Yet another Fusion-in-a-decade ckaim

[Timsup2nothin]

There wasn't any real necessity for them to go into fission, it was never anything more than a minority market with huge risks involved.

The game has changed now, there is a huge popular upswelling in support for alternative energy (and objectively there's a huge need for it as well), fusion is a lot safer and fossil fuels are becoming more and more uneconomic. The oil companies are going to have to switch their major trade at some point or they are going to go extinct.

What made it a 'minority market'? What created the overpowering financial risks?

There may be a 'huge upswelling of support' for alternative energy sources, but that support can be cut away from fusion just as easily as it was cut away from fission, and most likely will be, because fusion is no safer than fission in reality. Fusion just hasn't been beaten to death in the court of public opinion...yet...because there hasn't been any reason to do so.

 

[uppi]

Fusion would be somewhat safer than fission, because unlike fission reactions, you would need a star to get a runaway fusion reaction. And the end products are - although radioactive - not as dangerous as fission products.

But rationality as long been cast away when discussing nuclear power, so I agree that there will be quite some opposition to new nuclear reactor.

 

[Quackers]

So I've read up on this and efforts to build a fusion reactor begun in the 1950s. The theory behind a reactor has long been established but nobody has found a solution.
Is there a possibility that the maths is wrong and we're chasing a unicorn?

 

[Timsup2nothin]

Fusion would be somewhat safer than fission, because unlike fission reactions, you would need a star to get a runaway fusion reaction. And the end products are - although radioactive - not as dangerous as fission products.

But rationality as long been cast away when discussing nuclear power, so I agree that there will be quite some opposition to new nuclear reactor.

Actually, you can get a 'runaway' fusion reaction in a hydrogen bomb, just like you can get a 'runaway' fission reaction in an atomic bomb. And just like you can't get a 'runaway' fusion reaction in a fusion reactor, you can't get a runaway fission reaction in a fission reactor. However the fact that an atomic bomb is a much different device than a fission reactor has not kept the uninformed public from making that wild assumption, so it is unlikely that a fusion reactor will not be treated like a potential hydrogen bomb by that same public.

As to the fission products, that is a valid point. However, a fusion reactor will generate a tremendous neutron flux and activate structural materials just like a fission reactor does, only more so because the flux is greater, and activated structural materials are bad news. While that may or may not offset the actual fission products completely, it is a consideration.

 

[El_Machinae]

Well then, it's our job to learn (and propagate) the ways fusion is viable before the fear-mo here get any momentum. Fear-mongering only gets traction when it doesn't seem ridiculous. Nearly no one is afraid of lizard people, fer ex. It's why I recommended the lecture in my sig, upthread.

Quackers, the major issue is that a fusion pilot project always needed a minimum amount of investment. Getting politicos to risk the minimum amount has always been tough.

 

[Zelig]

You seem to not understand that if Lockheed says they have something, they have it. These people have been on the cutting edge for 50+ years. If they came out in public on a deadline, they likely have proven this will work ages ago. If you think a military funded project being publicly revealed means they haven't started, you're foolin' yourself.

You seem to not understand that Lockheed, like the DMV, NASA, the NSA and every other government agency (or government funded), isn't magic.

The NSA is Not Made of Magic

 

[uppi]

Actually, you can get a 'runaway' fusion reaction in a hydrogen bomb, just like you can get a 'runaway' fission reaction in an atomic bomb. And just like you can't get a 'runaway' fusion reaction in a fusion reactor, you can't get a runaway fission reaction in a fission reactor. However the fact that an atomic bomb is a much different device than a fission reactor has not kept the uninformed public from making that wild assumption, so it is unlikely that a fusion reactor will not be treated like a potential hydrogen bomb by that same public.

A badly designed fission reactor can become a (not very effective) nuclear bomb in a critical failure. And stopping the subsequent decay of fission products require cooling to be absolutely failsafe. Fusion reactions would be much easier to stop. Cutting power to a plant might be catastrophic for a fission plant, but will stop all fusion reactions in a fusion plant. In my opinion, a fusion plant has much less risk of a catastrophic failure with severe consequences for the vicinity than a fusion plant.

But I agree, that this will not stop the public from making wild assumptions.

As to the fission products, that is a valid point. However, a fusion reactor will generate a tremendous neutron flux and activate structural materials just like a fission reactor does, only more so because the flux is greater, and activated structural materials are bad news. While that may or may not offset the actual fission products completely, it is a consideration.

Structural materials can be chosen in such a way that it will decay fast on activation by neutrons. That moves the timescale required for the storage of nuclear waste from millenia to manageable time.

 

[Timsup2nothin]

A badly designed fission reactor can become a (not very effective) nuclear bomb in a critical failure. And stopping the subsequent decay of fission products require cooling to be absolutely failsafe. Fusion reactions would be much easier to stop. Cutting power to a plant might be catastrophic for a fission plant, but will stop all fusion reactions in a fusion plant. In my opinion, a fusion plant has much less risk of a catastrophic failure with severe consequences for the vicinity than a fusion plant.

But I agree, that this will not stop the public from making wild assumptions.

Like the one you are promoting?

A badly designed fission reactor can't even be a reactor, much less a bomb. A self sustaining fission reaction doesn't just happen. I don't know what kind of 'critical failure' you have been pitched by the fearmongers, but you should probably throw that one back. As to the 'much less risk' from a fusion plant, there's also much less risk from an entire laundry list of things that don't exist...however if/when fusion plants become part of reality the risks will have to be assessed and managed, just like they are now in fission plants all over the world.

Structural materials can be chosen in such a way that it will decay fast on activation by neutrons. That moves the timescale required for the storage of nuclear waste from millenia to manageable time.

Great. What do you plan on building this thing out of, since iron is one of the biggest problems? No iron, no steel...okay that pretty much eliminates everything currently in use for structural materials. Now what?

 

[uppi]

A badly designed fission reactor can't even be a reactor, much less a bomb. A self sustaining fission reaction doesn't just happen. I don't know what kind of 'critical failure' you have been pitched by the fearmongers, but you should probably throw that one back.

The very principle of a fission reactor is a self-sustaining fission reaction. And from there it is just a small step to an overcritical reactor that will explode if you don't stop it. A critical failure would be the failure to stop the fission reaction when you need to. You can take a lot of measures to prevent that, but the Chernobyl incident shows that this is not just a theoretical danger.

Great. What do you plan on building this thing out of, since iron is one of the biggest problems? No iron, no steel...okay that pretty much eliminates everything currently in use for structural materials. Now what?

Why should iron be a problem? On neutron capture, Iron will eventually become Fe-59, which decays fast to Co-59, which is stable. If that one captures a neutron you get Co-60, which decays to the stable Ni-60 on a longer, but manageable time scale. So Fe-56 does not end up in a long-lived radioactive state, even after 4 neutron captures.

 

[El_Machinae]

The shielding will need to be special material, not so much the structural materials.

The shielding will be a bit of a issue, all told. Just like eagles and windmills is an actual issue. It's just not a major one, like pregnant women being forced to avoid seafood, global warming, or petrostates.

 

[Timsup2nothin]

The very principle of a fission reactor is a self-sustaining fission reaction. And from there it is just a small step to an overcritical reactor that will explode if you don't stop it. A critical failure would be the failure to stop the fission reaction when you need to. You can take a lot of measures to prevent that, but the Chernobyl incident shows that this is not just a theoretical danger.

A small step? My car runs on combustion of gasoline, that doesn't make it 'a small step' short of turning itself into a thermobaric weapon.

The Chernobyl incident was a steam explosion and doesn't have any more relationship to an atomic bomb than the pressure cooker on my stove has.

Why should iron be a problem? On neutron capture, Iron will eventually become Fe-59, which decays fast to Co-59, which is stable. If that one captures a neutron you get Co-60, which decays to the stable Ni-60 on a longer, but manageable time scale. So Fe-56 does not end up in a long-lived radioactive state, even after 4 neutron captures.

Co-60 is one of the biggest problems to be managed in every nuclear plant I have ever been around or heard about. The fact you are asking why it would be a problem demonstrates that if you have any knowledge of the subject at all it is completely theoretical.*

Which again illustrates the problem. It's just too easy to say 'Fission? Eek! It could be a bomb!!' without having any practical knowledge and throw in enough technical words to convince people who don't know any better.


* For those who are not educated in this field:

The most common isotope of Uranium is U-238, which has a half life around 4.5 billion years. So if I have a chunk of Uranium in my hand and can hang onto it for 4.5 billion years half of the Uranium atoms will spontaneously decay, because they are unstable. So to give me decent odds of even a single atom in the sample decaying in the time it would take for me to get tired of holding this thing it would have to be a big chunk of Uranium. Now, every time one of these atoms decays it is going to produce radiation, so I'm not really interested in holding this thing, but because the decay rate is so slow I am not going to pick up significant exposure, unless as I said I'm holding a Uranium mountain.

On the other hand (so to speak) I might have a lump of Co-60. As noted, Co-60 has a much shorter half life. The 'manageable time scale' comes from having a half life of about five years. So if I give you a lucky coin with a million Co-60 atoms in it and you put it in your pocket half a million of those atoms are going to decay over the next five years. So you are going to be exposed to the radiation from, on average, a hundred thousand decays per year. From a small coin. Tiny slugs of Co-60 are used for radiotherapy treatment of cancer, because it is grotesquely radioactive. That lucky coin will kill you, and anyone who spends a lot of their time in the same room with you.

If you expose a significant amount of steel to a sustained high neutron flux you will produce a bunch of Co-60 dispersed throughout the steel. This will produce sufficient radiation levels in your reactor compartment to make it inaccessible...for the next couple decades. So if you are on the 'iron is no problem' bandwagon you better hope that bandwagon is powered by a reactor that can run completely maintenance free, because no one is going to be doing any.

Fission products can be highly radioactive also, but they are contained in the same shielding as the fuel, which is designed to contain emissions from the operating reactor. While people talk about the million year half life stuff as a 'long term problem', which it is, it is a long term problem with stuff that is not very radioactive. The truth is if you took all the long lived products and ground them up in an amount of rock comparable to the ore the fuel was originally refined from you would basically be right back where you started...with a mountain of very slightly radioactive stuff.

 

[uppi]

A small step? My car runs on combustion of gasoline, that doesn't make it 'a small step' short of turning itself into a thermobaric weapon.

The Chernobyl incident was a steam explosion and doesn't have any more relationship to an atomic bomb than the pressure cooker on my stove has.

And what was the cause of the steam explosion? A runaway fission reaction that could not be stopped any more, because the control rods were stuck. And the secondary explosion is assumed to have been a very small nuclear explosion.

Co-60 is one of the biggest problems to be managed in every nuclear plant I have ever been around or heard about. The fact you are asking why it would be a problem demonstrates that if you have any knowledge of the subject at all it is completely theoretical.*

I specifically referred to nuclear waste management. And for that 5 years half-life is not such a problem as the longer-lived waste products are for fission reactors. I agree that the shielding of a fusion reactor will be quite radioactive and that is a problem, but that problem is on the same order of magnitude as in fission reactors.

Which again illustrates the problem. It's just too easy to say 'Fission? Eek! It could be a bomb!!' without having any practical knowledge and throw in enough technical words to convince people who don't know any better.

I am sorry, but if you do not acknowledge the problem of an overcritical reactor, I ask you to stay away from any fission reactor.

On the other hand (so to speak) I might have a lump of Co-60. As noted, Co-60 has a much shorter half life. The 'manageable time scale' comes from having a half life of about five years. So if I give you a lucky coin with a million Co-60 atoms in it and you put it in your pocket half a million of those atoms are going to decay over the next five years. So you are going to be exposed to the radiation from, on average, a hundred thousand decays per year. From a small coin. Tiny slugs of Co-60 are used for radiotherapy treatment of cancer, because it is grotesquely radioactive. That lucky coin will kill you, and anyone who spends a lot of their time in the same room with you.

Come on. That is not even a nSv. You need to do better if you want to illustrate the dangers of Co-60.

 

[Timsup2nothin]

And what was the cause of the steam explosion? A runaway fission reaction that could not be stopped any more, because the control rods were stuck. And the secondary explosion is assumed to have been a very small nuclear explosion.

Loss of coolant flow. Same as every other steam explosion that has ever happened in any power plant, nuclear or otherwise.

To produce a sufficiently supercritical reactor to get anything like the reaction rate you get in a fission bomb you basically need some sort of control rod ejection accident, because you can't get there just on reactivity (control rod here exposes this much fuel), you need a substantial reactivity addition rate (control rod moving out and exposing more and more fuel, ejection meaning a very high rate of reactivity addition). Given that there was a steam explosion at Chernobyl and steam explosions make things move it is superficially plausible that a rod ejection accident may have occurred.

The only rod ejection accident I've ever heard of was the result of a steam explosion in a tiny experimental reactor. The small steam explosion occurred and drove a control rod out of the reactor while doing very little other damage so the critical geometry of the reactor was maintained. The reactor, designed to produce milliwatts produced kilowatts...for an incredibly short period of time before flying apart. If a rod ejection had happened at Chernobyl and generated a reactivity addition rate criticality it wouldn't have been considered a 'secondary explosion'. That little test reactor did more or less turn itself into a bomb.

Hence 'superficially plausible' at Chernobyl, but obviously did not happen.

Since that accident at the tiny reactor, control rod drive mechanisms have been designed to prevent rod ejections by forces that are not sufficient to destroy the critical geometry first. It isn't hard to do. The reactor that demonstrated the necessity of this precaution failed because the control rods were actually operated by a winch, with nothing but gravity holding them in. That isn't what they were doing at Chernobyl, I promise.

Steam explosions in power plant sized nuclear reactors make a gigantic mess, but they break up the reactor which shuts it down, they don't eject control rods and turn it into a bomb.

The general flaw here is that you keep making arguments that have nothing to do with bombs. Even if you have all the control rods stuck and can't shut a reactor down, that doesn't equate to a nuclear bomb. That's like an oil fired boiler with a stuck fuel valve. It might keep perking along, and if you can't keep drawing off steam you have a problem, but it isn't a bomb. It's a steam explosion in the making, but not a bomb.

Sorry if it seems like I'm picking on you, but you're continuing to dig into deeper and deeper holes so throwing dirt on you is just impossible not to do.

By the way, since you didn't acknowledge the 'problem' of thermobaric weapons are you staying away from cars? You needn't worry about me, because I'm retired and haven't operated a nuclear reactor in a long time and have no intention of doing so, but turning one into a bomb is on the same order as turning your car into a thermobaric weapon...the fuel is there, but that's about the extent of it.

 

[uppi]

Maybe you should get off your high horse and look at what actually happened at Chernobyl. Most of the control rods were ejected (which wasn't an accident but operator stupidity). There were two explosions, one of which was likely nuclear:

http://link.springer.com/article/10.1007/s00024-009-0029-9

The value of the ¹³³Xe/^133mXe isometric activity ratio for the stationary regime of reactor work is about 35, and that for an instant fission (explosion) is about 11, which allowed estimation of the nuclear component of the instant (explosion) energy release during the NPP accident. Atmospheric xenon samples were taken at the trajectory of accident product transfers (in the Cherepovetz area); these samples were measured by a gamma spectrometer, and the ¹³³Xe/^133mXe ratio was determined as an average value of 22.4.

 

[Timsup2nothin]

Or not.

About two to three seconds later, a second explosion threw out fragments from the fuel channels and hot graphite. There is some dispute among experts about the character of this second explosion, but it is likely to have been caused by the production of hydrogen from zirconium-steam reactions.

From your source...

This suggests a local character of the instant nuclear energy release and makes it possible to estimate the mass of fuel involved in this explosion process to be from 0.01 to 0.1% of total quantity.

Let's see...well known Zirconium-steam reaction problem produces explosive hydrogen, or wild chance as the steam explosion blows the reactor apart puts a tiny fraction of the fuel (and no more, just a tiny fraction) into a critical mass and geometry to spontaneously produce an atomic bomb.

While I'm sure that people who really want there to be some similarity between atomic bombs and fission reactors are glad to have a source they can link to, your source accounts for the 'dispute among experts' by providing a possible but highly implausible nuclear source for the second explosion. Since no one can prove it didn't happen you can cite it, but the chemical reaction that has happened in other reactor accidents, is a known issue, and accounts just as well for the second explosion is a whole lot more plausible.

As to my 'high horse'...you came up with the whole 'fission reactors can go up like a bomb' line, which I see no reason to just let pass as if it were suddenly improved from when it has been said by anti-nuclear activists with no knowledge in the past. Doing so would illustrate my point that knowledge cannot overcome fearmongering, but I think disputing it makes my point just as well.

Meanwhile, no control rods at Chernobyl were ejected. There is no mechanism by which an operator, stupid or not, can eject control rods. Control rods can be withdrawn, and at Chernobyl they were, just like they are at every nuclear power plant everywhere, using motors designated for that purpose. At the time of the accident the control rods were being inserted, not withdrawn, and most assuredly not ejected.

Your continuing further and further afield into using terms that you don't demonstrate any understanding of also helps prove my point, so thanks, but I think we've seen enough.

 

[uppi]

So what is your/their explanation for the ratio of metastable Xe-133 and Xe-133? That ratio is certainly not indicative of normal reactor operation. It might have been only a small part of the fuel taking part in that, but that is bad enough. That there is disagreement within the experts should make it obvious that the case is not as clear cut as you make it to be.

The control rods where removed by the operators to the point where the reactor was extremely unstable. and then they stuck (because they moderated the neutron flux and caused a power surge) when they tried to reinsert them. So there wasn't enough of them inserted to prevent the reactor from going overcritical.

The physical mechanism for a chain reaction in a nuclear bomb and a nuclear power plant is pretty much the same. It is just the parameters that are very different.

 

[Timsup2nothin]

So what is your/their explanation for the ratio of metastable Xe-133 and Xe-133? That ratio is certainly not indicative of normal reactor operation. It might have been only a small part of the fuel taking part in that, but that is bad enough. That there is disagreement within the experts should make it obvious that the case is not as clear cut as you make it to be.

Expert testimony is always for sale, and getting someone to say "well, this could have happened' is easy. But with a much more plausible hydrogen explosion as also possible all the pie in the sky possibilities in the world make very little difference.

As to the Xe-133 ratio, I offer no explanation at all. That includes the 'oh there was a nuclear explosion' explanation your source offers, because it doesn't make sense. They say 'an operating reactor produces this value, and an explosion produces that value'. Okay, great. Then they say their sampled value is about halfway between those values. Okay. So that would indicate that there was about equal amounts of 'explosive' fission as 'ordinary reactor' fission. But even they can see that if that had happened there would have been a crater, not a pile of wreckage. Given that there seems to be no plausible explanation for their sample, I would guess that their methodology is at fault. Taking airborne Xenon samples somewhere downwind seems pretty vague, since there has never been any occasion to try it before or since, so I'd disregard this out of hand.

The control rods where removed by the operators to the point where the reactor was extremely unstable. and then they stuck (because they moderated the neutron flux and caused a power surge) when they tried to reinsert them. So there wasn't enough of them inserted to prevent the reactor from going overcritical.

The term is 'withdrawn', not 'removed', and again certainly not 'ejected'. Withdrawing control rods exposes more fuel. This is how you do a reactor start up. Then they were inserted, which is how you shut a reactor down. Because they were not inserted fast enough to reduce reactor power fast enough to compensate for the loss of cooling the reactor heated up and caused a steam explosion, which did enough damage to make further insertion impossible (they got stuck in the wreckage). It also did enough damage to break the structural integrity of the core and eliminate the critical geometry that maintains the chain reaction, making insertion of the rods irrelevant since the reactor at that point is shut down anyway.

Now, you are positing that during that steam explosion some of the flying about fuel happened to collide and form a critical mass and geometry condition such as is found when the components of a nuclear bomb are thrown together by the triggering explosion. Given that the reactor was flying apart rather than imploding that is extremely unlikely.

On the other hand, there is no doubt that Zirconium (major structural component of any nuclear reactor) was exposed to high temperature steam. Zirconium oxidizes readily at high temperatures. So readily that it can steal the oxygen out of H2O, leaving the hydrogen to recombine into Hydrogen gas. This is a well known chemical reaction that occurs in all reactors (and accounts for why reactor designers would really like to find something that works as well as Zirconium they could use instead). So there is no doubt that the explosion could have been caused by this Hydrogen.

Since there is a simple answer and a highly unlikely answer, I go with the simple one. But you do what you want.

The physical mechanism for a chain reaction in a nuclear bomb and a nuclear power plant is pretty much the same. It is just the parameters that are very different.

And the physical mechanism of combustion of gasoline in a thermobaric weapon is exactly the same as it is in your car. That doesn't mean that if you crash your car it might turn into a thermobaric weapon spontaneously.

Creating either set of those 'very different parameters' is a pretty impressive feat of engineering. You don't accidentally accomplish those. To get a bomb, you have to make a bomb. You don't get one spontaneously out of a bunch of debris scattered from a steam explosion. Sorry if that takes all the excitement out of it.

 

[uppi]

As to the Xe-133 ratio, I offer no explanation at all. That includes the 'oh there was a nuclear explosion' explanation your source offers, because it doesn't make sense. They say 'an operating reactor produces this value, and an explosion produces that value'. Okay, great. Then they say their sampled value is about halfway between those values. Okay. So that would indicate that there was about equal amounts of 'explosive' fission as 'ordinary reactor' fission. But even they can see that if that had happened there would have been a crater, not a pile of wreckage. Given that there seems to be no plausible explanation for their sample, I would guess that their methodology is at fault. Taking airborne Xenon samples somewhere downwind seems pretty vague, since there has never been any occasion to try it before or since, so I'd disregard this out of hand.

That is such a weak attack on the methodology that you might as well say that you admit the argument is right, you just don't like it. Xe-133 is not a naturally occurring isotope, so the only source is a nuclear reactor. The properties of these nuclei is so similar that they should be transported exactly the same way in environmental conditions. So we have every reason to assume that the measured ratio has its origin at the damaged reactor.

The term is 'withdrawn', not 'removed', and again certainly not 'ejected'. Withdrawing control rods exposes more fuel. This is how you do a reactor start up. Then they were inserted, which is how you shut a reactor down. Because they were not inserted fast enough to reduce reactor power fast enough to compensate for the loss of cooling the reactor heated up and caused a steam explosion, which did enough damage to make further insertion impossible (they got stuck in the wreckage). It also did enough damage to break the structural integrity of the core and eliminate the critical geometry that maintains the chain reaction, making insertion of the rods irrelevant since the reactor at that point is shut down anyway.

Go and read your source again. The process of insertion of the control rods itself was what caused the power surge that led to the destruction of the reactor. Inserting them faster would have resulted in an even bigger power surge.

Now, you are positing that during that steam explosion some of the flying about fuel happened to collide and form a critical mass and geometry condition such as is found when the components of a nuclear bomb are thrown together by the triggering explosion. Given that the reactor was flying apart rather than imploding that is extremely unlikely.

On the other hand, there is no doubt that Zirconium (major structural component of any nuclear reactor) was exposed to high temperature steam. Zirconium oxidizes readily at high temperatures. So readily that it can steal the oxygen out of H2O, leaving the hydrogen to recombine into Hydrogen gas. This is a well known chemical reaction that occurs in all reactors (and accounts for why reactor designers would really like to find something that works as well as Zirconium they could use instead). So there is no doubt that the explosion could have been caused by this Hydrogen.

Since there is a simple answer and a highly unlikely answer, I go with the simple one. But you do what you want.

Lets put some numbers to your 'simple' answer: The yield of that explosion was 10 tons of TNT. To get the same amount of energy from oxidation of zirconium, you would need about 4 tons of zirconium. The zirconium is used to clad the fuel rods, using maybe 0.5 kg of zirconium. A power-generating reactor contains roughly 200 fuel rods (feel free to come up with better numbers than these rough estimates), so we get about 100kg of zirconium. Even if we make the unlikely assumption that all of it oxidized at once, that amount is in no way enough to account for the size of the explosion.

So your answer is simple, obvious and wrong.

And the physical mechanism of combustion of gasoline in a thermobaric weapon is exactly the same as it is in your car. That doesn't mean that if you crash your car it might turn into a thermobaric weapon spontaneously.

According to Hollywood it does...

But seriously, there is a risk of the gasoline in the car turning into a thermobaric weapon. If the fuel tank ruptures, you are a spark away from an explosion. Thus engineers have put a lot of effort to preserve the structural integrity of fuels tanks under all conditions to minimize the risk. And every time you get into a car you accept that risk and pretty much everyone would agree that the benefit of driving a car outweighs the minimal risk.

 

[Timsup2nothin]

And insertion speed relates to the difference between ejection and withdrawal how exactly?

There is a huge difference between 'supercritical' and 'blowing up'. I've made reactors supercritical. That is how you get from shut down to generating usable power. It's how you get from running at half capacity to running at full capacity. A supercritical reactor is just increasing in power output over time. Nothing spectacular about it. If it produces too much power for the cooling system, the reactor will break. To get it to explode you have to get the power level increasing so fast that before the reactor has time to break it can reach the energy density of a bomb, and that is just not doable. Believe me, I spent many a long and tiresome watch trying to figure out any way I could get it to happen, with plenty of educated and experienced operators considering possibilities (purely to pass the time, not because we were planning any acts of terrorism) and there just isn't anything workable.

Your ideas on the amount of Zirconium in a fission reactor are off by miles, by the way. Due to being neutron transparent Zirconium is the primary structural material in the core. If you think you can build a power plant core with half a kilo of structural material I can't change your mind. Not that it matters, since oxidation of zirconium isn't the energy source anyway. The problem is that oxidizing Zirconium in a steam environment produces free Hydrogen. Last time I checked Hydrogen explosions were fully capable of producing a pretty good pop.

I didn't attack the methodology, since there is no indication the methodology is documented in any available fashion. You came up with your link to a study that is not taken very seriously and asked me to treat it seriously. I won't.

Even in Hollywood cars just blow up, they don't turn into thermobaric weapons. With the right engineering twenty gallons of gasoline can do a whole lot more than blow up a car. However, just like flying debris doesn't accidentally come together and build its own atomic bomb that engineering doesn't get reproduced in a car accident.

Yes, a car's gas tank could be punctured in such a way that the edges of the puncture happen to duplicate an atomizing nozzle, and then the car could break up in such a way that a large weight lands on the gas tank without obstructing that nozzle (which would also have to be not pointed at the ground or any other nearby obstacle. The collapsing fuel tank could force the fuel through the makeshift nozzle and form a cloud of atomized fuel. The cloud would immediately start to condense into droplets, but if at just the right instant a piece of debris struck a spark near the center of the cloud...wait, need two pieces of debris for that, since we need the spark at elevation...but yeah, it is possible to get a thermobaric weapon in a car crash.

Just like flying bits of Uranium might smash into each other with sufficient impact to form an imploding critical mass when a steam explosion blows a reactor apart.

It's just not very likely.



Anyway, I'm done here, but thanks for illustrating my point. You seem like a reasonably intelligent person with access to the internet and some exposure to the theory behind a nuclear reactor...and having said 'a fission reactor can turn into a bomb' you would probably die rather than back off that statement and no one can make you, because despite it being totally implausible no one can say it is impossible. So arguing with the average joe public that hears ''fission reactor" and thinks "hey that's how an atomic bomb works" while having no clue about either is a lost cause. Unfortunately, as soon as someone really has a fusion reactor it will be mentioned in the same breath as "H-bomb" and that will be the end of that.

 

[uppi]

Not that it matters, since oxidation of zirconium isn't the energy source anyway. The problem is that oxidizing Zirconium in a steam environment produces free Hydrogen. Last time I checked Hydrogen explosions were fully capable of producing a pretty good pop.

Your accusations of ignorance might hold more weight, if you didn't go ahead and make ignorant statements like this one. You know that hydrogen explosions are bad news and then without thinking state that this is where the energy must come from. It cannot, and it is easy to show why:

When zirconium reacts with water it produces hydrogen. But in order to do that, it has to break up the water molecules. That costs energy and the energy is provided by the reaction of zirconium with oxygen. If there is an hydrogen-oxygen explosion afterwards, the amount of energy released is exactly equal to the amount of energy that was necessary to break up the original water molecules. So the hydrogen has zero net contribution to the total energy and all of the energy must have come from the oxidation of zirconium. So from the size of the explosion you can tell how much zirconium must have been involved if it really was caused by zirconium.

The argument gets a bit weaker, if you allow for a large amount of fluorine that would react more violently with hydrogen than oxygen. But even in that case the zirconium oxidation would contribute most of the energy. And if you have that much fluorine, the hydrogen doesn't matter much anyway, because fluorine will react with almost anything. (And you get tons of extremely nasty hydrofluoric acid)