Yet another Fusion-in-a-decade ckaim

[Timsup2nothin]

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.

Other than your failing to account for the kinetic energy of the steam molecules (which is what drives the oxidation reaction) your argument really would make me feel ignorant. Gee, maybe a little practical experience with the subject would serve you well, but I'm sure everyone who has been dealing with the issues of Hydrogen formation in reactors will be glad to have your assurance that there was nothing to worry about.

Why are you so committed to trying to support "fission reactors can explode like an atomic bomb"? It's a throw away statement that 99% of the public will accept without a blink. When someone doesn't the smart anti-nuclear activist just walks away, because that 1% of the public is totally meaningless in the grand scheme of things, and is almost always capable of supporting their position because they have experience in the industry. The last thing the anti-nuclear activist wants is to participate in a debate where actual facts start getting tossed around, because come of that 99% might pay enough attention to get educated.

 

[uppi]

Other than your failing to account for the kinetic energy of the steam molecules (which is what drives the oxidation reaction) your argument really would make me feel ignorant. Gee, maybe a little practical experience with the subject would serve you well, but I'm sure everyone who has been dealing with the issues of Hydrogen formation in reactors will be glad to have your assurance that there was nothing to worry about.

Now you're just digging deeper into your hole: The mean kinetic energy of the water molecules at the relevant temperatures is less than two percent of the reaction energy. For a precision calculation that might be relevant, but it won't change the scale at all. If you do not understand the physics behind it, all your practical knowledge is irrelevant when encountering unfamiliar situations.

Hydrogen formation is bad, but it is a symptom, not the cause. If something starts producing hydrogen from water, there has to be a highly energetic reaction somewhere that provides all the energy.

Why are you so committed to trying to support "fission reactors can explode like an atomic bomb"? It's a throw away statement that 99% of the public will accept without a blink. When someone doesn't the smart anti-nuclear activist just walks away, because that 1% of the public is totally meaningless in the grand scheme of things, and is almost always capable of supporting their position because they have experience in the industry. The last thing the anti-nuclear activist wants is to participate in a debate where actual facts start getting tossed around, because come of that 99% might pay enough attention to get educated.

Simply because out of control nuclear reactions were the cause of exploding nuclear reactors. For the end result it doesn't matter much, whether the nuclear energy is a direct cause or merely thermally activates secondary energy sources.

 

[brennan]

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

You spend the next 20 posts arguing about the reason. Safety. A fission reactor is entirely reliant upon dangerous unstable radioactive isotopes and upon concentrating a dangerous amount of these isotopes in a confined space and deliberately increasing the reaction rate.

Fusion involves sticking stable isotopes together into other stable isotopes and requires no more material than a tenuous plasma. If the fusing material in the ITER reactor suddenly escaped confinement altogether, the techs probably wouldn't even notice the room warming up.

Simply because out of control nuclear reactions were the cause of exploding nuclear reactors.

Chemical/steam explosions. Not atomic. Not by a long way.

 

[Timsup2nothin]

You spend the next 20 posts arguing about the reason. Safety. A fission reactor is entirely reliant upon dangerous unstable radioactive isotopes and upon concentrating a dangerous amount of these isotopes in a confined space and deliberately increasing the reaction rate.

Fusion involves sticking stable isotopes together into other stable isotopes and requires no more material than a tenuous plasma. If the fusing material in the ITER reactor suddenly escaped confinement altogether, the techs probably wouldn't even notice the room warming up.

Chemical/steam explosions. Not atomic. Not by a long way.

The thing is that those 'dangerous unstable isotopes' really aren't. Putting them together properly in a reactor makes them a power source. Putting them together properly in a bomb makes them destructive. All the talk about 'oh, storage forever' plays into the "radiation death" camp's rhetoric, but the reality is that these things with half lives in the millions of years do not undergo decay at a sufficient rate to present a significant risk other than the fact that they could be made into bombs. A whole lot of streets would be less radioactive if they were paved with Uranium.

As you say, the danger from a fission reactor ultimately comes from chemical and steam explosions, (mostly steam, since it is almost always some sort of steam explosion that allows chemicals to get together that by design wouldn't). The problem is that a fission reactor is so much more capable of producing a steam explosion than a combustion boiler due to the energy density.

All the power a submarine needs is produced in a volume of about fifteen cubic feet. Getting that energy produced is pretty easy. Keeping control of the process is pretty easy. Dispersing that energy out into usable forms is the hard part. Now fusion comes along and instead of starting from a trash can sized lump of 700 degree metal we can get all the energy needed from a thimble sized lump of stellar plasma. Great, but I don't see that making the dispersion process any easier...and since the problems with fission reactors are produced in that dispersion process fusion might not be any safer in practice.

My answer to what made fission a minority market with overpowering financial risks is that there was no way to overcome public hysteria. As you say, twenty posts later we still have an Uppi chanting 'It is made of Uranium! It's a bomb in disguise!!!', and without a much more educated public than we have twenty posts makes no more difference than two, and no less than two hundred. The public will still be scared of what they don't understand, and will be looking for ways to shut down your multi- million dollar investment. I don't see fusion having a magic bullet to get around that.

 

[Timsup2nothin]

For the end result it doesn't matter much, whether the nuclear energy is a direct cause or merely thermally activates secondary energy sources.

It doesn't matter much? Go to Japan and ask around. They can put Hiroshima and Fukushima in perspective for you. One was a bomb, the other wasn't, period.

 

[uppi]

The thing is that those 'dangerous unstable isotopes' really aren't. Putting them together properly in a reactor makes them a power source. Putting them together properly in a bomb makes them destructive. All the talk about 'oh, storage forever' plays into the "radiation death" camp's rhetoric, but the reality is that these things with half lives in the millions of years do not undergo decay at a sufficient rate to present a significant risk other than the fact that they could be made into bombs. A whole lot of streets would be less radioactive if they were paved with Uranium.

The millions of years stuff is not very problematic. The problem is with the thousands of years stuff. Technologically the waste problem could be solved by separating it and transmuting the semi-long lived waste. The problem is political, because that kind of technology tends to of the dual-use kind.

My answer to what made fission a minority market with overpowering financial risks is that there was no way to overcome public hysteria. As you say, twenty posts later we still have an Uppi chanting 'It is made of Uranium! It's a bomb in disguise!!!', and without a much more educated public than we have twenty posts makes no more difference than two, and no less than two hundred. The public will still be scared of what they don't understand, and will be looking for ways to shut down your multi- million dollar investment. I don't see fusion having a magic bullet to get around that.

Better education will not help. Among my colleagues with similar education I tend to be more in favor of nuclear power than most and postgraduate atomic physics is as close as an education gets without really specializing in nuclear physics (and these days specializing in nuclear physics is not a very good idea)

It doesn't matter much? Go to Japan and ask around. They can put Hiroshima and Fukushima in perspective for you. One was a bomb, the other wasn't, period.

Short term you are absolutely right. Long term I am not so sure: Hiroshima has been rebuilt fairly quickly. Chernobyl is still uninhabited.

 

[Luckymoose]

Simply because out of control nuclear reactions were the cause of exploding nuclear reactors. For the end result it doesn't matter much, whether the nuclear energy is a direct cause or merely thermally activates secondary energy sources.

Nuclear reactors don't explode. They are not bombs. Nuclear meltdowns have barely harmed anyone, and only three have even occurred in the last 70 years. Fukushima was so blown out of proportions by the media it isn't even funny. Far more people die from mining coal daily than have ever died from nuclear meltdowns.

 

[brennan]

The thing is that those 'dangerous unstable isotopes' really aren't.

Actually they kind of are. Plutonium is generally agreed to be the most dangerous element known; the cumulative effects of background radiation kills perhaps millions of people every year. The risks associated with nuclear power all derive from the possibility of contamination of an area with radioactive elements in one way or another.

since the problems with fission reactors are produced in that dispersion process

None of the big accidents were anything to do with the conversion of heat into electricity. Which is easy and something we've been doing on a massive scale for well over a century. They were all to do with the problems of confinement and containment of the reaction and the material involved.

I'm right with you on the issue of public hysteria. I remember when an MRI scan was an NMRI scan but they decided to drop the N. But fission really does have problems.

 

[Timsup2nothin]

Actually they kind of are. Plutonium is generally agreed to be the most dangerous element known; the cumulative effects of background radiation kills perhaps millions of people every year. The risks associated with nuclear power all derive from the possibility of contamination of an area with radioactive elements in one way or another.

None of the big accidents were anything to do with the conversion of heat into electricity. Which is easy and something we've been doing on a massive scale for well over a century. They were all to do with the problems of confinement and containment of the reaction and the material involved.

I'm right with you on the issue of public hysteria. I remember when an MRI scan was an NMRI scan but they decided to drop the N. But fission really does have problems.

The conversion of heat into electricity isn't the problem...it's the compact nature of the heat source and drawing the heat out to whatever equipment uses that heat. It's like the difference between a stove burner and a blowtorch. Take a hypothetical burner and blowtorch that generate the exact same amount of total heat...the burner boils the water in your kettle by heating the whole bottom of the kettle, and the torch punches a hole in the kettle at whatever spot it is aimed at...a dispersion problem.

This also illustrates the source of all the containment problems. If your kettle is on a burner and boils dry you have time to deal with shutting the burner off before the kettle is significantly damaged. But even if the water inside is circulating enough to keep the blowtorch from burning the targeted spot, if it boils dry you will damage the kettle pretty much immediately. Every reactor accident comes down to loss of cooling, generally after the reactor is shutdown. There just isn't enough material in the core to deal with the energy density.

Plutonium is dangerous chemically, far more than as a radiation source. The contamination of an area with radioactive materials is a problem when it is things like radioactive calcium that gets consumed and retained in normal bio-chemical processes. Or the unstable carbon isotopes in the soot from burning the graphite at Chernobyl (note to self and others, graphite moderator is a very bad idea). If you scattered enough Plutonium to add significantly to normal background radiation levels you would poison everything long before the radiation was even noticeable.

 

[brennan]

So... you agree with me? Maybe you should think about this.

 

[Timsup2nothin]

So... you agree with me? Maybe you should think about this.

Why? You seem reasonable enough.

We agree that the difficulties associated with fission reactors have nothing really to do with the fission process. It has to do with distributing the energy generated from something that for practical purposes is far to close to a 'point source'. A fusion reactor generating a comparable amount of energy will be even closer to a point source. That does not seem to be a step towards solving the problem.

We agree that the problems with spreading contaminants has more to do with their chemical nature than anything else. While a fusion reactor won't produce problematic fusion products the way a fission reactor produces problematic fission products, the vast majority of the problems encountered involving contamination from fission reactors has to do with materials activated by the neutron flux, not fission products. What to do with a tiny wafer of plutonium is a problem, what to do with a million gallons of water with higher than normal levels of tritium is a much more complicated problem. The fusion reactor will generate as much if not more neutron flux, so again this doesn't directly solve the main issue.

Which brings us back to the point you have readily agreed with, which I see as the main thing to consider. As soon as someone has an actual working fusion reactor it will lose the immunity it has had from those who will be looking at the problems it creates. And they will kill it just as surely and wastefully as they have killed fission as a power source.

 

[Ferocitus]

There have been some obtuse references to structural materials in this thread.
(I'm not sure why they were actually mentioned.)

However, there are some interesting limitations (for both fission and fusion
reactors) that occur because of the scarcity of several elements that are currently
necessary to prevent embrittlement of structural materials, e.g. beryllium, niobium,
yttrium, zirconium. Hafnium and some others are also highly desirable.
The extinction rates for some essential (non-fuel) elements are summarised in
Table 1 on p. 1616 of Derek Abbott's IEEE paper, "Is Nuclear Power Globally Scalable?"
http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=6021978

IMO, the onus is on anyone proposing a large-scale increase in the number of fission
(or future fusion) reactors to demonstrate how they will guarantee the continuing
supply of those essential elements over the entire lifetimes of the power plants,
especially when the same elements have many other industrial uses.
("We'll eventually solve those problems", doesn't get you off the hook!)

As someone once put it: Physics without engineering is just philosophy.