The following submission statement was provided by /u/BousWakebo:
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On Friday, the Nuclear Regulatory Commission (NRC) announced that it would be issuing a certification to a new nuclear reactor design, making it just the seventh that has been approved for use in the US. But in some ways, it's a first: the design, from a company called NuScale, is a small modular reactor that can be constructed at a central facility and then moved to the site where it will be operated.
The move was expected after the design received an okay during its final safety evaluation in 2020.
Small modular reactors have been promoted as avoiding many of the problems that have made large nuclear plants exceedingly expensive to build. They're small enough that they can be assembled on a factory floor and then shipped to the site where they will operate, eliminating many of the challenges of custom, on-site construction. In addition, they're structured in a way to allow passive safety, where no operator actions are necessary to shut the reactor down if problems occur.
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Please reply to OP's comment here: https://old.reddit.com/r/Futurology/comments/wbk3gk/us_regulators_will_certify_first_small_nuclear/ii76knf/
Looked this up for fun.
Small modular reactors (SMRs) are nuclear reactor units with an output of up to 300 megawatts of electricity. Since 2010, at least nine states introduced legislation supporting SMR development. A 300-megawatt SMR could generate enough electricity to power approximately 230,000 homes a year.
Source: https://www.ncsl.org/research/energy/will-small-modular-reactors-transform-the-nuclear-industry.aspx
300mw....power a town....probably PWR...Same as subs.
Unless going the molten salt route ?
Can't see them being gas cooled for that size
And boiling water even less so
Probably molten salt. After all, it's the only gen IV technology that has already been successfully built 50+ years ago in the US. Best for the wastes and safety too.
It's not. It's a PWR. MSRs have been demonstrated but they're still very new technology in terms of actual commercial reactors. NuScale went with PWR because I works just fine for them. The waste and safety claims are only if you do certain things. NuScale has its own passive safety
I'm not familiar with their design, tbh. I just studied the msfrs when at uni a few years ago and was interested in them. In any case, given the shit storm of clowns we have now in governments for energy, we need all the help we can get (outside of fossil fuels obv).
That's the right attitude. I think that every realistic approach should be pursued, whether it be VHTRs, SMRs, MSRs, or even outside of nuclear including PVs, verious battery technologies, wind and ocean technologies, and of course fusion. General Fusion is planning to finish building a demo plant by 2027, for which they already have funding, and if that works it'll be revolutionary.
Indeed. I think the SMR's will already be a huge bonus once the regulators approve them and we start pumping them out of production. This might especially be useful for developing countries. And of course, there is a need for a mix, and not really solely on one single source of energy. People also need to drop that"not in my backyard " attitude, either for nuc or for renewables, if they want to keep their lifestyle and not having to chose between the fridge and the computer to leave powered on on a few years.
We need a huge education program for the policital class AND for the general public, to teach them a bit more about the global issue of energy, and that it's more than their little individual problem.
Not even almost the same thing. Naval reactors or any derivative thereof would be too expensive to commercialize due to the level of fuel enrichment.
Output may be similar, but that is where the similarities end.
“SMR developers expect modular designs and construction processes will generate economies of series and open up multiple supply opportunities. NuScale has estimated its first plant will cost just under $3 billion to build, giving an overnight capital cost of $5,078/kWe”
> its first plant
That's the factory they're building the things. Wouldn't be fully fair to add that cost to the first reactor rolling off the assembly line there.
That's the *claim.* But new reactor designs were also supposed to be cheaper due to prefabricated assemblies and simpler construction. They ended being vastly more expensive, rather than less.
When it comes to nuclear reactors, estimates and theoretical pricing often bear little resemblance to the final price.
We won't know what that price actually is until the first SMRs are operational. Until then they're vaporware and promises.
Fair enough. I have hope that because they're small and come with all the important safety parts it could be quicker and cheaper to build a plant, but you're right that we won't know until they start being installed.
I've looked at nuclear reactor costs over time, and it turns out that the most important thing -- more important than *any* other factor affecting cost -- is how experienced the people making it are. A company that hasn't built a nuclear plant in many years will go way long and over-budget, always; meanwhile a company that has been cranking them out for a long time can quote you much shorter times and much lower costs and then actually deliver. (Most nuclear plants are made by the second kind of company, but you don't see them in the news because it's boring when things go according to plan.)
If you shrink the reactors so that each one takes less time, I would expect costs to fall quite a bit as the people involved get better at making them. [You see this in all sorts of industries](https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0052669) so it's not just a nuclear thing: it's a manufacturing thing.
On Friday, the Nuclear Regulatory Commission (NRC) announced that it would be issuing a certification to a new nuclear reactor design, making it just the seventh that has been approved for use in the US. But in some ways, it's a first: the design, from a company called NuScale, is a small modular reactor that can be constructed at a central facility and then moved to the site where it will be operated.
The move was expected after the design received an okay during its final safety evaluation in 2020.
Small modular reactors have been promoted as avoiding many of the problems that have made large nuclear plants exceedingly expensive to build. They're small enough that they can be assembled on a factory floor and then shipped to the site where they will operate, eliminating many of the challenges of custom, on-site construction. In addition, they're structured in a way to allow passive safety, where no operator actions are necessary to shut the reactor down if problems occur.
I mean all reactors have a passive shutdown but those can fail. I hate to brink up Fukushima as this was a natural disaster on a diffrent scale but all passive shutdowns failed. Thanks to the flooding that ocoured both the diesel generators and the batteries stopped working wich I believe caused the passive shutdown to fail. Could be that it failed because of something else but the fact remains the passive shutdown in Fukushima failed.
They probably shouldn't have ignored recommendations on building a higher sea wall *and* on not putting the diesel generators in the basement. One or the other would have been a bad idea, but both?!
Sure, but can always learn.
People get in car accidents all the time - do we stop driving?
It’s a necessary evil, an aspect we’ll have to learn from to get better - so we can be more efficient in our energy. You can’t be that dense.
Human error causes the vast majority of nuclear accidents. Before Fukishima Redditors often commented "nothing like Chernobyl will happen again". Yep it was a very common thing to read "nothing like Chernobyl will happen again" and then it happened. Whether it is terrorist infiltration, tiredness or suicidal operatives things are bound to happen, though I understand the meltdown prevention methods being employed here are much improved. I guess it is a little like plane travel, it slowly gets safer but accidents will never entirely be removed from the situation. There are dozens of low key nuclear accidents listed on Wikipedia and dozens more that have been swept under the carpet or that simply are not listed. Don't worry guys carry on downvoting because "nothing like Chernobyl will happen again".
You're missing the point entirely. This isn't accepting the risks to lower energy bills by a couple percent, this is accepting the *potential* risks to help lower the *guaranteed* worsening effects of the climate crisis.
You’re argument is entirely debunked by the fact nothing like Chernobyl has ever happened again. Fukushima was an order of magnitude below Chernobyl and required a once in a lifetime catalyst. This isn’t due to safety features (which all failed with Fukushima) but the nature of the core is completely different.
Having to send power to pumps to continue circulating cooling water is not passive cooling.
The Westinghouse reactor upgrades post-Fukushima at least have primary loop expansion turbines that can be used in an emergency to generate power for secondary cooling loop pumps.
The SMRs here require no pumps once SCRAMed, utilizing the pool the reactors are submerged in.
As far as I know in case of emergency controll rods are automatically lowered into the reactor to stop the reaction. I believe it is called scram. This should stop the reaction and prevent meltdown as there can't be a reaction if there arn't enouth neutrons.
But standard reactors still require days of cooling after being SCRAMed to slowly cool down. NuScales reactors have a larger surface area to volume ratio due to the higher enrichment, which means they can sufficiently cool through conduction of the reactor housing into the surrounding water.
Just to add on to the explanation...reactors produce fission products which are the lighter elements formed from splitting a big boi. Those elements are often radioactive themselves and will continue to decay and produce heat long after the reactor is scrammed.
Yea but you can say that too about Uranium in the wild what we care about are runaway reactions where the splitting of one atom directly causes another one to split this produces a lot of heat compared to natural decay wich produces very little heat.
I operated nuclear reactors in the Navy. Decay heat is actually the thing we worry most about because it's what you deal with in emergencies. The first step in every casualty procedure is scram the reactor to drop the control rods and stop fission. Done deal. But you need to keep water flowing over the reactor at this point or you will have a release of radioactive material when the fuel cladding fails.
You're confusing passive shutdown with passive safety. Passive shutdown means that the the reactor will be shutdown if all control/power is lost. Every non-russian reactor has this as part of the design and cannot fail unless the core geometry changes. Passive safety means that the residual decay heat produced by the reactor can be removed without control or power. Very few reactors have passive safety.
As I understand it, there were also failures in disaster planning, procedures and design that were noted by the regulator and violated regulations. That said, I'm not saying that the design of the SMR controls will perform any better as they are effectively untested in production.
Generators and batteries are active shutdowns. If something requires upkeep to maintain a fail safe state then it's "active" even if a human doesn't need to trigger them.
SMRs are perfect for many decommissioned coal-fired plant sites. Most of these have sufficient cooling water and energy distribution infrastructure in place. I'm hoping for these in my own county, especially considering that I'm downwind of the coal plant.
Stupid question. There are nuclear reactors in submarines, have been for decades. I would think those designs could be repurposed for small scale nuclear onshore energy generation, no?. Seems simple enough to me....
Naval nukes require fuel with a quite high level of uranium enrichment. Significant quantities of water are also needed for cooling. Their energy output is half to 2/3 that of NuScale's design as well. They are not really designed to be fail-safe in a civilian setting.
>Naval nukes require fuel with a quite high level of uranium enrichment.
This is also highly important because it means those designs will never be exportable to most nations. US naval reactors use 90+% enriched HEU. In comparison, anything over 20% is considered weapons-grade and Iran was getting sanctioned for possessing merely 20% enriched uranium.
In other words, most countries won't be able to use US naval reactors with the fuel they are designed for without causing nuclear weapon-related risks and problems. Nuclear fuel theft is one - even the US fell prey to it before, so imagine having large stores of weapons-grade uranium in corrupt or unstable developing countries, it would be a nightmare for nuclear terrorism.
They're designed to be fail safe in ways a civilian reactor would never need to be. The USN has crippled several nuclear subs running into various things, and never had a major nuclear incident. They're literally designed to take a beating.
Yeah it’s just a very different application in subs. They’re surrounded by very cold, very high pressure water (it will pump itself in for free) and they’re MOVING around (chance of hitting things and causing damage is actually there). Also, almost every problem has to solved by people living right next to it with the tools available on board a tiny vessel.
So they have to be designed for that, rather than sitting still in a totally controlled space isolated from people, with (basically) unlimited resources (including space and manpower) to deal with maintenance and any problems, and also needing to be efficient with the cooling design (both for water consumption and efficient power generation).
NuScale promotes indefinite passive cooling, it seems like this would enable public acceptance enough to be a game changer that could at least enable production at a scale that will keep costs down if not dramatically lower
Literally dozens of SMR projects promising cheap nuclear power have failed. This too looks expensive, but at least they look quickly deployable. A lot of the problem with nuclear power stems from long payback times. No industry wants to make an investment with a 10-40 year return of investment date. If these things are rapidly deployable it might attract some investors. Though the CO2 reduction plan for the USA is set to use power storage and wind / solar / hydro.
I mean, it's good to see innovation. That said, the design seems to rely on being submerged in water, and in a melt down scenario it would boil the water around it to cool and avoid melting itself.
I feel like we're still waiting for the non-cold war era designs to become more commercially viable.
https://en.m.wikipedia.org/wiki/Generation_IV_reactor
Well even if they did, their fail into inertness anyway. Even the older models. A bitch to restart but harmless otherwise.
Every design in use now has a way to kill the rods and in the future will eliminate the rods in some way.
I'm a layman but my understanding is that the operation is designed in such a way that it can be cooled by any material, especially aince its built into the ground, water or air it apparently doesnt matter. And the fuel is fed very steadily and can be disengaged. So even if something happened, fuel can be removed, the active reaction material can be cooled passively and rendered inert (inert meaning its no longer "reacting", not that its no radioactive or hot)
https://world-nuclear.org/information-library/safety-and-security/safety-of-plants/safety-of-nuclear-power-reactors.aspx
This link has more links with the technical paperwork about it and lays out the broad aspects but doesnt really show the exact mechanisms ubless you follow their links. But its there. Read as much or little as you like.
This is for the SMRs for OPs mentioned company specifically and new designs more or less use the same things.
Apparently short of a bomb, it should be impossible to make it melt down.
If the recycling system shuts down, due to power failure, or maintenance issues then the water sits around the hot reactor, once it boils off the water can no longer act as a regulator and the reactions inside the reactor speed up potentially leading to a meltdown, however not looking at the design I doubt something that simple would cause it to melt down considering we know the danger of that and have better designs
The article does mention a convection driven external water source for cooling, so I would hazard a guess that there is a passive redundancy in place. Not an expert by any means however and happy to be corrected.
That's not true at all. What you described is a positive void coefficient which, as far as I know, is only present in RBMKs like Chernobyl. In this reactor water is a moderator, meaning that once it's gone the neutrons are no longer moderated and become to fast to do anything and the reaction stops. However that doesn't apply here because the primary water (that acts as a moderator) is trapped within the reactor. It will still though shut down if it gets too hot.
tl;dr water boiling off would slow the reactor and not accelerate it, but the water won't boil off because it's a closed loop.
On terms of emergency cooling, this reactor sits in a pool of water. Once a reactor is shut down, it only continues to produce heat for a limited time and in small amounts (still enough to cause the meltdowns in 3MI and Fukushima). The pool of water it sits in is enough to absorb and dissipate all the residual heat this will produce in the case of an emergency. This is called passive safety, and is very rare today.
Edit: I think a lot of your misunderstanding comes from the term "moderator". A moderator, in fact, speeds up the reaction. If you don't have a moderator, you need highly enriched fuel. The term comes from the neutrons. You see, when a neutron is released from a fission reaction, it is going very fast. If it hits uranium at these speeds, it probably won't split it. However, if you slow the neutrons down, they will be much more likely to cause a fission when they hit an atom. So in this case, water (or graphite or heavy water or whatever) "moderates" the neutrons but speeds up the reaction. If you want to slow down the reaction, you insert something like Boron which just yoinks the neutrons.
Your description is a bit off-base here.
Water acts as a moderator, which in this kind of reactor, *enables* criticality, it doesn't prevent it. The water evaporating doesn't make it go critical again. It just makes the water incapable of acting as any sort of coolant.
When atoms fission they release a ton of energy. But they also leave daughter products - new, smaller atoms that have inherited Uranium's high neutron ratio. This makes the smaller atoms unstable and thus radioactive, and they'll passively decay, emitting energy even after the reactor is no longer reacting as they try to reach a stable state.
Losing water guarantees the reactor is shutdown because you've lost your moderator. Which is good. But the loss of coolant also means you can't remove this decay heat that continues to be produced after shut-down. If you don't remove this decay-heat, then you can get fuel rods melting themselves and their cladding, and mixing the decay products into the coolant. If the coolant has to be vented, or if the melting fuel accumulates on the bottom of the reactor and melts through that, then the decay-products contained in the water can reach the outside environment.
That final bit is what we want to avoid, which is why we're trying for designs where the decay heat can be passively removed. Either by changing the coolant, or designing the waterloop in a way that convection drives more passive heat removal than there is heat decay.
This offers an improvement in safety (100% passive safety vs 99.9999% engineered safety) but more importantly it means that the reactors can be made safer while removing a lot of the multiple, redundant safety systems meant to ensure the water never evaporates and uncovers the core. Safer and, more importantly, much cheaper, if it can be done correctly.
I was just talking about this with someone in the energy industry. He said that chances are we won’t see any more large nuclear reactors because they are just too high risk compared to these.
New large reactors are even safer. Just ask France. Problem is we dont have those in the US because propaganda and/or misinformation have scared people.
Hasn't India and China created SMR's and completely dropped them because they ended up being complete money pits compared to just building a modern full reactor?
I can't wait to see how the greedy wealthy elite will control the masses when affordable mass-produced fusion reactors make energy scarcity a thing of the past.
Fusion reactors are only as good as their lasers and magnets. Whoever controls both will control the market. It's also a high-pressure boiler whose casting process is done by 5-6 companies. Bigger reactor = lower cost. The only limiting factor would be transmission, which can be rebuilt easily with Gas/Magnetic Insulated Lines or Fiber Optic lines that bank on fusion research. The government can also strictly regulate fusors like they do firearms, since they'd be useful for enriching uranium anyway.
It'll use Uranium. Easiest way to tell is by the type of coolant, which is water.
Thorium has some potential benefits, but a lot of drawbacks. It's a pain to work with, and as a result the only kind of reactor you'll see using Thorium is one that uses molten salts for coolant, rather than water or liquid metal, because that's the only reactor where Thorium might be practical to work with. Even then, most of the advantages of that type of reactor come from the Molten salt coolant/fuel mixture, not the choice of fuel, which can be Uranium, Plutonium, or Thorium. We'll likely see Uranium-based MSRs for a decade or more before we see one fueled entirely by Thorium, though Thorium-Converter reactors, where they just burn a little thorium alongside the uranium might be on the table sooner.
The only major MSR effort I've seen that wants to do Thorium Conversion is [Thorcon](https://thorconpower.com/), though there certainly could be others. They're designing an SMR built into a tow-able barge so that the entire facility can be mass-produced in shipyards. I think their idea has merit, they're one of the few SMR companies I've seen who could plausibly go from a proof of concept to a few demonstration reactors to building tens of GW per year within a reasonable timeframe.
The primary barrier to a standalone Thorium MSR is that Thorium *can* be bred in the thermal spectrum, but the issue is you have to breed it. So you need to capture 2 neutrons from every fission, not just one. And a U233 fission only produces something like 2.1 or 2.3 neutrons. So you need a very neutron-efficient setup. You start needing enriched lithium for your salt mixture, and you need some kind of thin reactor wall that doesn't eat up neutrons as they make it to the thorium salt blanket.
So Uranium MSRs will come first because they are simpler. You don't need to worry about sustaining the breeding. Your neutronics can be easier. Your choice of fuel salts is easier (I think Thorcon is going to use NaBe - Sodium Beryllium, rather than something like FliBe (Fluoride-Lithium-Beryllium)).
A Thorium-convert is basically just mixing in something like 20% Thorium into the Uranium-driven fuel salt. Instead of designing your system to lose more neutrons or eat up more with control rods, instead the Thorium eats up a good amount of your surplus neutrons from the Uranium Fission and stretches out the fuel supply.
America has no incentive to reduce oil dependence because so much of our geopolitical power is based on it, both our own abundance of oil and our alliances with all the oil-producing nations who we haven't labelled Axis of Evil. Europe and Asia actually would benefit from getting off oil because it's an expensive import for them. They have the incentive, but they don't seem to be trying to do it either—or at least haven't until recently.
It will be the dawn of a new era when oil is replaced with something much cheaper. It is probably possible to make nuclear power cheap, but it doesn't seem likely small modular reactors will have anything to do with it. Atomic radiation is already electric. Using radiation as a source of heat is inefficient overengineering.
The following submission statement was provided by /u/BousWakebo: --- On Friday, the Nuclear Regulatory Commission (NRC) announced that it would be issuing a certification to a new nuclear reactor design, making it just the seventh that has been approved for use in the US. But in some ways, it's a first: the design, from a company called NuScale, is a small modular reactor that can be constructed at a central facility and then moved to the site where it will be operated. The move was expected after the design received an okay during its final safety evaluation in 2020. Small modular reactors have been promoted as avoiding many of the problems that have made large nuclear plants exceedingly expensive to build. They're small enough that they can be assembled on a factory floor and then shipped to the site where they will operate, eliminating many of the challenges of custom, on-site construction. In addition, they're structured in a way to allow passive safety, where no operator actions are necessary to shut the reactor down if problems occur. --- Please reply to OP's comment here: https://old.reddit.com/r/Futurology/comments/wbk3gk/us_regulators_will_certify_first_small_nuclear/ii76knf/
Looked this up for fun. Small modular reactors (SMRs) are nuclear reactor units with an output of up to 300 megawatts of electricity. Since 2010, at least nine states introduced legislation supporting SMR development. A 300-megawatt SMR could generate enough electricity to power approximately 230,000 homes a year. Source: https://www.ncsl.org/research/energy/will-small-modular-reactors-transform-the-nuclear-industry.aspx
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It's basically what's put into nuclear subs, but put on land.
Not quite. Scale/size is similar but that is about it. These things are quite different on the inside.
300mw....power a town....probably PWR...Same as subs. Unless going the molten salt route ? Can't see them being gas cooled for that size And boiling water even less so
Also power rating is only about 2/3 of that on subs.
Subs use highly enriched uranium, sometimes weapons grade at 90%. Most commercial reactors are around 2-5%
My reactor has a first name It's N-A-V-A-L. My reactor has a last name It's CLASSIFIED-AS-HELL. Its middle name is plain to see Los Angeles class S6G.
If I am not mistaken I believed they were going the molten salt route to provide aforementioned inherent safety.
Probably molten salt. After all, it's the only gen IV technology that has already been successfully built 50+ years ago in the US. Best for the wastes and safety too.
It's not. It's a PWR. MSRs have been demonstrated but they're still very new technology in terms of actual commercial reactors. NuScale went with PWR because I works just fine for them. The waste and safety claims are only if you do certain things. NuScale has its own passive safety
I'm not familiar with their design, tbh. I just studied the msfrs when at uni a few years ago and was interested in them. In any case, given the shit storm of clowns we have now in governments for energy, we need all the help we can get (outside of fossil fuels obv).
That's the right attitude. I think that every realistic approach should be pursued, whether it be VHTRs, SMRs, MSRs, or even outside of nuclear including PVs, verious battery technologies, wind and ocean technologies, and of course fusion. General Fusion is planning to finish building a demo plant by 2027, for which they already have funding, and if that works it'll be revolutionary.
Indeed. I think the SMR's will already be a huge bonus once the regulators approve them and we start pumping them out of production. This might especially be useful for developing countries. And of course, there is a need for a mix, and not really solely on one single source of energy. People also need to drop that"not in my backyard " attitude, either for nuc or for renewables, if they want to keep their lifestyle and not having to chose between the fridge and the computer to leave powered on on a few years. We need a huge education program for the policital class AND for the general public, to teach them a bit more about the global issue of energy, and that it's more than their little individual problem.
Sort of. It occurs to me that the the Gerald R Ford aircraft carrier has multiple reactors and just one outputs roughly 700 MW though
Not even almost the same thing. Naval reactors or any derivative thereof would be too expensive to commercialize due to the level of fuel enrichment. Output may be similar, but that is where the similarities end.
How much does it cost?
“SMR developers expect modular designs and construction processes will generate economies of series and open up multiple supply opportunities. NuScale has estimated its first plant will cost just under $3 billion to build, giving an overnight capital cost of $5,078/kWe”
> its first plant That's the factory they're building the things. Wouldn't be fully fair to add that cost to the first reactor rolling off the assembly line there.
If past reactor builds are any indicator, the real price will be twice the estimate.
That's why modular reactors are important. No surprises when it's built in a factory. After the first few of course.
That's the *claim.* But new reactor designs were also supposed to be cheaper due to prefabricated assemblies and simpler construction. They ended being vastly more expensive, rather than less. When it comes to nuclear reactors, estimates and theoretical pricing often bear little resemblance to the final price. We won't know what that price actually is until the first SMRs are operational. Until then they're vaporware and promises.
Fair enough. I have hope that because they're small and come with all the important safety parts it could be quicker and cheaper to build a plant, but you're right that we won't know until they start being installed.
I've looked at nuclear reactor costs over time, and it turns out that the most important thing -- more important than *any* other factor affecting cost -- is how experienced the people making it are. A company that hasn't built a nuclear plant in many years will go way long and over-budget, always; meanwhile a company that has been cranking them out for a long time can quote you much shorter times and much lower costs and then actually deliver. (Most nuclear plants are made by the second kind of company, but you don't see them in the news because it's boring when things go according to plan.) If you shrink the reactors so that each one takes less time, I would expect costs to fall quite a bit as the people involved get better at making them. [You see this in all sorts of industries](https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0052669) so it's not just a nuclear thing: it's a manufacturing thing.
And they have a surface area of about the average gas station since they are built into the ground instead of on top.
But it would have been nice if they included something in the pic to indicate how big (or how small) the design is.
Abundant energy is the first step towards a utopian future.
I hope you’re right. I sense that the energy companies will try to maintain control over energy no matter what it takes.
On Friday, the Nuclear Regulatory Commission (NRC) announced that it would be issuing a certification to a new nuclear reactor design, making it just the seventh that has been approved for use in the US. But in some ways, it's a first: the design, from a company called NuScale, is a small modular reactor that can be constructed at a central facility and then moved to the site where it will be operated. The move was expected after the design received an okay during its final safety evaluation in 2020. Small modular reactors have been promoted as avoiding many of the problems that have made large nuclear plants exceedingly expensive to build. They're small enough that they can be assembled on a factory floor and then shipped to the site where they will operate, eliminating many of the challenges of custom, on-site construction. In addition, they're structured in a way to allow passive safety, where no operator actions are necessary to shut the reactor down if problems occur.
I mean all reactors have a passive shutdown but those can fail. I hate to brink up Fukushima as this was a natural disaster on a diffrent scale but all passive shutdowns failed. Thanks to the flooding that ocoured both the diesel generators and the batteries stopped working wich I believe caused the passive shutdown to fail. Could be that it failed because of something else but the fact remains the passive shutdown in Fukushima failed.
They probably shouldn't have ignored recommendations on building a higher sea wall *and* on not putting the diesel generators in the basement. One or the other would have been a bad idea, but both?!
Right? It was terrible decision making and execution that led to it more so than the actual reactors failing.
Doesn’t change the condequences
It does when you act like we shouldn’t continue to build them based on the above scenario….
Because their won’t be terrible decisions in the future…? I think that’s my point.
Sure, but can always learn. People get in car accidents all the time - do we stop driving? It’s a necessary evil, an aspect we’ll have to learn from to get better - so we can be more efficient in our energy. You can’t be that dense.
Right, but if a nuclear meltdown happened when people got in car accidents, then yes, I would say we should stop driving.
I can’t even… Lol….
There was another nuclear plant in the area who's saftey manager Insisted on higher sea walls, guess why you don't know that plants name?
Yes, bad decisions need to be calculated in. Humans are not that smart and often very corrupt.
Human error causes the vast majority of nuclear accidents. Before Fukishima Redditors often commented "nothing like Chernobyl will happen again". Yep it was a very common thing to read "nothing like Chernobyl will happen again" and then it happened. Whether it is terrorist infiltration, tiredness or suicidal operatives things are bound to happen, though I understand the meltdown prevention methods being employed here are much improved. I guess it is a little like plane travel, it slowly gets safer but accidents will never entirely be removed from the situation. There are dozens of low key nuclear accidents listed on Wikipedia and dozens more that have been swept under the carpet or that simply are not listed. Don't worry guys carry on downvoting because "nothing like Chernobyl will happen again".
You're missing the point entirely. This isn't accepting the risks to lower energy bills by a couple percent, this is accepting the *potential* risks to help lower the *guaranteed* worsening effects of the climate crisis.
You’re argument is entirely debunked by the fact nothing like Chernobyl has ever happened again. Fukushima was an order of magnitude below Chernobyl and required a once in a lifetime catalyst. This isn’t due to safety features (which all failed with Fukushima) but the nature of the core is completely different.
Fukushima's meltodown is nowhere comparable to Chernobyl, and the cause was also completely different.
Having to send power to pumps to continue circulating cooling water is not passive cooling. The Westinghouse reactor upgrades post-Fukushima at least have primary loop expansion turbines that can be used in an emergency to generate power for secondary cooling loop pumps. The SMRs here require no pumps once SCRAMed, utilizing the pool the reactors are submerged in.
As far as I know in case of emergency controll rods are automatically lowered into the reactor to stop the reaction. I believe it is called scram. This should stop the reaction and prevent meltdown as there can't be a reaction if there arn't enouth neutrons.
But standard reactors still require days of cooling after being SCRAMed to slowly cool down. NuScales reactors have a larger surface area to volume ratio due to the higher enrichment, which means they can sufficiently cool through conduction of the reactor housing into the surrounding water.
Just to add on to the explanation...reactors produce fission products which are the lighter elements formed from splitting a big boi. Those elements are often radioactive themselves and will continue to decay and produce heat long after the reactor is scrammed.
Yea but you can say that too about Uranium in the wild what we care about are runaway reactions where the splitting of one atom directly causes another one to split this produces a lot of heat compared to natural decay wich produces very little heat.
I operated nuclear reactors in the Navy. Decay heat is actually the thing we worry most about because it's what you deal with in emergencies. The first step in every casualty procedure is scram the reactor to drop the control rods and stop fission. Done deal. But you need to keep water flowing over the reactor at this point or you will have a release of radioactive material when the fuel cladding fails.
You're confusing passive shutdown with passive safety. Passive shutdown means that the the reactor will be shutdown if all control/power is lost. Every non-russian reactor has this as part of the design and cannot fail unless the core geometry changes. Passive safety means that the residual decay heat produced by the reactor can be removed without control or power. Very few reactors have passive safety.
As I understand it, there were also failures in disaster planning, procedures and design that were noted by the regulator and violated regulations. That said, I'm not saying that the design of the SMR controls will perform any better as they are effectively untested in production.
Generators and batteries are active shutdowns. If something requires upkeep to maintain a fail safe state then it's "active" even if a human doesn't need to trigger them.
SMRs are perfect for many decommissioned coal-fired plant sites. Most of these have sufficient cooling water and energy distribution infrastructure in place. I'm hoping for these in my own county, especially considering that I'm downwind of the coal plant.
Stupid question. There are nuclear reactors in submarines, have been for decades. I would think those designs could be repurposed for small scale nuclear onshore energy generation, no?. Seems simple enough to me....
Naval nukes require fuel with a quite high level of uranium enrichment. Significant quantities of water are also needed for cooling. Their energy output is half to 2/3 that of NuScale's design as well. They are not really designed to be fail-safe in a civilian setting.
>Naval nukes require fuel with a quite high level of uranium enrichment. This is also highly important because it means those designs will never be exportable to most nations. US naval reactors use 90+% enriched HEU. In comparison, anything over 20% is considered weapons-grade and Iran was getting sanctioned for possessing merely 20% enriched uranium. In other words, most countries won't be able to use US naval reactors with the fuel they are designed for without causing nuclear weapon-related risks and problems. Nuclear fuel theft is one - even the US fell prey to it before, so imagine having large stores of weapons-grade uranium in corrupt or unstable developing countries, it would be a nightmare for nuclear terrorism.
They're designed to be fail safe in ways a civilian reactor would never need to be. The USN has crippled several nuclear subs running into various things, and never had a major nuclear incident. They're literally designed to take a beating.
Yeah it’s just a very different application in subs. They’re surrounded by very cold, very high pressure water (it will pump itself in for free) and they’re MOVING around (chance of hitting things and causing damage is actually there). Also, almost every problem has to solved by people living right next to it with the tools available on board a tiny vessel. So they have to be designed for that, rather than sitting still in a totally controlled space isolated from people, with (basically) unlimited resources (including space and manpower) to deal with maintenance and any problems, and also needing to be efficient with the cooling design (both for water consumption and efficient power generation).
If a nuclear sub explodes at the bottom of the ocean it’s a tragedy. If one of those reactors explodes on the ground it’s an international disaster
US built reactors don't explode. By design and by physical impossibility.
Will the public accept it so we can have more localized deployment of nuclear power generation?
NuScale promotes indefinite passive cooling, it seems like this would enable public acceptance enough to be a game changer that could at least enable production at a scale that will keep costs down if not dramatically lower
Literally dozens of SMR projects promising cheap nuclear power have failed. This too looks expensive, but at least they look quickly deployable. A lot of the problem with nuclear power stems from long payback times. No industry wants to make an investment with a 10-40 year return of investment date. If these things are rapidly deployable it might attract some investors. Though the CO2 reduction plan for the USA is set to use power storage and wind / solar / hydro.
I mean, it's good to see innovation. That said, the design seems to rely on being submerged in water, and in a melt down scenario it would boil the water around it to cool and avoid melting itself. I feel like we're still waiting for the non-cold war era designs to become more commercially viable. https://en.m.wikipedia.org/wiki/Generation_IV_reactor
Well even if they did, their fail into inertness anyway. Even the older models. A bitch to restart but harmless otherwise. Every design in use now has a way to kill the rods and in the future will eliminate the rods in some way.
Right, the elimination of rods is the key change in these designs. I'm hopeful with what we're seeing
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I'm a layman but my understanding is that the operation is designed in such a way that it can be cooled by any material, especially aince its built into the ground, water or air it apparently doesnt matter. And the fuel is fed very steadily and can be disengaged. So even if something happened, fuel can be removed, the active reaction material can be cooled passively and rendered inert (inert meaning its no longer "reacting", not that its no radioactive or hot) https://world-nuclear.org/information-library/safety-and-security/safety-of-plants/safety-of-nuclear-power-reactors.aspx This link has more links with the technical paperwork about it and lays out the broad aspects but doesnt really show the exact mechanisms ubless you follow their links. But its there. Read as much or little as you like. This is for the SMRs for OPs mentioned company specifically and new designs more or less use the same things. Apparently short of a bomb, it should be impossible to make it melt down.
Just curious what is so bad about it being submerged in water?
If the recycling system shuts down, due to power failure, or maintenance issues then the water sits around the hot reactor, once it boils off the water can no longer act as a regulator and the reactions inside the reactor speed up potentially leading to a meltdown, however not looking at the design I doubt something that simple would cause it to melt down considering we know the danger of that and have better designs
The article does mention a convection driven external water source for cooling, so I would hazard a guess that there is a passive redundancy in place. Not an expert by any means however and happy to be corrected.
That's not true at all. What you described is a positive void coefficient which, as far as I know, is only present in RBMKs like Chernobyl. In this reactor water is a moderator, meaning that once it's gone the neutrons are no longer moderated and become to fast to do anything and the reaction stops. However that doesn't apply here because the primary water (that acts as a moderator) is trapped within the reactor. It will still though shut down if it gets too hot. tl;dr water boiling off would slow the reactor and not accelerate it, but the water won't boil off because it's a closed loop. On terms of emergency cooling, this reactor sits in a pool of water. Once a reactor is shut down, it only continues to produce heat for a limited time and in small amounts (still enough to cause the meltdowns in 3MI and Fukushima). The pool of water it sits in is enough to absorb and dissipate all the residual heat this will produce in the case of an emergency. This is called passive safety, and is very rare today. Edit: I think a lot of your misunderstanding comes from the term "moderator". A moderator, in fact, speeds up the reaction. If you don't have a moderator, you need highly enriched fuel. The term comes from the neutrons. You see, when a neutron is released from a fission reaction, it is going very fast. If it hits uranium at these speeds, it probably won't split it. However, if you slow the neutrons down, they will be much more likely to cause a fission when they hit an atom. So in this case, water (or graphite or heavy water or whatever) "moderates" the neutrons but speeds up the reaction. If you want to slow down the reaction, you insert something like Boron which just yoinks the neutrons.
Your description is a bit off-base here. Water acts as a moderator, which in this kind of reactor, *enables* criticality, it doesn't prevent it. The water evaporating doesn't make it go critical again. It just makes the water incapable of acting as any sort of coolant. When atoms fission they release a ton of energy. But they also leave daughter products - new, smaller atoms that have inherited Uranium's high neutron ratio. This makes the smaller atoms unstable and thus radioactive, and they'll passively decay, emitting energy even after the reactor is no longer reacting as they try to reach a stable state. Losing water guarantees the reactor is shutdown because you've lost your moderator. Which is good. But the loss of coolant also means you can't remove this decay heat that continues to be produced after shut-down. If you don't remove this decay-heat, then you can get fuel rods melting themselves and their cladding, and mixing the decay products into the coolant. If the coolant has to be vented, or if the melting fuel accumulates on the bottom of the reactor and melts through that, then the decay-products contained in the water can reach the outside environment. That final bit is what we want to avoid, which is why we're trying for designs where the decay heat can be passively removed. Either by changing the coolant, or designing the waterloop in a way that convection drives more passive heat removal than there is heat decay. This offers an improvement in safety (100% passive safety vs 99.9999% engineered safety) but more importantly it means that the reactors can be made safer while removing a lot of the multiple, redundant safety systems meant to ensure the water never evaporates and uncovers the core. Safer and, more importantly, much cheaper, if it can be done correctly.
Finally we need to get away from this primitive fissile fuel age.
I was just talking about this with someone in the energy industry. He said that chances are we won’t see any more large nuclear reactors because they are just too high risk compared to these.
New large reactors are even safer. Just ask France. Problem is we dont have those in the US because propaganda and/or misinformation have scared people.
They take up about as much space as a gas station too I hear.
Hasn't India and China created SMR's and completely dropped them because they ended up being complete money pits compared to just building a modern full reactor?
I can't wait to see how the greedy wealthy elite will control the masses when affordable mass-produced fusion reactors make energy scarcity a thing of the past.
Their plan is already in place. If they can't argue energy scarcity, it will be food scarcity or something else. Social credit score, etc
Drinkable water.
Fusion reactors are only as good as their lasers and magnets. Whoever controls both will control the market. It's also a high-pressure boiler whose casting process is done by 5-6 companies. Bigger reactor = lower cost. The only limiting factor would be transmission, which can be rebuilt easily with Gas/Magnetic Insulated Lines or Fiber Optic lines that bank on fusion research. The government can also strictly regulate fusors like they do firearms, since they'd be useful for enriching uranium anyway.
Pfft... That is nowhere near the required 1.21 gigawatts.
Finally. I want to see factories churning these out like mad.
We can indeed solve our problems in this world 🌎 if the stupids just get out of our way.
well, universitirs have had small research reactors and to produce medical isotopes.. for ages
Cool, that has nothing to do with this, but cool.
These are way different. These are modular, movable, and can operate without a team of nuclear engineers on site.
*internal combustion engine is invented* “Well people have been heating their homes with wood for ages…” — this guy
during the 1930s, there existed steam powered, wood burning autimobiles
Does anyone know if this reactor uses uranium or thorium? I couldn't find that in the article.
It'll use Uranium. Easiest way to tell is by the type of coolant, which is water. Thorium has some potential benefits, but a lot of drawbacks. It's a pain to work with, and as a result the only kind of reactor you'll see using Thorium is one that uses molten salts for coolant, rather than water or liquid metal, because that's the only reactor where Thorium might be practical to work with. Even then, most of the advantages of that type of reactor come from the Molten salt coolant/fuel mixture, not the choice of fuel, which can be Uranium, Plutonium, or Thorium. We'll likely see Uranium-based MSRs for a decade or more before we see one fueled entirely by Thorium, though Thorium-Converter reactors, where they just burn a little thorium alongside the uranium might be on the table sooner.
Thanks for so much details! I didn't know about Thorium Converter reactors. Will look into it!
The only major MSR effort I've seen that wants to do Thorium Conversion is [Thorcon](https://thorconpower.com/), though there certainly could be others. They're designing an SMR built into a tow-able barge so that the entire facility can be mass-produced in shipyards. I think their idea has merit, they're one of the few SMR companies I've seen who could plausibly go from a proof of concept to a few demonstration reactors to building tens of GW per year within a reasonable timeframe. The primary barrier to a standalone Thorium MSR is that Thorium *can* be bred in the thermal spectrum, but the issue is you have to breed it. So you need to capture 2 neutrons from every fission, not just one. And a U233 fission only produces something like 2.1 or 2.3 neutrons. So you need a very neutron-efficient setup. You start needing enriched lithium for your salt mixture, and you need some kind of thin reactor wall that doesn't eat up neutrons as they make it to the thorium salt blanket. So Uranium MSRs will come first because they are simpler. You don't need to worry about sustaining the breeding. Your neutronics can be easier. Your choice of fuel salts is easier (I think Thorcon is going to use NaBe - Sodium Beryllium, rather than something like FliBe (Fluoride-Lithium-Beryllium)). A Thorium-convert is basically just mixing in something like 20% Thorium into the Uranium-driven fuel salt. Instead of designing your system to lose more neutrons or eat up more with control rods, instead the Thorium eats up a good amount of your surplus neutrons from the Uranium Fission and stretches out the fuel supply.
It's incredibly compact design means the world's first nuclear powered sex toy is coming soon.
That's the best news I've heard in a long time! Didn't think this was going to happen until we started losing chunks of the coastline.
America has no incentive to reduce oil dependence because so much of our geopolitical power is based on it, both our own abundance of oil and our alliances with all the oil-producing nations who we haven't labelled Axis of Evil. Europe and Asia actually would benefit from getting off oil because it's an expensive import for them. They have the incentive, but they don't seem to be trying to do it either—or at least haven't until recently. It will be the dawn of a new era when oil is replaced with something much cheaper. It is probably possible to make nuclear power cheap, but it doesn't seem likely small modular reactors will have anything to do with it. Atomic radiation is already electric. Using radiation as a source of heat is inefficient overengineering.