Molten Salt Reactors
whatisnuclear.com
whatisnuclear.com
The security aspect would make this a lot more expensive than it already is and cost is already on the high side even before you consider that. This is a problem with traditional reactors as well but they have the advantage that they are huge facilities and that there are only a handful of them; so securing them is relatively easy.
People are suggesting this as complementing renewables but the cold hard truth is that renewables are already dirt cheap and on track to continue to drop in price by magnitudes for the next decades. That includes battery storage as well. Already quite cheap, also dropping in price, and typically already factored into e.g. new solar bids that are killing competing bids for coal and gas plants (or in some cases shutting them down prematurely).
Even at the current prices, that's a problem for any kind of nuclear solutions being contemplated right now. At the low end of the spectrum, we are talking 2 cents per kwh currently. Imagine this dropping to something like half a cent or even less. At those prices, the security alone would make nuclear too expensive probably. A 1 mw facility would have basically be generating only about 500-2000$ worth of energy per hour but only at peak demand. There's no guarantee prices won't drop way below that either. Any kind of operational overhead would be a problem. Needing 24x7 intense security would be very undesirable.
Looking at current cost VRE trends, when variable sources contribute up to 4% of world energy, and surrounded by massive amounts of cheap but high-carbon natural gas, and assuming that the trends will just continue exponentially downward without serious complication, is optimistic.
Cost of integration of variable sources plus batteries is expected in many studies and somewhat intuitively to skyrocket as market penetration increases. When you have enough VRE to cover 100% including the big evening peak with batteries during a clear summer day, the extra generation you build to fill the other gaps gets curtailed. But you have to fill daily and then seasonal gaps, worldwide, including heat in winter and worldwide transportation (not just electricity). Buying that battery that is only even needed at all every third day is 3x the price, yet we prefer if the power doesn't brownout with this frequency. This is difficult. Already we're seeing NIBMYism in large solar installations in california and with transmissions lines. That gets worse with scale.
Nuclear today is a hedge against the possibility that deeply carbonizing with variable renewables + storage at world scale will be harder than we all think and hope it will be.
That said, nuclear certainly needs to drop capital and O&M cost dramatically if it wants to play the game. And security is indeed a big factor in this. Its competition in the small-footprint dispatchable world is natural gas with full CCS, which is also looking pretty cheap.
IMHO 5X cost reduction is basically a done deal even just applying simple economies of scale. You can argue whether this happens in five or ten years maybe but arguing it isn't happening seems futile. Beyond that, 10x is extremely likely to happen as well. There's a lot of research happening that would need to be a complete failure/waste of time for that to not happen. At worst it will happen slower that I might like. Maybe this happens over the next decade. Or two. Or three even. From there, 20x might be quite possible as well.
Beyond that we're indeed talking rapidly diminishing returns. 10X would mean 0.2 cent/kwh. 20x would cut that to about 0.1 cent. This indeed gets you in to territory where metering it becomes more expensive than is worth the trouble. The average household uses about 15000 kwh per year, or about 150$ worth of energy at these prices; much less outside the US. Much of that is going to be produced on people's roofs or in their back yards. At that point it turns into a fixed cost.
Historically the same sources producing the studies you are referencing have been off by magnitudes predicting current adoption and prices for both solar and wind. So, I'd consider that the pessimist glass half empty point of view. Not to dismiss it entirely but arguing cost increases seems a bit far fetched in light of current trends in the market.
>Not to dismiss it entirely but arguing cost increases seems a bit far fetched in light of current trends in the market.
I think what the parent was saying is that because solar and wind don't reliably produce energy, we will need redundancy. As the market share of solar and wind grows we will need to increase the amount of storage and power generation far beyond what we normally need to operate.
Let's say you have a city that uses 1 GWh of electricity per day. If you were to generate all the electricity with natural gas then you need to have 1 GWh plus some extra for redundancy to fulfill the needs of the city. If you generate 5% with solar and the rest with natural gas then nothing really changes. If the weather is bad then the natural gas plant will step in.
As the share of your solar power generation grows toil need more and more redundant storage and solar power generation. If you rely 100% on solar power generation and the weather can be bad for a week in a row over the city, then you'll need storage that will last for more than that entire week. Not only that, you'll also need extra power generation capability to be able to fill and maintain that storage.
Just to put this into perspective: the US uses about 10 TWh of electricity per day.
We are well past the point where tracking the sun was desirable. The apparatus that allows solar panels to track the sun is now much more expensive, especially when you consider the maintenance costs, than just using more static panels.
They are good enough. Low efficiency just means we have to buy more of them. Obviously we'd need solar plants (and maybe wind parks and other clean sources) to also power those with limited access to roof surface.
Of course, bad weather doesn't mean solar stops working; it just reduces the output. The effect is typically very local as well. So, all that means is that you need a bit extra capacity to cover for that or import energy from somewhere else where the weather isn't miserable.
When (not if) the price for solar and wind drops 10x, you'll be able to buy 10x more than what you need and still beat coal/gas/nuclear on price. 10x is an insane safety margin that would mean you produce more than you need even on the most cold, dark, and miserable day imaginable. And of course solar is not the only source of clean cheap energy. Wind would be another popular option.
Further south in Germany, Netherlands, etc. Solar is usable throughout the year and quite common. Obviously output in the summer is going to be much better than during the winter.
But such is not the nature of the logistic function, which is usually a more accurate model of how technologies penetrate. (yes, in the beginning it looks like an exponential)
There is also only so much more efficient the panels can get per sq m. Right now we are approaching 20% efficiency, so the idea that they are going to get 10* cheaper with complete ease seems to be pushing it.
Regardless solar and wind have a lot of externalities that aren't really priced into these 2c/kWh PPA prices. If you need to build a fleet of natural gas plants that are only operational 10% of the time and therefore cost 50c/kWh to take up the slack from low solar days it needs to be priced in somehow.
It's amusing to see "permitting costs" being presented as a barrier, when at the same time "get rid of regulations" is spouted as the panacea for reducing nuclear's costs.
You can place the nuclear generators in police stations, military bases, other locations that are already protected, there is no need to have a small nuclear generator in each electronic device like in Fallout.
- The prospect of every household having a battery backup big enough to smooth over spikes and dips is ludicrously wasteful. We are already struggling just mining enough to make batteries for cars and phones.
- the sheer scale of the wind and solar farms will leave major environmental impact to wildlife. Look at how massive area solar farms need, and know the area has to be cleared and desolate of life.
The wild life impact of solar is relatively minor compared to burning coal, intensive farming, and all the other things we do. We'd need to only cover a relatively small amount of land with solar to produce what we need. And ironically some of the most suitable land for this would be deserts that have relatively little wild life to begin with. Of course the impact of wiping out coal, gas, and petrol usage would be enormously positive.
Windmills do indeed kill some birds. Yet, these things seem to have barely any impact on e.g. the seagull populations in places like Denmark that have a ridiculous amount of wind mills.
Molten salt reactor is a stepping stone for fusion reactors. We need to master liquid and gaseous reactors before going plasma. Our civilization should aim for larger goals. We need some form of nuclear power to terraform other planets and spread earth's precious life and conciousness everywhere.
In space (actual space, not a planetary surface), it's difficult for nuclear to dissipate its prodigious amounts of waste heat. Solar, in contrast, can be made much lighter than on Earth, as there isn't wind and rain to deal with. And of course in general the Sun is available 100% of the time in space, further improving the economics.
But in any case, the argument wasn't that solar was necessarily better, it was that nuclear wasn't necessary. Solar can provide energy basically anywhere, with power beaming, even out into interstellar space.
MSR and many other fluid-fuel reactors run hot and it makes radiators small: https://www.flickr.com/photos/oakridgelab/31537153147/
Stefan–Boltzmann law: Radiation heat transfer is proportional to 4th power of temperature.
This does not rule out use of solar energy.
> During interstallar journey there is time delay in communication, so it may take hours to adjust the power beam when spacecraft moves a little bit
The vehicle tracks the beam, not vice versa.
> Fusion is like solar energy just near to us and MSR will be eventually replaced by fusion reactors.
Fusion is ridiculous when examined closely. It's like fission, only far worse from an engineering and cost perspective.
> Stefan–Boltzmann law: Radiation heat transfer is proportional to 4th power of temperature.
Which means waste heat from a reactor in space has to be radiated at higher temperature than for a reactor here on Earth, which means nuclear is worse off there than here. In contrast, solar works better in space, as I argued upthread.
Solar/Wind/Storage are beating almost everything. Everything they aren't... they will, very soon.
It's possible that MSRs could be scaled down and their liquid nature means that the reactor could simply be replaced on a schedule and the entire old reactor "reprocessed". But the investment won't be there with wind/solar/battery eating everyone's lunch.
And that's IF regulatory was simplified and IF you were able to get enough starting fuel to initiate breeding of the thorium.
There's nothing wrong with it. A cheap fission technology would be a good thing. But at this stage literally no one is interesting in throwing money at a technology that is now into its eighth (!) decade of maturity. The low hanging fruit got picked by our grandparents.
It did win against coal on a balance sheet. It's the environmental concerns that stopped nuclear from proliferation, not the economical.
It very much did happen for coal. That's what this whole global warming business is about.
This still isn't the case in most of the world.
Very, very few of these consequences have ever been priced into coal-fired power production; for decades, it's been a de facto subsidy. And while we're seeing some shifts needed to lower emissions to fight climate change, many of the identified externalities still aren't priced in. Nuclear energy never received that kind of benefit of the doubt, or the sort of friendly regulatory capture that let society ignore many of its own negative externalities and risks.
0. https://www.scientificamerican.com/article/graphic-science-h...
1. https://www.scientificamerican.com/article/the-human-cost-of...
2. https://journals.plos.org/plosone/article?id=info%3Adoi%2F10...
3. https://news.stanford.edu/2015/01/12/emissions-social-costs-...
Typically:
Known costs for (anything) < ( some storage cost * forever )
Maybe there's something wrong with my math?
Another issue is that solar and wind aren't really suitable everywhere. The further north you go the less economical solar becomes. A large chunk of Europe sits further north than the US.
So I think we already have the solution to the problem you’re describing: just pay to maintain a decent amount of the existing gas power plant. If they’re only there for backup, the impact on CO2 emissions will be negligible. You could even make the gas from renewable sources, since in this scenario the cost of the gas itself is negligible compared to cost of keeping the power plant operational.
This is incidentally another reason (current) nuclear is a dead end going forward. They’re a bad match for renewables. What we need isn’t more base load, we need more peaker plants, load following plants, backup plants and energy storage. Nuclear isn’t a good solution in any of these categories.
The UK sits further north than almost all of the USA (excl. Alaska), and has a climate not exactly known for its abundant sunshine. But large-scale solar farms are now commercially viable here without subsidy. (eg: https://www.clevehillsolar.com)
Closer to the equator where seasonal variation is less and demand is driven more by air conditioning than heating solar is an excellent choice.
In the UK, this turns out to be seasonally complementary with our wind turbines. In the winter months, wind speeds are stronger and more consistent (especially off shore). In the summer, there is less wind, but the gap is made up by solar. The net result is pretty consistent renewables production year-round.
> "it's not a solution to decarbonizing."
Every kWh of energy produced by a solar panel in the UK (or wind turbine, for that matter) offsets a kWh that would otherwise be produced from fossil fuels, typically from imported natural gas.
Additionally, the cost to operate the grid is based upon the size of the distribution network and maximum carrying capacity. If we all build local storage that takes us off the grid 90% of the time, we are still going to have to pay the utility roughly the same amount to maintain the network as we do today. Check your power bill, the generation costs are probably less than half of your monthly total, so the rest is going to come back to you one way or the other.
Does anyone have numbers, how fast (yearly added kWh per capita) has any country built solar+wind lately? Or plans to build in the near future? When Sweden built nuclear in 1976–1986, they added 640 kWh per capita per year. Will some country or state beat that record?
Source: this figure
https://science.sciencemag.org/content/sci/353/6299/547/F2.l...
in this article
One of the aggravating factors at Windscale was their inability to perform maintenance tasks behind the reactor. They had canisters of radioactive material smashing open behind the reactor and it took them ages to even notice. That was a very simple reactor design; basically a nuclear pile. It was also an awful design that was irradiating England even before it caught fire.
Decontamination and radiation mostly make it more expensive rather than more difficult.
A MSR does not need any sort of valve to drain the fuel. ORNL-MSBR was designed to drain the core when pumps stopped working. The real advantage of freeze valve is that is uses no moving parts and maintanence free/friendly.
ORNL-4528: "The fuel salt pump and its sump, or pump tank, are below the reactor vessel, so that failure of the pump to develop the required head causes the salt to drain from the reactor vessel through the pump tank to the fuel salt drain tank."
> ... While it is thus possible to use uranium-233 as the fissile material of a nuclear weapon, speculation[8] aside, there is scant publicly available information on this isotope actually having been weaponized ...
[1] https://en.wikipedia.org/wiki/Uranium-233#Weapon_material
"The fast critical mass of U-233 is almost identical to that for Pu-239 and the spontaneous fission rate is much lower, reducing to negligible levels the problem of a spontaneous fission neutron prematurely initiating the chain reaction -- even in a “gun-type” design such as used for the U-235 Hiroshima bomb (see Table 1)."
[1] U-232 and the Proliferation-Resistance of U-233 in Spent Fuel - http://scienceandglobalsecurity.org/archive/sgs09kang.pdf
Even thermal coal is getting out priced by solar/wind+ batteries. And the latter will always get cheaper due to economies of scale and learning rate reductions not to mention core technological advances.
Nuclear would have kept us out of the carbon free energy mess decades ago but it's not the answer in 2019.
Not a disadvantage for all MSRs. Both lithium and beryllium can be avoided. FLiBe is required for efficient MSRs and MSBR.
>Mobile fission products
It is the only disadvantage common to all molten-salt reactors and all fluid-fuel reactors. Pumps and pipes have to handle a hot radioactive liquid.
> Material Degradation
Common to all nuclear reactors, solar, coal boiler tubes, etc. Components used in reactor core do not last long. MSRs dispose nickel tubes and LWRs dispose zirconium tubes and uranium.
>Proliferation...The problem with MSRs, then, is that the fuel is already completely cut open and melted. >it will be difficult for the IAEA to distinguish plate-out losses from actual proliferative losses.
The fuel salt loop can be sealed tamper-proof. The entire fuel salt loop is analogous to a fuel assembly. Weigh the entire fuel salt loop. Vapor pressure of actinide-halide salt is very low at operating temperatures. Actinides don't move out of this loop.
I had never heard of this idea, and thought it was super interesting. Imagine aircraft that could stay in the air indefinitely (for some practical purposes), carrying massive loads without fuel being a concern.
Similar to nuclear aircraft carriers and submarines, at least conceptually.
This is not a disadvantage for all MSRs. Only breeders need chemical plant. Not fair to compare a solid-fuel burner to liquid-fuel breeder.
Let us compare liquid fuel breeder vs. solid-fuel breeder: Reprocessing solid-fuel involves more complex chemical plant with physical mechanisms to declad and convert solid-fuel to a processable liquid. Fabricate processed liquid to solid-fuel and put it back in the reactor. Solid fuel breeders have additional physical and chemical processes/steps.
Both India and China have massive deployments of renewable energy, yet the demand for energy is outstripping projected build-out. LTFR is going to be one of the best answers if it can be made safe.
From there it seems like India, Australia & the US all have large thorium reserves.
There is certainly heaps of it.
For example - https://www.nextbigfuture.com/2017/12/china-spending-us3-3-b...
[1] https://energy.mit.edu/research/future-nuclear-energy-carbon...
One would still use more efficient short term storage (and over-installation of renewables sources) for diurnal load leveling.
Hydrogen can also be turned back to electrical power (at lousy efficiency) with cheap hardware. In particular, simple cycle gas turbine power plants with efficiency of 40% cost maybe $400/kW. Compare this to $8-10K/kW for a new nuclear power plant.
The problem being that it only operates ~2% of the time compared to ~100%, and has a shorter operating lifetime in practice, and that isn't counting the cost of storing the hydrogen nor the energy cost to produce it.
Storage also has the further disadvantage that you have to over-spec it. It has to be built for the highest capacity you might need and the longest duration, which you don't know ahead of time. If you build less than you need you're in big trouble, but if you build more, you pay for it and get nothing.
Meanwhile that kind of storage will have more difficulty finding investors, because if it turns out that some cheaper or better alternative comes along, an investment in nuclear might have to average generating power below levelized cost, but at least you recover most of the capital. Putting in $100 in capital only to have the net present value fall to $80 sucks, but not nearly as much as putting in $100 in capital for a complete write off because you were expecting to be selling to the grid 2% of the time when it turns out to be 0% between demand based pricing and better than expected competing storage technologies. Which means higher capital costs (meaning interest rates) that reduce relative competitiveness even further.
Which ignores the cost of using nuclear during that other 98% (or whatever) of the time, when it is very expensive compared to the alternatives.
Yes, the cost just during that 2% is high. But the total cost is lower than if nuclear has to be forced down the consumer's throats 24/7.
One problem with nuclear was all the excess power created at night, so they would pump water uphill at night and then run it down to generate power at the daytime peaks.
Of course with PV the timing was reversed but the need similar. If they hadn’t decommissioned their nuclear plants the combination would have been even better.
That means you get paid less during the day when solar is the cheapest provider, but you still match its price and supply your full generation capacity even then, because you can, because anything is more than nothing and the incremental generation cost is effectively zero. Then you make more at night when solar requires storage, and even more still whenever the day was overcast and energy prices had to rise high enough to suppress demand enough that the depleted storage isn't fully exhausted before sunrise.
The capacity factor is always 100%, it's the price you get at any given time that varies. But price variability in itself is no problem either, as long as the average price is above average cost. And that average includes not only times that it rains for multiple days in a row, but also winter, and that with consideration of people also needing to switch from oil and gas to electric heat.
And that's the killer. Add enough solar and wind and the average price craters, even if solar and wind cannot handle everything (without help from dispatchable sources and/or storage).
Which means you have a problem.
It's physically possible to build enough solar and wind and storage to even handle extended periods of low sun and low wind. But if you do that then on a normal day with a normal amount of sun and wind, you have a large oversupply and the price falls to zero and everybody goes bankrupt.
That happens less if you add real baseload like nuclear to the mix, because something with a fixed generation capacity doesn't have a periodic shortage requiring you to compensate with an overcapacity which bankrupts everybody on a normal day.
What drives all this is that the levelized cost of energy from solar and wind is much less (a factor of 3 or 4) than the levelized cost of energy from new nuclear plants.
Nuclear, or at least many existing nuclear plants, has an additional disadvantage: it cannot cut output rapidly. If power from renewables suddenly floods the market, prices can go negative. Renewables can just stop selling in that situation, but nuclear is forced to continued to run and eat the negative revenue. The low power density of the renewables sources, usually depicted as a negative, is the source of this advantage: sunlight absorbed in PV modules can just be allowed to dissipate as heat there with no negative effects.
(In fairness, I should also mention that there are subsidies in the US that encourage renewables to keep generating even at negative prices. These subsidies will have to go at some point, and perhaps that point is now.)
What will be the final death knell for nuclear will be when short term storage gets cheap enough that the times when that's discharging will also be economic death zones for nuclear plants. I expect few of the existing operating nuclear power plants to survive after that.
It seems like you're expecting this to be a slope rather than a cliff.
The problem with generation methods with no incremental generation cost is that absent some coordination/collusion, you go straight from a price somewhere above breakeven to basically zero as soon as you have any significant amount of oversupply, because everybody would rather get something than nothing.
So even if the average wholesale price is currently above 2c/kWh and you can bring capacity online that generates at 2c/kWh, you won't, because the act of doing it would create oversupply, cause the average market price to fall to below 2c, and you and everybody else would lose their shirts.
It's basically a market that bankrupts everybody without some coordination, but part of the value of that coordination includes preferring some amount of stable generation capacity to avoid the high cost of supply emergencies when low supply from the unstable generation methods coincide with each other.
> What drives all this is that the levelized cost of energy from solar and wind is much less (a factor of 3 or 4) less than the levelized cost of energy from new nuclear plants.
This isn't accounting for variable supply and demand. The price it costs to generate in the summer sun isn't the real price when the unmet demand is in the winter night, and it isn't going to be economical to shift the demand by six months using energy storage. But if you had enough solar to provide heat in cold climates in winter you would have so much oversupply the rest of the year that you wouldn't make a cent for nine months out of twelve.
> Nuclear has an additional disadvantage: it cannot cut output rapidly. If renewables suddenly flood the market, prices can go negative. Renewables can just stop selling in that situation, but nuclear is forced to continued to run and eat the negative revenue.
If that actually started happening on a regular basis there would be obvious solutions like resistive heaters or on-site energy storage which can be charged during those periods and then sold for a profit when prices are higher. (Thermal storage could work really well considering the reactor generates heat to begin with and they already have existing heat-to-electricity systems on site.)
And that's assuming all of this "smart grid" stuff doesn't ultimately succeed in preventing that from happening by increasing consumption as prices fall so that they don't actually go negative to begin with.
> What will be the final death knell for nuclear will be when short term storage gets cheap enough that the times when that's discharging will also be economic death zones for nuclear plants.
It's only speculation that this will actually happen. And even now people like to use overly optimistic numbers. Storage costs a certain amount if you charge it up every day and then discharge it again every night, but if you want the storage to be able to handle generation undersupply over a period of a week or more, you need a lot more of it which will generally go idle, which requires you to charge higher average prices per kWh.
> I expect few of the existing operating nuclear power plants to survive after that.
The existing nuclear power plants will keep going as long as the market price is above the operating cost. The capital costs are sunk.
Everyone will use candles at night?
It's remarkable you were able to read that into what I wrote, when that wasn't at all what I wrote.
The point I was making was that intermittent renewables can screw up the market for nuclear, even if the renewables themselves do not supply baseload.
You may be under the misapprehension that if there is a base level of demand on the grid, then that base level of demand can only be supplied by baseload power sources like nuclear or coal. This is not the case. It was in the case in the past that baseload sources were the cheapest way to satisfy that demand, but there's no law of physics or economics that requires that to always be true. And increasingly it's NOT true.
Sorry I missed your point, but your still misunderstanding what’s needed.
In a molten salt reactor, most fission products either stay dissolved in the salt mix or are lost from the mix as stable gases. The noble metals are different. Their tendency is to reform as solid metal. They tend to accumulate as a metallic layer or plate of metal over other solid surfaces they come into contact with. That's what is meant by plating out.
Here is a document that specifically addresses noble metal plate-out in molten salt reactors:
http://www.skyscrubber.com/Molten-Salt-Reactor%20Technology%...
See section III.C.
Author assumes that MSR components should last as long as vessels and secondary heat exchangers of solid-fuel reactors. The author should understand that vessel and primary heat exchanger of a fluid-fuel reactor is anologus to fuel rods. Solid fuel reactors just dispose primary heat exchangers or fuel rods every few years. Example: Zircolloy tubes worth a MSR vessel + heat exchanger is just disposed along with partially fissioned degraded solid fuel every 4.5 years in a LWR. Zircolloy (Hafnium separated nuclear grade zirconium + additives) is more expensive than commercially available nickel based alloys.
Graphite is a solid with a crystal structure. Crystal structure degradation under radiation is permanent and there is nothing anyone can do to reverse it. Solar panels degrade similarly. Nuclear industry handles solid-fuel rods which are far more radioactive than MSR graphite and complains that it can't handle MSR graphite. Just shows that either industry is incompetent or it is not interested in efficient fluid-fuel reactors. Does nuclear industry aims >1000 GW of nuclear capacity? Does nuclear industry care to solve global energy related issues? Efficiency really matters when we have >1000 GW of installed nuclear capacity. If all energy is obtained from nuclear, (12000-16000 GW) even seawater uranium get used up in 40-60 years with inefficient solid-fuel reactors.
That can't be right. About 200 tonnes of natural uranium is needed to produce 1 GWe per year in conventional reactors [1]. That's 3,200,000 tonnes per year if you mean 16000 GW in the form of electricity, or closer to 1 million tonnes per year if you're referring to primary (thermal) energy. Seawater contains about 4.5 billion tonnes of uranium [2]. That's well over a thousand years' worth of uranium, either way.
[1] https://www.world-nuclear.org/information-library/nuclear-fu...
All 4.5 billion tons can't be extratcted. More we extract, concentration decreases and harder it gets. I keep asking this question: If seawater extraction of metals is practical, why aren't we extracting other costly metals now? https://twitter.com/AchalHP/status/1011661441412337665
Molten salt is one of about a dozen advanced reactor techs that has huge potential.
Hard part is economics. Hazardous coolant has been a pain to maintain cheaply so far.
Also seawater uranium replenishes from erosion and plate tectonics so it will effectively never decrease in concentration, even if we pull it out at world scale.
http://large.stanford.edu/publications/coal/references/docs/...
Once we setup a pebble/advanced fuel making factory, closing it will takes decades (because people may lose jobs) and the new solid-fuel factory will again pause nuclear innovation for another 100 years. The only way to continuously improve nuclear reactors is to go fluid-fuel. No engineered fuel, so no job loses. Reactor innovation is independent of fuel factory. Nuclear fuel becomes a commodity instead of engineered speciality. Example: MSRE ran U235 and U233 without any modification.
Secondly, solid fuel reactors throw away fuel along with heat exchange surfaces (clad). Fuel also undergoes crystal structure degradation along with other solid structures. Maybe there is enough fuel in the seawater, but there may not be enough places suitable for geological repositories.
Solid-fuel reactors always need excess reactivity reserve. Always needs control rods, and if someone (or a bad actor) pulls all the control rods, reactor gets supercritical. Needs highly skilled people and needs security.
For emergency shutdown of solid-fuel reactor, poison is added to coolant, not fuel. In an emergency, poison is added to the liquid-fuel, permanently destroying the fuel. Emergency can be anything, from a natural disaster to terrorist attack. Fluid-fuel reactors offer unbeatable safety features against anything.
Fusion reactor runs hotter and again fuel is in fluid state.(Fluid: Liquid, gas & plasma.). But only runs for 10-100 minutes. Demonstrated fission reactors run for thousands of hours continuously.
We either stop using those transport modes, or revert to prior forms (wind), or wire-based electrical systems (rail, canals, trucks).
A Google X Project tried and failed.
https://inis.iaea.org/collection/NCLCollectionStore/_Public/...
If extracting gold is only 300 times harder, that puts the lower bound cost at $108,000 per kilogram of gold. That's significantly more expensive than the market price of gold.
Indeed, extracting uranium itself from seawater is not cost competitive with conventional terrestrial mining at present. But the process has been demonstrated on a technical level. Either terrestrial uranium deposits will have to get closer to exhaustion or seawater extraction will have to be much more cost optimized (or both) before seawater extraction of uranium is economically competitive. I was only addressing your technical claims about the exhaustion of seawater uranium, not making economic claims.
Inefficient technologies will hit some constraints if not others.
We may run out of time: A pressure vessel production cycle is over one year[1]. By the time we reach >1000GW someone may make fusion practical or China's competent nuclear industry may start selling MSRs to everyone.
We may run out of highly skilled people required to build and operate these complex machines. The safety is highly dependent on operations and management throughout the life cycle of complex machines. From manufacturing to operations there is tiny margins for error. (Not a physical constraint.)
LWR technology is associated with military ships and submarines, no one shares it. Few countries control the technology and there are only a few places in the world to make pressure vessels. (Not a physical constraint.)
We may run out of waste disposal sites. A geological repository needs special rock formations away from earthquake zones.
The article is written by a nuclear industry professional who tells that routine things done by the nuclear industry today when applied to MSR is a "disadvantage". They open the lid of an LWR every 18 months and replace/shuffle highly radioactive fuel assemblies and say that it is a disadvantage for them to replace graphite. That is totally unfair.
[1] VVER pressure vessel production cycle needs 3 years. https://www.youtube.com/watch?v=91yVhrSZ5jQ
NuScale pressure vessel R&D: https://www.energy.gov/sites/prod/files/2016/10/f34/02%20-%2...
TL;DR Even small pressure vessels (used by nuscale) have lead times of about a year. A megafactory can build like 1 or 2 vessel per month. At 1.5GW/year/factory, we need like 22 factories to keep up with the production schedule if we need to reach 1000 GW of small-LWR capacity within, say 2050.