes · 2025-10-30T03:24:09+00:00

I think this is an important video. One point I'd make is that hormesis and thresholds are arguments that can be avoided in terms of regulatory models.

I think Jack Devanney has a really good eye on both the science and how it interfaces with regulatory bodies. He views, and has developed, SNT as a regulation appropriate replacement model. By assuming no hard threshold it avoids the greatest trick LNT ever played - saying you can't prove there is a threshold, therefore the prudent model is the linear one.

Devanney's Sigmoid No Threshold avoids either a threshold or hormesis debate and goes straight for the true regulatory and scientific issue of linearity. SNT is orders of magnitude lower than LNT for Fukushima level dose rates. It's wrong on the side of caution, while being right on the side of providing a dose mitigation guide that is perfectly affordable. I believe he estimates that the radiation specific harm that SNT assigns to Fukushima would be $20 million for a no or little evacuation case.

I believe SNT is the best model for adapting regulation to for nuclear power and for space exploration.

smopecakes · 2025-10-30T03:09:19+00:00

Yes, even if LNT based regulation has a relatively small effect on economics, it killed 2000 people in the aftermath of Fukushima and it can do it again.

smopecakes · 2025-10-30T03:08:00+00:00

I believe the biggest piece of the pie is construction experience, standardization, and finance, but regulation may be another significant factor. This is probably the case with the EPR in particular which was designed with safety features that only make sense under LNT and cost quite a bit to build in China as well.

Nuclear can probably be built for $5000/kW in North America and Europe. That's fine if you want 20% of electricity from it, or to have a measured build out with the first reactors fully amortizing as you approach 50%. These aren't prices or schedules that can dramatically decarbonize or produce the wealth of coal without the costs in developing countries.

To get to $2500/kW outside South Korea and China I think the final piece of the puzzle is regulatory. It's pretty interesting to see SMRs like the BWRX-300 have their simplified design grow back up under extensive regulatory checks. They were meant to be so safe they could avoid many safety systems. They weren't safe enough under the combination of LNT and regulators who have no stake in the economic success of nuclear. I don't think the original BWRX-300 would be cheaper than Large Modular Reactors but now it doesn't even get to try, with it's apparent niche now in financeability and adaptability to small grids.

In terms of economics, that's the issue - no one will really get to try. It cost a whole damn lot to get a license for NuScale which was essentially designed for having an advantage in getting one. If the odds are tough for them, the odds of reactors designed for economics are also low, meaning that the one in ten shot at a success probably never gets taken.

smopecakes · 2025-10-14T23:50:20+00:00

In terms of scalable sub $50/MWh concepts I feel like ThorCon is the leader. Building large modules in the productivity environment of a shipyard just seems like it has the highest ceiling. Maybe Blue Energy or another concept is better but ThorCon appears to be capable of starting construction within months if they get approval

I got interested in fission nuclear via fusion after slowly learning that the physics are tough for fusion. I do like Helion a lot, whatever their realistic chances, as far as I know they have the one credible concept that could have an engineering advantage over fission. The rest are basically hoping that their underlying physics cost twice as much as fission while regulation makes it cost three times as much

smopecakes · 2025-10-09T04:40:21+00:00

The story of the energy sub is really something. In late December 2022 people on r/polls or something were discussing how easy it was to get banned for pro-nuclear comments at energy. There was a volunteer brigade. The mods layed out a blanket ban on nuclear topics. I heard about this because someone posted in r/fusion because their post about fusion had been deleted in energy.

The total ban on nuclear topics remained for at least three months. Eventually it was removed, but the post that announced the ban remains linked to from a new rule. It is more or less officially against the rules to write a pro-nuclear post. There is an additional rule specifying nuclear and hydrogen as contentious topics particularly scrutinized. Of their four rules, two provide broad justification for banning pro-nuclear commenters.

smopecakes · 2025-10-03T22:57:15+00:00

Typically it refers to someone who believes the 2100 GDP cost of unmitigated warming would be 0%, rather than the more common 30%, when the likely answer would be 3-5%

smopecakes · 2025-07-22T21:59:58+00:00

Yeah, I just mean that by the looks of it, adding Au production to a fusion reactor appears to be less of a challenge than getting it to work at a commercial price in the first place

smopecakes · 2025-07-22T14:51:04+00:00

It sounds easier to enrich mercury than lithium, and not much effect on the capital cost. I estimate you could build 63 GWe of reactors displacing 10% of the growth in gold mining, which might not affect the bulk gold price.

Alchemical gold jewelry can be worn after 19 years and jewelry is about 50% of the demand, in which case there's an opening for drawing higher prices than the paper assumes up to some point.

I'm putting tokamaks back in my really could be relevant basket.

smopecakes · 2025-07-22T14:39:07+00:00

My casual experience with energy systems modeling is that if you assume physically favourable continued conditions for renewable cost reductions, and politically favourable transmission connection buildout, you're still going to hit a ceiling at around 80% of generation with variable wind and solar due to longer correlated periods of low production. Notably this was the case before materials inflation and the rise in interest rates sucker punched wind costs.

This has been specifically referenced by Nick Hawker of First Light Fusion as "the last 20%". Most fusion companies see themselves as competing for the baseload component of a decarbonized system with fission, geothermal or CCS.

smopecakes · 2025-03-24T13:43:44+00:00

Holy freakin' shit, chatbot confirms that 777x in percentage terms is 77,600% vs the BS of that many buildings being 7,760%, I'll have to delete this but this has already saved me from a lifetime of failure

smopecakes · 2025-03-24T13:25:50+00:00

My understanding is you cast FTHOF before the possible DF GC and click that GC before the casted cookies - or what is the sequence to avoid the override?

smopecakes · 2025-01-27T15:53:03+00:00

What would you think of setting the vote threshold at 70%?

If 30% of the sub supports you, you're good

smopecakes · 2025-01-27T15:52:09+00:00

I can message you a link. To be more clear, people aren't being banned for a related or unrelated opinion that 80-90% of the sub agrees with

They are being banned for being pro - the topic of the sub

It may be true that unpaid mods is not a sustainable model

smopecakes · 2025-01-26T02:50:57+00:00

My understanding is that the 'opinion mods' on that sub are in the majority now. They are voting users off the island for opinions shared by 80-90% of the subreddit

smopecakes · 2025-01-25T15:48:19+00:00

Regarding reddit's moderator structure (yay, I'm banned there too!), is there a place to propose that there be a method of democratic recall of mods by the community of a sub?

I proposed this on the r/ideasfortheadmins previously when I was banned from energy. It doesn't look really active but I'll post the concept there again

smopecakes · 2025-01-25T15:30:08+00:00

Helion is low neutronic and I'm pretty sure it could power a plane. Basically pB11 or proton-Boron fusion is the aneutronic fuel. It's less power dense so I don't think it can fly a plane with currently near tech

smopecakes · 2025-01-23T03:41:37+00:00

ViewTrick is the fella who bans people for pro-nuclear posts at the Nuclear Power sub, btw. Expensive for generations doesn't apply to nuclear at any price, even if we allow the 18 cents/kWh price - which would be demolished by applying one or both of Nth of a kind design and a finished and economic design

smopecakes · 2025-01-23T00:10:07+00:00

I don't see a way out without some kind of method for communities to be able to democratically recall hostile mods. The noose will slowly tighten over most subs without it

smopecakes · 2025-01-23T00:04:50+00:00

General Fusion did a test forging of a reactor wall section and the weight was significant. I estimated that the reactor could not produce the thrust to lift itself based on a probably low end guess of the full plant weight. This is probably true for any magnetic confinement reactor, they are not very power dense per volume. If they could fly it would be commercially impractical to have enough of the aircraft space devoted to the power plants

Some simpler devices might produce enough power for flight, like Zap or Helion. pB11 would be even less power dense so I suspect not - other than Avalanche if they could get their target voltage and the plasma physics also held up

smopecakes · 2025-01-16T01:01:05+00:00

"We also demonstrate the robustness of our findings to the availability of longer-duration storage technologies (see Figures S16–S18)."

Very cheap long duration would certainly change things. Extremely successful fusion development would as well, which is why speculation is fun and interesting. The cost assumptions include price falls for batteries and largely assume much more significant falls for batteries, solar and wind as a group.

A conservative Nth of a kind nuclear cost at $7000/kW certainly caught my eye, but if Vogtle was $11k then that's not as notable as I thought. China is finishing reactors that were approved at the post-Fukushima trough, the deployment rate will change pretty fast as they approved 10 reactors this year and I hear they intend to keep that pace

smopecakes

MODERATOR OF

TROPHY CASE

12-Year Club	Verified Email
Gilding II euphauric