Small nuclear reactors: tiny NuScale reactor gets safety approval | Hacker News Reader

Small nuclear reactors: tiny NuScale reactor gets safety approval

popularmechanics.com

703 pointsnatcombs541 comments

Here is the NRC website about this reactor:

https://www.nrc.gov/reactors/new-reactors/smr/nuscale.html

Here is an interesting sub-report:

https://www.nrc.gov/docs/ML2022/ML20224A525.pdf

Information withheld for security reasons. One item concerns the "ultimate heat sink". What happens when the ultimate heat sink is lost?

Well a design assumption is that it is not lost:

https://www.nrc.gov/docs/ML2020/ML20205L410.pdf

"A key assumption of the PRA is the availability of the UHS to provide an adequate heat sink. To support passive heat removal with the DHRS or ECCS, the reactor modules are housed and partially submerged in the UHS such that most of the outer surface of the CNV directly contacts the UHS, which is a large pool of water in the reactor building (RXB). "

DHRC is decay heat. CNV is reactor containment vessel. So drain the pool and the reactor is in trouble.

It's really hard to comprehend just how much heat a reactor can make from decay alone. Like... boiling a hot tub in only a minute.

And so a pool of water is not enough because it will boil away. A continuous flow must be present that can not be interrupted.

You need a sufficiently large reserve to allow the reactor to cool, not an infinite supply. Reactors can be shut down and in this case the pool is sized to absorb all decay heat from the shutdown, plus a significant safety margin.

Great, and ideally gravity can be used to move it. Remember, at Fukushima power to the pumps was lost.

Afaik some reactor designs drop the core in a tank below in case of emergency.

The article states the whole reactor will be submerged in a pool of water, making it passively safe.

Reactor cores continue to produce waste heat when shut down, and water evaporates. It’s passively safe till you run out of coolant, then it’s actively dangerous.

In this case the pool boils off slowly enough from thermal load to let decay heat reduce to the point where air cooling is adequate. So it remains passively safe unless there is a sudden loss of water from the pool.

Engineering a very resilient pond does not feel like as complex a problem as engineering highly complex cooling systems to be resilient.

And if you size the pool right it will by cool before the pool boils off. It's simple math and engineering.

The reactor is submerged in the pool. It’s a passive design.

It also helps to not be running a reactor based on designs from the 1950s and then decades later ignore all the known potential problems.

It does, but it makes sense to explore fail-safe designs.

Depending on a lack of incompetence in dangerous systems works until it doesn't. To the extent that these things can simply halt when incompetently managed, they should.

If anyone disagrees, I'd like to know why they think the next hundred years are going to be so much freer of political shortsightedness and corruption than the last hundred.

Fukishima is a perfect example. Unit 1 had been retrofitted with an isolation condenser, which should have been able to prevent a meltdown even with no power, but it wasn't activated, for reasons that remain murky.

https://en.wikipedia.org/wiki/Isolation_condensor

Sounds like a quite simple design indeed, and only one valve opening away from use?

Nothing has to move it. It’s in a pool and always there. The pool is big enough to sink all of the decay heat of the reactors it hosts, without needing a refill or heat exchange.

And if the pool gets a leak?

Patch it? Keep adding water? There's lots you can do with a (non-catastrophic) leak, and building water vessels that don't leak in your lifetime is honestly not that hard.

Leak to where? It's below grade and it's not under any pressure greater than atmospheric.

The elephants foot in Chernobyl was so hot that melted the concrete and dug into the soil. Is this pool bottom impossible to melt?

1. Don’t let that happen.

2. There have been proposals before for core dilution buckets: a wide shallow dish under the reactor full of something like gallium for the hot core to dissolve into. As it spreads out into the dish, the heat and radiation fluxes become less unmanageable, and the core material becomes less critical.

3. Don’t let that happen. :-P

Chernobyl is not a good comparison, because that reactor design had a number of flaws that nobody in their right mind would have designed into it even then, let alone now. (The Soviet Union was not in its right mind.) And then on top of that, the operators were running an experiment with the reactor without having thought through the consequences.

Chernobyl was an ancient design that didn't have many safeguards. This one had safety built in from the start, and it's smol and can be contained easily.

It was a cheaper design, and better for enriching uranium. At the time it was built there were already many passively-safe reactors in operation.

The elephants foot was generated because of the failure to cool the core when the pumps failed. This design puts the core in thermal contact with a giant water reservoir to keep it from ever getting hot enough to melt.

Around 600-700 kWh per cubic meter depending on temperature. The reactor outputs around 200 MW thermal.

So if you have one of them in an olympic size swimming pool 50x25x2 meters, 2500 m^3, it'd need ~8 hours to evaporate the whole pool at full output.

If you assume decay heat as 1% of regular output (https://en.wikipedia.org/wiki/Decay_heat), you'd need to add (or have stored) ~3 m^3 of water per hour, or slightly less than a liter per second, to keep it from melting down.

If you assume an average of 2% for the first two hours, that'd be 8 MWh -> 12-13 m^3 for the first two hours, so a 5x5x5 = 125 m^3 pool (only considering the part above the "must always stay submerged" level) should be able to cool it for days.

I think _as long as the containment pool is intact_ (and you manage to SCRAM the reactor), this isn't going to be a major issue. But if e.g. an earthquake breaks the pool...

Makes me think; the water will not boil if the pressure goes up, was the Fukushima explosion caused by a hidden mechanism where if the water starts to evaporate, the steam can't go anywhere as to push the pressure up to keep it liquid?

That was a hydrogen explosion.

Seems to me that you are also assuming that the water is not dumping any heat on its own. I would bet that most of that decay heat is going to conduct from the water to the pool containment vessel and from there to the rest of the environment faster than the reactor is putting more heat into the pool.

According one of their videos[1] by the time the water has boiled away the reactor will be cool enough that it can be air cooled.

[1]https://www.youtube.com/watch?v=h--FAVoAQvk

Making statements as fact does not help to clarify the discussion. Try posing a question instead. You are not adequately informed on reactor design or operation

It's not necessary as discussed elsewhere, but even if it was a concern simply build it near a river, below the water level and dig a connecting canal (that is normally closed off). In the very worst case just lift a sluice gate and the tank will remain topped up.

Have people really found no way to dump it in an emergency with t^4 transfer?

What is t here?

I assume they meant T^4 radiation (Stefan-Boltzmann law): https://en.m.wikipedia.org/wiki/Stefan–Boltzmann_law

Nuclear reactors run at cool temperatures compared to say gas turbines. And they are powerful. So the surface area for radiative cooling is proportional to the power divided by temperature to the fourth power. So the cooling would need to be very big.

Right, but there is no shortage of metals and ceramics that can maintain cohesion (and strength!) at high temperature -- I'm thinking about those videos the machinists post of tools slicing through metal at an obscene rate with incandescent tooling. You don't even need ceramics to do that, there are steel alloys that stay hard and strong enough to slice through (soft) steel while incandescent, although for wear optimizaton they typically only actually do it with ceramics. In any case, it seems like someone should be able to figure out a "retract rods, let them glow" mode that dumps the energy into the sky like a lightbulb.

I'm sure there's a reason why it hasn't been done. Maybe you really do need high enough temperatures that you can't engineer compatible cladding, or it's hard to make IR windows low-loss enough to pass the energy, or something. Still... fourth power! The temperature you need the "lightbulb mechanism" to withstand is the fourth root of power/area! That's a powerful wind at one's back! It's easy to think of reasons why it might be impossible but if it's "just" a hard engineering problem then that's where things get interesting.

My non-expert guess is that given the large amount of power you have in a small area in a nuclear reactor, it would be hard to reach equilibrium while keeping the fuel solid.

If the fuel is in a liquid state (as in a molten salt reactor), then you could more easily since you could have it pour into a wide container, increasing surface area. (Basically the freeze plug approach).

It would be more possible for a high temperature reactor that can stand the high heat. A regular low temperature reactor would require a huge radiator for the same power.

>> What happens when the ultimate heat sink is lost?

What's an example event where the ultimate heat sink might be lost?

No expert, but if it's a pool of water then an earthquake might cause a leak?

Or an attack, of course. Or some other event (social unreset, invasion, coup, etc...) causes an evacuation of staff and it boils off during the resulting excursion.

People tend to have poor mental models for the long tail of external failures that happen in real life. It's easy to imagine that things that have never happened in the last century would Never Happen. But... they will, somewhere.

Nuclear sites are designed to withstand a strike from a commercial airliner (747). Like you, the designers imagined many of the events you mentioned and more. A good rule of thumb is that if you, a non-expert, can think of a scenario within 10 minutes, an expert has probably already thought of this scenario. Nuclear power plants and weapons sites have always been considered targets and thus considered extra scrutiny in their design.

Wow. How do they design them to withstand a strike from a 747? That seems really difficult.

A whole lot of concrete, mostly.

They shot an F4 target drone at a block of "reactor grade" concrete wall back in the 80s and they took measurements and did science on the resulting lack of damage and concluded that a reactor can shrug off one of anything. They didn't change containment buildings to be plane proof. It's just a side effect of the design required to contain a melting down reactor with a sufficient safety factor.

video of the test https://www.youtube.com/watch?v=F4CX-9lkRMQ

Yes. A NRC requirement for utility scale reactors after 9/11. One wonders why nuclear reactors are so expensive.

It's a good reason to design reactors to be as small as possible, with a small containment building. Much easier to build.

You'd hope so. Reactors yes, but not spent fuel pools. Everyone misses things. I've found 3 design flaws myself in the industry. Not too big of a deal as actions can be taken to mitigate some of the flaws. The other flaws are less probable of causing an issue due to redundant and diverse systems but there's always the off chance...

>but not spent fuel pools. Everyone misses things

Everyone who remembers the post 9/11 "but what if the terrorists attack X" pandemonium knows that spent fuel pools are outside the containment building. That was one of the scenarios that got paraded around to maximize FUD.

I was involved in closing of case, when terrorists wanted to create dirty bomb and throw it at Ukraine. S*it happens.

Wanted to is very different than doing. As far as I'm aware there has never been a dirty bomb attack. You could effectively create a dirty bomb with less radiation with more easily obtainable materials (still pretty expensive and labor intensive). The threat would be similar to a more radioactive substance because the biggest damage is the fear (that's what terrorism is about. They could do MUCH more _damage_ if they weren't as concerned about striking fear). The reason it hasn't been done is because it is impractical and difficult to do without killing yourself. There's better and far easier ways to strike fear into people's hearts. Killing a single person is more effective for them than increasing the chance of getting cancer in one's lifetime by 10% for a dozen people. The much bigger threat is a briefcase nuke but that is several more orders of magnitude difficult/expensive to obtain.

There is plenty of people which want to kill themselves for few, but common reasons, like cancer. It's not a stopper for terrorists.

NuScale claims "The reactor building is able to withstand aircraft impact". The reactors and spent fuel pool are in the same room:

https://www.researchgate.net/figure/Cut-away-view-of-reactor...

https://interestingengineering.com/crashed-jet-nuclear-react...

> the designers imagined many of the events you mentioned and more

Designers are awesome. Sadly they were also unable to find some time in 50 years to raise a wall a few m so it can stand a Tsunami. It seems that the extra scrutiny, was not so extra in the real life when the company will need to allocate real money.

The event you are referring to was also a freak event. The Tohoku earthquake was the 4th largest _ever_ recorded and the largest ever recorded in Japan (by 0.2M, it is a log scale btw). The closest earthquake to that, in the region, in the previous 100 years was 0.7M lower (and the 6th largest ever recorded, in the area). The Tohoku earthquake also resulted in one of the largest tsunamis ever recorded.

We should note that a lot of rare things happened all at once, more than just the freak earthquake and freak tsunami. There is no such thing as perfect. But consider that there were no lives lost due to the reactor accident. Yes, there is economic damage, but that is the worst. Lives were not lost and the environment was not irreparably damaged. Nature has actually started to take back the region and it more looks like a scene out of I Am Legend rather than The Road or The Book of Eli. I do not intend to dismiss the event, as it is concerning (and we've learned a lot since then), but however you measure it coal or oil or gas have had far greater environmental (or human/health) impacts than nuclear. The difference is that it is more in our mind. Despite the Fukushima cleanup estimate (2x Chernobyl's) costing about 9x Deep Water Horizon (2010) I'll let you decide what costs more[0], even if we ignore all the costs to health and atmosphere. There simply is no free lunch.

[0] https://ourworldindata.org/oil-spills

There’s no free lunch but wind and solar are a hell of a lot cheaper than this.

Economically cheaper, but that isn't the only factor that we're discussing. We're also talking health and environmental.

> consider that there were no lives lost due to the reactor accident.

Repeating this again is infuriating. No lives lost? seriously?

> "The event you are referring to was also a freak event. The Tohoku earthquake was the 4th largest _ever_ recorded and the largest ever recorded in Japan"

There is no doubt that the 2011 earthquake was an extreme event, but it's incorrect to say that it was not foreseeable or that the plant's safety systems could not have prevented the disaster.

Further up Japan's coast, the Onagawa nuclear plant was much closer to the earthquake's epicentre. It was subjected to extreme shaking, far more than any other nuclear plant in history, and like Fukushima was also flooded by the tsunami.

Yet it was able to shut down safely as designed in the hours that followed, and its structure was "remarkably undamaged" considering the extreme magnitude and duration of the shaking. 2 of its 3 reactors are expected to be restarted soon following structural repairs and seismic upgrades.

I am not trying to say that things couldn't be designed better. They could (that is never _not_ true). But it is also important to remember that this was a crazy accident as well and several uncommon things had to go wrong at once. The reactor was designed to withstand 100 year earthquake and tsunamis (that's equivalent to flipping almost 7 heads in a row) (we're also not accounting for the odds of the tsunami). But what I am suggesting is that there is a limit. Sure, we could foresee 100 heads landing in a row, it is certainly possible, but at the end of the day you have that end up with an acceptable amount of risk. I do not think 100 year events (1:99 probability) is correct as climate change is changing those odds, but it isn't like this was engineers being lazy and dumb. You are using post hoc analysis to justify actions made without that knowledge. As they say, hindsight is 2020. I do want to remind you that this was the largest earthquake to EVER hit Japan. That's much harder to predict and extremely reasonable to believe such an event is unlikely during the expected lifetime of the reactor.

You don't even need a tsunami, as a plain immaterial "cascade" can wreak havoc: https://en.wikipedia.org/wiki/Forsmark_Nuclear_Power_Plant#J...

> an evacuation of staff and it boils off during the resulting excursion.

It is trivial to design a system that powers off when unstaffed. Without power, this reactor will SCRAM and passively switch to air cooling over the course of a month.

Presumably, a skilled attacker could compromise the passive safety systems and force a meltdown, but wouldn't it be easier to steal some spent fuel and disperse it?

Once an attacker is inside the plant, with just some Wiki knowledge, any plant is as good as melted down. It's a much better plan to simply drain the spent fuel pool.

I think it takes a bit more than Wiki knowledge to drain an in-ground pool... you would need to keep a large pump running for hours, under duress.

You don't need to be an expert. Ask anyone who has owned an in-ground pool. Leaks are rare but do happen.

Nuclear power plants were designed with this in mind. It would take a substantially larger earthquake to damage a nuclear power plant and cause it to leak than a commercial pool. Such a comparison is in bad faith and disingenuous.

Cool it (pun intended) with the accusations of bad faith. Unless you have enough data to prove it, don't accuse it.

"Substantially larger" is not the same as "impossible". And, given substantially larger consequences if a reactor pool breaks (compared to a swimming pool breaking), I don't think the question is out of line.

We learned from Fukushima that natural disasters don't always follow the parameters that we expect them to.

It's a people problem.

People are fallible on the best days, assuming everyone did their very best from nuclear physicists to construction workers, mistakes are made. You take steps to reduce the risk. Research gets review. Engineering schematics get review. Construction gets inspection. Still some mistakes will get through.

And people always act their very best all the time right?

You can even have a perfect design, perfect construction, that is mismanaged years after it's built, after the original engineers and bureaucrats lose control.

The same people problems apply to basically every human endeavor, but nuclear's capability to cause accidents that have a lasting impact is pretty scary. You don't feel even a twinge of existential dread when you think about? If you don't, then I don't think I want you working on a reactor.

This. Humans are spectacularly bad at this kind of scale in time/project budget/size...

We are scary good at it actually. For example check out this and think about the architects who started vs those who finished it: https://en.m.wikipedia.org/wiki/Florence_Cathedral

I was actually going to reply with something similar, but I don't think this stacks up to the damage that can be unleashed in a nuclear accident. Building this took a few lifetimes. Nuclear accidents can have effects that are orders of magnitude larger and longer.

I am not sure something built by the catholic church, one of few institutions that lasted for the last 2k years, is the perfect example.

Unless we plan on getting the pope to build nuclear power plants, which does sound cool.

A sufficiently large pool can be built, that any plausible leak will take many days. Think about it: a million liters of water take a long time to dissapear, after all lakes stay there for a long time without rainfall. Weve built many many ponds, it's not hard.

I'm not sure it's that simple.

It's literally a big hole with water in it; what are you unsure about?

Our largest manmade lakes are created by dams, and you can find plenty of example of dams failing in ways that don't take many days.

If our smallest manmade lakes (swimming pools) can leak a lot, and our largest manmade lakes (dams) can also leak a lot the idea there's an in-between size that doesn't leak might need a bit of elaboration.

There's a big difference between a dam and a pool; the pool is supported by the ground, and even if you bash holes in it, the water still has to find somewhere to go. Also, pools are not typically built from concrete and stainless steel.

The safety requirement here is not "doesn't leak", it's "holds most of the water for 30 days (after which water is not required)". You would have to get an implausibly-large leak, during a situation where nobody can add more water for a month.

The water in a glass can take a long time to evaporate, but if you put your fist inside the glass and press you will have a sudden loss of 2/3 of the water in seconds.

There are pools and pools and there are leaks and leaks. Anybody that has built an aquarium knows that a 80cm high design is much more complicated to made leak-proof than a 40cm high design holding the same water.

A shallow pool would not be enough to contain a small nuclear plant, so you need a non standard bigger pool. Higher the pool, higher the weight of water column, the force pressure against the walls will increase, and the leak will be much faster because the water weight in the upper level of the pool will force the water in the low levels to go out. If your leak is in the upper side of the pool will be a small self contained problem but if the bottom leaks is a different thing. As the bottom needs to support much more force against it and there is a weak area when walls meet bottom, is more probable to fail first.

It’s not bad faith or disingenuous. Fukushima happened because of an earthquake, remember?

An earthquake that was one of the largest ever recorded and resulting in one of the largest tsunamis ever as well. So you know, pretty common circumstances.

That the '1000 year tsunami' happened 40 years after commissioning is more suggestive of engineering incompetence than bad luck. And unlike bad luck, incompetence is a lot more prevalent.

You just defined bad luck. They did plan for better than a 100 year earthquake. They met those standards. Problem is sometimes you flip 10 heads in a row (equivalent to 1000 year event), when they could only handle 7.

evaporation?

Many inland rectors are built on waterways. A plant can shut down due to drought. That's a slow enough process that you have plenty of advance warning, though.

Some are built on man-made reservoirs held together with dams..

Wasn't the big push (or maybe big PR push) for more research and development of Thorium reactors a few years ago because they fail closed/safely? That seems like the kind of thing you'd want for smaller reactors (which I assume means more and more geographically diverse, but don't really know).

There's no research being done on materials to safely contain molten radioactive salt, that research could be dangerous, pretty much only superpowers would have the resources to do the research.

This was being done three years ago: https://www.powermag.com/thorium-molten-salt-reactor-experim...

Also, I believe Copenhagen Atomics is doing this at the moment, but couldn't (quickly) find a reference.

That's cool, thanks for the link.

> materials to safely contain molten radioactive salt

Wouldn't a giant steel or stone vat work, in theory?

The problem is that the nuclear reactions produce many random materials which in turn might be corrowive to the reactor veasel. Dont forget that the vessel has to last decades, so even minor corrosion is a big deal.

You'd still need a heat exchanger at some point, and you want a lot of surface area and thin walls for that.

Random thought experiment -- why not just drop it in the middle of a lifeless desert, forget about heat exchangers, and just let it slowly melt its way down through the crust of the earth? Assuming it went straight down and into the mantle, it would probably not impact the ecosystem.

brb inventing teleportation

Wouldn’t be particularly helpful for power generation since the salt needs to be cooled by water to create the steam to make the power.

Like an uncontained nuclear reaction spewing radioactive materials over a large area?

That's more or less what terrapower plans to build: dig a hole fill it with nuclear stuff and let it burn for decades.

Even in a desert, you'll cross the water table before reaching the mantle. And people prefer to consume electricity in hospitable locations.

"probably" being the key word here; Chernobyl was in a fairly remote area but the fallout spewed over a big part of Europe.

If you go to the desert to make use of the space, might as well build a solar array instead.

Metals melt at lower temperatures than salt.

Also think of how saltwater effects metal. That's just a bit of salt dissolved in water. Molten salt is like that, but way more concentrated, and hotter. Corrosive reactions go faster when you add heat. Molten salt is like metal's worst nightmare.

That's before you even add the radioactivity into the mix, I believe that makes this problem an order of magnitude harder than just trying to contain molten salt, which is already kinda pretty hard.

Stone, maybe, something like a specialized ceramic could work?

No, steel doesn't work, the salt is too corrosive. It's a very challenging problem, imagine you have half the periodic table floating around in a very radioactive salt at high temperature.

Early molten salt reactor experiments used Hastelloy N (nickel: 71 wt%, molybdenum:16 wt%, chromium: 7 wt%, iron: 5 wt%, others:1 wt%), which apparently works. But as others have noted, there is ongoing research to further improve it.

Bill Gates is funding a company called Terrapower that is planning to bring compact MSR to market in the next 10 years. They already have working prototypes but are still a few years behind NuScale.

Wasn't Terrapower trying to develop a travelling wave reactor? Or is that a MSR design as well?

Terrapower is (was?) developing multiple technologies. They got approval for their traveling wave reactor (which uses molten sodium, not molten salt, but they are easily confused for obvious reasons) last week. Not sure if they're going to keep developing other techs.

Really? I literally read dozens of papers about it a decade ago, at least... I guess I don't work adjacent to there so maybe no one else does either. Odd, I never have heard a reason why they were all that much worse than alternatives other than for corrosion and licensing costs, I am surprised that such a well defined problem just stopped being studied.

I suppose at some point it's not competitive with solar so what's the point. Maybe we reached that threshold recently.

Ok, there probably is actually lots of research going on, what little I know of it is several years out of date by now, at the time, advocates for the tech complained about the lack of research being done and I took them at their word.

Yes. Molten Salt Reactors (MSR), while operating very hot, are not operating under a lot of pressure. A pressurized water reactor (PWR) does, and if there is a leak or other problem, it can turn into an explosion.

you are confusing two different characteristics of reactor design.

one is whether or not the coolant is highly pressurised relative to atmosphere, the other is what the thread was originally about, which is how reactivity changes with respect to temperature. this is the temperature coefficient of reactivity.

https://www.nrc.gov/reading-rm/basic-ref/glossary/moderator-...

the people you were responding to were referring to the latter. specifically, if a reactor becoming more reactive results in more or less total reactivity. this characteristic is related to, but independent of, how pressurized the coolant and/or moderator are.

While not under pressure, molten fluoride is still molten fluoride. It needs to be contained well. You wouldn't want water getting anywhere near it.

The pool is big. It is easy to fill holes in the ground with water. In some parts of the country very hard to keep them dry.

>What happens when the ultimate heat sink is lost?

The reactor ceases to transmit power and is shutdown for maintenance?

Reactor's aren't boolean. If a reactor has no heat sink and attempts to shut down, there's still going to be a catastrophic amount of heat to disperse.

That said, rapidly losing the UHS should be incredibly rare/difficult (as several other posters have mentioned).

If it's big enough and makes enough noise, it will be harder to lose.

> So drain the pool

As I understand it, the pool has no drain. There's nowhere the water can go. Which would make sense for a passive safety feature.

those fools making reactors with drains in them. So many cooling accidents could have been avoided!

> DHRC is decay heat. CNV is reactor containment vessel. So drain the pool and the reactor is in trouble.

In some reactor designs overheating slows and eventually stops the reaction in a controlled/deliberate manner. The reactor system may still fail irreversibly, but it wouldn't necessarily meltdown in a way that risks widespread contamination or excessively expensive site remediation, such as by exposing unapproachable material.

I have no idea if this design has that quality.

I haven't had time to read all of the info, but I get the impression that this is still a pressurized water reactor, just on a smaller scale. It will fail in pretty much the same way as current reactors like Fukushima and Chernobyl. I believe that the point is that the pool provides an extra level of failsafe against coolant loss, and additionally that the substantially smaller size of the core limits the amount of heat build-up in a meltdown.

Fukushima is a BWR design using water moderator, closed with a lid bolted on a flange. It uses two pumps. Chernobyl is a RBMK design with graphite moderator and a highly positive void coefficient.

This reactor is a much smaller PWR with a double containment and natural circulation, without these failure modes.

In a standard commercial pwr the containment building is a steel shell surrounding the entire system, then there is a void of varying width then that large cement building that you can see when driving by. That building is called the shield building.

Yes. This is not an inherently safe design. However, it adds a second level of safety, in that each reactor has its own coolant loop that would have to fail first, followed by a second failure of the large pool. It looks like the large pool is also passive, in that it does not rely on circulator pumps to provide cooling.

Nuclear engineer here. I've read through a good portion of the regulatory submission to the NRC and have a few takeaways that oppose some of the less-well-informed takes in this thread:

- The reactor differs substantially from existing PWRs by encasing the primary in double containment, using natural circulation flow for both normal operation and emergency cooling. There are no pumps needed (or installed) to move coolant through the reactor.

- During normal operation, the primary is entirely contained within the primary containment, and circulates naturally, using the differential temperature and gravity. The steam system can is used to remove heat.

- During an emergency, valves open to admit the reactor coolant into the backup containment. These valves are normally held shut by hydraulics with positive control from electronics-- their failure mode is to open with no other operator action in case of a loss of power. No additional operator action is needed to initiate the emergency cooling flow, which is also a natural circulation loop to the backup containment shell, which then conducts heat to the pool.

- The backup containment shell is designed to withstand hydrogen explosions such as those that occurred at Fukushima, and which was possibly prevented at Three Mile Island by venting (whether there was a hydrogen explosion at TMI-2 is not fully understood).

- There is no mechanism for positive reactivity addition via graphite moderator rod such as in the Chernobyl design. The specific failure mode at Chernobyl is not possible with this reactor.

- The pool is specified as a stainless-steel-lined reinforced concrete and designed to withstand earthquakes. The safety systems are such that no reactor electricity supply is needed to remove heat-- the pool could be filled e.g. from a fire truck, and the immediate decay heat from shutdown does not require any additional heat removal or water addition. So the failure mode we saw at Fukushima (inability to remove decay heat due to loss of electricity) and hydrogen explosion breaching containment does not apply to this design.

> During normal operation, the primary is entirely contained within the primary containment, and circulates naturally, using the differential temperature and gravity. The steam system can is used to remove heat.

If it's using gravity, what happens if this whole reactor gets tilted? What happens at 10 degrees? 45? 90? 180? Are there any critical angles where it would melt down?

I'm curious how you would make such a design that would be both using gravity yet tolerate being moved around.

>what happens if this whole reactor gets tilted? What happens at 10 degrees? 45? 90? 180? Are there any critical angles where it would melt down?

Ahh i see, a flat earth believer ;)

I suppose earthquakes and other disasters happen (and possibly tilt the reactor) however Earth is shaped?

Sure, you are right but i see HN needs the ⸮ ....

I'd be more concerned about possible coolant loss and/or valve failures because of corrosion.

https://www.sciencedirect.com/science/article/pii/B978184569...

This is very interesting, can reactor like that be used on a ship or submarine(probably stupid question but I am curious). I remember reading some Tom Clancy novel that had a reactor with cooling that used no pumps as a major technical story point.

On submarines that might be a liquid metal coolant, as used on a few soviet submarine reactors. Lead-bismuth eutectic is most likely, it would be sensible to avoid sodium/potassium coolant on a submarine.

What is the maximum external temperature the design can operate in? Can you build it in hot places to power air conditioning and things like that during the worst days?

I think that the only impact the outside temp has on this is how it relates to the cooling efficiency of the steam loop. External temp will have almost no effect at all on the reactor itself or its operation.

Those reactors are small compare to usual one, but they still operate in a power plant like a gas or coal one. It's not a home or neighbourhood nuclear reactor.

So it requires gravity. It may seem trivial, but how would this thing react if suddenly not mounted vertically, say if it got knocked onto its side while running? Would coolant still flow as planned?

Anything that knocks a fully functional multiple thousands of tonnes of concrete, steel, water and fissile material onto it's side was already going to fuck up your day.

As far as I'm aware we've never had a nuclear reactor go sideways, and it's kinda ludicrous to even ask. It's one of the most massive structures, built on bedrock because it's too heavy to be built on anything else, and even these "small" reactors will be incredibly heavy.

They are vertical cylinders to be suspended vertically in a pool of water, not massive squat objects sitting on bedrock. They are thin and relatively top-heavy. It is not ludicrous to ask what could happen should they not remain as vertical as designed.

From a planning perspective, if verticality is a requirement then that verticality has to be protected as strongly as any other aspect. Any attachment or mounting points that maintain verticality must therefore be earthquake proof. If, as in the pictures, these reactors are held in place from the top, horizontal shaking from even a small earthquake would put massive strain on that joint. It isn't just the long/thin/heavy reactor but all the water sloshing around too. A super-strong joint and maybe something important bends/breaks under load? A flexible joint to allow the reactor to sway? Sway how much? What happens at the travel limit of the joint? Can we risk the reactor contracting its neighbours? These are not trivial engineering questions.

I was assuming they'd bury these.

I think they are not trivial but relatively easy parts of the design. I’m sure they can design support structure to withstand whatever arbitrarily large earthquake you throw at it. The structure doesn’t need to be particularly light or compact so there shouldn’t be any design constraints getting in the way of strength. The heat transfer problem is much much harder and they’ve already solved that apparently.

I;m not saying it is impossible, just interesting. One option could be to suspend these reactors on cables from above. That might let them swing around all they want during even a huge quake. The water would act as the dampener. Not much extra engineering required.

As other Nuke submariners in this thread can attest, there are definitely PWRs designed to tolerate massive rolls and “angles and dangles.” I guess it depends on your definition of sideways.

This is a great question!

From reading the NRC submission, the support structure for the modules is Seismic Category 1 (rated for design basis earthquake). This includes the entire Reactor Building, its foundation, and requirements for the site on which it is built. The reactor building is also designed to withstand an impact from a large commercial aircraft. Note that conjecture that the modules are top-heavy appears to be unfounded given the configuration described in the NRC submission.

Elsewhere in the probabilistic risk assessment, they address a module tipping over if it is dropped in the operating area-- the most probable scenario for a horizontal module.

In the case where the drop causes the containment to be breached and does not permit inflow of water from the pool (ostensibly due to pressure difference) the result is core damage and a release of radioactive contamination to the pool.

I encourage interested readers to look at Chapter 19 of the NRC submission. Much of the document is at a level where a lay engineer can understand it. NB: I am not affiliated with NuScale or the NRC.

Safety on the ground is one thing, the other is whether this sort of design might be used in less-than-earth gravity. We need passive/fail-safe reactors for space and this thing looks like it could fit inside a rocket.

One module weighs 762 tons, which is more than 10X the capacity of Falcon Heavy.

I'm amazed that convection alone provides enough flow. I mean this is compared to the massive pumps that previous reactors needed. An innovation of the AP1000 was that the massive pump was fully inside the containment (actually attached to the steam generator) and they had to show that it would work without service forever.

https://www.neimagazine.com/features/featurethe-world-s-larg...

Anyway, what if the valves to the backup containment open while it's running at full power? I mean the electronics fail so the valves open. I suppose the steam generator is still running, but even so lots of heat would be dumped into the pool. Maybe there is an interlock so that the reactor scrams in this case.

Layman's question: I don't see how this small reactor is so unique or why it took so long to be developed for regulatory approval. The article claims it produces about 50MW of power with a planned 60MW version. Well, there are already very compact reactors in use on today's aircraft carriers (the A1B and A4W) that produce a much larger 500 to 700MW per module and are also relatively small (after all they fit on individual ships). And obviously deemed quite safe for the exact same reason -they're on ships that travel to all major ports and contain thousands of crew members right inside the same metal hull that the reactor is in. Even more compact and fit into an even smaller vessel quite safely for the crew: submarine reactors like the S8G, which produces over 220MW and measures only 42 x 55 feet in size, with a weight that's not unreasonably greater than that of the NuScale

Basically: What's so dramatically difficult about doing the same for a terrestrial compact reactor to make something like the NuScale take so long to get approval?

The $1/2 billion they had to spend due to paperwork related to certification of the design. From an earlier comment[1] from a different thread about this approval quoting NuScale's press release:

"NuScale spent over $500 million, with the backing of Fluor, and over 2 million labor hours to develop the information needed to prepare its DCA application"

Military reactors don't have to go through this process and those designs (modified to work on land, etc) would.

[1]https://news.ycombinator.com/item?id=24346808

In other words, the "impracticality" of compact, safe terrestrial reactor designs is almost entirely created by an immense mountain of bureaucratic hurdle that the military is excepted from? I can see the need for safety and careful documentation of contingencies but the scale of what you describe is simply dismaying.

Thank you for that answer and link. checking further now.

Also, I can't even begin to imagine how much paperwork would be necessary (in literal visual, procedural terms) for the cost of fulfilling it to reach half a billion fucking dollars and 2 million man hours to fulfill. What would this even contain? Multiple 200+ page technical laboratory test breakdowns for every single nut and bolt and washer in the reactor set-up?

Naval reactors use fuel that is enriched to weapons grade. I'm pretty sure we don't want that sitting around in towns all over America.

I think it's disingenuous to argue the economics of nuclear without mentioning:

"DOE reported that it faced an estimated $494 billion in future environmental cleanup costs — a liability that roughly tripled during the previous 20 years."

https://www.gao.gov/assets/700/696956.pdf

How much is the future environmental cleanup costs of coal and oil?

If you consider the climate, about 100 times that.

Is there a paper on that? 40 trillion sounds like a lot and I’m curious how that number is generated.

If you could solve climate change for less than that, I think it would be splendid.

To put that number in context, which is just an order of magnitude, it's $5,000 for every person on Earth, about 1.5x the current US national debt, and just under the combined market cap of NYSE+NASDAQ.

As an existential problem for humanity that doesn't currently have a solution, I think that's a decent cost estimate.

Climate change his hardly an existential threat for humanity. We survived the last ice age with stone tools, this is a less severe change. Economic impacts from things like rising sea levels really depend on how much we spend on maintaining things as they currently are vs adapting to the new normal.

Aka do you live below sea level, raise the city, or move somewhere else. https://en.wikipedia.org/wiki/Raising_of_Chicago

The last ice age occurred gradually over the span of millennia. Anthropic climate change is occurring in an instant by comparison. Not to mention, humanity survived by mass migration, something that's a lot harder for integrated global economies to do. Few believe humanity is going to go extinct. But extinction of industrialized civilization is a more real concern. And the collapse of industrialized civilization will undoubtedly entail the death of over 90% of the human population.

An instant in geological time not a literal instant. Death of modern civilization is always a risk, but not directly from climate change.

The global food surplus is projected to continue even in the worst case. Energy and raw material production is similarly not a major concern. People continue to live in Dubai which demonstrate how extreme local conditions can get without forcing exodus. Further, few places are expected to get even that bad.

Yes, changes to weather patterns, sea levels, invasive species, even diseases are likely. But, collapse of civilization is only really a risk if WWIII kicks off.

I like your optimism, people would just live in inhabitable places or relocate and would be welcome, such gentlemen. I expect WWIII.

What specifically is going to cause mass migrations in your mind, and on what time scale? Sea level rise on the order of 5 feet in 80 years is hardly going to make most countries uninhabitable. Over longer time scales will see much larger increases, but the yearly change is never projected to be that rapid.

Water availability is a concern for farming and industry, but not really people. Desalination is cheap enough for personal use even in India. Every 10 gallons a day is an extra ~4$ per year. Projecting US use age on global poor is unaffordable, but the global poor don’t use nearly that much water.

As armchair academic I kind of understand you. People live in all sort of horrible conditions today - famine, malaria, diseases. As living person I ask myself what if my home was destroyed by flood? What if there is no water to grow food? What if person from the country which caused most of CO2 emissions [1] expects me to be contempt? Shouldn't I blow them up? Maybe all I need to commit is a good preacher.

Last mass migration caused by ISIS. COVID caused reduced oil consumption is enough to make a trouble for oil exporters. Global warming is worse - drought, flood, fires. World is extremely fragile, resources supplied from another part of the world, even today cobalt mining is horrible, what would be then? I've heard of another civilization and broken supply chains [2].

[1] https://ourworldindata.org/co2-emissions#cumulative-co2-emis...

[2] 1177 BC: The Year Civilization Collapsed (Eric Cline, PhD) https://www.youtube.com/watch?v=bRcu-ysocX4

Supply disruptions occur with every war or crisis yet modern economies are extremely resilient. The trap is thinking the economy needs exactly what it’s getting rather than it being the result of a giant optimization problem on available resources. Just look at the US GDP drop from Covid vs the percentage of people staying home.

I also think that you are assigning agency to the general public in ways that are unlikely to hold up. Clearly groups could whip up hatred over global warming, but they can do that over just about anything. The root cause is almost never as important as the people guiding things and the goals being pushed.

As to [1] what’s interesting to me is the US emissions are currently about 1/2 of China’s and dropping fairly quickly while China’s are still expanding rapidly. Dropping US emissions will continue to help, but it’s currently less important than slowing how fast China’s increase. And thus someone aims the mob at a slightly different target.

Humans aren’t at risk from climate change, it’s all the other species without our powers of quick adaption.

Even for Humans, some regions of the world will be simply to hot to be continuated habited.

I doubt that because technology is so powerful and adaptable. Dikes can protect lowlands. Air conditioning can make hot summers tolerable. Food can be grown in more northern climes.

But coral can’t adapt to warmer more acidic waters overnight. Polar bears can’t darken their fur in a couple generations to hunt in perpetual summer tundra.

The technology you talked about is only available in developed countries. What about the people in parts in Africa who already have problem in terms of food insecurities?

As their economies grow, they will continue to get more tools to solve the problems, unless they are stopped by a massive pandemic of socialist dictators.

Dikes can also lead to the destruction of swamps or coastal habitat reducing natural ways of capturing the carbon. In some places they can also lead to further land corrosion which counterproductively will only increase flooding. So dikes are no way a silver bullet to protect lowlands from the effects of the climate disaster.

Air conditioning does not protect workers that need to work outdoors, or people that live in areas with limited access to electricity.

And this says nothing of the other effects we still have no way of combating, including forest fires, stronger hurricanes, prolonged droughts, increased pesting of climate tolerant species, mass migration of climate refugees from the worst affected areas, and—eventually—conflicts and even wars arising from this mass migration. There is no technology that can save us from these effects.

Yes the effects of the natural world is indeed devastating. But there is no way the society as we know it can survive these changes. At best I see humanity regressing to another imperial age with constant wars around the planet, massive exploitation of the majority of the human kind, technology only serving to increase this exploitation, frequent famines, no relief after natural disasters (except for the wealthy few). And even this can’t last forever as at some point the mass of humanity will not bear it any longer and we can expect a societal collapse at a scale not seen since the Bronze age collapse of the 12th century BC.

You Malthusians have only been wrong for 300 years, be prepared to be wrong for a few hundred more.

The world is awash in excess capacity.

It is very disingenuous of you to call me a Malthusian. The Malthusian theory sets a cap at population growth and predicts an inevitable scarcity driven famines and conflicts after a certain period of unhindered growth. It says nothing about the effects of real outside changes in the environment.

In fact these worries—and the fact that we are calling for drastic changes to prevent this disaster—is in fact counter to any Malthusian theory. A true Malthusian would state this collapse is inevitable. We state they are certain if we allow the climate disaster to progress unhindered.

People fleeing the climate alone could collapse the global food chain. I personally thing we're a little too interconnected in the name of efficiency.

There's a very real risk that climate change could knock us back globally to a pre-agricultural level. If that happens, there's almost certainly no coming back: the only way we know how to get to our current level of civilization is by extracting substantially all the easily-extractable energy from the Earth's crust. We only get to do that once. This, today, could well be as good as it ever gets, for the only tree of life that we know for sure exists in the universe.

Surface level coal deposits are available across much of the globe, but let’s ignore that.

Agriculture can go a long way with animals, wood, and stone. Extracting energy from wind and rivers is easily attainable from that basis. At which point we would have serious energy to work with. Hydro electric dams provide 6.1% of the total U.S. electricity. That is plenty of energy to kick start industrial manufacturing and get to wide spread solar power.

The next civilization may be extracting most of it’s materials from our cities, but that’s an advantage if anything.

Burning all accessible fossil fuels would cause an increase in CO2 similar to that at the end-Triassic mass extinction.

The human race will almost surely survive. Whether our current civilization survives is much less sure.

This is in no way to disagree with your overall point, but marine cloud brightening looks like it might be a fairly cost-effective solution to climate change. It's unproven, but not an insane gamble either, and it has little risk of second-order consequences if it doesn't work. All that at a cost of single-digit billions per year.

https://en.wikipedia.org/wiki/Marine_cloud_brightening#Costs

It seems to me to make more sense combating the problem at the source. This just seems to add more complexity to the problem. Did anyone else think of Snowpiercer when they saw this?

I think we can look to austrailia for many many many examples where we thought something would work out when we fucked with nature on a large scale without really studying it.

IE. Canetoads.

Not from seeing Snowpiercer, but from everytime I hear some other crazy science scheme. It's like the pharma industry creating ways of dealing with symptoms rather than the cause of the symptoms. It's the ultimate Old Lady Swallowed a Fly.

We have many proven solutions to the climate disaster, including, carbon tax, renewable energy, cleaner and more efficient infrastructure, telecommuting, international agreements, etc.

Going after a single unproven solution (yes this includes non-existing types of nuclear energy too) is just magic at this point and it doesn’t work.

I wouldn't say those approaches have turned out to be sufficient by themselves, so far. Why not keep improving them, and try additional measures with some hope of success and little risk?

All of these solutions have been deployed on small scales and are proven to work. However they always stop short of implementing on the scale required for the problem. International agreements in particular worked really well to stop the destruction of the ozone layer. However they have never agreed on enough carbon emission reduction for any significant reduction in climate harm.

All of those reduce emissions but they don't stop them and they don't do anything about the existing already-too-high levels.

We have methods of removing carbon out of the atmosphere. They all have the same thing in common, they require a whole lot of electricity. We have something in our back pockets that can generate a whole lot of electricity without any additional carbon...

This rhetoric of new nuclear is gonna solve the climate crises reminds of how GMO was poised to increase our food safety and end world hunger.

It didn’t. And since I’ve learned that new technology doesn’t save us when there is an underlying social issue that is causing it. With GMO the issue is food distribution. In the climate disaster the cause is a little more complex but undeniably a few actors are making an unfair amount of money while polluting the climate for the rest of us.

I find more hope in solutions like carbon tax, international agreements, greener infrastructure, and general climate justice, then for an unproven magical technology that will be deployed on top of the existing social problems.

Never underestimate the tendency of the rich to shift the cost to others while keeping the profit. New nuclear is not going to change that.

You ever notice that the countries where the people are pissed off at the rich for taking too much, pissed of at the government and pissed off about climate change are all countries where basically everyone is fed, clothed and has running water and stable electric power?

Advancements in technology (including GMO crops) and productivity in general have massively raised standards of living in the developing world.

Raised standards of living are what permit people to give a crap about things like oppressed people in the next village over and climate change. Reducing the cost of commodities, like energy and grain, by any means raises standards of living, especially at the margins, and is what permits more people to care about abstract things.

I’m not sure anything you say here is true:

* I really doubt GMO has raised the standard of living for the average person.

* I really doubt people in less then stable economy have any less salt towards the rich, the government, or polluters.

* I really doubt there is a correlation between the standard of living caring about your neighbors.

So to answer your question. No. I have never noticed that countries where people are pissed at the rich are the people that live in stable economy. To prove you wrong, take a look at Greta Thunberg’s twitter feed. She is constantly retweeting people from poorer countries being pissed at the rich for ruining our climate.

>I really doubt GMO has raised the standard of living for the average person.

Then you are absolutely not paying attention at all whatsoever. In fact, the majority of the impact of GMO crops has been felt in countries where there was literally not enough food to go around. You’re welcome to your organics in a country as food secure as in the west but starving poor and middle income countries is not okay.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4218791/

Thank you for this correction. I guess there are in fact evidence for greater crop yield and more farmer profits with GMO crops.

However this doesn’t really take away from my point that GMO didn’t fix world hunger. Farmers can save money by using less pesticide and have better crop yield all they want but that still doesn’t fix food not going to where it is needed.

This—on its own—doesn’t even take away from my weaker claim that „I doubt GMO has raised the standard of living for the average person“. Sure it has raised the standard of living for the farmers that have the option of swapping to GMO crops that previously needed a lot of pesticide. But unless you believe in some trickle down economic theory that will not automatically raise the standard of living to anyone else.

That all said I do find it a little handy that the quoted study only talks about maize, soy, and cotton. One of these is not even a food crop. And the two food crops here are notorious for giant industrial scale farms where much of the yield isn’t even for human consumption, but turned into feed for the meat industry. See it’s a problem of distribution. The profits of more maize and soy yield grown with less pesticide will most likely stay with the farmer, and even if they reduce the price of their price product, the profit from the cheaper crops will more likely go to the cattle farmer up stream with the cheaper feed. The standard of living for the average person will just remain the same, or—at best—marginally improve.

How do you feel about golden rice?

They have been growing golden rice for over 15 years now. And they have yet to deliver on the promise of providing the lacking nutrients to the people who need them.

I mean sure. If GMO can help people, sure go ahead and grow them. But the fact is that so far GMO crops are limited to large agriculture giants and is not used to help with the global food safety net. Particularly not for feeding the poorer parts of the world.

In addition, dietary vitamin A deficiency can easily be fixed now (as well as 20 years ago; and even 120 years ago) with better food distribution. We have been shipping food for millennia. We don’t need golden rice or any other GMO to fix this problem.

Just to clarify, I’m not against them researching and growing golden rice. I am against them lying about how this crop can save the world from a problem that can be already easily be fixed with existing methods.

I can't think of a specific paper/s off hand but having been at labs where they do climate modeling and going to every talk I could I've heard estimates of tens of trillions to hundreds. So the ballpark at least passes my sniff test, though I know that this isn't a hard source. It is also difficult to estimate the damages and costs of climate change which is part of why costs vary so widely. (e.g. do you include events like Katrina?)

Just because someone modeled isn’t particularly compelling. Peer review, meta studies, and testable predictions are critical.

Million acre forest fires are expensive to deal with. Likewise, drought, relocating billions of people displaced by sea level increase. Might be an under-estimate.

.... or even any other power plant or hydroelectric dam.

This is IMO a positive for nuclear, not a negative. You're forced to confront the cleanup as opposed to fossil fuels, where you just blow your waste out into the atmosphere and make it the commons' problem.

If only a method for permanent disposal of nuclear waste actually existed.

There are good permanent disposal methods available. The deep geologic repository under construction in Finland is probably the best example. More info here: https://whataboutthewaste.com

People use "what about the waste" as a reason to not use nuclear. Yet, fossil and renewable biofuel waste is (as mentioned) just dumped into the biosphere where it ends and estimated 8 million lives early per year, according to the WHO.

https://www.who.int/health-topics/air-pollution

Unfortunately that doesn't quite solve the problem of getting waste from reactor to storage site.

It’s not really much of a problem. You leave the waste in a cooling pond at the plant for a couple of decades while you wait for all the really threatening stuff to decay, and then drive it where it needs to go in a truck. It’s a bunch of big metal rods in canisters. It can’t really “spill” and if it does you just pick it up and put it back in the truck. Uranium and plutonium are really not very threatening to human life.

Besides the obvious NIMBY problems, are there any problems with sealed casks transported by train?

No. These things are tested to a VERY high standard.

https://www.youtube.com/watch?v=1mHtOW-OBO4

Getting the waste to a storage facility is very easy. You put it on a semi trailer and move it to the storage site: http://large.stanford.edu/courses/2015/ph241/avery-w2/images...

Nuclear waste is radioactive, but not so radioactive that it's unsafe to stand next to a container. Most waste is stored on site.

It actually doesn't make sense to move nuclear waste to permanent storage because some reactor designs can use this waste as fuel.

That option doesn't exist in the US.

We have no permanent disposal facilities, not even in the planning stage.

https://www.gao.gov/key_issues/disposal_of_highlevel_nuclear...

https://www.wipp.energy.gov/ is one, though that's for government rather than commercial waste.

It's a matter of political will at this point.

The 2012 Blue Ribbon Commission on America's Nuclear Future report [1] literally said that:

"Ensuring access to dedicated funding – Current federal budget rules and laws make it impossible for the nuclear waste program to have assured access to the fees being collected from nuclear utilities and ratepayers to finance the commercial share of the waste program’s expenses.

We have recommended a partial remedy that should be implemented promptly by the Administration, working with the relevant congressional committees and the Congressional Budget Office. A long-term remedy requires legislation to provide access to the Nuclear Waste Fund and fees independent of the annual appropriations process but subject to rigorous independent financial and managerial oversight."

[1] https://web.archive.org/web/20120807061024/http://brc.gov/si...

We do have a permanent disposal facility built, but congress chose to forbid its operation. This is a self inflicted problem: we don't have a permanent disposal facility because we refuse to use the permanent disposal facility we built.

https://en.m.wikipedia.org/wiki/Yucca_Mountain_nuclear_waste...

FYI, to the ready point, as Wikipedia notes: "The DOE was to begin accepting spent fuel at the Yucca Mountain Repository by January 31, 1998 but did not do so because of a series of delays due to legal challenges, concerns over how to transport nuclear waste to the facility, and political pressures resulting in underfunding of the construction."

The anti-waste-disposal crowd in the environmental movement feels exceedingly disingenuous.

The amount of goal post moving they've engaged in over the decades makes it clear that their actual goals are to prevent any waste disposal site from being constructed, rather than specific, actionable complaints.

Which is insane, from a net-benefit perspective, as the alternative is to leave nuclear waste dispersed around the country, closer to population centers.

Not to mention the waste associated with semi-conductors. Long term waste is not just a problem associated with nuclear. It is also worth mentioning that the major waste issues are associated with DoE weapon sites and not as much power sites.

I would also encourage other's to click on acidburnNSA's profile as this is where their expertise lies and they have written extensively (with plenty of links) on the subject.[0]

[0] https://whatisnuclear.com/waste.html

https://whatisnuclear.com/waste.html

The world is filled with naturally occurring phenomena far more dangerous than a big pile of low-grade nuclear waste. The really dangerous stuff ceases to exist after a few decades of sitting in a cooling pond, and then what’s left has such a long half life that it’s not particularly threatening. Water is an incredible radiation dampener, and the ocean is already chock full of dissolved uranium. The only reason we don’t just toss our low-grade fission waste into an oceanic trench somewhere is that it’s valuable and wherever we put it we know we’ll probably change our minds and want it back for reprocessing at some point.

You're underplaying the danger and overplaying the value. Who exactly is investing in this "green gold"? If it's so valuable why does no one actually want it, and why is the DoE stuck with half a trillion liability?

Isn't the "green gold" as you state it what the traveling wave reactor folks https://www.terrapower.com/our-work/traveling-wave-reactor-t... hoping to use to generate their power?

A nuclear concept product. It's probably eternally "10 years from commercialization".

They are stuck with the liability, because President Carter Banned reprocessing of Uranium in 1977, and nobody has changed it. If we reprocessed Uranium, we would end up with much less low level waste, and some very, very small amounts of more radioactive materials (that can be burned in some other types of reactors)

> President Carter Banned reprocessing of Uranium in 1977, and nobody has changed it

Are you sure? Wiki says:

"On 7 April 1977, President Jimmy Carter banned the reprocessing of commercial reactor spent nuclear fuel. The key issue driving this policy was the risk of nuclear weapons proliferation [...] President Reagan lifted the ban in 1981, but did not provide the substantial subsidy that would have been necessary to start up commercial reprocessing." https://en.wikipedia.org/wiki/Nuclear_reprocessing#History

> Who exactly is investing in this "green gold"?

France[0]

> If it's so valuable why does no one actually want it,

I mean France does... we actually gave them the tech. The reason we stopped is more political. But more people do this than just France, but they are the biggest example since 17% of their entire grid is powered from recycled nuclear. The other reason we don't do it is that it is just cheaper to buy more Uranium than setup reprocessing plants. France doesn't have as easy of a supply chain so it makes sense for them to recycle. Obviously the US's supply chain could change, so access to that waste is a potential benefit.

[0] https://www.world-nuclear.org/information-library/country-pr...

In France this 'success story' led to a state law (2015-992, from 2015, the "loi relative à la transition énergétique pour la croissance verte") stating that the part of nuke-produced electricity must fall to less than 50% in 2025, from 72% then, and that renewables must replace it.

In France nuke-power is backed by gas (which produced 10,3% of gridpower in 2017).

The sole reactor currently planned (Flamanville-3) is a complete disaster, more than 10 years behind schedule and 4x overbudget.

https://en.wikipedia.org/wiki/Flamanville_Nuclear_Power_Plan...

I'm unsure what you are suggesting here, so I want to be extra clear about the French policy and current state of affairs. As in stands, France has one of the lowest CO2 emissions per capita[0][1].

No one is saying that we should _only_ use nuclear. Not diversifying your energy portfolio is a terrible idea. France is trying to reduce its dependence upon nuclear (which is a good idea) and replace its fossil fuel infrastructure first. This is because renewables are becoming cheaper. The plan is to have a diversification of nuclear + renewables (which is what pro-nuclear advocates are fighting for). Nuclear serves as a baseload and backbone and is supported by renewables to fill the gap.

You will not find pro-nuclear supporters upset with France's decision to reduce their dependence on nuclear. In fact you will often find support. As battery technology gets better and cheaper and as price of renewables continue to fall you will also find that pro-nuclear advocates will cheer this on.

There is a big misconception that many believe people are arguing nuclear vs renewables or arguing that the grid should be _only_ nuclear. What we are arguing for is nuclear + renewables vs renewables + coal + oil + gas. The reason being that _today_ we have the technology to dramatically reduce our carbon emissions with _current_ technologies. We are looking at countries that already have successful models for emissions and saying "hey, we should do something similar to that, since it clearly works." It would be insane to not look at what models are already successful and try to say that the technologies they use are counter productive. The proof is sitting right there, all you have to do is look. We are arguing for models closer to Sweden (since we, the US, have lots of access to hydro) than were are for France's current system (though their goals would also be a good model to consider).

[0] https://ourworldindata.org/grapher/co-emissions-per-capita?t...

[1] https://www.electricitymap.org/zone/FR?wind=false&solar=fals...

[1.5] Note that Sweden also uses a significant amount of nuclear

Grid should only be nuclear. Renewables and batteries will be major source of pollution going ahead. I am not sure why green groups are pushing those.

I'm not "suggesting" anything, I just let us remember that France plans to considerably reduce its nuclear power capacity. If my assertions aren't clear or if a proof is missing please feel free to ask.

FYI I'm French.

> France has one of the lowest CO2 emissions per capita

Apples and oranges...

France has wayyyy less factories than Germany, however it imports goods produced elsewhere. CO2 emitted in order to produce those goods is to be accounted for!

Real CO2 emission: France: 6.92t/year/capita in 2017 Germany: 10.83t/year/capita in 2017

Source: https://ourworldindata.org/grapher/prod-cons-co2-per-capita?...

https://ourworldindata.org/grapher/prod-cons-co2-per-capita?...

Moreover Germany is richer than France (=> more equipment => more CO2 emitted).

GDP per capita (PPP): 52.4k€/capita versus 47.6

At this point from your data 9.13/5.2 (1.75) ratio we are back to 9.74/6.92 (1.4)

Germany's climate is much colder (=> more heating => more CO2 emitted). Heaters in Germany are massively oil-based systems because there was an historic low taxation on heating oil. Sadly I can't find solid data.

Food for thought.

> Not diversifying your energy portfolio is a terrible idea.

Yes, indeed. However it doesn't imply that we must use each and every energy source, without any consideration for all its characteristics. Nuclear plants and their waste are dangerous, and contrary to a common belief they cannot solve the climate challenge while letting us avoid changing our habits.

> You will not find pro-nuclear supporters upset with France's decision to reduce their dependence on nuclear

Some, in France, think that we should go full nuclear, and they fight for it. Example: https://www.enviscope.com/lassociation-des-ecologistes-pour-...

Other think that we may have to chose a "100% renewables" option. Example: https://www.ouest-france.fr/environnement/nucleaire/nucleair...

In 2010 in the US 8.4% of the energy comes from nuclear plants, and renewables (hydro included) produce approx 6% Source: https://en.wikipedia.org/wiki/Energy_in_the_United_States#En...

That is to say in order to only 'decarbonate' the energy sector (there are other sectors to decarbonate!) thanks to nuclear power the US should deploy ~11 times more nuclear power capacity than it already has, and adapt or retrofit all energy-consuming equipment in order to have it use gridpower (or to embark some nano-reactor). This seems completely unrealistic, from many perspectives. Even a mix (nuclear + renewables) with 3 to 5 times more nuclear seems unrealistic.

'CO2-clean' energy production as a whole isn't possible.

Electricity production accounts for 27% of CO2 emissions, and 63% (of the electricity) is produced by fossil fuel, and 20% by nukeplants). Source: https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emis... => quickly reducing CO2 emission by 27% by producing all gridpower does not imply any adaption/retrofit of any existing stuff, however it implies a 5-fold increase of nuclear capacity or a balance with renewables (taking into account the baseload) and would not be a decisive progress as the GIEC invites us to "fall by about 45 percent from 2010 levels by 2030, reaching 'net zero' around 2050". Source: https://en.wikipedia.org/wiki/Special_Report_on_Global_Warmi...

Therefore, indeed, "the proof is sitting right there, all you have to do is look": in order to reduce emissions we have to consume wayyyyy less energy and stuff.

> What we are arguing for

IMHO the sole realistic option is "let's drastically reduce our energy & stuff needs", or even "degrowth". Even an "all-nuclear gripower" plan, which is completely out-of-reach, cannot fix the climate problem: gridpower offers only about 25% of the consumed energy in advanced countries, and beyond energy-production many human activities emit huge amounts of CO2 in ways we cannot modify, or at best cannot modify quickly (agriculture comes to mind, as in the US it produces ~10% of the emitted CO2, and feeding cows with gridpower may prove to be difficult).

> _today_ we have the technology

We don't know, _today_, how to make a fool-proof nuclear plant nor how to effectively dispose of its waste. We don't know how to solve the NIMBY challenge. Financing a nuclear plant becomes more and more difficult. Even building it is a major ordeal (see the EPR projects). And even if we fix all this there is no all-nuclear approach able to tackle the challenge (dividing CO2 emissions by 3).

> Apples and oranges...

I can change that to CO2eq/capita/kWhr and it is still true ([1] above shows that).

> Nuclear plants and their waste are dangerous,

I'm not trying to dismiss that. But you also shouldn't dismiss the impacts of other resources. There is no free lunch here. For example, heavy metal contaminants are stable and stay toxic forever. We likely have to deal with these contaminants similarly to nuclear (put them in giant sealed holes in the ground that won't ever have access to the groundwater).

> Some, in France, think that we should go full nuclear, and they fight for it.

I am happy to explicitly call them dumb (as opposed to my previous implicitness). They are clearly uninformed on the matter.

> Other think that we may have to chose a "100% renewables" option.

This relies on two things happening (one of, or a combination). 1) The grid is massively overbuilt, 2) battery storage massively improves. These things are possible. The argument for nuclear is, again, based on what we have right now and saying that we shouldn't bet too much on future technologies. It is too risky of a bet. This isn't a big problem for France because you are starting at a very good emission rate, but in other countries it is important because every day we continue to argue we use more coal and oil. Unlike France, we are a much larger nation that is much less population dense and that massively eats into our efficiency of our grid. As for France, I hope you can get to 100% renewable. Like I said in the previous comment, we will be cheering you on. France is what many of us envy. Where we wish we could have started from. Following that path 50 years ago the situation today would be much different. I hope we can get to 100% renewable. I do. I'm just not willing to put all my eggs in one basket.

> That is to say in order to only 'decarbonate' the energy sector (there are other sectors to decarbonate!) thanks to nuclear power the US should deploy ~11 times more nuclear power capacity than it already has

I'm really frustrated at how many times I've said "nuclear __+__ renewables" and you ignore the "+" and assume a "-". I'm sure there are those out there that believe it. I have implicitly and explicitly called them dumb. But if you believe that I am one of those people I would ask you to read my comments again or stop responding if you will not discuss in good faith. I have been extremely clear on the issue. The issue was the thesis of my previous comment.

> Electricity production accounts for 27% of CO2 emissions,

Even though this isn't where you were going with it, this is a topic I'm __majorly__ concerned about. In the public discourse we only discuss electricity and transportation. As per your source, that accounts for a little under 60% of the total problem. Worse, the US is only 15% of the problem (I remember a presidential candidate this year getting booed for saying that we need to do more because of this). 25% of this is land use and agriculture. Another 25% is electricity and heat. And 21% is industry. We can do a lot in many of these sectors, but we still need new technologies. Gates wrote a good article about the subject matter[0] (actually if you dig there are a few). I actually also heavily advocate for CC and sequestration, again because I don't want to bet too much on things going just perfect. And in fact we need negative emissions, not 0. If you listen to many of the climate scientists, you will hear this from them when they feel like they can speak freely. This is why they often talk gloom and doom, because what they can say without pissing a ton of people off is far from where we need to be.

> in order to reduce emissions we have to consume wayyyyy less energy and stuff.

The genie is out of the bottle. You can't put the toothpaste back in the tube. So maybe CC&S. Costly, but it can work.

[0] https://www.gatesnotes.com/energy/my-plan-for-fighting-clima...

Germany spearheaded the decline in emissions in the European Union. Source: https://www.iea.org/articles/global-co2-emissions-in-2019

> There is no free lunch here

Indeed, however the risk induced at run-time and by its waste seems higher with nuclear than with renewables.

>> Other think that we may have to chose a "100% renewables" option.

>This relies on two things happening (one of, or a combination). 1) The grid is massively overbuilt, 2) battery storage massively improves.

A third quest is local production (solar roof panels and the like).

A 4th quest is energy and matter savings (less production => less nefarious emissions).

Also let's not neglect that "renewables" is a mix (solar, wind, hydro...).

As for the 1) (grid) we also have many subpathes, continental-level interconnections and smartgrid being the most prominent, all useful for all "sources" (even nuclear) and all already actively explored.

> The argument for nuclear is, again, based on what we have right now

What we have now is ageing nuclear powerplants (see https://en.wikipedia.org/wiki/List_of_nuclear_reactors#Franc... , this is also true in the US ) needing huge maintenance-and-security-related retrofits, and running projects of plant-building which fail or run massively over-schedule and over-budget (see Flamanville and Olkiluoto). Fukushima bumped up the NIMBY effect. Massive and expensive R&D done for 10's of years delivered no quantum leap (breeders, for example, albeit benefiting for huge R&D budgets, are in the mud since the 1950's... but some nuclear advocates consider them today as a promising path!).

Financing a nuclear powerplant becomes more and more difficult because it is very capital intensive and only realistic along with the aforementioned mass-production challenge, and the fact that the cost of renewable energy production falls sharply.

In other words one nuclear powerplant costs way too much, we lost the capacity to build it on budget and schedule, there are less and less sites willing to host a plant... and we need to build many (10x the existing capacity, for an all-nuke gridpower, see https://en.wikipedia.org/wiki/Electricity_generation#Methods... , given that it is vastly insufficient when it comes to our climate-related goal ) in a short timeframe.

Moreover, after 70 years of nuclear plant activity, we don't have waste long-term repositories, hence we will offer dubtious gifts to our children, and their children, and so on...

Is it really a realistic path or a dead-end?

Are we willing to bet on this or (XOR) on deploying on the 3 major leads summarized above? Each egg in the nuclear basket isn't used for the main 4 quests, and therefore isn't IMHO wisely used.

In France the nuclear sector maintains approximately 220000 jobs, and this is a huge factor for politicians (in order to be elected you better avoid to condemn those jobs).

> In the public discourse we only discuss electricity and transportation

Sadly this is true and I'm also concerned. We do "still need new technologies", however "I'm just not willing to put all my eggs in one basket" nor do we "want to bet too much on things going just perfect", and giving the urgency (we indeed need to quickly reach a "negative emissions" status) I'm convinced that the quest 4 cannot be avoided: we need to reduce the amount of energy and stuff we "use". This is the only sure method readily available. Most politicians and citizen hate it because this is a dark promise.

The potential for CC&S is limited in Europe. About this and some "100% renewables" approaches: https://onlinelibrary.wiley.com/doi/abs/10.1002/wene.128

There are even more ambitious plans, some not from crackpots: https://www.cell.com/one-earth/fulltext/S2590-3322(19)30225-...

> Germany spearheaded the decline in emissions in the European Union.

I'm not sure why this is relevant. France has constantly been one of the best in Europe and Germany has been one of the worst (revisiting my link[0]). I'm not sure what you're trying to argue here. That everyone can improve? Of course. That Germany cares more than France? Well probably. It is a much larger problem then them for France. France left their hose and all their faucets on over night. Germany busted a water main and their house is sinking. Makes sense that they are more concerned. Or maybe you're suggesting that German had a larger reduction in emissions? Congrats, they are almost at the peak of France's output. Either way, I don't get what you are suggesting here.

More importantly, why are you still thinking I'm anti-renewables? Have I not been clear on this matter? I'm also not convinced you're reading what I write anyways because we've addressed several of your concerns already and you're pushing claims on me that I don't hold and have already reiterated that I do not hold. I might as well quote the Jabberwocky.

[0] https://ourworldindata.org/grapher/co-emissions-per-capita?t...

The Germany/France ratio of emissions is relevant because the real difference of emissions if much lower than your graph shows (at worse 1.4 instead of 1.7), and I described (above) why: France has less industry (<=> emissions for stuff is done elsewhere), is less rich (less stuff) and its climate is less cold. It is pertinent because it shows that nuclear power isn't a major factor there. But we both already agree on this (nuclear cannot solve the climate challenge) because you wrote other CO2-emitting sectors "land use and agriculture, heat, industry".

I don't think you are anti-renewables, please quote any sentence of mine letting you believe it. I don't think that nuclear is part of a solution, that's my point here, and my arguments are in https://news.ycombinator.com/item?id=24381421

You seemed to miss the part where I, twice, referenced CO2eq emissions per capita from energy along and not country wide.

Your sentence was "France has one of the lowest CO2 emissions per capita" (see https://news.ycombinator.com/item?id=24371196 ), and in our context I understood that you presented it at a result mostly due to the use of nuclear power, however it absolutely isn't (nuclear power only offers a tiny fraction of this achievement, at the price of many new difficult problems).

Literally the first sentence https://news.ycombinator.com/item?id=24376918

> "Germany spearheaded the decline in emissions in the European Union."

Yes, but this is possible because Germany's emissions are amongst the highest in the EU to begin with.

Although Germany is making progress and can be commended for it's investment in renewables, more than 30% of it's electricity is still produced from coal (hard coal and worse, lignite), which results in one of the highest grid carbon intensities amongst it's European peers.

Building new nuclear is one thing (there are valid economic and environmental arguments against this), but Germany's decision to close existing nuclear plants, some with many years of life remaining, was a political and emotional one rather than rational and scientific.

Keeping existing nuclear plants operating would have allowed more time to develop and expand renewables, enabling coal plants to be closed earlier and reducing CO2 emissions faster.

> to close existing nuclear plants, some with many years of life remaining, was a political and emotional one rather than rational and scientific.

Seems debatable because it seems that, in Germany, most/many (?) citizens are not willing to see nuclear plants running nearby.

It may not be rational. I think it is. There are counter-arguments, and counter-counter-arguments, and so on... up to the point of the debate confining to ethics/metaphysics: do we have the right to create long-lived dangerous waste? Or even the simple "do those who accept have the right to expose those who don't, given that nobody can behave in order to escape the effects of a disaster?" All this leads to much more generic debates (politically dangerous), moreover no politician wants to remain in history as the one who maintained some nuclear plant which, afterwards, caused a disaster.

> Keeping existing nuclear plants operating would have

... induced risks. Even field experts warn us about it.

In France: https://www.liberation.fr/futurs/2016/03/03/il-faut-imaginer...

In the US: https://www.washingtonpost.com/outlook/i-oversaw-the-us-nucl...

>Nuclear serves as a baseload and backbone

Not in France, the nuclear plants here can do some load following (to some extent).

>You will not find pro-nuclear supporters upset with France's decision to reduce their dependence on nuclear. In fact you will often find support.

I cannot agree here, there is a growing movement mainly lead by Jean-Marc Jancovici deploring the shutdown of safe and profitable nuclear power plant.

The main argument being when you already have a low carbon energy production, the money invested in the construction of new renewables power plant will better used in home insulation subsidies or subsidies for a heat pump.

> Not in France, the nuclear plants here can do some load following (to some extent).

They can in do but the economics makes more sense to run high for long periods. The nuclear output of France doesn't typically vary much throughout the day, but yes they do have the capacity to.

But yeah, all we are fighting for is that nuclear is __part__ of the solution (not __the__ solution. Big difference).

> all we are fighting for is that nuclear is __part__ of the solution (not __the__ solution. Big difference).

It seems to me that all this is about the balance between the relative importance of nuclear in the solution and its costs, along with the risks it induces.

Having nuclear as part of the solution implies mass-production of plants parts (building a few plants is much more expensive and projects are nearly always way behind schedule), risk and waste, decommission costs... If nuclear power could solve the challenge (that is to say let us live as we do now while reaching the GIEC's objectives) it could be justified, but it fails far from it.

Well it isn't like there is any other technology that can d it. The idea that renewables can do 100% is still theoretical. Likely, but theoretical. I'd rather not put all my eggs in one basket. Rather I'd look at Sweden and France which have some of the lowest CO2eq/capita (for energy). We should look to the future, but we should also follow what is already working. We can figure out how to burry a few dozen six packs worth of radioactive material after we solve the much larger problem. Besides, if you've been paying attention to this thread, that's a solved problem (just costly and needs will).

I would rather reduce the energy I consume than tolerate all burden induced by nuclear power (risk, waste for our descendants, overcentralization...).

I repeat: after 70+ years of nuclear power exploitation there is no active and sufficient long-term waste repository. This doesn't seem to be a trivial problem. It is "solved in this thread", but not IRL.

France's program is effectively government run, and heavily in debt. I cannot find indication that reprocessing is profitable in the short term, but obviously it has advantages in the long term by reducing waste. That said it does not eliminate the waste issue, nor is France buying up spent waste from neighbors to cash in, nor are they dumping it in the ocean or children's playgrounds (it is still extremely harmful).

I think it would take the deep pockets and standardization of a government-run program to truly see nuclear be done properly, but I doubt there is appetite for a similarly run program in the USA.

A nuclear waste reprocessing program should be 100% government run, or at least government controlled, because part of the process involves refining the plutonium that could then be used to make nuclear weapons. This is why most countries don't reprocess their spent fuel, it's considered a nuclear weapon proliferation risk to reprocess, and the downside of accumulating spent fuel waste is considered minor in comparison to the risk. Buying spent waste from neighbors would be unexpected, because (a) waste reprocessing is more than self-sufficient, and (b) there's not much in the way of transportation infrastructure because countries are extremely cautious not to lose track of spent reactor fuel due to proliferation concerns.

The reason for not dumping it in the ocean is exactly as stated above. It's extremely valuable, in large part because of the plutonium content, and it's senseless to throw away something so valuable that the nation may eventually have a need for.

There are reprocessing methods that are less sensitive to proliferation, such as pyroprocessing where you never have pure plutonium.

Still, there are risks, and I agree it makes sense for reprocessing facilities to be government controlled.

That being said, without also deploying breeder reactors at scale there's not a lot of benefit from reprocessing.

> The other reason we don't do it is that it is just cheaper to buy more Uranium than setup reprocessing plants

Is it cheaper to buy more Uranium and deal with the so-far-and-growing half-trillion dollar cleanup liability than to set up and operate reprocessing plants? Of course I wouldn't be surprised if that liability is considered "tomorrow's problem", so no one in power cares about it.

> I wouldn't be surprised if that liability is considered "tomorrow's problem", so no one in power cares about it.

I was talking to an environmental scientist that other day who was lamenting that the liability for solar panel waste was being treated as "tomorrow's problem", and no one in power cares about it.

If we factor in the tomorrow problem nuclear looks even better, because we have a chance of being able to deal with it. Nobody attempts to solve the decommissioning problems of most waste, there is too much of it so we just dump it in landfill and hope there isn't anything too nasty in it. There is no plan at all to deal with it beyond 100 years or so, and it doesn't get less toxic over time.

You should inform that environmental scientist that Veolia in France has a pilot facility that can recycle 95% of the materials recovered from retired solar panels. The other 5% can be used as feedstock for asphalt aggregate.

Keep in mind, panel longevity is upwards of 25-30 years, at which point they'll still be producing 80-90% of their rated output. Inverters (single or micro) can be recycled in traditional electronics recycling processes.

https://www.veolia.com/en/newsroom/news/recycling-photovolta...

Solar does not have the special handling and proliferation issues that nuclear waste does. Disposing of or recycling broken solar panels is significantly less complicated than spent nuclear fuel and waste byproducts.

Recycling and disposal does need consideration for renewables, as well as nuclear. You cannot just say "Well no one is looking into it for solar, so nuclear should get a free pass too!", especially when nuclear waste is so much more hazardous. Also when considering the infrastructure costs associated with setting up proper reprocessing facilities, no it does not obviously come out ahead. It's incredibly expensive upfront.

> Solar does not have the special handling and proliferation issues that nuclear waste does.

That is also what I'd expect to see if people aren't taking the issues seriously, so it isn't really evidence of anything.

> You cannot just say "Well no one is looking into it for solar, so nuclear should get a free pass too!"

Sure I can. The evidence to me suggests that, for equivalent amounts of effort and adjusting for the energy produced, nuclear waste dumps will do far less damage than solar waste dumps after adjusting for the energy produced. The amounts of waste are tiny to the point where it is unclear to me why anyone cares. If proliferation is a problem, bury it 2km underground in a desert and don't tell anyone where it is. Good luck recovering that on the sly.

Are you suggesting I am not taking it seriously, while also saying "Sure I can" when it comes to ignoring nuclear waste storage issues? Waste amounts are "tiny", and "bury it in a hole somewhere", ignoring time and cost components. Hard to take you seriously.

> Are you suggesting I am not taking it seriously[?] .... [it is h]ard to take you seriously.

I was sorely tempted towards sarcasm by that combination.

But I'm suggesting exactly that, and that we should standardise to not taking the waste of either solar panels or nuclear particularly seriously, given they are both very minor problems that can be handled by the people involved.

Given how we've so far failed to deal with our nuclear waste in a reasonable way, after decades of opportunity to figure it out, I think it's a mistake to call that a "minor problem".

I don't know much about solar waste handling, though someone upthread suggests there's a French company that can recycle 95% of the components of retired solar panels with the remaining 5% going to other uses. Of course, no idea how much that process costs, but I'd bet it's nowhere near as hazardous to deal with as nuclear, and doesn't have any of the nuclear security requirements since I don't expect people can make nuclear bombs out of retired solar panels.

So we can just put it all in your house and you'll be cool with that? After all, there are more dangerous things out there, and we won't be putting any of those in your house, so that makes it okay right?

"Would you be willing to have your house turned into a waste dump?" is a challenge that would seem to strike down virtually every industrial process dating back to the Stone Age.

I don't think anyone would say that a lot of industrial processes aren't extremely toxic and dangerous. The question was asked due to the downplaying of the dangers of nuclear waste. Just because something like dimethylmercury is possibly more toxic than radioactive waste, doesn't mean radioactive waste is safe, or that you want to be near it.

This question is asked in incredibly bad faith. No one anywhere has suggested storing waste (nuclear, coal ash, solar manufacturing, or any other kind of waste) in anyone's home. Or even their neighborhood.

He did kind of suggest that it'd be okay to just dump it in the ocean, which would be a terrible idea.

Absolutely, why not? As long as the waste dealer is offering a deal that is satisfactory for me as the landowner/waste site, I would happily store said waste. Your question is a bit absurd; nobody is suggesting to keep it inside of someone's home. Should an individual not be allowed to make rational decisions about their land and property? If I owned 20 square miles in the desert, why shouldn't I be allowed to lease my land to waste storage companies? The waste storage people are already regulated to death, for a good reason, and as long as the waste on site is stored safely why should I or anyone else mind?

In my personal philosophy, as a landowner you are responsible not only for yourself and your neighbors, but also for the next 7 generations of people who will be using that space after you. So to me, no you have no right. But that's just my own opinion.

I suppose you don't have any right to put solar panels on your home, then, given that they're full of chemical waste that remains dangerous indefinitely.

Personally, I would agree that it's your responsibility for your own land, but I also don't believe in forcing owners to do what I personally want them to do. If you can own a farm without polluting across the street, say,to my house, I really can't care what you do. If you want to sell the farm and throw up a bunch of houses, again, as not as you don't screw with my land and my ability to pass it on to future generations.

I do NOT agree that I an responsible for my neighbors or their land and this is part of the issue. If my farm dumps a bunch of crap or ejects a ton of pollutants into the air, this harms my neighbor and should be limited. If instead, I build my farm and is net 0 pollutants to your land, why exactly should you be able to do on 'my' land, or put another way, who is the victim?

To frame this another way that I think is fairly similar to nuclear, I think large scale organic farming is extremely taxing to the land in the long run and is a fairly terrible agricultural practice at our current scale. Does this mean we should enact laws and regulations to stop organic farming? I'm really not so sure, I can understand both sides and I don't think this type of legislation will ever be so cut and dry.

Your neighbors and county can certainly challenge the use of "your" land. I think you're assuming that ownership means you can "do whatever the hell you want". Ordinances, zoning, right of way, eminent domain, and federal regulations often restrict what you can do and may require ceding control of parts/all of your land, and if your neighbors are really pissed, they could certainly raise hell and make it very difficult.

Of course, this, I believe, the person I was responding to was somewhat implying and what I was hoping to hint upon in my comment. The discussion around nuclear, and really most politics, is around ownership and the limits to what you can do with what we call 'yours'. Just because I want to personally dump a bunch of waste, unprotected from my neighbors, doesn't mean I should be allowed to potentially pollute their land or contaminate their water. I find it far easier to have discussions like these when you remember that land 'ownership' (in the US anyway) is really a lease agreement to the government and your neighbors, our country may use the word ownership, but it really isn't in the most literal sense.

We could dump it into the ocean and not worry about it. There's so much cooling capacity and radiation shielding in the oceans alone that we'd never run out of space, so all of the current disposal strategies are way above and beyond what's needed. Containment is solved problem.

It's important to note that other energy types also produce waste. For example, coal ash is incredibly toxic and hard to dispose of, and we create much more of it every year.

Another option which is completely safe and permanent* is drilling a borehole few km down and dumping the waste there. It's not coming back no matter what. The research done into it shows that "only" 800 boreholes would be required to store literally all nuclear waste ever produced.

https://en.wikipedia.org/wiki/Deep_borehole_disposal

*to a point where it was actually brought up as a negative, because if we ever wanted to recycle that waste into something else, it's literally impossible this way.

There's one in Finland:

https://en.m.wikipedia.org/wiki/Onkalo_spent_nuclear_fuel_re...

They have thought thousands of years ahead and set up many different types of warning signs and symbols in case a future civilization discovers it.

I think the difference is that the one in Finland can still be entered like a normal tunnel. The deep borehole is literally just a vertical shaft that goes 5-6km down, you put the waste on the bottom and fill it back up. No geological process is bringing the waste back up in any conceivable timescale, and even if the entire civilization collapsed no primitive society can dig to 5km depth, so there's no need for much long lasting signage, no one is going to stumble upon it by accident.

No, they put zero warnings. Warnings only make it more likely that someone decides to start digging.

The idea that civilisation collapses and then recovers to the specific extent, where it is advanced enough to have coal-mines or similar, but not to know about radiation. Then it must find this particular repository and start digging, and die. Thousands of years must pass but they must dig up this sight withing a particular 100-year period of their development.

This is such a stupidly contrives scenario that you might as well plan for an alien incasion or zombie apocalypse. Lime prerequisite for that theory is civilisation collapsing, our investment in making sirebcovilisation does not xollapse is zero. You deal with it by making sure civilisation does not collapse.

Then they will know about radiation.

And than there is Asse: https://en.wikipedia.org/wiki/Asse_II_mine

You just don't know.

The time frame is too long. It's too long for natural causes and far too long for human civilisation. The earlier we stop producing this crap, the better.

Sure, but that's why I suggested deep borehole storage - there is no known geological process that can bring up material stored at 5km+ depth into the surface on any sort of human timescale. A mine, even at 700m depth, is just too shallow for long term storage.

But there are many human processes which can.

....and? If you wanted highly dangerous materials to use for some evil purposes it's 1000x easier to just manufacture some poison rather than dig 5km deep. I'd argue that making radioactive isotopes in an accelerator is still easier than digging. Not sure what your concern is here.

> They have thought thousands of years ahead

That level of stupid theatrics really annoys me. If society has regressed then it will be a godsend to rediscover nuclear power. If society has advanced this is like the Romans trying to anticipate modern problems.

> It's not coming back no matter what

If you can drill down to put it in, can't you also drill down (or use the same hole) to get it out?

Well, yes, technically. I meant more that the waste won't come back on its own, through tectonic movements, earthquakes, meteor strikes or pretty much any other natural process known to man. You could drill down to retrieve it, but then it's a very specific thing serving one specific purpose. It's not like mine repositories, where they are at a much shallower depth and could be entered "easily" from the surface.

Are you trying to piss off Namor?

Or use the waste (which is still highly energetic) in a traveling wave reactor a la terrapower?

Yes, waste reduction through sustained reuse through different reactors is a good process. Eventually there will always be some waste to deal with though.

> We could dump it in the ocean and not worry about it

This is the things that make me cringe when I see this people saying again "This time will be different, we promise".

Look mum, radioactive tornadoes coming from the ocean...

Do you not understand how water dampens nuclear reactions, or how large the ocean is?

Learn about trophic chains, cycle of water in this planet, sea currents, tidal forces and oceanography.

What do you mean by this time? Nuclear waste has already been dumped in the oceans before (prior to new regulations). 8 nuclear submarines have been lost and there's no environmental impact detected.

This has been well studied by several groups including the US Navy, which is one of the biggest nuclear operators with over 80 reactors currently in warships. In the event of catastrophic loss, the plan is to just leave it because the oceans already have billions of tons of radioactive material and infinite capacity to absorb more.

Also nuclear reactors have occurred naturally [1] and without any serious fallout or contamination risks, showing that containment is really not that challenging. Most people think nuclear is scary because of popular science and culture, and they lack the knowledge and understanding to know any different. It's similar to people not trusting vaccines because they don't understand medical science.

1. https://blogs.scientificamerican.com/guest-blog/natures-nucl...

Absence of evidence is not evidence of absence. Deep sea ecosystems are extremely fragile and we need to leave them as is if we want to feed people

Time to just get rid of the mess hiding it under the rug and saying that "There is not our fault, it was yet like that when we arrived and now is somebody else's problem" has passed.

We deserve better, much more honest and much more smart people this time.

There is plenty of evidence - of no impact. As I said this has been extensively studied and there's so much radioactive material in the ocean that it makes no difference.

Also maybe you misunderstood the post because dumping in the ocean wasn't a real proposal. The point is that containment is solved, and indeed solved by very smart people. It's politics and general ignorance that has hampered nuclear power, not technology.

> There is plenty of evidence - of no impact.

There is plenty of evidence of the opposite in fact and is not difficult to find at all. We can choose to close the eyes to not see it, but the truth is stubborn:

Techa river (Russia): Used as dumpster from dismantled nuclear submarines until 2004. 25 times more probable than normal of having limb and organ malformation in newborn babies from people living there, plus a bonus 40% increase of probability of having cancer. This is the harvest of just 50 years of activity. What would you call that?

How do you keep the nuclear waste contained in salt water for thousands of years? The radionuclides will end up sooner or later in the water.

You don't? The volume of water in oceans is so big that this won't be a problem as long as you don't dump it in coastal waters. Keep in mind that there's plenty of reactors from sunken nuclear submarines in oceans right now.

The kind of nuclear submarines governments are trying to raise and properly dispose of, because they're worried bioaccumulation will taint their fish stocks? [1]

[1] https://www.bbc.com/future/article/20200901-the-radioactive-...

And governments are known for not over reacting to anything related to nuclear power /s

And in this case, the government of a country whose primary export is oil.

Don't fool yourselves, we are talking about one of the richest extant fisheries of Atlantic cod. This is pretty serious stuff for Maine, Newfoundland or Massachusets, for example.

We are talking about trying to keep your "fish and chips" safe to eat, or maybe not.

Last time the fisheries collapsed in 90's 37.000 people lost their job only in Newfoundland and the social impact was massive. It has not recovered still after almost 30 years with a record of lowest captures registered in 2016.

No need to keep it contained, the oceans have billions of tons of dissolved radioactive material already. Adding more isn't going to change anything.

Dumping in the oceans isn't a serious proposal. I was pointing out that waste is not a huge problem.

If only a method for permanent disposal of carbon dioxide emissions from gas plants actually existed.

Sigh... If only a method for converting carbon dioxide emissions into another gas actually existed in nature.

Plant trees and burn coal? That’s your plan?

Every time I read something like this, my hubris alarm goes off. We couldn't even get trans-fats right, so I don't see how we're going to cover all the contingencies for something like this.

Well, you need the trees to make more coal. Think of the children.

Lots of methods exist, but they're too expensive or don't scale well.

Exactly. Scalable solutions to deal with the waste don't exist.

I think the modern (3rd generation?) Reactors have been designed to use much more of the fuel, leaving considerably less as waste, and actually potentially using preciously used spent fuel as fuel, which of course would be cleanup. The problem is approval and building of anything new.

It does. The long-lived wastes can be recycled into fuel in breeder reactors.

It does. It’s called a breeder reactor.

Breeder reactors research was quite huge (one of the first breeder was built in the US in 1951).

Then this technology has been, for all practical purposes, abandoned by nearly all countries that were researching and developing it. See https://en.wikipedia.org/wiki/Breeder_reactor#Future_plants

One of the most (if not the most) ambitious project was Superphénix, costed billions and failed flat. https://en.wikipedia.org/wiki/Superph%C3%A9nix

The sole officially actively pursued pertinent design, BREST-OD-300 ( https://en.wikipedia.org/wiki/BREST_(reactor) ), was planned to be built in 2020 ( https://www.world-nuclear-news.org/NN_Fast_moves_for_nuclear... ) and real work didn't even began ( https://www.world-nuclear-news.org/Articles/Russia-awards-co... ). Moreover it will only (when built, if ever, but not before 2026) be a demonstrator (low power).

Superphénix was politically killed. The technology was promising.

If only a method for permanent disposal of excess CO2 was viable.

Do you mean, like coral reefs?

SpaceX can launch it into space?

And if something goes wrong at launch spread it over a nice big area

Hmm, that’s a point. But I believe we haven’t had any unexpected falcon disassemblies in a while.

Alternatively, maybe we can railgun it into space.

Phenomenal plan, until the next rapid unscheduled disassembly peppers the landscape with radioactive isotopes like a poor man’s dirty bomb.

Many such methods exist.

There are no methods that have 100% answers for every "what if 5 things go wrong at once?" question.

That's true for everything, but those questions only get asked for nuclear energy.

What happens if the power goes out? Use a UPS. What happens if the PSU goes out? Use dual PSUs. What happens if the network goes out? Use dual NICs. I'm stuck on the 4th&5th. You're right. Only nuclear has 5 questions asked.

It does exist: reprocessing. Every other nuclear-using country besides the US does it. The only reason the US doesn't is stupid politics.

SpaceX rocket to the sun.

Thank you. I don't get why this is not considered as an option anywhere.

cost per mass and risk of spreading the waste over a large area in case of missile failure

Because it's a really really bad idea, for several reasons.

1. If your rocket has a failure during launch, you're likely to spread the nuclear waste over a large land area.

2. Even though we really haven't generated that much nuclear waste, it's still many many rocket-launches-worth. That gets expensive. Much more expensive than sticking it in a hole in the side of a mountain.

3. Launching something into the sun takes a huge amount of rocket fuel. It takes a Falcon-9 with a mass of ~550Mg to get a payload of ~22.8Mg into low earth orbit with a velocity of ~8km/s. The Earth is moving around the Sun at ~30km/s, so to launch into the Sun, you need to depart from the Earth at (at distance) ~30km/s. Earth's escape velocity is ~11km/s, which means that from low earth orbit, you need to get up to ~32km/s (sqrt(30^2 + 11^2)). So your ~22.8Mg payload in low earth orbit needs to include a rocket that can add ~24km/s to its velocity. If we assume a rocket with a fairly decent engine, with an Isp of 4km/s, then we can plug that into the Tsiolkovsky rocket equation. The remaining payload that can be flung into the Sun is a grand total of 57kg. All the rest of that ~22.8Mg is rocket fuel. Per SpaceX Falcon-9 launch. This is not an effective way to get rid of nuclear waste. (Note, it may be possible to increase efficiency by making use of gravity assists from other planets, but you still need to actually get to other planets first, so a pretty hard limit on the payload-into-the-Sun is the payload-to-Mars, which is ~4Mg. Still not very much.)

Thank you. I did consider 1st point, but I dismissed it (maybe wrongly) with higher success rate of launches in the future, crashproofing payload etc. But the 3rd did escape my mind (no pun intended)

Based on a Google search, we produce 10,000 tons of 'High Level' nuclear waste every year. This is far more than the total annual lift capacity of all launch providers combined.

For context, it would require 71 Saturn V launches every year just to get that tonnage up to Low Earth Orbit!

You can get rid of almost all of the really dangerous stuff by putting it in a breeder reactor and turning it into electricity and short-lived nucleotides.

I always have the feeling many people greatly overestimate the amount of nuclear waste that was actually produced. So far we have produced an estimated 370000 tonnes of nuclear waste globally, which can be stored in about 22.000m³. [1]

This would fit in a 5m high storage facility the size of an American football field (which is even smaller than a European football field). As an additional comparison, the small Amazon fulfillment centers have about 40000m² of area [2] . Assuming the same 5m height, a small fullfillment center is nearly 10 times bigger than necessary to store all globally produced high-level nuclear waste.

Sure, the waste is hard to dispose and dangerous. But it really isn't much.

[1] https://www.world-nuclear.org/information-library/nuclear-fu...

[2] https://www.aboutamazon.com/amazon-fulfillment#how-big-are-f...

Please don't put it all in a "5m high storage facility the size of an American football field". Google for "nuclear favourable geometry" for why.

We don't have a good track record of confronting the cleanup of nuclear waste. The US federal government recently shipped a secret load of waste into Nevada. Nevada was very unhappy about that and claimed it was done in secrecy because it was illegal. After a bit of a fight, the feds caved and have agreed to remove the waste.

There is no plan for this stuff. The repository that was built in Nevada was never actually approved and it is not legal to use. So everyone that was planning on sending stuff there has just been piling it in the side yard waiting for something. New Mexico is now trying to open up a waste site.

But if you operate a reactor in Tennessee, right now you have no idea where to store the waste so you just keep piling it higher and deeper on site.

Source: rumour and gossip

The only proper source

How can a multi million dollar construction start without necessary approvals?

DOE and NRC have requested something approaching $200 million over the last two years for Yucca Mountain even though it has been killed and revived and killed again. It's been dead for years, but it never really dies. They continue to pour money into it. But, as previously stated, they aren't allowed to use it.

Nevada has fought hard against it. But people outside Nevada (and some inside Nevada) keep trying to jam it down Nevada's throat. The illegal midnight run was just one example.

There had been some $10 billion sunk into the project 10 years ago. You can guess who has the incentive to keep pouring 100s of millions more into a supposedly cancelled project. If the whole point is to funnel giant money into somebodies' pockets, the legal status of the facility has nothing to do with the money allocated for it.

Instead we will burn 700,000,000 quadrillion gigatons of rocket fuel to send all this poison to the sun.

Or just use wind and solar?

It's tax payers paying for outdated technology. Invest that money into renewables: end of story

I'm all for renewables becoming the standard, but I really doubt that nuclear as a concept is "outdated technology". There's a lot of room for improvement, and they can help a lot in the short-term for reducing the ever-growing threat of climate change.

My understanding is that these DoE sites are weapon sites, such as Hanford. These are a different ball game than power plants. They use different technologies and have different kinds of waste. Sure apples and oranges are both round fruits, but aren't one to one comparisons.

List of sites https://www.dnfsb.gov/doe-sites

"In 2015, President Obama found that a separate repository for defense-related radioactive waste was required. DOE reported that defense waste is smaller in volume, less radioactive, and thermally cooler than commercial spent nuclear fuel, stating that a defense repository may be easier to develop."

https://www.gao.gov/key_issues/disposal_of_highlevel_nuclear...

But crucially, commercial spent nuclear fuel is in containers. Spent waste from weapons development was often just dumped in a pit and buried. Our priorities were very different in the 1940s and 50s. Seriously look at this picture [1]. That encapsulates the attitude towards nuclear safety during the early cold war. The soviets just dumped their waste into a lake [2]. Not to mention we detonated a thousand or so nuclear bombs, many of them above ground.

1. https://en.m.wikibooks.org/wiki/History_of_Nevada/Nevada_and...

2. https://en.m.wikipedia.org/wiki/Lake_Karachay

This doesn't really counter my argument. The key part is that it has different kinds of waste. There are more factors than the radioactivity. For example sites like Hanford have melted fuel, which might have inspired that green goo that people associate with nuclear waste, but a power plant only produces solid waste. Aerosols and liquids have vastly different storage requirements and added complexity requirements than storing the typical fuel pellets and solid matter from power generating reactors.

>Aerosols and liquids have vastly different storage requirements

So whip the aerosol into some epoxy and when it cures throw it in the cask with the rest of the stuff.

If you just want to make something that's not solid and reactive into something solid and non-reactive modern chemical science has nearly infinite options.

While I agree with you, for the most part, there is a cost and complexity issue. I was really just trying to tell marsh that they aren't making accurate conclusions from the selected data that they are pulling from to generate their absurd anti-nuclear stance.

Isn't more of Apples to Macintoshes to Honey Crisp to Granny Smith? It's all nuclear waste, but just a different variety.

Almost everything on Earth contains some potassium, uranium, or thorium and thus is radioactive. Its all nuclear waste (from many big, nuclear events in the cosmos), just different varieties

It isn't. Because we're talking about vastly different types of waste with vastly different toxicity and radioactivity. Power plants also don't produce liquid contaminants. This difference means not only quantity differences, but also vastly different methods for storage are required. Ability to contaminate the local environment is also vastly different. Please stop just guessing at what waste actually involves and read up on it before making such claims.

Ah yes, the perfect is the enemy of the good.

It disingenous of you to argue that all DoE cost from the last 60 years have any implication on a modern nuclear site build. When nuclear started they had no idea how to do things and had to do a lot of things very fast.

The waste majority of those cost are not because of civilian nuclear reactor, but rather creation of nuclear weapons.

Site cleanup cost are a factor, but not a huge one considering a site can be active for 60-100 years.

Yes. It appears to very explicitly is about DOE sites, national labs with waste dating back to the Manhattan project and Cold War. This figure would seem to be better described as the clean up cost for our nuclear weapons programs with maybe a small side dish of reactor research in places like INL.

The defense waste is just a fraction of the total:

"The U.S. commercial power industry alone has generated more waste (nuclear fuel that is "spent" and is no longer efficient at generating power) than any other country—nearly 80,000 metric tons. This spent nuclear fuel, which can pose serious risks to humans and the environment, is enough to fill a football field about 20 meters deep. The U.S. government’s nuclear weapons program has generated spent nuclear fuel as well as high-level radioactive waste and accounts for most of the rest of the total at about 14,000 metric tons, according to the Department of Energy (DOE). For the most part, this waste is stored where it was generated—at 80 sites in 35 states. The amount of waste is expected to increase to about 140,000 metric tons over the next several decades. However, there is still no disposal site in the United States."

https://www.gao.gov/key_issues/disposal_of_highlevel_nuclear...

Ok now you’re conflating two separate things. The link and original figure you shared was about DOE sites. From your link: “EM’s mission is to complete the cleanup of nuclear waste at 16 DOE sites...” You suggested this was connected with commercial reactor waste, it wasn’t about that.

Commercial reactor waste is not anywhere near the same kind of beast. It’s contained and easily disposed of when the US eventually embraces science again. Other countries don’t have as much problem and are building deep geologic repositories. Canada even let local communities bid to take the waste.

If your in the PNW take a visit to Hanford when you can. What they did on these DOE sites during the nuclear weapons programs is absurd to think about with what we know today. They just buried all kinds of random toxic stuff everywhere and didn’t even keep records.

> a football field about 20 meters deep

That's not actually a lot is it?

Also, all commercial reactors already pay a fee for nuclear waste disposal. There is tons and tons of money available that has been stored for 50+ years.

The problem is that the government is totally incompetent and instead of developing a solution the money accumulates and politicians are in deadlock.

Both the solution for long term storage for the US has basically been known since the 50 (not Nevada) and the way to reduce the 'waste' has also been known since the 60s. That noting is actually done is not a technical issue.

However, commercial 'waste' is actually valuable material that we can easily store for 100 of years without much trouble or cost, and its not very dangerous either. This 'waste' will actually serve as a fuel for future reactors. Even if you believe that the whole nuclear energy industry will totally collapse and go away. The fees collected would allow for the development of a waste destroying reactor.

Perhaps you'd like to link to some figures for the cost of permanent disposal of commercial waste?

Or were you just planning to let the grandkids deal with that?

All US reactors already pay a fee that takes care of waste. This fee accumulates in government accounts because government because political deadlock. Since start of operations tons and tons of money has been gathered threw this process. Its completely because of government failure that no progress have been made. The fee was designed to be enough to handle the waste and it would be.

Is this the cleanup cost for civilian power generation? Or for military reactors and nuclear weapons, too? Because all the nuclear waste from civilian power generation occupies a volume the size of a football field in footprint and less than 10 yards high. https://www.energy.gov/ne/articles/5-fast-facts-about-spent-...

How many pecks is that?

Show me the cleanup cost plan for the Hoover dam, or literally any other major infra project.

This is a roadblock put up against nuclear power plants alone.

Can LFTR reactors rebreed/run on spent fuel waste, and has a cycling process for filtering out inert elements?

Seems like we should be running those just for those.

That's also an 'if we clean it up'. Nuclear waste decays, and there is not a lot you can do about that.

If reactors, or the placement of them, are designed to be left in-situ after decommissioning, then the cost becomes a lot less. Moving spent fuel from one site to another makes little sense when the original site has already been designated nuclear.

As others have said, this kind of number is always pitched at nuclear, and not hydro, or coal, or any other form of power.

Cleanup and storage is easy in the technical sense, over those timescales and for what's being gained we end up ahead. I say leave storage to the spooks to circumvent the nimbys and call it a win. Let congress argue after they've had a taste of the results.

This is huge. Not only are micro reactors far more economical, it dramatically reduces the need to maintain a massive nationwide grid and provides flexibility to people in remote areas including greater autonomy. Efficiency should be greater without massive transmission line losses. Might start fewer fires in California too.

The economics are yet to be borne out. I believe the NuScale cost (feel free to correct me if this information is wrong) is still above the cost of renewables and storage [1] but below that of traditional PWRs (684Mw @ $3 billion [2], ~25 cents/kwh [3]), which is competitive in places like Hawaii (which is still relying heavily on diesel fuel for what solar isn't providing) and geographies with limited land or renewables potential, but not elsewhere (storage aside, you're still competing with renewables around 1-3 cents/kwh at utility scale).

Congrats to NuScale for making it through to the other side of US nuclear regulatory purgatory. Optimism is warranted ("all of the above" to replace fossil fuels), but cautious optimism. It's not real until a commercial reactor is generating. Vogtle is still not done [4]. I hope I get to see a factory churning out prefab reactors ready for shipment.

EDITs (to not pollute thread with replies): A carbon tax in the US is very unlikely, and you cannot count on economies of scale until you have arrived at scale.

[1] https://www.lazard.com/perspective/lcoe2019

[2] https://www.nuscalepower.com/benefits/cost-competitive

[3] https://news.ycombinator.com/item?id=24346808

[4] https://news.ycombinator.com/item?id=24061448

I think it also depends on CO2 charges if any.

For example, right now we have a pretty serious externality with CO2 for coal and other sources, what are the costs that folks would assign to CO2 to clear to needed target? That could bring comparative cost (with CO2 impact) down a bit.

Thing is this kind of design benefits massively from economies of scale, same kind of thing that has drawn the price of PV down and other green energy.

This kind of design actually starts out with losing massive economics of scale of traditional PWR and hopes to get it back by economics of scale in manufacturing.

I don't think NuScale will have much trouble competing with traditional PWR, but if they can compete in the overall market is a huge question.

Up until recently the "economy of scale" meant massive reactors when it came to nuclear, and small modular reactors were abandoned because people didn't think they could be economical.

We have radically different construction skill sets now than we did in the 1970s, so the economics may be different now, and it could have been that the planners were wrong before.

But I'm any case, until a few of these have shipped, I'm not sure we'll know the true cost.

These are manufactured like airplanes, a few at a time. Whereas solar has massive plants with hundreds of thousands of the same part assembled and shipped. I'm hopeful that they will provide another tool in the fight against climate change, but not super optimistic. There are many many technologies that are at a similar stage of development that could be used instead, such as cheap hydrogen electrolyzers, long-duration storage flow batteries, etc. And if these other techs succeed, they will also help SMR nuclear, assuming SMR nuclear can compete with renewables on cost!

Given the general cost disease affecting large construction projects, I think that massive reactors are an unviable proposition in western countries at this point. While the reactor core designs seem to be templatized, the projects to build them are not, and so there is huge inefficiency. E.g. see https://www.nytimes.com/2017/07/31/climate/nuclear-power-pro....

If NuScale can build hundreds or thousands of these small reactors, they should be able to perfect a turnkey installation playbook that would hopefully reduce costs significantly, and perhaps more importantly, reduce variance on project spend/timelines. I think an unpredictable total cost of ownership is one of the things hurting nuclear projects.

The big question in my mind is whether they can deploy enough of these to get to that scale, given that there's a fairly universal NIMBYism against nuclear power, even where this would be displacing CO2-emitting sources.

> same kind of thing that has drawn the price of PV down

A nuclear power generator is a complex beast, that requires a ton of material, of very different kinds, worked into some detailed and non-repetitive patterns. (Have you looked at a steam turbine?)

PV is a simple pattern of a few different substances, repeated over and over again.

Even if scale was all going into the PV price, nuclear will never be able to achieve the same amount of it.

It kills me that people keep not factoring in long term damage to the earth when they figure out how much energy costs.

I'm not an expert, but I'm not convinced about it reducing the need to maintain a nationwide grid.

Nuclear reactors take ages to ramp up and down. It's basically going to be generating the same amount of power 24x7, but demand is going to fluctuate. The more other areas you're connected to, the more opportunity there is to send that power to someone who can use it.

Obviously there's a law of diminishing returns at some point, so maybe the grid doesn't need to be as large as possible.

There are alternatives like energy storage (batteries, etc.), but you'd have to compare all the costs and benefits.

I can see that if these are distributed, the grid can be more of a mesh than spokes on a wheel.

solar can do the same sort of thing.

> Nuclear reactors take ages to ramp up and down.

Naval reactors are apparently very fast in this regard, so it's evidently not an inherent property of nuclear power.

(The USN also has an unparalleled record of safely operating reactors; more that 5,000 reactor-years clocked without major incident.)

Does it count that a Navy man was killed at SL-1?

https://en.wikipedia.org/wiki/SL-1 https://www.findagrave.com/memorial/67718734/richard-carlton...

SL-1 was an Army reactor, so I would say it doesn't count. I'd also not count the USS Thresher or the USS Scorpion, since reactor accidents weren't the reason those sank.

Relative to how many people die every year from wood and coal smoke? I would say it doesn't count in a relative sense.

> Naval reactors are apparently very fast in this regard, so it's evidently not an inherent property of nuclear power.

Ramping up is easy, ramping down... not so much.

It's not as much of an issue if you swim in your coolant, hence naval reactors are unique in being able to ramp both up, and down quickly.

Most civil reactors are next to lakes or rivers so it seems like they should have plenty of water. Is it a matter of civil reactors using smaller[cheaper] plumbing and pumps? My intuition is that Naval reactors are built to be very responsive because that's useful for naval applications, but civil reactors aren't built like that because that ability has less relative value for civil reactors.

Nukes are slow from a cold start but they can throttle up and down with load.

https://en.wikipedia.org/wiki/Load_following_power_plant#Nuc...

Modern nuclear plants with light water reactors are designed to have maneuvering capabilities in the 30-100% range with 5%/minute slope.

Wow, that's pretty fast. So 12 minutes worst case. TIL.

Still, I wonder if the economics don't favor running near 100%. You've already paid the high up-front cost of the equipment, and fuel costs are low, so I assume you're better off selling excess power when possible.

I'd be willing to bet there are some significant thermal efficiency losses at 100% that would push you down closer to (made up number incoming) 80% at idle

Of course. Though with increasing deployment of intermittent sources like wind and solar, occasionally the wholesale price can drop lower than the marginal cost of the nuclear plant (or even negative, if said power sources receive production subsidies regardless of the wholesale price), in which case it makes sense to throttle down.

Future grids with more intermittent renewables will have increasingly volatile prices, but not necessarily lower on average. So generators that can produce during high price periods (e.g. if wind and solar aren't producing much) can make a lot of money then, compensating for less income during low price periods.

What's the maneuvering ability of a coal plant? I looked at the article, but didn't see it.

Gas turbines are the ones that ramp the fastest and are used to handle dynamic peaky loads. Nuclear/coal are generally used as the baseline power because they're more efficient.

Fastest is a coal/Gas/Oil fired Steam Turbine driven power station sitting at full pressure sitting as spinning reserve

> Nuclear reactors take ages to ramp up and down.

Run them at full blast and dump the extra energy into direct air carbon capture? Of course that would require building the CC plants but it could be planned for.

That's the whole point of creating grid-scale storage - giant batteries, lots of smaller batteries, pumped storage, pressurized air storage, traction railways, etc - or smarten up loads like EV charging so they can ramp up/down to soften the fluctuations in demand from other sources.

You'd probably just connect carbon capture plants to the grid, and run them when electricity is cheap for any reason (presumably any fossil sources have no reason to run at this time...)

On a grid with enough opportunistic loads, you'd never need to ramp down reactors.

> This is huge. Not only are micro reactors far more economical

No, they aren't. They are more expensive per unit of power produced, by far bigger than any other powerplant in practical use.

The only way I see nuclear getting economical is it getting bigger. Nuclear's biggest advantage after the cost of fuel is its huuuuuuge power density, and power scalability. With currently technology level, it's possible to generate multiple gigawatts from a single reactor.

> it dramatically reduces the need to maintain a massive nationwide grid

It would not. Grid maintenance are quite non-linear, and high voltage lines are actually much cheaper per unit of electricity transferred than residential links.

Very high voltage DC transfer is very economical, efficient enough for intercontinental connections, but very expensive.

Bigger means bespoke. More NRE, more paperwork, more one-offs. Smaller means the entire supply chain is simpler and easier. Management is easier. And of course, the more times you do something, the easier and cheaper it gets.

Mass production is a no-brainer.

> Mass production is a no-brainer.

This is very much an unproven assumption. There is nothing in the history of nuclear technology to suggest that what most industries experience, an industrial learning curve that lowers production cost, will be found for these reactors. In fact, just the opposite - the more experience we get with them the more likely we are to find problems that are very expensive to fix. This is even more true now that they've given up on doing serial production in a single factory.

I doubt it will reduce the need for a grid much. The most efficient way to deploy these is probably in clusters next to an existing big substation on an EHV line. The local substations are likely to be increasingly constrained by solar and wind that have to be distributed. Nuclear has no such requirement so why bother with hundreds of sites when you just need a few bigger ones?

> Not only are micro reactors far more economical

Experience to date has been the opposite. They have diseconomies of scale in construction and operation. The proponents claim they will make up for this somehow, for example by making the reactors in factories, but note that NuScale has given up on that and is going to have the parts fabricated by others and assembled on site, just like larger reactors.

Source for that plan B? Curious what they are telling their investors, then.

"In answer to a question I posed to Nuscale at the town hall we have learned that the plan to save costs by fabricating the modules at a remote factory and shipping them to the Idaho site has been abandoned. The artful response to my question said that Nuscale engaged with approximately 40 … pressure vessel fabricators worldwide and … determined that Nuscale will use existing factories … in lieu of building its own factory.

The major module subcomponents will be manufactured at multiple manufacturer locations and shipped to a single location for assembly prior to installing into the facility.” This signifies the failure of one of the major cost-saving features of the Nuscale project, which was to forestall this exact scenario."

https://losalamosreporter.com/2020/08/22/get-out-of-the-fluo...

Thanks.

I'm guessing that official line, accurate or not, is future larger deployments may be constructed differently, and this reneging is just for the initial run.

A small town could probably use one of these, however I don't think farmer Joe and 3 or 4 of his neighbors are going to be able to afford one of these to keep the electric smokers going for thanksgiving...

Four links down: "The staff has determined that the plant design meets the applicable requirements for the design certification stage of licensing. ... The NRC staff’s issuance of this FSER does not constitute a commitment to issue the design certification"[1] The actual review document is not up yet; search for "ML20023A318".

It's not that this is smaller. It's comparable to Shippingport or Vallecitos. The argument is that it's safe enough against meltdowns not to need a full containment vessel, which makes it cheaper. The idea is to have a group of these sharing the same reactor pool. What they do if there's a leak into the cooling pool. Does that take down all the reactors?

Anyway, the plan is to build the first one at the Idaho Reactor Test Station, 830 square miles with reactors spread miles apart. If something bad happens there, it's not a major problem.

[1] https://www.nrc.gov/docs/ML2023/ML20231A804.pdf

> If something bad happens there, it's not a major problem.

Well, unless you're in Idaho like some of us. ;-)

The whole point of having 830 square miles of reactor test station is to keep the problem on the property if something goes wrong. See the SL-1 disaster. It happened there, but nobody outside the test station was affected.

If you have 20 minutes, the video linked in the comments of the earlier HN post is quite informative, giving a much better technical explanation than the original article: https://www.youtube.com/watch?v=7gtog_gOaGQ

It is fascinating, for example, how a slight change in the packaging of the fuel (as sand-sized pellets coated with carbon) affects the safety/stability of the design, and how resonances in the cross section for neutron absorption come into play (they broaden at higher temperatures, dampening rather than enhancing the overall reaction speed, as temperatures rise).

One thing not addressed is physical security. As pointed out by @adrianmonk it would take many of these tiny reactors to generate the same amount as a typical older reactor.

Older reactors are designed like fortresses, supposedly able to take a direct hit by a commercial jet and survive. They have armed guards, etc.

It would be interesting to see how they would try to protect these. Typical electrical substations are protected by a chain-link fence and a padlock.

The idea is to put multiple reactors at the same site, not to spread out mini reactors all over the landscape.

So the end result would be a powerplant that produces about as much power as a "normal" nuclear power plant, just that it contains many small reactors instead of a few big ones.

This undermines some of the claimed benefits. A bunch of little Fukushima Daiichi reactors in the same location wouldn't have fared any better than the actual Fukushima Daiichi reactor.

In this particular case, a power plant with these nuscale reactors would probably have survived a Fukushima type accident. One effect of being small is that the reactors are designed to be passively cooled after shutdown, using convection instead of pumped flow. So there is no need for emergency diesel generators to keep the coolant pumps running.

Sure, it's safer for reactors to tolerate flooding, if indeed these reactors actually do tolerate flooding. Definitely that would be a better design in flood/tsunami-prone areas. No design (from history, especially no reactor design) is perfect. A set of smaller reactors that were not co-located would be more tolerant of site-specific vulnerabilities in their design.

> ... if indeed these reactors actually do tolerate flooding

The reactor modules are partially immersed in a pond, the ultimate heat sink. Cooling is passive, i.e., no cooling pumps, and does not require electrical power.

I think you're screwed either way.

The odds that a concentrated site has an event are much higher with colocation. But the changes of having an event at multiple locations are higher if they're spread out.

Some things that I believe would matter for colocation would be:

- chance of cascading failures

- economies of scale/safety in numbers (1 large team vs many small)

- plant-to-home efficiency (n fewer reactors due to smaller transmission losses)

>A set of smaller reactors that were not co-located would be more tolerant of site-specific vulnerabilities in their design

That depends on what risks you are trying to mitigate. IF you are talking about site specific natural disasters and freak occurrences damaging a site. Then spreading them out increases risk of failure.

If you are worried about power loss after a site destroys a site, then colocation is worse. Of the two, damage to a site is the more pressing concern.

What's the radius around a reactor where a critical core can trigger fission in the next reactor over?

You'd have to place both cores within the same reactor pressure vessel, which isn't possible.

So as long as the reactor vessel is intact it absorbs 100% of the neutrons? Going out as well as coming in?

Because in a failure you’ll have only one pressure vessel between the two cores. If everything else goes right.

> So as long as the reactor vessel is intact it absorbs 100% of the neutrons? Going out as well as coming in?

Neutron diffusion is a statistical process, so yeah, a small amount of neutrons will escape through the reactor wall. But not enough that the neutron flux from one reactor would influence the next one in any measurable way.

> Because in a failure you’ll have only one pressure vessel between the two cores. If everything else goes right.

Yes, also in this case.

In practice, 0.

Uh, there are a bunch of reactors at Fukushima. It’s in the name: “daiichi” means “complex-1”, there is also a “daini”, etc.

Article gave absolutely no indication of its dimensions. How "tiny" is it exactly?

> The reactor measures 65 feet tall x 9 feet in diameter. It sits within a containment vessel measuring 76 feet tall x 15 feet in diameter.

Per: https://www.nuscalepower.com/technology/technology-overview

you forgot to mention that those 23 m high containment vessels are places in in a pool which of course have to be much bigger than that: "The reactor and containment vessel operate inside a water-filled pool that is built below grade."

We'll see of this is in any way or form sustainable, especially since uranium is also a finite ressource.

>We'll see of this is in any way or form sustainable, especially since uranium is also a finite ressource.

I believe at current consumption rates there is still several hundred years worth of uranium. Presumably Fusion will have been figured out by then or we've killed ourselves with a climate disaster or something worse.

Nope, at the current rate of consumption it will last 70-80 years:

https://en.wikipedia.org/wiki/Peak_uranium#:~:text=According....

First section your Article: "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).[9]"

Doesn't seem clearcut

I wouldn't worry too much about running out of nuclear fuel. There's also Pu used in MOX fuel, breeder reactors, nuclear fuel reprocessing.

Almost all predictions of running out of ores have been wrong. They’re based on “proven reserves,” but mining companies don’t bother proving much beyond 50 years worth.

No, these are the reserve that are available at a given price. It is very sensitive to technology. Moreover, price of uranium is a small part of the cost of a powerplant, so there is not as much price sensitivity. We're still good for around ~200 years.

Also, fuel can be reprocessed, and we can use other things than Uranium

There's ~4 billion tons of uranium dissolved in seawater, too. Which is enough for a millenia or three - if we used it for all of our power needs.

Add in breeder reactors and reprocessing providing a factor of 200 improvement in fuel usage, and we have enough uranium for millions of years.

How much energy would it take to extract one ton of uranium from the ocean?

Well, according to "Sustainable Energy Without the Hot Air"

>Japanese researchers have found a technique for extracting uranium from seawater at a cost of $100–300 per kilogram of uranium, in comparison with a current cost of about $20/kg for uranium from ore. Because uranium contains so much more energy per ton than traditional fuels, this 5-fold or 15-fold increase in the cost of uranium would have little effect on the cost of nuclear power: nuclear power’s price is dominated by the cost of power-station construction and decommissioning, not by the cost of the fuel. Even a price of $300/kg would increase the cost of nuclear energy by only about 0.3 p per kWh. The expense of uranium extraction could be reduced by combining it with another use of seawater – for example, power-station cooling.

https://www.withouthotair.com/c24/page_165.shtml

https://www.withouthotair.com/c24/page_174.shtml

Do you know if withouthotair is actively maintained? I used it in school more than a decade ago and I would love to reread a new version. I know the author died in 2016.

This article estimates that the cost of seawater extraction would be roughly 10x the current market price, although not much word on the energy consumption.

[0] https://sci-hub.tw/https://doi.org/10.1016/j.pnucene.2017.04...

That is not really the point, it doesn't matter if there is 4 or 40 or 400 billion tons of uranium, the point is that it is finite. At some point, there is none, or better there is no more usable ressources available. This can be shifted with technology and better knowledge but it is still finite. And that is all the point I wanted to make.

The sun also will burn out eventually, and every other star as well.

at that point the Earth will also be uninhabital and gone and if we found a new planet to live on, there will be another sun.

And at that point we'll have access to uranium from asteroids and other planets.

Its not tiny at all, these are gigantic 'modules'. Its only small in comparison to a normal PWR reactor.

Just barely too big to go on a standard tractor trailer. But small enough to be portable by a oversize load tractor trailer. Kind of like the blades for very large wind turbines in west Texas.

went across the a few years back and saw a LOT of those on trucks on the interstate. Maybe not a lot, but you notice when a truck is carrying something several hundred feet long down the road.

The weight (590 tonnes according to wiki) is likely to be an issue. You need specialist vehicles that connect to a waterway or railroad.

Yeah there is no way that will be transportable on a road unless it is transported in parts. 75 tonnes is about the limit with special permits. I wonder if the 590 tons includes the fuel?

Maybe tiny refers to the power output. The article says it makes 50 megawatts.

Compare that to a nuclear plant near me which has two reactors that each generate 1280 megawatts.

So it would take about 25 of these to equal the power output of a traditional nuclear reactor.

Yes but it's inherently safer. Utility scale nuclear was scaled up from naval reactors which are smaller, use highly enriched uranium as opposed to LEU and are safer. Alvin Weinberg, the father of several LWR designs cautioned about the safety of utility scale reactors (17:51):

https://youtu.be/EviEN0ScOwg

The NuScale design also uses LEU and a plant is comprised of up to 12 of these modules sitting in water pools. You can view it as a battery pack where batteris are continously rotated as they are refuelled.

To nitpick, some naval reactors are designed to use LEU. E.g. French submarines run on 7% enriched fuel. And reportedly Chinese subs also use LEU.

They are intended to replace small coal plants out West where coal is the only viable option for baseline load.

As a huge fan of nuclear power, I never felt like NuScale style 'SMR' were all that great of an idea.

Yes, it gains you some of the economics of factory construction and that you can start small and scale a location, but on the other side you lose that again because you lose the economics of scale that traditional PWR gets.

I really believe we should be a nuclear society by now, and that regulations both around reactors and fuel availability prevented this from happening. In the 1960 lots and lots of innovative reactors were build, often with relatively low budgets at that. The amount of untapped potential in nuclear energy is incredible. We don't need fusion, fission is plenty energy dense, if we can't figure out how to make fission practical, we want with fusion either.

Yet here we are in the year 2020 and we are still building new PWR reactors. But the reality is, in the US it is essentially impossible to build anything else. Regulations are designed so that the only reactor that can really get approval is a PWR.

If you attempt to build anything new, you have to basically pay the government to study your design and after a unknown amount of time and money, the government might develop a new regulatory framework. By the time that happens of course you have run out of money already, no buissness plan that depends on the government figuring out how to regulate a new type of reactor would ever really happen.

The good thing at least is that the DoE in the last 5 years seem to have realized that their whole approach was a problem and they have done a lot of good things to try to change. Outside of the US the energy sector is government controlled or to small for a nuclear reactor startup to have a large enough market to make a new reactor worth it.

Canada has established itself as basically the only viable place for new reactor development, with Terrestrial Energy and Moltex Energy (moved from Britain to Canada because regulation).

So, good luck to NuScale, I hope they can prove me wrong and deploy many of these in an economical way.

>Yes, it gains you some of the economics of factory construction and that you can start small and scale a location, but on the other side you lose that again because you lose the economics of scale that traditional PWR gets.

You mean they lose operational efficiency ? Economies of scale come from the ability to mass produce.

You forgot to mention the largest differentiator - eliminates the possibility of a global catastrophe.

Not in nuclear they haven't historically. Economies of scale drove light water reactor designs from tens of megawatts to hundreds to over a thousand universally from all vendors around the world historically. The big institutional nuclear economics reports all agree that going big improves nuclear economics. The hypothesis that SMRs will somehow overpower this is popular but is very much unproven. This agrees with OECD reports like last month's [1] and all the older ones listed in [2].

[1] http://www.oecd-nea.org/ndd/pubs/2020/7530-reducing-cost-nuc...

[2] https://whatisnuclear.com/economics.html#improving-modern-nu...

> You mean they lose operational efficiency ?

Historically, one of the few successful ways to lower the price per generated power from a nuclear power plant has been to make the reactor larger. So yeah, there's a reason why the latest traditional PWR designs such as the French EPR are huge (1600 MWe).

The gamble with these small reactors like Nuscale is that series production of the reactors in a factory would make up for the loss of the traditional economy of scale due to size. It remains to be seen how well that will work out.

If you can pump out standardized large scale reactors like France did, then they are way more efficient than these smaller reactors.

The problem of course is that takes a large government to mandate a huge public project, which is not really likely these days. The advantage of these small reactors for now is that they hopefully prevent expensive,bloated, one-off site designs that go over budget and miss their schedules.

Economics of scale are the reasons modern Gen3+ reactors are so huge.

From AP1000 wikipedia:

> The design traces its history to the System 80 design, which was produced in various locations around the world. Further development of the System 80 initially led to the AP600 concept, with a smaller 600 to 700 MWe output, but this saw limited interest. In order to compete with other designs that were scaling up in size in order to improve capital costs, the design re-emerged as the AP1000 and found a number of design wins at this larger size.

So modern PWR are usually build with 1GWe one location one reactor, huge economics of scale in terms of the size of the power plant. A AP1000 is not much bigger then an AP600.

> You forgot to mention the largest differentiator - eliminates the possibility of a global catastrophe.

I disagree. First of all, I think the possibility of a global catastrophe with a traditional PWR are already incredibly small, and when talking a modern build like an AP1000 the NuScale doesn't have that much better safety characteristics.

PWR are inherently problematic and require tons and tons of complex engineering to make them save and the error potential in such a solution are always there.

> Yes, it gains you some of the economics of factory construction

They have given up on that, I read.

Previous Discussion 2 days ago

https://news.ycombinator.com/item?id=24345288

Yikes - that is a classic example of a post that accumulated lots of upvotes but stayed underwater the whole time: http://hnrankings.info/24345288/. This is a known problem and it's on our list to fix.

Since that story didn't get much attention (relative to the interest in it), we won't call the current thread a dupe.

"The design is based on Multi-Application Small Light Water Reactor developed at Oregon State University in the early 2000s. NuScale is a natural circulation light water reactor with the reactor core and helical coil steam generators located in a common reactor vessel in a cylindrical steel containment. The reactor vessel containment module is submerged in water in the reactor building safety related pool, which is also the ultimate heat sink for the reactor. The pool portion of the reactor building is located below grade. The reactor building is designed to uphold 12 SMRs. Each NuScale SMR has a rated thermal output of 160 MWt and electrical output of 50 MWe, yielding a total capacity of 600 MWe for 12 SMRs."

Amazing how many people in this thread don't understand nuclear and are spouting rampant fear mongering. Nuclear is fundamentally a safe technology, and these new reactors are safer than anything before. Think about how many deaths have actually been caused because of nuclear compared to coal power. The difference is dramatic.

I don’t understand what makes small reactors desirable. Don’t you loose economies of scales, not only production, but also demand (ie if you have small local sources of electricity you miss the diversification of the demand you have in the central grid and you need to overprovision a lot more)?

When I first heard about these small scale reactors 10+ years ago I remember the goals were to build them to be maintenance-free and disposable. They build a self contained unit that needs minimal labor to run, is highly failsafe, and pumps out ~50Mw for roughly 20 years. When it's done they drop the whole unit (roughly the size of a train car) into a concrete grave onsite and plug in a replacement.

I'm not sure if the goals for this project are the same, or if the goal of a low-maintenance reactor are even possible, but it sounded pretty cool.

> Don’t you loose economies of scales

On the contrary, you gain economies of scale. The way the economies of scale work is if you build n identical widgets, it costs you less than n times the cost of building one single widgets. In other words the unit cost of a widget goes down as the number of produced widgets increases.

If you want to produce a bigger widget though, you generally have diseconomies of scale. For example the Saturn V rocket was about 20 times bigger than the Titan 2 rocket (from which it was derived) but cost about 60 times more.

So, if a Gigawatt-size nuclear power plant is too expensive to build, you build 20 plants of 50 MW each. This is how you achieve economies of scale.

How is nuclear compatible with variable renewable energy sources? It can’t ramp up or down quickly, so it’s not good for filling the gaps in the day when the sun is not shining. And solar is now so cheap during sunny days that the excess power is curtailed or at a negative price.

San Francisco in the summer :D

I kid! AFAIK you most want this kind of immense baselines power for heavy industrial activities.

Also AFAIK, if these are simple/easy/small enough, you could co-locate the heavy consumption with the generation which'd cut power consumption (due to transmission) by something like 30% (on top of infrastructure maintenance savings). Kinda like Netflix putting boxes in local switches (if I have those terms correct).

Nuclear can operate in load following mode for a long time now. It's already done in Europe.

https://www.oecd-nea.org/nea-news/2011/29-2/nea-news-29-2-lo...

Even if nuclear could level up and down instantly, it's economically incompatible with variable renewable sources. If the plant is not operating nearly all the time the cost of power from it goes up and up.

Is Bill Gates an investor in NuScale? Or am I thinking of another modular reactor startup in the PNW?

Bill Gates is involved with TerraPower, the other PNW based nuclear startup

Thank you

Thinking about the cooling pool:

Could you just make an off-shore in-ocean "farm" of these?

Salt water might add to your corrosion issues. Also, physical security of nuclear reactors is a big deal. Now you need a navy to do it.

Half-kidding, and it wouldn't deal with the saltwater corrosion issues, but....

Legit use for Project Plowshare harbors?

And if you have a reactor leak, you just say it didn't matter, because Plowshare already contaminated everything.

This is insane, but it has a certain consistent logic to it...

> Could you just make an off-shore in-ocean "farm"

Not! Ocean is inherently unstable!.

The first serious storm would dislodge and damage the whole farm crashing one module against the other before to vomit them in the shore. Some modules just would dissapear.

And then you have a humongous environmental damage and a really expensive rescue problem trying to clean the fragmented mess.

Don't offshore wind farms do okay?

Is a totally different scale than a nuclear powerplant. A chain of entire cities will not be made unhinhabitable if a wind farm dislodges. Fishermen industries and touristic areas will not be distroyed. We have more room for losing one or two each 20 years (that is what will happen) and rebuild it again

Fish cages and other offshore structures can be moved to earth in tornado season or when necessary. Moving a nuclear farm, would be much more difficult.

AFAIK, put em deep enough - which isn't that deep - and you're basically fine? It's why subs (AFAIK) DGAF about storms.

Mutual impact issue sounds pretty resolvable with a big steel frame and the like.

You will have still many deep currents that shouldn't be underestimated. Is not so simple.

> The current design, which still has several steps until it can be constructed in the wild, is for 50 megawatts per module. NuScale seeks to apply for a 60-megawatt version next.

I'm very impressed by that output. It will make a difference with areas of high solar and wind generation, which can't maintain a sustained high duty cycle.

I expect these types of reactors to be in places to augment solar and wind, not replace it.

Have they announced an estimate of how much a reactor/cost of energy production will be? That’s kind of the most important factor, isn’t it?

$0.24 per kwh is a rough estimate I've seen for NuScale. Typically initial costs for microreactors right now are around $0.25 to $0.30/kwh which is about the cost of energy created by diesel generators. Natural gas is much lower. However they hope that as we make a lot of them the cost will drop.

Wow. That’s substantially more expensive than I was expecting. It’s been years but we always assumed ~$0.08/KWh for on-site natural gas generated electricity on US based projects.

I wonder how much more would that be if the median carbon-tax proposal was added?

We did some calcs to that effect since we were operating in Australia, and they had a $25/ton carbon tax at the time. If my memory serves, it would increase natural gas costs by ~25%. So it'd likely still be right around $0.10/KWh.

Actually I take that back - our calcs were all based on ~$4/mmBTU gas but I just looked and gas prices have been below $3/mmBTU for years. So $0.08/KWh is probably a worst case even if we had a reasonable carbon tax.

Right now they are bespoke reactors so that means that they will cost a ton. But if they are turning them out like Toyotas then the cost will drop really fast.

The hope is that it will be similar to the drop in cost for solar that we've seen in the past ten years. Solar originally cost about $0.28/kwh and now it's around 6 cents.

I don't know why they are bothering to try and build this in the US. Between the insane regulations, the anti-nuclear lobby, and the NIMBYs, they don't stand a chance.

Surely they would have a much easier time selling things like that elsewhere? Growing nations would probably love reliable power that could be plonked down off a ship and added to incrementally.

The ratio of the weight of the reactor assembly for these reactors to their power is about an order of magnitude worse than the similar ratio (using weight of the reactor vessel + pressurizer + steam generators) of a conventional PWR. How is this going to be competitive?

I understand they've given up on making that part themselves in a factory of their own, btw.

Things are always different when deployed, I want to see how it performs before real world before getting excited.

From the article: "In the event of any runaway reactor event, NuScale says, the reactor quenches itself in its pool, making it 'passively safe.'”

So what happens when an earthquake causes a rupture of the pool barrier and all the water leaks out?

This is a solved problem. Tokyo is a good example.

https://en.wikipedia.org/wiki/Earthquake-resistant_structure...

NRC Release: https://www.nrc.gov/reading-rm/doc-collections/news/2020/20-...

Also https://apnews.com/910766c07afd96fbe2bd875e16087464

edit: and https://arstechnica.com/science/2020/09/first-modular-nuclea..., via https://news.ycombinator.com/item?id=24345288

If you build one of these things don't you also need to build an impervious shell around them so they can't be attacked? I have read that the existing reactors can withstand air crash impacts, etc.

I was looking for a reference to the physical size of the reactor and couldn't find it. The sites only say "smaller". Any links with size info and requirements for containing infrastructure?

fyi, OSU college has a 1-megawatt research reactor.

https://www.oregon.gov/energy/facilities-safety/facilities/P...

https://www.corvallisadvocate.com/2012/got-nuke-state-of-the...

McMaster University in Hamilton, ON has a reactor as well:

https://nuclear.mcmaster.ca/facility/nuclear-reactor/

Reed college in Portland has a 250kW one operating since 1968.

https://reactor.reed.edu/about.html

UC Irvine has one underneath the chemistry building https://faculty.sites.uci.edu/trigareactor/

The University of Florida has a 100kW training reactor since 1959[0].

[0] https://en.wikipedia.org/wiki/UF_Training_Reactor

University of Illinois had one for many years in Urbana. My uncle ran the reactor and then babysat the fuel for a decade or so after it was decommissioned. It takes that long to get the fuel disposed of apparently.

One of the problems in the US is that there are research reactors and production reactors, nothing in between. Research reactors are to small to prove out many concepts.

So startups have to essentially go from nothing to first commercial reactor in one step, without iteration.

North Carolina State University has a little 1 MW training reactor for it's Nuclear Engineering track.

https://www.ne.ncsu.edu/nrp/about/pulstar-reactor/

The University of Texas at Austin has a 1-megawatt nuclear reactor:

https://nuclear.engr.utexas.edu/netl/triga-reactor

BUT... it also has two 74-megawatt gas turbines that supply the campus with electricity and steam:

https://utilities.utexas.edu/chp/about-carl-j-eckhardt-combi...

A lot of universities around the world have research reactors.

Back when I worked at my alma mater, I could see the reactor building across the yard from the coffee room. Still waiting for that third eye to start growing out of my forehead.

Mizzou has a 10MW:

https://www.murr.missouri.edu/

I just recently watched this video/tour of MIT's reactor, pretty interesting.

https://www.youtube.com/watch?v=5QcN3KDexcU

Why is most important left out? So, power output 50MW ...

How long does one "charge" last?

What is the price of unit and per kWh?

What is the maintenance procedure?

How long is the life?

What after expiry?

Fwiw, any nuclear reactor design in history was sold as 100% safe. In reality, shit happen. Contractors use subspec material, things on the building site get overlooked and inspectors miss things or get told to look away,

But hey, I'm sure, this time, it will be different. 100%.

Nuclear power is comparable in safety to solar and hydropower. https://ourworldindata.org/safest-sources-of-energy

Watch the "A is for Atom" episode of Adam Curtis' Pandora's Box series. It's linked in one of my other comments. Basically industrialists and sales people got involved, brushing off scientists' concerns. And irresponsible politically connected engineers in the USSR. That's why we have Chernobyl and Fukushima.

However, these are lessons learned. Today it's quite hard to come up with a reactor design without many safeguards and passive safety features, like it's quite hard to come up with a car with no seatbelts or airbags.

Nothing is 100% safe, who said Nuclear power is? Nuclear power always has been and still is one of the safest ways to generate electrical power and this is what counts. Solar power for example causes a lot of fatalities due to accidents that happen during installation and has it's own environmental problems, yet nobody talks about it.

What if they build this on a floating oil rig type situation and fallback dumps it into an ocean fed pool (like a box with gaps for ocean water going down 100ft) far enough off the coast to have power lines but easy enough to recover?

Great, we really need a way to produce massive amounts of green energy.

What’s keeping the nuclear fusion so long? It’s much safer.

Can we use Thorium for now?

So, what's the size of one of these tings?

small? how small is small?

Tiny? how tiny is tiny?

Each containment, vessel which produces 50MW of electric power, can fit on a truck. Each site might contain up to 12 separate reactors. That was basically the design constraint so the can be manufactured off site and shipped as one unit.

A regional power company might seek permitting at 10-20 locations. If some locations didn't get a permit or if other locations proved to be uneconomical to produce power at the time of construction, they could just build at the sites they chose. Basically takes the two phase pre-construction permitting and post-construction operating permit which has been killing nuclear power and streamlines it. Because the designs are standard and modular they will be pre-approved to operate.

Best news I’ve heard in years.

why do we bother with this junk when we have a very large fusion reaction that is located several million miles away from us & delivers it's energy to us in the form of photons every single day.

> every single day

As a California resident, I would like the option to run A/C after sunset.

Finally, 1.21 gigawatts for my DeLorean.

@natcombs would you mind emailing hn@ycombinator.com? I'd like to suggest something so we can send you repost invites in the future.

Aren't BIG nuclear plants with universal distribution system BETTER from security/safety/management perspective?

Boom!

"Officially safe" is a hilarious term which tries to predict the possibility of an MCA or "Maximum Credible Accident." Of course, Three Mile Island, Chernobyl, and Fukushima were also "officially safe" when they were built.

The passive safety is a big leap forward. Removing humans from that process makes it safer.

"In the event of any runaway reactor event, NuScale says, the reactor quenches itself in its pool, making it “passively safe.”"

Any plausible scenarios where the pool leaks?

What a bad faith post.

> Three Mile Island

Was handled reasonably well, resulted in safety improvements to procedures and designs for future reactors.

From https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3...

> The approximately 2 million people around TMI-2 during the accident are estimated to have received an average radiation dose of only about 1 millirem above the usual background dose. To put this into context, exposure from a chest X-ray is about 6 millirem and the area's natural radioactive background dose is about 100-125 millirem per year for the area. The accident's maximum dose to a person at the site boundary would have been less than 100 millirem above background.

Not exactly the end of the world.

> Chernobyl

Accident caused by Communists who did not care about what happened to Ukrainians, as usual for them, and experimented with something that any nuclear physicist could have told them was a terrible idea. This is like blaming vehicles and calling them unsafe after reaching over from the passenger seat and yanking the wheel to drive a truck into a crowd. The moral of the story here is to keep Communists away from anything important, which applies to farms, industrial sectors, food distribution, and really most things more complicated than a pitchfork or a torch.

> Fukushima

Was reasonably safe for its long life, but they cheaped out on the necessary wall and drainage functionality; should probably have been decomm'd and replaced before this happened.

The problem in the nuclear industry is that anti-nuclear people like you form public opinion that causes it to be difficult for it to move forward. New plants based on newer designs are orders of magnitude safer - e.g. the CANDU Canadian reactor which is more fail-safe than most, and the push towards 4th generation reactors.

Get out of the way and let the planet have a clean base load energy source, or be sitting here bitching about carbon footprints 50 years from now when it should be a solved problem already.

> Accident caused by Communists who did not care about what happened to Ukrainians

There were many such RBMK reactors spread all over the Soviet world that had the same flaws . There are many problems with your summary so can I just recommend that you watch the HBO mini series "Chernobyl" instead? It's a great watch.

That mini series is indeed a great watch but it's also not exactly factual.

Are there inaccuracies around the portrayal of why and how the reactor failed?

I don’t think there are fundamental inaccuracies about that, but there are many exaggerations about the immediate aftermath. E.g. the fireman’s hand burning from touching a graphite fragment stood out as a particularly egregious one. And it is in fact shown that the disaster was caused by incompetence and carelessness, which does support GGPs point.

Flaws? The meltdown was caused by a deliberate action on behalf of people with control of the plant.

I haven't watched Chernobyl because I prefer to not get my history from television shows with a narrative axe to grind.

My understanding is that those actions were only capable of causing the problems they did because of specific design choices involved in the coolant and moderation systems. Is that wrong?

That's not wrong so much as it is a disingenous way of looking at the problem. It's like saying the Titanic only sank because there was no system that prevented them from sailing it into an iceberg; I mean, alright, sort-of true, but sort of a "missing the forest for the trees" sort of take, isn't it?

Not really. We understand a lot more about human error now than we ever have, and we design for it. A design which allows for human failure and fails safe is less good than one which does not. It would have been possible at the time to design out those failure modes. Does that not make it reasonable to talk about a flawed design?

I don't know if this bit is true, but specific reference is made in the show to the displacer rods being made of graphite because it was cheaper than an alternative material, which caused a problem because they acted as an accelerant rather than a moderator when the cooling rods were partially inserted. Fine as long as the control rods don't get stuck, or get pushed out by evaporating steam. Again (if true) that's a design choice which made the situation worse than it might otherwise have been. Is that not a flaw?

Inherent safety of CANDU:

https://inis.iaea.org/collection/NCLCollectionStore/_Public/...

But keep in mind that the NRX reactor it was based on had an accident:

https://www.cns-snc.ca/media/history/nrx.html

(famously, Jimmy Carter was part of the NRX clean-up crew).

> Communists who did not care about what happened to Ukrainians

They didn't really care what happened to _anybody_, not just Ukrainians. Ukrainians (as well as about 30% of Russians) just happened to live in that particular location. The plume made it all the way to the Nordics and Germany, and I, as a kid, had to take iodine tablets in Russia, even though officially everything was "under control" for a few days. Then the narrative shifted to showing the heroism of the "liquidators", never fully acknowledging how dangerous any of this really was.

Good point, I agree entirely. It's clear that nuclear power needs to be under the control of responsible governments, built in safe locations (i.e. not on fault lines, not in tsunami zones), and needs solid maintenance budgets.

All of these things are solvable problems, but if we don't solve them before all the current nuclear plant techs age out, we won't be able to apprentice people and keep the culture of solid maintenance alive. At that point, they really do become an albatross.

This was true in USA too. They took pretty good care of the scientists who knew enough to call out unsafe conditions, but laborers etc. at e.g. PGDP were regularly exposed to poisons and radiation. EEOICP was put together late enough that many of the affected workers had already died.

>> Fukushima

>Was reasonably safe for its long life, but they cheaped out on the necessary wall and drainage functionality

They didn't "cheap out" on the seawall at Fukushima. You may be referring to how the plant design was sited closer to the ocean but the seawall was constructed to not be overtopped by the highest tsunami possible. At the time the plant was constructed the theory was that tsunamis were generated in part by underwater landslides and the topology of the surrounding ocean was taken into account to come up with the largest possible tsunami it would have to block. The science behind tsunami formation was flawed during construction and once that theory was later improved no one ever reconsidered the implications for the seawall design.

I agree that public perception is the largest problem by far with nuclear energy but you're not helping your argument by brushing real problems under the rug like this.

Bad faith post? Call me when the Nuclear Industries Indemnity Act (which socialises all costs over $12.6B in case of an accident) is repealed.

What happens if the passive cooling pool drains? Let me guess, “That will never happen!”

https://en.m.wikipedia.org/wiki/Price–Anderson_Nuclear_Indus...

I think picking a few accidents and saying that all nuclear is unsafe is such a disingenuous argument any more. All of those plants were based on extremely old designs and there have been tons of improvements. How about we focus on the "portable" nuclear power that is used by the US Navy for submarines and aircraft carriers safely.

This seems like fretting over a term.

Everything is 'safe' until we discover it isn't and improve. Many things have improved over times. Calling them safe seems fine, we can do so understanding the process of learning and advancing.

Can someone refresh my memory?

Is generating electricity directly from the products of fission proven [mathematically] to be less efficient than

decay->steam->mechanical->electrical

or is just that the applied science of steam power is so far ahead of everything else?

My peace of mind would be much greater if the energy transfer went through solid state systems instead of a working fluid that is pretty good at carrying the bad products of a [malfunctioning] reactor.

Has there even been a case of the steam being problematic?

Most of the time? Isn’t that why everyone was pushing for molten salt or pebble reactors?

I was going to say coincidence but this was clearly Google doing creepy stalker things after it saw what else I was searching for on the Internet (even not using google.com) This popped into recommendations an hour after you asked:

https://youtube.com/watch?v=q3d3rzFTrLg

The problem is heat. fission produces a ton of it and it has to go somewhere. Yes, you can absorb radiation thrown off by fission, but you still have the problem that heat will melt everything.

So you throw water (or salt) on the reactor, heat it up, and do work with the steam that is ultimately produced.

It has less to do with steam being the ideal route and more to do the the practicality of dealing with heat.

AFAIK, most reactors are closed loops anyways, so there's not much of an issue with water carrying away radioactive materials.

Most people are worried about the reactor transitioning to an open loop against the wishes of the maintainers.

But that’s good info, thanks. Molten salt still has to heat transfer to steam because we don’t have any thermovoltaics in the 50% efficient range.

I think I now understand that most of the heat comes from absorbing neutrons, which don’t like to generate electricity (vs betavoltaics and gammavoltaics). And any device inside the pressure vessel would be altered by those neutrons, need to be accounted for as another source of decaying particles, and need to be replaced.

And/Or, you’d want a completely different reaction and then need a neutron generator capable of running continuously.

That about right?

I was thinking Nuclear would be the stable baseline for renewable. But this is not a sustainable option. We need to enforce hydrogen.

Do not submit to the fallacy of nuclear waste disposal. First Elon needs to fix space travel and make transport into the sun feasible. And we will have iter by then.

Why would you need to put it in the sun? That would be a huge waste of energy, just stick it in a stable graveyard orbit, or just get it fast enough to escape Earth's gravity

Hydrogen can be a practical fuel, but you need energy to extract it, which could very well be nuclear

Or solar. Or wind. Or tidal. The beauty of hydrogen is its a great way of time-shifting intermittent energy on a large scale (assuming a large enough water supply) for later use. I’m talking primarily about electricity generation as opposed to fuel for vehicles.

Hydrogen is not a good (at the moment at least) source of energy or fuel for cars or industry (chemically speaking, obviously much better together with Deuterium and Tritium for fission, though we are still from such a technology). Steam reforming, which is currently the most common way of hydrogen production, uses natural gas and water and produces plenty of CO2 [1]. Nice summary as for cars fuel application here [2].

[1] https://en.m.wikipedia.org/wiki/Hydrogen_production

[2] https://m.youtube.com/watch?v=f7MzFfuNOtY

Hydrogen is an answer to the question "how do renewables serve 100% of the grid?". It enables renewables to cover that last 10% or so, and rare prolonged dark/calm periods, without excessive amounts of overcapacity or batteries.

ITER is not a power plant, but if one could turn its gross fusion output to electrical power at 40% efficiency it would cost $100/W (vs. $10/W for fission and $1/W for solar). Not sure why you think this will be something worth waiting for.

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