An easier way to make a reactor? The K40

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Doug Browning
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An easier way to make a reactor? The K40

Post by Doug Browning » Sun Mar 11, 2012 7:58 pm

From my intro page:

No plans or interest in building a fusor per se. But I would like to investigate a potassium 40 reactor, K40. This is a 1/10,000 part impurity in normal potassium that is radioactive by electron capture (10.7% decays by electron capture, converts to Ar40, P+e- = N, with 1.46 Mev Gamma) the other 89.3% decays to Ca40 with emission of an electron with a max 1.33 Mev. I would like to find out if this can be made into a stimulated decay by electron bombardment. (anyone have info on cross sections for electron bombardment of K40? optimum electron energy level? resonant tunneling?)

Unlike most "untouchable" radioactive decays, electron capture cases (no nucleons are added or expelled here) have been shown to be rate modify-able by extreme pressure, which increases electron density in the atom/nucleus (S or K shell electrons). One would think that smacking the nucleus with an electron would qualify for increased electron density. Is there an optimum energy for this? The impinging electron does not feel the nuclear force, so the usual, formidable, nuclear fusion barrier is removed, but some threshold energy may be required to de-stabilize the nucleus. (native S or K shell electrons don't have the requisite energy to destabilize the nucleus, hence a billion+ year lifetime for the K40 nucleus)

Energy required should be less than the 0.789 Mev required to reverse neutron decay (N = P + e- + 0.789 Mev ) due to the additional positive nuclear charge here. (some estimate is possible from a close packed spheres model, the proton at the surface, with half of the surrounding 6+3 particles as neutrons. So the electron is interacting with 5 protons at about 2.8x10^-15 m ; note the almost zero change in binding energy between B10 and Be9, ie, the door appears to be open)

Since the normal radioactive decay is exothermic with around 1.46 Mev gamma ray emission or 1.33 Mev electron emission , one expects that any incident electron energy will either increase the gamma ray or the emitted electron energy or produce X-rays . One would think the electron capture channel would be the favored one (to Ar40 + gamma ray) with an excess electron provided. (But maybe it can also just emit two electrons and follow the Ca40 decay channel as well? Maybe tuning the electron projectile energy can select which channel? Being able to select the Ca40 channel would provide an efficient direct electrical energy conversion via electron capture.)

If workable, this should be a LOT easier than trying to do fusion. No neutrons, just 1.4 Mev gamma rays or beta rays. And projectile electrons are ATTRACTED to positive nuclei (not repelled! aka Fusion). Such a stimulated decay approach would provide a convenient throttle for variable power generation. Worst case is to just accumulate enough K40 for normal mode radioactive decay into heat for warming the house. So some laser K40 isotope separation experiments will be investigated for practicality, although even that may not be necessary. (10 tons of ordinary potassium in an insulated bunker, it still puts out the same heat....)

If the K40 separation and stimulated reaction processes can be made to work out acceptably, then the 99.99% "waste" depleted potassium stock will be sold as premium non radioactive fertilizer for non radioactive food production. (non radioactive, non cancerous organic food? The average human body suffers 4400 ionizing potassium decays per second from K40 toxicity, not trivial. Have you taken your anti-oxident today?
(hey, don't laugh, some outfit is currently trying to make deuterium substituted amino acids for resistance to free radicals for "life extension". ............NASA, a long trip to Mars through radiation?)

So this potentially could be a reactor that LOWERS world wide ambient radiation and produces practical power for a song, comparatively!

Don

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Carl Willis
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Re: An easier way to make a reactor? The K40

Post by Carl Willis » Mon Mar 12, 2012 6:14 am

Don,

The positron decay branch of K-40 is already naturally highly predisposed toward electron capture since the decay energy is low, with over 99% of decays in this branch occurring via electron capture (less than 1% by positron emission). I don't see how increasing electron availability to the nucleus could help you much further if the goal is to speed up decay. (On the other hand, you could noticeably slow down the decay of K-40 by stripping it and otherwise removing electron availability, forcing it to emit the positron.)

-Carl
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Re: An easier way to make a reactor? The K40

Post by Doug Browning » Mon Mar 12, 2012 6:30 pm

So you are saying that the positron and e capture branches all start out in positron mode? With the positron "capturing" an inner shell electron in most cases (going to Ar40 in either case). (by the way, is there some way to get Qtool to accept an e- for a projectile? Or another tool?)
One issue I see with that scenario is it would likely produce a .511 + .511 Mev gamma ray(s) instead of the 1.46 Mev observed? (I guess one would have to take into account any kinetic energy of the positron too.)

I still have to wonder if injecting an extra electron into the nucleus momentarily would not hurry the annihilation of a "transient positron" there. Maybe with further consequences if the gamma ray energy is absorbed by the nucleus instead of escaping. But it seems unlikely to cause any nucleons to escape due to binding energy issues with light weight nuclei. Maybe just a delayed gamma ray emission. One would then be faced with the prospect of waiting for the target to "cool down" after a targeting session. Hot K40?

The "transient positron" may be the sticking point to timely interaction, since the quarks in the nucleons have fractional charges. The electron has to interact with two quarks, at a minimum, to get a unit charge. This will certainly slow things down, but the nucleus is dense, with classical spacings on the order of the classical electron radius. So the issue may become one of how long the electron can stick around before getting ejected from the nucleus. This would seem to favor a low kinetic energy electron projectile, just enough to get in the "door".

A show stopper would be if it actually requires virtual momentary GUT energy levels (10^15 Gev) to reconfigure the quark's charges. Certainly this is a real concern seeing the billion+ year lifetime of K40. But there are plenty of other K capture nuclei around which have very short lifetimes, some in microseconds, so this does not seem to be an issue.

On the other hand, firing an electron into just any old nucleus does not produce an annihilation obviously. So it would seem that the electron's presence must interact with a nucleus wide potential before anything can happen. The nuclear potential must be already near an unstable level for anything to happen easily. K40 seems to be there, and it is relatively small in size (faster interaction hopefully). But this may indicate a faster reaction (decay) time comes with increasing electron kinetic energy, to overcome or tunnel thru the nuclear potential barrier to nuclear reconfiguration.

The electron may also have to approach with a specific energy if it's wavefunction has to resonately build up within the nuclear well for a nucleus wide interaction. There could be some narrow energy bandwidth to the interaction if that's the case.

Then there is the other 89% branch of decay with electron emission to Ca40. This would seem to require some added energy to the nucleus to activate (some energy barrier to overcome or tunnel thru by the departing beta electron). An impinging electron with sufficient kinetic energy could provide that energy if it doesn't just sail right thru without interacting. This would indicate perhaps an optimum kinetic energy for interaction, too much and it sails thru with no interaction, too little and it maybe gets annihilated to the Ar40 path.

Again the fractional charge issue enters to get a unit charge assembled for the departing electron. And it has to get two electrons spit out now, but maybe the incident one will remain intact. So one might see a shortening lifetime as the incident electron kinetic energy goes up, eventually just sailing right thru with a decreasing cross section at some level as the interaction time shortens.

It would seem that the positron annihilation path to Ar40 would be more likely to work.
So one would certainly like to know the minimum threshold energy to getting an electron "in the door". And particularly if there is some resonance energy for enhanced reactivity. (and maybe there could be another resonance band for the Ca40 path too)

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Re: An easier way to make a reactor? The K40

Post by Carl Willis » Mon Mar 12, 2012 10:13 pm

Don,

Electron capture always competes with positron emission, except for situations where electron capture is the only energetically-possible decay pathway to the (Z-1) product. The prevailing theory, in concordance with observations, accounts for no "intermediate positron." If there were such a thing, you would see annihilation radiation from EC decay. This isn't the case. Convention says that unless the decay energy exceeds 1.22 MeV, a positron cannot be created at all.

Electrons generally do not have a measurable influence on radioactive decay of a nucleus. One exception is EC decay, where they are simply a necessary ingredient. Other exceptions only apply to nuclides whose decay energies are so small that the energetics of the electronic surroundings become important, and even then the effects are hard to measure. Certainly K-40's decay modes (1300-1500 keV) are beyond these influences. All these influences depend on electrons having high availability to the nucleus, thus favoring bound inner-shell s-orbital electrons for which the concepts of resonances and energy-dependent cross-sections seem pretty irrelevant. By contrast, high energies are needed for electron-induced photonuclear ("electronuclear") reactions. To be clear, those are not radioactive decay but (g,X) reactions where X is some nucleonic species.

Detectably modifying the decay of K-40, to say nothing of a practical application thereof, would seem to be sufficiently distant from the realm of amateur laboratory capability to warrant discouraging a drawn-out discussion here--at least until someone gets their hands dirty on the subject.

-Carl
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Re: An easier way to make a reactor? The K40

Post by Doug Browning » Tue Mar 13, 2012 1:16 am

Well, seeing as how the S shell electrons can pass right thru the nucleus without interaction, it must be the lack of a strong force component to the electron which is limiting the interaction. How about bopping the K40 nucleus with a proton (or even better maybe, an anti-proton) with just enough energy to shake things up? A resonant fender bender, pieces start falling off.

Or how about a positron. The nucleus might take notice of antimatter.

Hmm, or how about just banging two K40s together, not enough to fuse or anything like that. Just want to supply the energy needed to get over the decay threshold. The resonant fender bender thing. You could run them in a fusor even. Hopefully, single ionization level would be sufficient, so that most of the charge would be neutralized and inner electrons would be available.

The more I think about the K40 + K40 collision, the better I like it. Two birds with one collision for starters. Then there is a good chance that even glancing collisions are useful here. Reving up the nuclear orbital spins should be just as effective as a head on. Throwing off an electron or positron or even gamma rays are excellent ways for the nucleus to ditch the angular momentum. That could even be how normal capture decays operate. The probablistic rain of background virtual particles could be like a series of coin flips, which after billions of years (for K40) manage to get the orbital spin up sufficiently once (in one direction) to throw something out. (like getting "heads up" a 100K times in a row)

I rather like turning the tables on fusion. There you have to come up with the perfect confinement. Here we get to poke the holes in the confinement (nuclear potential). And electron capture nuclei like K40 are right on the edge of failing already. I like these odds better.

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Re: An easier way to make a reactor? The K40

Post by Chris Bradley » Tue Mar 13, 2012 8:58 am

Don Bowen wrote:
> I would like to investigate a potassium 40 reactor, K40.

What's your time-scale/plan of action? Are you building an electron gun, or betatron, or how else will you synthesise high energy betas?

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Re: An easier way to make a reactor? The K40

Post by Doug Browning » Tue Mar 13, 2012 1:05 pm

"What's your time-scale/plan of action? Are you building an electron gun, or betatron, or how else will you synthesise high energy betas?"

At this point I'm just throwing some ideas out, waiting for the flame throwers to bake them a little, then re-adjust them again ... Thus far, banging K40 against K40 looks like the needed approach, since electrons are just too wimpy to interact with nuclear potentials. Need something with strong force interaction. So K40 + K40. This could even be done in a fusor setup. Some idea is needed of how much energy it takes to provoke a capture decay in K40, and what the cross section targeting odds look like. I'm not sure if something like Qtool will correctly account for all useful modes of collision here (not knowing it's internals), since glancing collisions may be useful or even required. No fusion expected obviously, hoping for maybe just low Kev energies to set off the little buggers. Too high of an activation energy and there will be all kinds of losses from K40 orbital electron ionizations.

"The more I think about the K40 + K40 collision, the better I like it. Two birds with one collision for starters. Then there is a good chance that even glancing collisions are useful here. Reving up the nuclear orbital spins should be just as effective as a head on. Throwing off an electron or positron or even gamma rays are excellent ways for the nucleus to ditch the angular momentum. That could even be how normal capture decays operate. The probablistic rain of background virtual particles could be like a series of coin flips, which after billions of years (for K40) manage to get the orbital spin up sufficiently once (in one direction) to throw something out. (like getting "heads up" a 100K times in a row)"

I rather like turning the tables on fusion. There you have to come up with the perfect confinement. Here we get to poke the holes in the confinement (the nuclear potential). And electron capture nuclei like K40 are right on the edge of failing already. I like these odds better.

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Re: An easier way to make a reactor? The K40

Post by Chris Bradley » Tue Mar 13, 2012 1:23 pm

Don Bowen wrote:
> At this point I'm just throwing some ideas out, waiting for the flame throwers to bake them a little, then re-adjust them again
You can do theoretical science by building on existing knowledge that logically leads to an implied conclusion, or practical science by performing an experiment never been seen before. You're not going to find something never been seen before simply by making unfounded conclusions. If you want to propose a hypothesis and experiment that is more speculative and doesn't quite fit either case, then I think that's OK so long as you simultaneously propose a clear means to test it so that both the hypothesis and testing means can then be critiqued together.


> Thus far, banging K40 against K40 looks like the needed approach
Have you any idea the Coulomb barrier height between two K-40 nucleii!?


> electrons are just too wimpy to interact with nuclear potentials.
An electron is only as wimpy as the potential through which you accelerate it. Have you heard of an electron collider before?

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Re: An easier way to make a reactor? The K40

Post by Doug Browning » Tue Mar 13, 2012 2:00 pm

Experiment can follow when I think it is likely to work. I'm not one for typing out billions of random sequences on typewriters until Shakespeare results! But I do have the equipment for a vacuum system at hand.

At this point the K40 + K40 thing could be tested in a simple fusor if some means of isolating K40 from bulk potassium were available. No neutrons expected, just gamma rays or beta particles. This could be useful for determining if a particular collision energy is preferred. Any isotope supply houses out there? Otherwise, I'll probably have to investigate laser separation first. Laser ionization of just the K40 component of ordinary potassium might be possible within the vacuum/reactor chamber itself on an as needed basis.

The Coulomb barrier between two K40 nuclei needs some careful clarification at this point since it is not required to breach it entirely, like for fusion. We just want a fender bender here, not a re-designed nucleus. Also the effect of orbital electrons in shielding the nuclear charge needs some clarification (hopefully just single ionization of the K40 is required to manipulate it, and there are techniques for re-neutralizing atomic beams once accelerated). Clearly the orbital electrons will be helpful in shielding the nuclear charges up until close encounters of the 3rd kind occur. It may not be necessary for the nuclei to get much closer than the bottom electron shell, which is after all at X-ray type energies (maybe a sufficient jolt to trigger a decay).

I was only implying that the electron doesn't have the strong force component to interact strongly with the nucleus efficiently. S shell electrons go right thru the nucleus all the time with no effect. A surplus Gev or Tev e- accelerator (Tevatron on Ebay yet?) would knock the socks off a quark in the nucleus, but would probably leave the rest of the nucleus undisturbed. The energy balance would tank my power bill too. We just need the right tool here, something low power should do.

Next step up from a fusor test would maybe be an ion gun for K40 ions, an electrostatic acceration tube (if under 100 Kev is sufficient), then a drift tube for re-neutralizing the K40 in gas possibly, then a solid K40 target.

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Re: An easier way to make a reactor? The K40

Post by Chris Bradley » Tue Mar 13, 2012 3:13 pm

Don Bowen wrote:
> The Coulomb barrier between two K40 nuclei needs some careful clarification at this point since it is not required to breach it entirely, like for fusion....Next step up from a fusor test would maybe be an ion gun for K40 ions, an electrostatic acceration tube (if under 100 Kev is sufficient), then a drift tube for re-neutralizing the K40 in gas possibly, then a solid K40 target.

Careful clarification? Quite the understatement! OK, I'll have to quit here now as it is all a bit silly - the Gamow tunneling factor is a function of the exponent of the product of the nucleii charge. So, for example, what we know from experiment is that the peak cross-section of strong-force mediated deuterium-deuterium is of the order of 10^-2 barns, and that, by comparison, the fusion cross-section of C-12_C-12 is of the order of 10^-103. A full HUNDRED orders of magnitude lower.

And you want to try to fuse K-40_K-40? This'll likely have a strong-mediated fusion cross-section some 400 orders of magnitude lower than DD! I would therefore find it highly surprising if such a fusion event has ever been witnessed to know if that is true or not.

So your theoretical musings have now ended, there is nowhere to take them at that point of fact. If you want to discover 'new physics' that quantum physics cannot explain, then you'll have to do an experiment, as there is simply nothing-at-all that supports your theoretical machinations.

QRT.

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