(NOT COLD FUSION!) The byproducts of BASIC fusion...

[-Velocity-]

Idk, should we be worried some guy is trying to build a fusion reactor?

Considering high school students have built actual working fusion reactors as science fair projects, and his reactor on the other hand has zero chance of working, I would say no. If you don't believe me about the former sentence, look up "fusor".

[JMBuilder]

Considering high school students have built actual working fusion reactors as science fair projects, and his reactor on the other hand has zero chance of working, I would say no. If you don't believe me about the former sentence, look up "fusor".

Wow... You sound so sure that it's impossible... Your loss!

But anyway, the only risks of the reactor are possible localized gamma ray radiation (easily avoided by submerging it in a pool of water), burning myself or melting components.

ASIDE FROM COLD FUSION, I don't want this thread to get locked. I just wanted to ask some questions about what the effects of two atoms fusing would be.

[Kryten]

You don't think the reactor components becoming high-level radioactive waste comprises a risk?

[JMBuilder]

...How do electrodes BECOME radioactive waste?

[Ralathon]

You don't think the reactor components becoming high-level radioactive waste comprises a risk?

You only get problems with that if your reactor produces neutrons and you keep it running during extended periods of time. The amount of energy a fusor (easy to make fusion) or the 'cold fusion' reactor this guy is trying to build produces is so small it won't become a problem for years.

[JMBuilder]

It's not the reaction itself that you collect energy from. The reaction boils water and turns turbine chargers.

[Kryten]

...How do electrodes BECOME radioactive waste?

Well, it doesn't, because there's no practical way it'll be exposed to neutron radiation unless it's placed close to an actual reactor. But, assuming that's what you did, transmutation into radioisotopes from neutron bombardment, as I said about two pages back.

[JMBuilder]

Ah, that makes sense.

[OdinYggd]

...How do electrodes BECOME radioactive waste?

Transmutation by neutron bombardment.

If your reactor works well enough that fusion takes place and significant neutrons are emitted by it, those neutrons can transform the entire reactor and surrounding area into radioactive materials of variable and possibly lengthy half-lives.

And to date most fusion reactions have been found to emit significant neutrons bursts when they aren't emitting loads of gamma radiation.

I didn't know about the whole diproton thing, someone should probably post details of what is known about that mechanism. It sounds to me like that could be a real crippler for any fusion project.

In a nutshell though, fusing materials less massive than iron yields energy.

More massive than iron, fusion consumes energy. And as you get progressively more massive the amount of energy needed gets higher and higher. On the other hand fission of materials heavier than iron yields energy again, and since these elements are relatively easy to obtain and provoke into a stable reaction fission energy is attainable with nowhere near the effort required for fusion.

What interests me though is what happens if you put the same gas composition as the sun into a fusor device. In the sun it uses a carbon-nitrogen fusion cycle instead of a straight D-D hot fusion. Not really sure if that would make the required temperatures higher or lower.

[JMBuilder]

My idea is H-H fusion, so the only radiation is gamma radiation.

I spoke with someone who works at a nuclear reactor, and his biggest concern is that the electrode might destroy itself from all the pressure.

[K^2]

In the sun it uses a carbon-nitrogen fusion cycle instead of a straight D-D hot fusion.

Actually, for smaller stars, such as our Sun, proton-proton chain is the dominant fusion reaction. CNO cycle dominates in larger stars.

The fastest reaction rate you will get in a fusor is with deuterium-deuterium reactions.

As for proton-proton reactions, the main factor slowing things down is Pauli repulsion, which effectively requires a p->n decay, and that's a weak process. So by using either deuterium or a heavier nucleus to catalyze things, you speed the process up dramatically.

My idea is H-H fusion, so the only radiation is gamma radiation.

No, it's not. H-H reaction can ONLY produce a deuterium. Deuterium, in turn, can react with another hydrogen to give you a tritium. Tritium will react with deuterium to give you helium + neutron. In any proton-proton chain, there will be a fraction of reactions that produce fast neutron radiation.

Edit: It's going to be a small fraction. D + H -> T is a very small branch. Ground state He3 is stable, so it can only decay to T from an excited state. But if you have a sufficient reaction rate to produce power, you will have some neutron radiation.

There is also the fact that sufficiently hard gamma radiation can cause fission of some otherwise stable heavy nuclei. So there is danger of secondary radiation from gamma as well.

Edited October 7, 2013 by K^2

[JMBuilder]

K^2, are you sure you know what your talking about? I DID speak with an expert on nuclear physics, and I asked him about that. He said that you only get gamma rays.

[FlexGunship]

K^2, are you sure you know what your talking about? I DID speak with an expert on nuclear physics, and I asked him about that. He said that you only get gamma rays.

Mass is not significantly annihilated in a fusion reaction.

Deuterium is an interim product of the proton-proton fusion chain which is the only chain that starts with nothing but hydrogen atoms. The end result will always be helium of an H+H reaction because the energy cost of fusion decreases until you reach the final products: (He^4)+2H. This is called a cascade reaction.

The stages are this:

1) 2[H+H] -> 2[e(+)+v+D]

2) 2[D+H] -> 2[(He^3)+y]

3) 2[(He^3)] -> (He^4) + 2H

H = hydrogen

e(+) = positron

v = neutrino

D = Deuterium

(He^3) = Helium with one neutron

y = photon of gamma radiation

(He^4) = Helium with two neutrons

Bold indicates an outside addition to the reaction. Total is 6H.

Underline indicates an output of the reaction. Total output is (He^4)+2[H+e(+)+v+y].

In the conditions which allow step (1) occur, all other steps will occur spontaneously. You cannot just do the first step of the fusion chain and then halt it.

There are other hydrogen-based fusion reactions... but this is the only one to start with two standard hydrogen atoms.

This is your process for light water fusion. Until you discover a second process (presently unknown to science) for proton fusion, you are out of luck. Very smart people have spent a long time working on this problem. There is good reason for it going unsolved and unapplied in all but high-energy experimental reactors.

Edited October 7, 2013 by FlexGunship

[Ralathon]

K^2, are you sure you know what your talking about? I DID speak with an expert on nuclear physics, and I asked him about that. He said that you only get gamma rays.

That's because hydrogen fusion only produces gamma rays.

H + H = D + positron + energy. The positron quickly annihilates with a random electron to produce more gamma rays.

However, this is only the first step of all the reactions you'll get. The deuterium will subsequently start to fuse into helium 3 and tritium. Those will subsequently fuse in a myriad of ways, quite a few of which produce neutron radiation.

The thing is, that first step is by far the slowest step in your reaction. It's why the sun isn't out of fuel in a few million years. It is really rare for H+H to equal D, most of the time the H's bounce right off without fusing because the p-->n+e(+) conversion is reliant on the weak nuclear force (which, as the name implies is rather weak).

[Idobox]

Seriously, I don't think you should worry about radiation.

A simple temperature probe could be used to cut off the reaction if, contrary to all expectations, a reaction occurred, to keep it at safe levels.

Also, neutron radiation in DT fusion is actually good, since you can use it to transmute Lithium into more tritium. Given that tritium has only a half life of 11 years and is produced in small quantities in PWR, it is very useful to be able to make more than you consume.

[FlexGunship]

Seriously, I don't think you should worry about radiation.

A simple temperature probe could be used to cut off the reaction if, contrary to all expectations, a reaction occurred, to keep it at safe levels.

This is the stuff that's stagnating the conversation. What kind of temperature probe is functional in a fusion reaction? Additionally, how would you go about stopping it? Throw water on it? Just turn the temperature down? If you have a self-sustaining thermonuclear reaction (necessary for a positive net output of energy) then how would you stop it? This isn't fission... there's no rod to stick in the middle of the reaction.

[Ralathon]

This is the stuff that's stagnating the conversation. What kind of temperature probe is functional in a fusion reaction? Additionally, how would you go about stopping it? Throw water on it? Just turn the temperature down? If you have a self-sustaining thermonuclear reaction (necessary for a positive net output of energy) then how would you stop it? This isn't fission... there's no rod to stick in the middle of the reaction.

The OP is trying to build a cold fusion reactor. So the temperatures aren't going to exceed the boiling point of water (and most likely they won't exceed room temperature...), a PT100 should do fine. And if I recall the idea behind cold fusion reactors correctly they needed an active current to keep electrolysis of the water running. So just shut off the power when you see the water boiling or the PT100 is showing spikes.

If you have a self sustaining fusion reaction the easiest way to stop it is to simply let the plasma escape into the atmosphere. Adiabatic expansion in combination with mixing with the normal air will stop the fusion pretty quickly.

[Idobox]

Also, the fact that despite important funding and lots of time by a lot of people have failed to prove the existence of cold fusion means that if anything happens, it will be on a small scale.

The original experiment cost 100 000$ and saw the temperature of water rise from 30 to 50C. Not exactly a Tsar Bomba.

In my opinion, the OP's time would be better spent reading the original paper and the papers that refute the claims. Or try to work on sonofusion or polywells.

[-Velocity-]

Also, the fact that despite important funding and lots of time by a lot of people have failed to prove the existence of cold fusion means that if anything happens, it will be on a small scale.

The original experiment cost 100 000$ and saw the temperature of water rise from 30 to 50C. Not exactly a Tsar Bomba.

In my opinion, the OP's time would be better spent reading the original paper and the papers that refute the claims. Or try to work on sonofusion or polywells.

Yup. Polywells may be the best chance outside of laser (inertial) confinement and big tokamak magnetic confinement, and would be MUCH cheaper and more practical than either of the two, and unlike cold fusion, polywells at least seem to have a chance at actually working. Oh and finally, you might even be able to build a polywell in your garage too.

[Anton P. Nym]

Also, neutron radiation in DT fusion is actually good, since you can use it to transmute Lithium into more tritium. Given that tritium has only a half life of 11 years and is produced in small quantities in PWR, it is very useful to be able to make more than you consume.

Another byproduct of using lithium as a neutron blanket is.... Helium-3. Frankly, if we ever do get an He3 reactor going it'd be far cheaper and easier to feed it that way than to scrape the top 10 micrometers off the Moon.

-- Steve

[JMBuilder]

I see the problem! In regular fusion, yeah, you get all those different reactions. In Cold Fusion, it's one step. The lattice fuses Hydrogen into a Helium-4 isotope, which then exits the lattice, decaying back into Hydrogen.

[andrewas]

So if you start with a pair of deuterium nuclei, and end of with a pair of deuterium nuclei, where is the energy coming from? And, for that matter, what takes apart the He4? He4 is stable.

Or maybe you meant to fuse regular hydrogen-1 into helium-2. Problem is, He2 immediately collapses back into a pair of H1, again leaving you with no net energy change. On very rare occasion He2 instead undergoes beta decay into deuterium. That is an energy producing reaction, but its one that runs very slowly even under the conditions found in the core of the sun, so its not a good candidate for any type of fusion reactor.

[Kryten]

I see the problem! In regular fusion, yeah, you get all those different reactions. In Cold Fusion, it's one step. The lattice fuses Hydrogen into a Helium-4 isotope, which then exits the lattice, decaying back into Hydrogen.

You just said that even your pet crackpots don't claim to have caused fusion reactions in light water, i.e. without deuterium.

[JMBuilder]

Yes, I meant Helium-2. Fusion produces a heckuva lot of heat even without neutrons.

[K^2]

If your He-2 decays back to H+H, you get no energy output.