I literally came here to say the same thing. It reads like someone is just trying to remarket the concept to people in their 50s and up to accept nuclear power as their one true God.
Seems like the pebbles are much smaller in these. I recall one very mundane but difficult issue with previous pebble bed reactors was pebbles jamming and other mechanical problems with the fuel. These seem like they'd flow like that weird pseudo-sand stuff in kids toys.
These very small fuel particles are embedded in larger graphite structures with whatever geometry is convenient for handling. (Pebble bed pebbles are one such possibility, and PBRs have been made which use TRISO-based fuel pebbles.)
I remember watching a documentary on nuclear power in the US and how the thorium reactor was the focus of a lot of research in the 70s, but I can't remember for sure.
To clarify: molten fueled reactors (like LFTRs) trivially can't have their fuel accidentally melt, because their fuel is already molten. (And there are some nice options for dumping their fuel into a subcritical passively-cooled configuration in case of an emergency.) This is different from TRISO fuel, which isn't supposed to be molten in normal operation but which structurally limits the spread of fuel and fission products at high temperatures.
No. LFTRs have fluid fuel. There are some solid-fueled clean molten salt cooled reactors that are called Fluoride salt cooled high-temperature reactors (FHRs).
I read a detailed report of the one in Germany. Thing totally sucked. Two big problems the indestructible alumina pebbles cracked and contaminated the reactor. Second was inhomogeneous burn rates. I think I remember some pellets got stuck when they decommissioned the reactor.
THTR-300 https://de.wikipedia.org/wiki/Kernkraftwerk_THTR-300 . Not alumina pebbles, graphite pebbles with enclosed BISO particles (predecessor to TRISO from the original article). Whole containment is contaminated with graphite dust, very high beta radiation levels. They had problems with broken graphite pebbles all over the reactor because the pebbles were brittle, often got jammed and had to be unjammed by force. They even produced a radiation release to possibly "blow out" graphite dust from the gas pipes that had collected there.
Yes, and no. Most(?) pebble bed reactors have used triso style fuel (there was a similar earlier fuel type called biso, don't know if any reactors using it were ever built), but triso fuel can be used in other reactor types as well.
And yes, triso is pretty cool tech. Like the article says, it can withstand exceptional temperatures without any fission products escaping.
That is not a property of the graphite, its a property of the atmosphere (CO₂, He) or lack thereof (H₂O, molten salts) around the graphite. The Chernobyl core started burning as soon as external atmosphere hit the graphite after an explosion.
High temps are very good for efficiency, but are difficult for safety. Only China is building VHTRs right now. If anyone ever builds a supercritical water reactor then it would give you decent efficiency without the problems of exotic coolants.
Because the article isn't clear: no, this isn't about pebble bed reactors. This is about a type of fuel where a little bit of uranium has been encased in a number of protective layers, such that the fuel will remain safely contained in its tiny packaging even at very high temperatures. You take a bunch of these poppy-seed-sized things and embed them in graphite rods or pellets, which both keeps them in place and acts as a moderator for the reaction. These can then be used in a variety of reactors, including (but not limited to) pebble bed reactors.
The confusing part about the article was that it initially stated that they were very small, and then went on to speak about billiard ball size. Does that mean that the protective coating is very thick, or that there’s a range of sizes for the actual uranium mass?
I remember reading in one of Feyman’s biographies about how he visited an early fuel plant, and was horrified to see them storing what amounted to a near a critical mass in barrels, in long rows. we’ve come some way since.
The TRISO fuel particles are very small -- about a millimeter or so in diameter. The "billiard ball sized" fuel pebbles designed for the Xe-100 reactor are graphite balls with a bunch of TRISO fuel particles embedded in them.
I went through a phase of reading about nuclear power and in particular the nuclear accidents. It feels like we kinda got to the Comet¹ stage of Nuclear power and gave up. We still learn lessons from each accident, for example Fukushima has resulted in Passive auto recombiners being installed which convert hydrogen back to water. It also added provisions for using mobile generation and cooling (fire trucks).
I certainly don't have the answer but to how we can make nuclear power fool proof but I do feel like we should still be asking the question.
> We still learn lessons from each accident, for example Fukushima has resulted in Passive auto recombiners being installed which convert hydrogen back to water.
Seems we are on a global level not very much learning from incidents. These are common (mandatory?) in Germany and colloquially named “Töpfer-Kerze” after the minister who had them installed: https://de.m.wikipedia.org/wiki/Reaktorsicherheit#T%C3%B6pfe... Klaus Töpfer was responsible for nuclear security from 1987-1994. This would have been the time to learn.
However, many operators didn't want to spend the money, which is why Fukushima didn't have a PAR at the time of the accident. The problem with Fukushima is that I fear we do not learn from accidents. Otherwise, Fukushima wouldn't even have been in operation at the time of the accident as it is an old reactor model well past its design life. The location was, as we have known before the accident, poorly chosen. Safety measures, such as PARs, seawalls and properly redundant power supplies were skipped or badly implemented due to the cost involved. All this was known before the accident, however neither the operator nor the national oversight took any action before it was too late.
The problem with nuclear power is that nobody is interested in fixing obvious flaws if it ruins the profitability of an existing plant. No matter how safe your new modern design is, it won't lead to the shut down of existing unsafe plants.
The article is conflating two very different kinds of "meltdown". A meltdown during actual reactor operation is the kind the article is talking about in the first paragraph, and the kind that the type of reactor discussed in the article is designed to make impossible, according to the rest of the article.
But the meltdown at Fukushima was caused by lack of decay heat removal after shutdown, which is different from what could or could not happen during actual reactor operation. So there are two kinds of "prevent meltdown" that are required, not one. The article does not talk at all about how, or whether, the type of reactor it discusses would prevent a meltdown of the second kind, the kind that happened at Fukushima.
They are designed to be operated at much higher temperatures because the use gas as a coolant where they can effectively use natural convection to remove decay heat.
Yes and no. Not all gas-cooled reactors can work completely through convection cooling without melting, some do need fans even to just remove decay heat.
Also, reactors containing graphite (as many pebble-bed reactors will) do need a oxygen-free atmosphere, otherwise the graphite will ignite. So only convection of the proper uncontaminated protective atmosphere will work.
The article is (confusingly, and a bit confusedly) discussing a type of fuel, not a reactor design. The type of fuel in question can withstand very high temperatures, whether from fission or from decay products, without letting the fuel out of its little protective shells.
Normally they do, but when you shut it down you need something to get rid of the decay heat. That's why nuclear power plants have these emergency generators. Those failed at Fukushima, leading to the meltdown.
Some newer designs opt for passive decay heat removal, eg through convection.
In American PWR designs decay heat removal post loss of power is accomplished by natural circulation. Height and temperature differences between the steam generators and the reactor vessel produce flow of primary liquid between the two. Heat is rejected via the secondary system. The limiting factor becomes make up water to the secondary side of the steam generators.
They have to shut down during the earthquake to ensure they maintain coolable geometries. Cooling is easier at lower power.
Some Fukushima reactors did have some self-powered safety features, like a little steam turbine that comes from the boiling coolant and is hooked to a coolant pump. These features are at least a little related to why some reactors failed at different times than others in Fukushima.
But seriously, there is enough decay heat to do more of this so it's a pretty good point.
Fort St. Vrain ran the reactor cooling pumps off of process steam, but had lots of problems with steam leaking through the bearings and contaminating the coolant. Electric pumps don't have that problem.
Running some kind of heat engine off decay heat should be possible, but it would be very different from the primary turbines, (You probably couldn't use it during normal operating temperatures, but it'd still have to be connected to the coolant circuit) have to be nuclear rated, (expensive!) and only be used in an accident scenario where you lose external power and the diesel generators are then destroyed, or run out of fuel.
> The article does not talk at all about how, or whether, the type of reactor it discusses would prevent a meltdown of the second kind, the kind that happened at Fukushima.
It's immune to meltdown.
The first important safety feature is the fact that it simply doesn't melt. The fissile material is contained in a ball of graphite (which is theorized to sublimate directly to carbon vapor somewhere north of 7000F) and silicon carbide. (decomposes to silicon and carbon somewhere north of 5000F) They tested the fuel at 3200F and none of it failed. The zirconium cladding on the fuel at Chernobyl, Three Mile Island, Fukushima, etc all failed somewhere in the ballpark of 2000F.
The second thing is called Doppler broadening; once the uranium fissile material gets that hot, it ceases to be able to sustain a nuclear reaction. The uranium nuclei are zipping around too quickly for thermal neutrons to effectively induce fission. Normal zirconium cladding fails before this effect can become significant.
The net result of these two effects is that you don't need coolant. As the temperature increases, the rate of decay decreases to the point where the device will passively cool itself without coolant. This equilibrium point is really stinkin' hot, but the entire facility will have been designed around this fact.
The reactor design itself is fairly interesting in its uninterestingness: the only interesting dial an operator has is the coolant pump. If you pump more coolant in, you get more power out; that's it. Turning the reactor "off" just means turning the coolant pumps off, which in most other types of reactors is the thing that causes the disaster. There aren't control rods, I don't think it even has a SCRAM facility.
Can anyone speak to the implications for this type of Triso fuel and radioactive waste? Is there less radioactive waste once it is spent or how similar is it to other types of nuclear fuel in that regard?
It ought to be safer since the fission products are encased in the protective and non-corroding triso structure. That being said, used LWR fuel rods are also enclosed in protective cylinders (see eg the designs for the Finnish Onkalo storage site). Both safe enough per current best knowledge.
If one wants to do some fancier recycling and reprocessing rather than once through, I understand this is relatively undeveloped.
TRISO fuel has some very interesting capabilities as noted in the article. It also has some challenges. Traditionally, the challenges are:
* Very low power density requiring absolutely massive reactor vessels for a certain power level
* Very expensive fuel fabrication ($10k/kg), hopefully can be brought down
* Difficult to reprocess (this is probably fine until nuclear produces like 50% of the world's energy, at which we will begin to challenge the fuel resources)
Also traditionally, these are high temperature gas-cooled reactors. A new twist is the molten-salt cooled (basically just melted salt, not fluid fuel like in full-on molten salt reactors) TRISO-fueled reactors. These are called FHRs.
The FHRs seem like a nice combination of the safety of Triso fuel and the higher power density and low pressure of MSRs. Wonder why they haven't been studied more..
It is a pretty new reactor idea, and has lots of benefits. It was popularized recently by MIT Professor (formerly of ORNL) Charles Forsberg. Here's a full presentation showing the case from 2012 [1].
But the high cost of nuclear power is probably due to the extraordinary (and perhaps very excessive) safety procedures, no? It's not like the raw material or basic principles are very expensive. So I presume the idea is to hope that having a more intrinsically safe fuel will allow those expensive safety procedures to be relaxed (although, given the sclerotic nature of nuclear regulation, probably not).
Yes this is the idea. Cost in nuclear is completely coupled to safety. The hypothesis of triso is to reduce costs by improving safety.
Also, triso allows temperatures that allow nuclear heat to be used directly in industrial processes and thermal energy storage. These can also improve economics.
The safety procedures don't help the cost, but even the non-nuclear part of a nuclear power plant is expensive. The "nuclear island" is just 1/3rd the cost of a nuclear power plant. All externally heated thermal power plants have become uncompetitive now. Not just nuclear, but also coal, geothermal, and concentrating solar thermal.
So, TRISO is depending not just on the nuclear island being cheaper, but the non-nuclear part somehow becoming less expensive. This probably involves very high temperature, for example for nuclear air Brayton. But any time you go to higher temperature material problems rapidly accumulate.
In any case, there will always be a cost premium to the nuclear part of a nuclear power plant, if only because it has to be very reliable because it can't be repaired if something serious breaks. In (say) a coal fired power plant one can send workers into the guts of the shut down plant to fix or replace things. In a reactor, I don't think that's possible, even if the fuel has been removed. The residual radioactivity is too high.
> All externally heated thermal power plants have become uncompetitive now. Not just nuclear, but also coal, geothermal, and concentrating solar thermal
Are you saying that an externally heated power plant is unlikely to be cost competitive even if the source of energy is free? If not, your overall comment doesn't make sense to me. If so, that's an extraordinary that could very well be true, but I haven't heard anyone argue it and I'd be extremely interested in further reading/links/citations.
Yes, that is the direction things are going in. The remaining thermal power technology that's still (for the moment) viable is combustion turbines, which are internally heated (combined cycle does have an externally heated bottoming cycle, but only 1/3 the power output goes through that, and it shares the generator with the combustion turbine proper.) But even combustion turbine sales are falling; that's what's gotten General Electric in such trouble lately.
Much appreciated! Are there any forward-looking doc's you can recommend that discuss this in more depth, especially any that try to get at the basic physics or economics? It's truly startling to me, and to the extent it's true it really changes the way people should think about future energy tech.
> But during the INL tests, Demkowicz demonstrated that triso could withstand reactor temperatures over 3,200 degrees Fahrenheit.
> ...
> Sell says. “It is physically impossible—as in, against the laws of physics—for triso to melt in a reactor,”
3200 F = 1760 C
> The first phase lasted only several seconds, with temperatures locally exceeding 2,600 °C, when a zirconium-uranium-oxide melt formed from no more than 30% of the core.[1]
It seems like it's yet to be demonstrated that Triso fuel can withstand the highest recorded temperature inside a nuclear reactor. I get that the physically impossible quote is probably partially puffery, but IMO puffery is not appropriate when it comes to nuclear reactors.
All the major incidents with nuclear power are despite dozens of safety systems, redundancies, clever designs etc.
This is because nuclear power is tightly coupled and complex. Humans have never mastered such systems. We have them and we accept they fail sometimes (eg fires at conventional power plants: 200 plus years of engineering and they still happen). But with nuclear that isn't an option.
This is why people are unconvinced by clever new fuels or "it's totally guaranteed this time" engineering. You can't fix a systems/human nature problem with new fuel cells.
France is choke-full of nuclear power plants. Can you remember a major nuclear power incident in last, say, 30 years?
I think that reactor standardization really paid off there. They have few types, a wide operation experience, and apparently well thought-out procedures.
This, of course, is hard to achieve without a massive rollout planned ahead.
One thing I like to remember is that there are still 10 RMBK reactors in operation. Fundamentally the same design as the reactor 4 at Chernobyl. In fact, one thing a lot of people don't realise, the 3 other reactors at Chernobyl were restarted and ran until 2000 (actually, reactor 2 shut down earlier because of a non-nuclear accident with its generator) when the EU paid to have them shutdown.
The Chernobyl reactors were all perfectly safe. It was almost impossible for them to suffer a meltdown. That's the problem here: greed and incompetence and pride can't be fixed with better cooling systems. Today's perfect reactor is just as dangerous as the perfect reactor at Chernobyl once someone wants a bonus or needs to improve efficiency or doesn't want to admit he is confused and turn the thing off...
Perfectly safe is a long stretch. As originally installed they had numerous design faults, the control rods operated too slowly, the carbon tips of the control rods could locally increase reactivity when they were being inserted, the reactor was too large and consequently hard to control, they lacked the secondary containment structures which were common place in western reactors of the era.
Sounds like you have read Charles Perrow's 1984 book Normal Accidents [1]. New fuel systems are actually key to safe design, IMHO. All the major nuclear power incidents, that I'm aware of, are due to one underlying problem: zirconium clad fuel rods produce large amounts of hydrogen during loss of coolant accidents (LOCA). Nuclear power plants weren't supposed to go BOOM but it turns out they do so readily with hydrogen explosions.
Even with zirconium clad fuel rods, the CANDU reactor design seems to have managed the complexity and tight-coupling issues surrounding nuclear power generation; the design, however, never managed to reduce the immense capital costs involved.
Price-per-Performance is all that matters and in an age of cheap natural gas. I'm not convinced that new nuclear reactor designs will find anything other than niche markets. There are many lessons to learn from Charles Perrow but complete distrust of engineering should not be one of them.
My gut is that you can run a nuclear plant safely for 100 years, but as time goes on, you have fewer guarantees, and eventually something weird will happen to screw up your plans. I don’t think nuclear fission as we have it today makes sense except as a bridge to somewhere else.
I feel like the real issue is something that plagues many complex systems: very smart people design something that fails to take into account the very fallible humans which will be responsible for actually running the systems. Scientists and engineers seem to overestimate the capabilities of humans to screw things up. Systems should be designed to be somewhat 'overdamped' so that lack of control results in the system shutting down safely.
Capitalism being what it is, it doesn’t matter how much this improves safety, newer plants will keep pushing for tighter and tighter safety tolerances chasing after efficiencies until this is just as risky as the current fuel.
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[ 3.2 ms ] story [ 153 ms ] threadI remember watching a documentary on nuclear power in the US and how the thorium reactor was the focus of a lot of research in the 70s, but I can't remember for sure.
And yes, triso is pretty cool tech. Like the article says, it can withstand exceptional temperatures without any fission products escaping.
I have a background in chemical engineering and still had no clue that nuclear reactors operate at the temperature of a pizza oven. That's wild.
http://nucleargreen.blogspot.com/2011/03/does-nuclear-grade-...
High temps are very good for efficiency, but are difficult for safety. Only China is building VHTRs right now. If anyone ever builds a supercritical water reactor then it would give you decent efficiency without the problems of exotic coolants.
1000°F = 538°C
2000°F = 1093°C
I remember reading in one of Feyman’s biographies about how he visited an early fuel plant, and was horrified to see them storing what amounted to a near a critical mass in barrels, in long rows. we’ve come some way since.
I certainly don't have the answer but to how we can make nuclear power fool proof but I do feel like we should still be asking the question.
[1] https://en.m.wikipedia.org/wiki/De_Havilland_Comet
Seems we are on a global level not very much learning from incidents. These are common (mandatory?) in Germany and colloquially named “Töpfer-Kerze” after the minister who had them installed: https://de.m.wikipedia.org/wiki/Reaktorsicherheit#T%C3%B6pfe... Klaus Töpfer was responsible for nuclear security from 1987-1994. This would have been the time to learn.
However, many operators didn't want to spend the money, which is why Fukushima didn't have a PAR at the time of the accident. The problem with Fukushima is that I fear we do not learn from accidents. Otherwise, Fukushima wouldn't even have been in operation at the time of the accident as it is an old reactor model well past its design life. The location was, as we have known before the accident, poorly chosen. Safety measures, such as PARs, seawalls and properly redundant power supplies were skipped or badly implemented due to the cost involved. All this was known before the accident, however neither the operator nor the national oversight took any action before it was too late.
But the meltdown at Fukushima was caused by lack of decay heat removal after shutdown, which is different from what could or could not happen during actual reactor operation. So there are two kinds of "prevent meltdown" that are required, not one. The article does not talk at all about how, or whether, the type of reactor it discusses would prevent a meltdown of the second kind, the kind that happened at Fukushima.
Also, reactors containing graphite (as many pebble-bed reactors will) do need a oxygen-free atmosphere, otherwise the graphite will ignite. So only convection of the proper uncontaminated protective atmosphere will work.
Why can't nuclear reactors at least have the option to power themselves?
Some newer designs opt for passive decay heat removal, eg through convection.
Some Fukushima reactors did have some self-powered safety features, like a little steam turbine that comes from the boiling coolant and is hooked to a coolant pump. These features are at least a little related to why some reactors failed at different times than others in Fukushima.
But seriously, there is enough decay heat to do more of this so it's a pretty good point.
https://en.wikipedia.org/wiki/Fort_St._Vrain_Generating_Stat...
Running some kind of heat engine off decay heat should be possible, but it would be very different from the primary turbines, (You probably couldn't use it during normal operating temperatures, but it'd still have to be connected to the coolant circuit) have to be nuclear rated, (expensive!) and only be used in an accident scenario where you lose external power and the diesel generators are then destroyed, or run out of fuel.
This was also the problem at three mile island.
That's the singular safety selling point of Gen IV reactors that have passive cooling features.
It was demonstrated in April, 1986 at EBR-II in Idaho, weeks before Chernobyl. Very few people have heard of this awesome capability.
https://en.wikipedia.org/wiki/Experimental_Breeder_Reactor_I...
It's immune to meltdown.
The first important safety feature is the fact that it simply doesn't melt. The fissile material is contained in a ball of graphite (which is theorized to sublimate directly to carbon vapor somewhere north of 7000F) and silicon carbide. (decomposes to silicon and carbon somewhere north of 5000F) They tested the fuel at 3200F and none of it failed. The zirconium cladding on the fuel at Chernobyl, Three Mile Island, Fukushima, etc all failed somewhere in the ballpark of 2000F.
The second thing is called Doppler broadening; once the uranium fissile material gets that hot, it ceases to be able to sustain a nuclear reaction. The uranium nuclei are zipping around too quickly for thermal neutrons to effectively induce fission. Normal zirconium cladding fails before this effect can become significant.
The net result of these two effects is that you don't need coolant. As the temperature increases, the rate of decay decreases to the point where the device will passively cool itself without coolant. This equilibrium point is really stinkin' hot, but the entire facility will have been designed around this fact.
The reactor design itself is fairly interesting in its uninterestingness: the only interesting dial an operator has is the coolant pump. If you pump more coolant in, you get more power out; that's it. Turning the reactor "off" just means turning the coolant pumps off, which in most other types of reactors is the thing that causes the disaster. There aren't control rods, I don't think it even has a SCRAM facility.
If one wants to do some fancier recycling and reprocessing rather than once through, I understand this is relatively undeveloped.
* Very low power density requiring absolutely massive reactor vessels for a certain power level
* Very expensive fuel fabrication ($10k/kg), hopefully can be brought down
* Difficult to reprocess (this is probably fine until nuclear produces like 50% of the world's energy, at which we will begin to challenge the fuel resources)
Also traditionally, these are high temperature gas-cooled reactors. A new twist is the molten-salt cooled (basically just melted salt, not fluid fuel like in full-on molten salt reactors) TRISO-fueled reactors. These are called FHRs.
[1] https://whatisnuclear.com/assets/FHR_Project_Presentation_Ja...
TRISO will also make dealing with spent fuel more difficult, as the dry casks are going to have to be much larger.
Also, triso allows temperatures that allow nuclear heat to be used directly in industrial processes and thermal energy storage. These can also improve economics.
So, TRISO is depending not just on the nuclear island being cheaper, but the non-nuclear part somehow becoming less expensive. This probably involves very high temperature, for example for nuclear air Brayton. But any time you go to higher temperature material problems rapidly accumulate.
In any case, there will always be a cost premium to the nuclear part of a nuclear power plant, if only because it has to be very reliable because it can't be repaired if something serious breaks. In (say) a coal fired power plant one can send workers into the guts of the shut down plant to fix or replace things. In a reactor, I don't think that's possible, even if the fuel has been removed. The residual radioactivity is too high.
> All externally heated thermal power plants have become uncompetitive now. Not just nuclear, but also coal, geothermal, and concentrating solar thermal
Are you saying that an externally heated power plant is unlikely to be cost competitive even if the source of energy is free? If not, your overall comment doesn't make sense to me. If so, that's an extraordinary that could very well be true, but I haven't heard anyone argue it and I'd be extremely interested in further reading/links/citations.
> But during the INL tests, Demkowicz demonstrated that triso could withstand reactor temperatures over 3,200 degrees Fahrenheit.
> ...
> Sell says. “It is physically impossible—as in, against the laws of physics—for triso to melt in a reactor,”
3200 F = 1760 C
> The first phase lasted only several seconds, with temperatures locally exceeding 2,600 °C, when a zirconium-uranium-oxide melt formed from no more than 30% of the core.[1]
It seems like it's yet to be demonstrated that Triso fuel can withstand the highest recorded temperature inside a nuclear reactor. I get that the physically impossible quote is probably partially puffery, but IMO puffery is not appropriate when it comes to nuclear reactors.
___
1. https://en.wikipedia.org/wiki/Corium_(nuclear_reactor)#Chern...
This is because nuclear power is tightly coupled and complex. Humans have never mastered such systems. We have them and we accept they fail sometimes (eg fires at conventional power plants: 200 plus years of engineering and they still happen). But with nuclear that isn't an option.
This is why people are unconvinced by clever new fuels or "it's totally guaranteed this time" engineering. You can't fix a systems/human nature problem with new fuel cells.
I think that reactor standardization really paid off there. They have few types, a wide operation experience, and apparently well thought-out procedures.
This, of course, is hard to achieve without a massive rollout planned ahead.
Sounds like you have read Charles Perrow's 1984 book Normal Accidents [1]. New fuel systems are actually key to safe design, IMHO. All the major nuclear power incidents, that I'm aware of, are due to one underlying problem: zirconium clad fuel rods produce large amounts of hydrogen during loss of coolant accidents (LOCA). Nuclear power plants weren't supposed to go BOOM but it turns out they do so readily with hydrogen explosions.
Even with zirconium clad fuel rods, the CANDU reactor design seems to have managed the complexity and tight-coupling issues surrounding nuclear power generation; the design, however, never managed to reduce the immense capital costs involved.
Price-per-Performance is all that matters and in an age of cheap natural gas. I'm not convinced that new nuclear reactor designs will find anything other than niche markets. There are many lessons to learn from Charles Perrow but complete distrust of engineering should not be one of them.
[1] https://en.wikipedia.org/wiki/Normal_Accidents
1) https://en.wikipedia.org/wiki/AVR_reactor
2) https://en.wikipedia.org/wiki/THTR-300