I'm pretty excited about these. It takes nuclear in a new direction. What disappoints me though is that of the people doing this research that I've contacted, none of them are reaching out to the "other side" (things you would pump the heat into) here. A packaged closed cycle steam turbine system for electricity generation, for example, would be an excellent add-on here.
The Navy has some great small turbine systems (although they typically use the ocean as a big thermal sink for their re condensers), and the folks who design geothermal plants could have a role here if they wanted, but so far not much work there that has appeared in the sources I tend to scan.
As a result I'm concerned that these things with hit the market with no "shovel ready" plans to put them into production, and the lag between that and when you can put them in production will kill the reactor developers. I have seen it in other industries and it hurts to watch it unfold.
OTOH, power generation from industrial waste heat is an increasingly hot topic these days. Whether steam turbine or organic Rankine cycle, finding something compatible in the 1-10 MW scale should be quite straightforward.
The other replies handle the large issue now, but let me go point by point.
> Why is nuclear the silver bullet that will save us?
Not supposed to be that, as others said.
> The waste will be around for longer than we are. We have no solution other than 'lock it up'.
If we sacrifice a Cubic mile to save the planet that's a god trade. Paul is a lot bigger than Peter here.
> Accidents do — and most like will — happen. How will increasing the volume of reactors not increase this risk?
The Tsunami was far worse than the meltdown; I am afraid people's fear-memory often conflates the two. I'm willing to admit the official stats with Chernobyl might be a coverup, but still, tons of poor people around the globe get sick or die from perhaps-illegal fossil fuel pollution. It's not a worse coverup than environment justice issues in the US.
The annoyance here among pro-nuclear people is that other thing's problems get to slip underneath the radar, but nuclear's don't.
> storage
Consider storage will require tons of lithium. The ecological damage from that mining will also be catastrophic, and the ecosystems might take as long to recover.
I'm not saying we shouldn't do lithium-ion batteries. We have little choice we're going to need more. Same thing with nuclear. Same thing with not decommissioning dams as soon as we like.
The fact is with all routes, avoiding ecological collapse will cause local environmental issues. What irks people is the singling out of nuclear, as if other things didn't have issues too, and other essential systems (like top soil) repair as slowly as some radioactive isotopes degrade.
We have designs now that are vastly safer than Chernobyl.
> Fukushima is going to release the waste water into the sea
Why are you even bringing that up? They're going to filter out basically everything, and the released water will be completely safe.
Anyone that complains about the trace amounts of tritium had better be thousands of times more upset at coal power. Even more, they should see intentional radiation release numbers as a motivator to use tons of nuclear in the short to medium term just to get off coal faster. Coal releases so much radioactive material into the air.
> Fukushima is going to release the waste water into the sea
So a bunch of nuclear scientists did a calculation and the results sound scary. And Korea is using it as a political tool. Japan and Korea are at each other all the time, though this may not be common knowledge to Westerners. But if you need a sniff test for this to pass, remember that you can go swimming in a nuclear reactor and people actually do, as many may have learned from the XKCD What If[0]. So just take that story and add a ton more water and add convection so the distribution becomes far less homogeneous. It should pass your sniff test now.
So is the water in the story for the link. The problem is that contaminated is not a binary function. If the material is sufficiently dispersed in the water radiation levels won't rise much (I say rise because sea water is already naturally radioactive, as most things are. Which one could say that sea water is "contaminated" but that wouldn't be useful). If it isn't sufficiently distributed then the distance between you/a fish/sea creature is going to play a big factor since water is really good at stopping radiation. Basically think about you and your wifi router. If there's a metal wall between you and the router you're not getting a signal. Attenuation is the key concept in both radiation and the wifi router. Though this is obviously the fall back for "if they mess up" which isn't likely.
> Why is nuclear the silver bullet that will save us?
Because you can generate power without adding CO2 to the air, or other pollutants. It works 24/7/365 and it requires no new "science" to produce.
However, the root of your question appears to me to be founded in some misconceptions you have about nuclear power. It isn't uncommon because the information in most popular press articles about nuclear power is over 50 years old.
To put that in perspective, imagine arguing the utility of an electric car when your data point is gas at 30 cents a gallon (the price in 1965[1])?
But to talk about nuclear power with current data about how you would design a power plant (and these are the new designs we're talking about), the risks of them leaking any radioactivity, and the risk to people should that radio activity leak and it makes our decision to keep building fossil fuel plants look pretty stupid. It really does turn the whole question on its head.
Nuclear is demonstrably cleaner, safer, lower risk, and potentially lower cost (although how do you price the cost of destroying the planet right?) than any other baseload technology. It even surpasses hydroelectric in terms of externalized costs of habitat destruction.
But I recognize that if you base your analysis on an idea that any new nuclear plant would be identical to the ones at Fukishima (built in 1967) or Chernoybl (built in 1972) it does seem odd that we would want more of that.
I think it's foolish to think we have things 'right' now.
In 1967, I'm pretty certain the engineers responsible thought they had it everything in order.
I take the view we will always fuck up.
With nuclear, the fuck up will always have larger, longer lasting consequences.
--
Edit:
> Nuclear is demonstrably cleaner, safer, lower risk, and potentially lower cost (although how do you price the cost of destroying the planet right?) than any other baseload technology.
I'd agree it's cleaner if we didn't have the waste problem.
You're making a false equivalence. It's not a case of nuclear or fosil fuels. We have other options.
What I hear you saying is that you have no confidence that we can learn from experience, and that our understanding of the process of radio active decay, and the effect of radiation on humans is incomplete.
If that is correct, then I'd Do you fly on airplanes? Have you compared the risks of flying in 1967 and the risks of flying today?
I have a belief that human ingenuity will be able to generate truly clean power. If you believe that too, then this period of nuclear usage, is a transitory period.
If this transitory period has the ability to create substances that will potentially cause bother to generations living in thousands of years time, I think that's a problem.
> I have a belief that human ingenuity will be able to generate truly clean power.
There's no such thing as truly clean power. Even renewables have huge environmental consequences. Hydro floods huge areas of land[1]. Renewables and batteries require huge sums of metals to be mined[2]. Solar and wind also take up huge sums of land that could otherwise be left alone. Everything has trades offs, there's no reason nuclear cant be one more tool in the tool shed.
> Why is nuclear the silver bullet that will save us?
I'm not sure many people make this argument. Although the people that do are very vocal. But they are wrong. The general consensus around nuclear is that it adds to the number of solutions we can use. Considering the inhomogeneous nature of climate and regions nuclear may have advantages in certain areas, whereas other areas it may be unnecessary. Anyone claiming "one size fits all" is just selling snake oil. Essentially the argument comes down to "why time one hand behind your back when trying to solve an extremely important and challenging problem?"
As for waste, it isn't as big of a deal as you might think. Though this is more difficult to understand without an expertise in the subject matter. Mostly this is due to the complexity of understanding the different types of waste, amounts, and the vastly different levels of radiation in those waste products. Most of these conversations are akin to people talking about rocket science without knowing Newtonian mechanics. Just listen to the experts and see what they are saying. You're on HN, so I trust you can understand the nuance that scientists use, though I know that sometimes this can get confusing to the public. Like how "disagreement" isn't much of a disagreement but more quibbling over minor details.
> I'm not convinced nuclear needs to be part of that solution though.
That's cool. But just recognize that the scientific community disagrees. Though many have given up on even trying to push nuclear as being a minimal part due to these types of responses. I just want you to be aware of how your personal and non-expertise stance stands compared to the scientific community.
Being part of that scientific community, having gone to many lectures on the subject, having personally sat down and having beers with these friends, I think I can make that claim.
Also, if you don't believe me you can just fact check me. Search the internet. Attend a public talk, there's tons! I appreciate the skepticism, but your basis of doubt is that you don't like what I have to say rather than having some other reason to not believe me.
So yes, I would say you are being rude. Especially considering you are calling me a lobbyist. I used to work in radiation shielding and no longer do. I even used to work with the DOE. But I'm not even tied to those things anymore. Seriously, just go talk to some actual scientists. We love to talk about our research.
Most of the people I'm referring to are climate scientists. I'm not saying "nuclear scientists believe" I'm saying "climate scientists generally agree that".
But again, the rudeness isn't the skepticism, it is that the skepticism is caused simply because you disagree with me. I don't even see what expertise you have to disagree with as you're not even pointing to anything except "la de da." You have no evidence that I'm wrong, and I don't expect you to find any (though of course there are scientists that disagree, but that's not what consensus means. Nothing is absolute. You yourself said this). The DOE has plenty of talks that are public (online and in person), I encourage you to attend one, or several. Mostly because they are interesting and I think anyone interested in climate should. And to clarify, DOE is doing a lot of the climate modeling. Yes, they also handle nuclear, but they do far more than that and it isn't the same teams of people.
So either I'm shilling for an industry I'm no longer in, or your preconceived notions are wrong. I'm a bit peeved that your response to me disagreeing with you is to claim that I'm a lobbyist. There is no conspiracy going on here. It doesn't even make sense considering how costly nuclear is and how small of a percentage it is of the power sector. Jumping to conspiracy is a bit odd.
You're very vocal in this thread but your comments don't demonstrate basic knowledge of climate nor nuclear technology. Maybe sit this one out and go to a few lectures before coming back. I'm happy you're passionate. This is a subject I deeply care about too. But in science you have to constantly ask yourself if your preconceived notions are wrong. Because frankly nothing is "obvious" as the general public likes to claim.
But I don't have anything else to say here. You can continue to believe I'm part of this big nuclear conspiracy theory but I just want you to know how insane that sounds to me and others here. There's much simpler and more obvious explanations that this grand conspiracy. Especially since we're also advocating for renewables. I can't even figure out how your conspiracy theory makes sense (yes, I know you're not the only one that believes this). Like why would a conspirator ask you to get more informed in the general principles like climate and renewable energy? I don't get it and I don't think I will ¯\_(ツ)_/¯
> If John Oliver dedicates a whole episode to that problem
I'm not sure. He also got a lot wrong. Here's a response from an environmental scientist that specializes in nuclear waste disposal[0]. Honestly that episode caused me to be more critical of him. Of course it is always easy to fall victim to the Murray Gellman effect, but we should try our best not to and if some authoritative source is incorrectly characterizing a field you're intimately familiar with, you should be more careful with that source in the future. I mean he is a comedian first and foremost and the conclusion does essentially come down to "experts are dumb" which is a little insane to hear and rather insulting. Especially with a topic that is extremely complex and difficult to understand.
Many view fission as a stop gap to fusion. I also think the scale of nuclear waste is vastly over estimated by the general populace.
Generally, it produces very little waste in terms of spent fuel[1] and much of that can be recycled. That does require building newer, modern reactors though.
> The waste will be around for longer than we are. We have no solution other than 'lock it up'.
This is another thing that people don't really understand. Radioactivity is viewed as a monolith in pop culture. There's a perception that a radioactive thing will kill you in thousands of years. In reality, the length of time that something is dangerous is inverse to how dangerous it is, ie, the longer it's radioactive, the less deadly it is (and vise versa). Plutonium-239, the long term radioactive byproduct (24,000 years) is not that deadly [2] compared to the much more radioactive cesium-137 and strontium-90 which both have a half life of around 30 years [3].
> Logically, renewable and storage on a microlevel seems to make more sense.
Only assuming technological advances are made that we can't count on. Current day we don't have storage solutions that will do it, and most micro stuff doesn't work well enough to meet current demand anyway....
> Logically, renewable and storage on a microlevel seems to make more sense.
For northern countries where wind is the primary renewable sources, there does not exist any clean storage that is currently deployed and getting investments. The current "storage" being combined with renewable are fossil fuels, primarily oil and gas. The subsidize for energy stability goes to fossil fuels, the investment for bigger reserve capacity goes to fossil fuels, the national energy plan here in Sweden as an example is fossil fuels for stability and renewable for cheap production.
Lithium batteries as an example are great when the charge cycle and capacity is measured in hours, like for solar. It works, it is cost effective, and it helps reduce the dependency on fossil fuels. For wind you have charge cycles measured in weeks and capacity demand that can last months.
There are a few experimental project (likely heavily subsidized, and none that I can find that operate on buying wind power and reselling it weeks later), but the flow of money goes very distinctly towards fossil fuels right now. Nuclear provide at least an working alternative, and the occasional accident is a much better future than the non-accidental climate change that is occurring right now.
That said, I would prefer if we simple banned fossil fuels as a strategy to provide gird stability and forced the market to decide on storage vs nuclear.
Qualitatively, every choice is equal, because a qualitative argument can't distinguish between a big problem plus a small benefit and a big benefit plus a small problem. Quantitatively, you can make rational decisions. So, the answer to your questions are, "how much will building more reactors increase the accident risk," and "how much nuclear waste will be produced in the course of normal operation?"
This is a good point, 'how much’ is an important question.
But then, it seems society sometimes make the decision to take somethings off the table entirely.
I look at the accident at Fukushima, and earlier (when I was small child) Chernobyl and I can't help wondering whether some risks aren't worth taking when there are alternatives available.
I'm sure risk analysis was taken seriously in Japan. Often we miss things, and the people answering 'how much', quite frankly get it wrong.
All excellent questions, these should be addressed every time nuclear is considered.
I'm not sure existing nuclear is all that competitive with renewables+storage, but better designs absolutely could be. Better designs also wouldn't produce long-lived waste, and could also transmute existing long lived waste into short term. This will require R&D.
Increasing the number of wind turbines increases the risk of collisions with aircraft. What level of risk is acceptable to you? That's the question, not "will there be any increase in risk at all".
I think it's more akin to putting out a structure fire with water. You stop the immediate threat and save lives and some property.
And while some property damage will result because it's all getting soaked, it's still better to have something left than nothing, and while an un-burnable building would be nice, it doesn't exist yet.
There is no waste! Our descendants will regard it as magic/mysterious cultural heritage of long forgotten times, much like we do view the Pyramids of Giza today.
I like these guys but get annoyed at the 1kWH == 1 Typical House. While a case can be made that over a 24h period a house may consume 24kWh the fact is that "typical" houses burst to anywhere between 5kW and 10kW depending on appliances (AC + Freezer compressor + Oven baking a roast and boom you're at 10kW) As a result if you hook a thousand houses to a 1MW reactor you're going to get a crap ton of brownouts.
<raises hand>
Two EVs, electric oven, refrigerator, air conditioning here...
We installed solar when we moved in but would need massive storage to handle peak loads "locally" at our house.
Burst loads are the wrong number too. You still want to average over many households, but not average over wide swaths of time. Maybe you need to design for a peak of 75% of AC units plus 15% of ovens plus 20% of fridges being on simultaneously.
True, it is more complex than it might seem at first glance. One of my EE classes had us go out to a power plant to tour it and they talked about some of the complexity (because grid wide you get larger swings). They used to count on something like 80% of the households turning on the oven at 5PM while dinner was being prepared. They had actuarial staff that really dug into these numbers because some conditions would require starting up a 'peaker' plant and that took 3 - 4 hours to bring online from dead stop, about 1.5 hours from a "warm" start.
Would these types of systems not be great for drop-in replacements in natural gas electricity generation facilities? Much like natural gas can replace coal through a plant upgrade.
Not in its current iteration. The biggest advantage of natural gas generators is the possibility to ramp them up and down quickly, making them an ideal choice for peaker plants or load following. For nuclear, on the other hand, the options for throttling the output are quite limited - both physically and economically.
As a mitigation, combining them with battery storage would be an option, but then again it would still be cheaper to use wind or solar instead of nuclear as the source of energy.
Those work fine, but are not cost-effective power sources. They're more for isotope production.
There's a Russian reactor in this category, the RITM-200.[2] It's a land-based version of their current generation icebreaker power plant. This is one of the very few "small modular reactors" that actually exists. There are about 30 proposed designs.
Here's the first real power reactor in that category. From 1957. [3]
Some of the designs are not made to be refueled. In those the fuel gets loaded in at the factory and sealed up. Though in that case they are loaded up with quite a large amount of fuel (like a couple tons of plutonium for a ~30y lifespan)
In such designs you really would only need high security at the factory as stealing fuel from a reactor that is not meant to be opened (you would have to cut into it) and that is on without someone noticing is really really hard.
edit: Would also like to add that such designs are not actively being pursued anymore. The tradeoffs just are not worth it. We know how to securely transport fuel around so that is not that big of an issue really.
I once heard that stealing nuclear material from a reactor design like this was akin to stealing a lit bar-b-bq grill by hand. Not impossible but not very easy or practical.
It is, and it's standard practice. Suicide bombers are almost always part of a team that provides them with instructions and know-how, sometimes equipment and money, and first and foremost with a goal to die for. Also, lots of these attacks are part of a greater political scheme, and I would assume pretty much all attackers are aware of that. If your sacrifice means your side gets access to actual freaking atomic bombs, I mean, I could see that be pretty enticing.
And if not there's always the option to make people do lethal things against their will. People have been sent to their deaths by the millions over the course of history, that's totally doable.
IMO, dotting the landscape with such reactors is just asking for some state or other to take them and use them to leapfrog a lot of the effort required to build nuclear bombs.
You do realize the lengths states like Iran are going to enrich enough Uranium for a few simple bombs? If this works as a shortcut, it doesn't have to be easy or practical. And besides, it might be a lot easier if you don't care whether the people cracking the thing open will survive the ordeal, or whether radioactivity gets released to the environment.
If you treat these things like nuclear weapons they won't be very useful. Securing those bombs is enormously costly. You can't do the same for thousands or more of such reactors deployed for decades, all over the world, under civilian control.
Given that even the US Military doesn't have infinite resources, how can you guarantee there will be a fast response, or any response at all, or even that anyone will notice 20 years after deployment if someone with the resources of a nation state tries to get at that Pu? There might be wars where that reactor is deployed, there might be natural disasters, people might switch to 100% renewables and lose interest in the reactor, ...
My thought is, 30 years isn't enough. In 30 years you need to open the reactor and swap out the fuel, which is too tricky an operation (securing the fuel going in & out) to do cheaply and at scale. 30 years is within the lifetime of most people, so people are hesitant to cause a problem that they'll have to deal with. If these things can be buried in lead & concrete for 60+ years then maybe it'll happen.
If it pays for itself and then some then in 30 years you recycle the used reactors and replace them with new ones.
Recycling would mean sending the spent reactor back to the manufacturer who would have the tooling and skilled labor needed to safely open the reactor and extract the spent fuel (and then dispose of it safely).
How exactly are you going to steal the fuel from inside the reactor if it is running?
Only option is to cut into the reactor (and thus destroy it). And now you have just cut a hole into a nuclear reactor that is ON and killed yourself (or triggered a whole bunch of safety features stopping the nuclear reaction and maybe not kill the attacker but for sure notified the authorities)
Basically such a reactor is started once installed and never turned off until end of its lifetime.
> And now you have just cut a hole into a nuclear reactor that is ON and killed yourself (or triggered a whole bunch of safety features stopping the nuclear reaction and maybe not kill the attacker but for sure notified the authorities)
So somebody can strap a bunch of explosives to it and cause a good bit of quite radioactive material to spill (I don't mean a chain reaction, just the normal radioactive waste). You don't need to steal it if your goal is to have a dirty bomb.
That's certainly a concern - but if we're stipulating people with huge amounts of explosives and ill-will, they can probably also do a lot of damage without the nuclear reactor anyway.
The spill is contained within the containment facility. I guess they could use enough explosives to also breach the containment facility. But if they're capable of that, they probably have the means to do even more damage by targeting a skyscraper. Multiple orders of magnitude more people died in 9/11 than in Fukushima.
Right there's no huge containment facility, but there's still a concrete dome over the reactor isn't there?
I'm still not seeing how our hypothetical terrorist A-team inflicts more damage by attacking a microreactor versus attacking a populated area directly.
> Right there's no huge containment facility, but there's still a concrete dome over the reactor isn't there?
I'm pretty sure these aren't intended to be used with a concrete dome or anything as substantial as that. Look at the pictures in the article, and some of the referenced benefits:
Can be used for emergency response to help restore power to areas hit by natural disasters
- "Can be quickly removed from sites and exchanged for new ones"
- "Can be used for emergency response to help restore power to areas hit by natural disasters"
That doesn't really mesh with needing to build a concrete dome on site.
Regardless, the point remains: the question that needs to be asked isn't "are these sites vulnerable to attack" it's "can an attacker inflict more damage here than through conventional means?"
I'd imagine that a big concrete bunker in the ground effectively burying this thing would probably be pretty good security. Taking a look at how nuclear missiles are in silos and having a variant of that approach. Not saying it's the best approach, just that it's should be fairly solvable.
Then again, it is nuclear that we're talking about, so.....
You can have tamper sensors and a great deal of tamper resistance. Add canary pinging of a remote service and alerting and you can have an armed response team on site within minutes of any attempt to hack the thing.
Probably not really. It's much less than normal reactors - e.g. the infamous Chernobyl 4th block had 217 tons of uranium fuel in it, so a couple tons = two orders of magnitude less.
The micro-reactor designs I looked up generally fell into one of three categories:
1. Very high enrichment fuel because they need fast load-following, e.g. for naval use.
2. Very high enrichment fuel because they're for use in space, and lower mass is better.
3. Reactors for ordinary power use, with fuel that's enriched more than most, but still nowhere near enough to be practically useful for weapons.
An example of #3 is the Westinghouse eVinci micro-reactor, which uses fuel enriched to a little under 20% U-235. Weapons-grade uranium is closer to 90%.
People often confuse the difference in enrichment needed for weapons and reactors. Typically a reactor is 3% where a weapon is 97%. It becomes significantly harder to create that much enriched uranium which is why experts call Iran's production a bluff. Past their agreed levels, but nowhere near enough for weapons. The whole Iran deal relies on this fact actually.
What is the threat model for fuel theft? Weaponizing uranium requires enrichment well above even what maritime reactors use. Note that the difference between 90% enrichment and 99.9% enrichment isn't a factor of 1.1 difference, it's a two-order of magnitude difference - the remaining impurities need to be reduced by a factor of 100, each of those extra nines is another order of magnitude. And even if fuel does get enriched, it requires extensive nuclear physics research and engineering effort to produce a fission device. The only groups proven to be capable of this are state actors, which can set up their own enrichment facilities and have no real reason to steal uranium.
An alternative threat model is not producing a bomb, but dumping radioactive waste in a populated area. While damaging, radiation is a relatively slow killer save for the most intense doses. The amount of damage that it would be able to inflict is minimal relative to the amount of effort requires to break into a nuclear facility and exfiltrate fuel. The question that should be asked is, does this present a larger potential for harm as compared to the same amount of effort put into conventional means of destruction (bombing buildings, shooting up crowded areas)?
Enriching HEU to weapons grade is trivial by comparison to enriching natural uranium to even just 20%. Really, the difference in effort needed is enormous. Yeah, you still need centrifuges, but you need many fewer centrifuges and many fewer passes.
Also, you can make a bomb with uranium enriched to much less than weapons grade -- you'll just need a lot more of it compared to weapons grade uranium.
> Enriching 90% uranium to weapons grade is trivial by comparison to enriching natural uranium to even just 20%
Naturally occurring uranium is 99% U238, and 1% U235 (and some U234, but that's a trivial amount). 20% enrichment means that 80% of the fuel is U238. You only need to take out 1/5th of the U238. In order to weaponize uranium, U238 concentration needs to be reduced to 10% or below. You need to take out about 90% of the U238. Sure, if you're staring with 20% enriched uranium you'll need a factor of 20 less input material. But that's not very significant, uranium isn't particularly expensive. The factor that's limited by centrifuge capability is the final enrichment purity. That's why one of the main things nuclear weapons inspectors look at are centrifuges.
> Also, you can make a bomb with uranium enriched to much less than weapons grade -- you'll just need a lot more of it compared to 99% enriched uranium.
No, you can't. The presence of too much U238 prohibits a runaway nuclear reaction regardless of the amount of uranium. You can get fission from lower enrichment, but not runaway fission. It's like flare versus a firecracker. And that's a desirable trait in electric power generation. The main principle of weapons inspection is to ensure that a country's enrichment facilities can only enrich uranium to a purity sufficient for power generation, but below weapons applications. The height and diameter of the centrifuges are the main factors here.
I for one would love a molten salt reactor in everyones backyard. https://www.forbes.com/sites/llewellynking/2020/10/13/new-de... Maybe a scaled down version that could be deployed in communities thereby decentralizing electrical generation and distribution.
So, do these operate on the same design principles as the various Gen 2 reactor designs that have been involved in nuclear accidents, e.g. Three Mile Island, or Fukushima? I raise this question not out of an anti-nuclear hysteria, but a wondering if the safety issues that seem inherent in those designs are addressed in these micro-reactor designs.
I'm not particularly worried about shutdown mechanisms, but more so about containment of decay heat after an emergency shutdown event. By my understanding, our current reactor designs still produce decay heat for a time after shut down, and that heat still needs to be dealt with. And it was this decay heat and the failure to control it that lead to the Three Mile Island and Fukushima incidents.
Decay heat isn't a concern for naval reactors because 1) they're much smaller than a commercial power reactor, with order(s) of magnitude less output, and 2) they have the ocean to use as a heat sink to prevent overheating. Micro-reactors probably also have the first advantage, with outputs ranging from 1-20 MW. However, 60-1200 kW is still not as easily shrugged off when you don't have an ocean to dump heat into. IME, 60-1200kW is enough to heat steel, if not to melting, to certainly a loss of strength, and that does give me some worry about damage to containment.
So I guess my main concern is thus: Are these things being designed to be able to safely shed their worst-case heat completely passively in an emergency?
If so, awesome, and I look forward to the possibilities these designs open up.
The shutdown mechanisms are specifically about the containment of heat. The problem is generally about a reaction not being shut off. Gen 3 and beyond reactors, which includes these, don't have these problem at all. But neither do Gen 2's, anymore.
But if we're going to talk about the 3 accidents, we should note that they are quite different.
Chernobyl was a positive pressure reactor. Only the Russians were ~~dumb~~interested in building these. Everyone else was afraid because their ability to explode and instead chose reactors that couldn't explode. The accident happened not just because of this, but because the xenon spike and not a great understanding of the science.
TMI had a bunch of things go on at once. Relief valve stuck open but indicating close. Not enough water during SCRAM. Turning off ECCS due to bad indications. Then the hydrogen explosion. Resulting in about a dental x-ray's worth of radiation for a limited number of people. We now have hydrogen absorbers and have upgraded reactors to ensure these events don't happen again. [0] (this channel also talks about all the events).
Fukushima was caused by the largest earthquake and tsunami ever recorded in the region (so lower bounding to 1k year event) and one of the largest ever recorded anywhere. The reactors were designed to withstand quakes and tsunamis. The tsunami and earthquake were much larger than anyone expected to ever happen in the region. Reactor got destroyed and it is hard to track where all the material went, which is why they have the region closed down (background radiation levels aren't so bad, but you don't want to risk consumption of reactor material. Similar to why the surrounding area of Chernobyl is closed).
The reason I bring all these up is because we should note that even Gen 2 reactors have been retrofitted with improvements from these events, and have been this way for a long time.
> The shutdown mechanisms are specifically about the containment of heat. The problem is generally about a reaction not being shut off.
Indeed? I was of the understanding that the shutdown mechanisms were specifically for halting the chain reaction, and largely a solved problem with mature tech, and it was containing the decay heat of Gen 2 designs that was the trickier problem.
I am happy to be wrong about the latter, though perhaps not as happy to be wrong about the former.
If the reaction is shut off then heat will decrease, not grow. So like TMI is an example where they thought the reaction was quenched but wasn't actually, due to bad sensors and other sensors not being near one another/easy to compare (this is fixed and obviously sensors have become more reliable since then). The reaction won't start up again without some source. If reactions were easy to maintain we would have had nuclear reactors long before the 50's.
These could have been fielded at any time in the last three decades. That they haven't been may be a consequence that they offer relatively little scope for the wholly-legal institutional corruption that has driven nuke power construction throughout its lifetime in the US.
When construction costs are allowed to balloon 4x-10x over quoted cost, the great bulk of that amounts to a conduit from the public purse to private pockets over a decade or more. Projects where that is possible out-compete projects, for backing, that merely promise normal value for money spent. We see this dynamic not just in nuke projects, but in urban transit tunnels, military and manned-space procurement, fusion research, and abortive bullet-train projects.
That we do not see it in most current solar and wind power projects with, instead, costs plummeting well below anything than could ever be matched by nukes, may be a consequence of some combination of the projects' short terms, idealistic contractors, and dead-simple accounting. It will take decades to drive costs back up to where they will be good conduits for corruption. It remains to be seen whether hydrogen projects can be made to serve in such a role, but there is strong demand.
I wonder if it would be feasible for a neighborhood to get together and get one of these for everyone to share. In theory 1MW powers about 400 homes. Or for a new development to put one in and tout "free electricity for 50 years" as benefit of the development.
Or a condo complex getting one with their condo fees.
You seem to have overlooked the refreshment expenses!
"The agenda included three items: approving the plans for the plant, discussing a new bicycle shed for employees, and the refreshment expenses of the Welfare Committee."
Which is actually really important because heating and cooling are big contributors to climate that aren't as obvious as electricity and transportation.
There's actually interesting issues with how property paid for through mortgages are impacted by nuclear regulations. I recall something deep in my mortgage about how (I think) the nuclear regulatory control act placed restrictions on local use vis a vis nuclear energy.
Large reactors are usually 4GW thermal power converting to 1 GW electric, so you're going to get, I don't know, 10%-25% electrical conversion efficiency out of this, so 0.1MW to 5MW of electrical power.
On the plus side you can probably dual-use this to run communal home heating systems, maybe even hot water.
It'd be great for cold-climate towns (or space-colony applications) provided you can get some funding together.
Hey we know what is going to be the hot product to buy for bitcoin miners :-)
I was thinking about data centers (20 - 50MW) and a "farm" of them to provide N+1 redundancy would be an interesting thing. 99% carbon neutral as well.
...which plays in the same league as any large and modern wind turbine.
Minus the proliferation risk of somebody stealing this comparatively small reactor and builds a dirty bomb with it - oh, and you still have to dismantle it and store safely for millenia after use.
No, thanks... looks to me like nuclear is dead in the water.
> Minus the proliferation risk of somebody stealing this comparatively small reactor and builds a dirty bomb with it - oh, and you still have to dismantle it and store safely for millenia after use.
No, thanks... looks to me like nuclear is dead in the water.
The proliferation risk seems like a valid concern, but that we have to store radioactive material for millennia isn't a valid criticism of nuclear in general because we already have to store nuclear material and the costs associated with storing more waste are marginal (if you can safely store a little nuclear waste then you can safely store a lot of it).
Nuclear is perfect for district heating. Thermal power plants have poor efficiency because of the need to convert thermal energy into electricity. You basically get a whole load of waste heat. If you do need the waste heat then you can't beat thermal power plants.
> minus the proliferation risk of somebody stealing this comparatively small reactor and builds a dirty bomb with it
Using that logic, we should stop production of ammonia fertilizer.
> and you still have to dismantle it and store safely for millenia after use.
The fact is that the entire worlds nuclear waste can be contained in about one swimming pool, which can be placed in the middle of a mountain or some other geologically stable area. You can't say that about coal, or wind (junk turbines that can't be recycled), or solar. The death rate per terawatt-hour of generated nuclear is far less than any other fuel source.
The idea that Nuclear is a dead end has been made popular by pop culture from the 1970's and bad science driven by an agenda to keep everyone on a globalized fossil fuel monopoly run by the military industrial complex.
I consider Nuclear fission as necessary evil as we don't have other so efficient and same time devastating energy source. However, we as a human kind have left this technology not developed as much as we could from efficiency and safety point of view. With my youtube degree in nuclear physics I would say we are somewhere where internal combustion engines were in 1930ties.
Made me think of a seemingly abandoned LLNL project for what is in effect an autonomous breeder cycle reactor that serves as a 30 year 100 MWe nuclear battery.
This goes along with the coronal mass ejection risk story that was on the front page a day or two ago. Is a nationwide electric grid even a good idea anymore? Yes, it's more efficient, but it's also more fragile, in that a failure in critical infrastructure can cause nationwide blackouts.
Imagine if most places had a microreactor, a small fossil fuel generator, renewable + storage, or some combination of these, and each small to medium sized community of homes had their own. Things would go wrong all the time on the small scale, but there would be no such thing as a nationwide blackout.
This is interesting, because usually I see nationwide grids being touted as MORE resilient, not less. The idea is if power is knocked out in one area, you can still get it from elsewhere. This came up a lot during the Texas situation.
Texas is what I would still consider a "nationwide" power grid. I was thinking of something very very decentralized, like individual neighborhoods. It wouldn't completely solve what happened in Texas, but blackouts would be contained to small areas for hopefully shorter amounts of time, as failure in one area would have no effect on other areas, and individual neighborhoods could probably coordinate and conserve power usage as needed better than an entire state.
I think there's a balance. You want a slight surplus in your local area and connected so you can pump it somewhere else when that somewhere else goes down. Though IIRC Texas has far more problems than just not being connected (also far more than just renewables either, which was a big talking point).
IANAElectrician, but IIRC the biggest problem isn't the grid size per se, but how grid operation requires always matching the amount of power coming from all producers and the amount being used by all consumers. Like a tightly-sealed water-pipe system where the pressure is uniform throughout, and too much pressure pops things, while too little won't go anywhere.
So it's a coordination problem, and ideally you'd have a big-grid which can be arbitrarily partitioned (and recombined) to ensure producer-consumer matching as you get more and more of each involved again.
It's one of the few cases where the phrase "smart home" doesn't make me cringe: Imagine a neighborhood of houses in a brownout situation all coordinating to dim the lights and space out their high-energy usage, like running refrigerator compressors.
A better national grid for renewables will be hugely redundant, with few single points of failure, because renewables are distributed throughout geography.
If something takes out that sort of infrastructure, it's probably going to take out the local micro reactor too.
Existing solutions for micro grids are getting super cheap too, if we didn't already have tons of transmission built out, starting a grid from scratch today would probably include not only far less transmission, but far more storage, which also hugely increases resiliency.
Having tons of storage and solar right behind the meter, by which I mean 10%-40% of buildings, would hugely increase the resiliency of the grid, if utilities would embrace the Information Age build bottom-up infrastructure in addition to top-down.
Are there examples of how a failure at a power plant could affect the national grid?
As mentioned by another comment, one advantage of a national power grid is the ability to transfer power from other places during power failures. But I'm not sure how a power failure would affect the rest of the grid.
> Are there examples of how a failure at a power plant could affect the national grid?
A failure at any single power plant is very unlikely to cause cascading failures in the rest of the grid because one power plant usually can't generate enough power relative to its grid.
Gross oversimplification but all of the power plants in a national grid are essentially coupled together [1] as a giant circuit made up of a ton of electromagnets - the generators converting coal/natgas powered steam or water/wind to electricity. These electromagnets are all operating at the same frequency in phase with each other which literally means that the generators spin in sync at ~60hz. These generators are often (usually?) heavy turbines with a lot of angular momentum so normally when you connect a power plant, it stays in phase just due to the sheer inertia of the rest of the grid because power follows phase [2].
When the phase changes suddenly - like when connecting a generator that is out of phase with the grid - all that inertia of the generator essentially slams into the electromagnetic force generated by the incoming current. If the rest of the grid (of hundreds/thousands of other generators) produces significantly more power, it'll just destroy the connecting one as if you brought a turbine powered jet engine to an instantaneous dead stop - the momentum of the blades will literally rip them off of the shaft. However, if the newly connected generators are producing a significant amount of power relative to the rest of the grid, like when a corona mass ejection hits or a large islanded subgrid is poorly reconnected, the resulting differential can generate a wave (again, gross simplification) that travels through the grid with enough power to destroy every single generator connected to it.
A single power plant just can't generate enough power to do damage to the rest of the grid [3] but if a natural disaster severed the connection between two regions of a grid and they drift out of phase, they must be carefully reconnected because they might have enough power to seriously damage other power plants.
[1] Some parts of a grid might be separated by HVDC which in effect isolates the parts
[2] Power flows from the faster generators to the slower ones, speeding them up until they hit equilibrium.
[3] There are exceptions depending on grid topology, but generally grids are designed to avoid them
Nuclear has quite a few major perceived problems: bureaucracy/authoritarianism, uranium (fuel) reserves, capital-intensive projects, risk of accident, proliferation, waste disposal, real decommissioning costs...
One of them is the NIMBY effect, and it may be a show-stopper for such microreactors, which need to be produced in large batches in order to be affordable. I can't imagine how a sufficient amount of them will be accepted by the population. Even maritime underwater versions will probably be rejected.
This is a utmost clever and when well executed safe way of ditching the waste product from large nuclear powerplants in everyone his backyard.
I remember reading about a japanese ( i think Toshiba produced ) microreactor some decades ago only to find out that it ran on ordinary decay and exothermic reactions.
Actually nothing but a fancy battery that converts heat into electricity. Not a /reactor/ in the meaning that springs to mind when reading the word.
I watched a video about the economics of nuclear reactors and the main focus was that the time it takes to break even is much longer for nuclear reactors if compared to coal and natural gas. Couldn't something like those microreactors solve that problem?
The main issue is that the first thing you have to do is secure your financing then you're paying interest on your loans over the near decade it takes for the regulatory approval apparatus to do its thing. If this allows you to get approval for a one reactor site with the right to expand to 24 more reactors of a given design without re-approval it might be very significant.
The other issue is that each nuclear reactor site is effectively unique. So there's whole piles of paperwork that need to be checked and re-checked to ensure that all procedures and everything is correct and up-to-date.
With small modular reactors and similar, all the critical bits are made on a production line, and completely standardized. This will drastically reduced the paperwork and training needed to operate it safely.
That's the goal smaller safer and economies of scale, PowerPoint size reactor complexes are rarely built and are one off designs with high level similarities.
What if we socialized production of these, turned them out in quantity, to be owned and monitored by the Department of Energy, in order to increase national security.
Not only that, but global warming is slated to destabilize many regions of the planet. The quicker we can move en masse away from oil, the less severe that transition will be.
"When goods do not cross borders then soldiers will."
Trade keeps people from trying to take things, and when they take them, they prefer to take them off of corpses. Isolation leads to jealousy and we're already isolated enough.
You’re saying we should be in favor of fossil fuels because it will.. prevent war? Gotta imagine the Middle East might have some experience here with regards to the peace bringing properties of oil.
Ah oil, the path to peace for so many countries! No but in all seriousness there certainly must be better goods to trade which could replace oil, if peace is the goal.
Last year, yes, for the first time since 1949. But even in 2020, we were importing more crude oil than we were exporting. The difference was due to the refined products that we exported.
Hydro power runs on water,best if its not all full of radiation so you can drink it.
Wind power runs on air,be nice if it was a lot cleaner for breathing purposes and real bad if it was all nuked up.
Solar power runs on light of a bright sunshiny day,unlike nukes with that deadly glow in the dark
Nuklear scnooklear go away.
Hydro power runs only where there is enough water moving.
Wind power runs only when there is enough wind.
Solar power runs only when it's sunny enough, and never at night.
Batteries are not nearly good enough to smooth this out.
So ... all these things are great, but not enough to replace fossils practically at current tech.
Are they hinting at e.g. the option of using these for a similar blackout to the recent Texas one.
Just ship in as many of these "on demand" and handle momentary demand spikes.
Quite far - miniaturization of nuclear reactors is generally quite hard.
We haven't put much effort into miniaturizing terrestrial reactors, and naval reactors have other design concerns which limit, but space reactors are a good gauge of the state of the art. From the (production!) American SNAP reactors of the 60s and the contemporary (production!) Soviet BES-5s, to the current Kilopower design studies and prototypes, there's been basically zero progress in reducing size. Fission has some hard floors on reactor (and bomb) size, because of the logic of criticality.
That design floor for power reactors is quite large - the core itself is usually on the order of 50-75cm long by 20-30cm diameter, but the heat-to-electric conversion machinery and, more importantly shielding, will quadruple or quintuple that length.
And that's with the cheats enabled by space applications, where you only need to shield in the direction of the spacecraft. For general use a similar design would fill a shipping container, like the linked microreactors tend to.
Fusion is maybe a more plausible route to small power sources on the order of decades, because there's a clear parameter to tweak: magnetic field. Better superconductors -> stronger magnetic field -> smaller minimum size.
I appreciate you taking the time to answer rather then just downvoting me :)
Sounds like pretty much what I would have expected in terms of limitations, so we'd need something much more energy dense (Like fusion) and a more compact way to remove the heat and convert it to power.
Note the "more importantly" - one of the reasons the conversion machinery is bulky is because you need all that space for radiation shielding anyway, and the conversion stuff tends to serve dual purpose.
Active nuclear (fission or fusion) reactors put out a lot of radiation, much more than even high-level waste.
Quite a few... The issue isn't so much on the nuclear side as it is the size of thermal energy recovery systems. Attempts to miniaturize turbines haven't worked super well, though they have been made since a bottle of fuel has a much greater energy density than most batteries.
The Navy has some great small turbine systems (although they typically use the ocean as a big thermal sink for their re condensers), and the folks who design geothermal plants could have a role here if they wanted, but so far not much work there that has appeared in the sources I tend to scan.
As a result I'm concerned that these things with hit the market with no "shovel ready" plans to put them into production, and the lag between that and when you can put them in production will kill the reactor developers. I have seen it in other industries and it hurts to watch it unfold.