Mr. Wizard
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Hafnium Isomer Explosive
There was a blurb in the paper today about military interest in a new explosive that used the triggered release of gamma rays from a hafnium isotope.
It was supposed to have 10^4 times the power of TNT. It looks interesting. Can you imagine the possibility of using it as a rocket fuel? It looks as
if it is not a chain reaction, but rather is 'set off' by exposure to a milder beam of x-rays, and would be scalable and controllable. There
are quite a few Google hits; here is one:
http://www.newscientist.com/news/news.jsp?id=ns99994049
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DDTea
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There was a small controversy caused by these "Haf-bombs" some time ago... Personally, I find them to be very scary. The goal is to make a
more "usable" nuclear weapon; but to make weapons more usable means that they are more likely to be used. That's a frightening
concept. I'm glad you suggested a peaceful use for them--rocket fuels. Sorry to take this discussion a bit of course, but that's my input.
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vulture
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This is going to be hideously expensive considering the fact that you need extremely pure hafnium, separated from any zirconium because this will
greatly interfere.
I wonder if this could be used to lower the critical mass of "normal" nuclear weapons?
If somebody would succeed in "poisoning" the hafnium with zirconium the weapon would be worth shit.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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Proteios
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hmmm interesting. However this aint like regular nuclear energy.... where the energy is already there and all you need is the chain reaction to
release it. With the Hf You have to put all the energy in first using a nuke reactor or syncatron....(to pump to the excited state... which then has
the 30y halflife) very expensive and time consuming buisness.
Other than that this it has many similarities to laser technology... pumping to cause a population inversion, then releasing it, with the exception
that the stimulated emmision comes from a different wavelength x-ray. There in i would see the biggest problem in getting yield out of these things.
You need enough x-ray flux, of the correct wavelength to stimulate the release of the gamma rays. If this does not happen in ms.... obviously the
Hf will just turn into a cloud of vapour and disperse. This is basically the same problem with yields on nukes.... you have to hold the mass critical
for as long as possible. For 1g....about 1/100th of a mole of Hf......1e21 nuclei.....have to be stimulated in ms......the only thing that i know
that can produce x ray fluxes like that is nukes.
I also note in the new scientist article... they say they get 60x more energy out than they put in.....not that they get 100 % yield for every photon
they put in (e.g. gammas are much higher in energy than x rays). This points to a fairly low input xray-output gamma ray ratio.... I would guess
1/1000.
With funds separation of Hf and Zr should be no problem....i dont know any of the chemistry of these elements.... but typical methods for isotope
enrichment.... gas centrifuges, prepscale mass spectrometers etc should have no problem in separating these two....at a cost.
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vulture
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Hafnium and Zirconium are probably the most difficult elements to separate, because of their similar ion radius and similar behaviour of the salts and
complexes.
IIRC, separation requires a load of recrystallization/recomplexation.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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Geomancer
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Scary indeed. What's more, there's an outside chance nuclear isomer explosive have already been fielded--by the Soviet Union. Remember the
"red mercury" rumor? Mercury happens to be one of the elements thought likely to generate usable high energy nuclear isotopes.
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Mr. Wizard
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Some other sites mention other isotopes, including Zirconium, having the same characteristics. I'm not sure Zirconium contamination would be all
that problematic. If they can do gas diffussion to separate U235 from U238 they can do the same with Zirconium(atomic weight 91) and Hafnium, (atomic
weight 178). With almost 100% difference in mass, a diffussion plant should be able to do a LOT better than the 238/235 ratio of 1 %. There is some
question about replication of results in the tests. It might be deception, or it might be a 'cold fusion' fiasco. Who would want the world
to know about this sort of thing? The specific impulse of this fuel ( for rockets) would have to be fantastic, even if manufacturing it cost an arm
and a leg. Maybe we can recycle that nuclear waste? Anyway, it's an interesting idea to follow, with a skeptical eye.
[Edited on 13-6-2004 by Mr. Wizard]
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Proteios
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on thinking about it further..... the nuclear activity states will be independant of the chemistry. Zirc. impurities wouldnt matter.....except in
lowering the number density of the Hf.
This is completely plausible... unlike the cold fusion which had issues.
Zr will have different nuclear properties. Nuclear activity states are not like chemical periodicity... they depend upon the number of protons and
neutrons.
As a bomb there are technical problems.... how do you get a triggering xray pulse powerful enough to give you a good gamma yield!
As a form of energy storage there is potenital (im thinking space travel power source, kilotonnes of 'kerosene energy density' material
could be taken up by kilos of activated Hf.... of course you have to put that energy in first!!!!) .... but also serious problems. Most notably, in
order to get useful energy out of this.... you need an effective way of harvesting the energy in the gamma rays... usually done by abosorbtion
(convertion to heat).... problem is......gamma rays have very good penentration... they dont interact with matter well. The heat yield is likely to
be poor. Gamma rays also tend to be bad news for the higher organic life... which do not cope with exposure to ionising radiation well.
The main gripe with nuclear sources in space is the green lobby get very tetchy about 'what if there are problems at launch?' This would
not be a problem with a Hf power source.
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Cyrus
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Not sure if this helps,
but Pop. Mechanics recently had one of the "we have looked into a crystal ball and in the future everyone is going to do this!" articles
about private airplanes powered by halfnium. IIRC, the radioactive halfnium was subjected to a ton of x-rays, and supposedly gave off 50X- I
don't remember the exact #, as much energy as is put in, which heats some water to drive a turbine.
Mind you, this was about 4 meters away from the pilot!. From what these other posts are saying, that doesn't sound too safe!
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unionised
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Last I heard, someone had looked into this and tried to replicate the original results. They couldn't.
Looks like another "cold fusion"; makes good newspaper copy; doesn't work.
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IvX
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Perhaps these would be power plants of the future?Considering the X-ray laser maybe in the future there may be (enough funding for)a gamma laser.Hell
perhaps the hafnium could be sent to space to absorb energy :p
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unionised
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Perhaps not.
The excited state of Hf doesn't grow on trees and the idea of releasing the energy by irradiating it with Xrays doesn't work.
It's not exactly easy to get an Xray laser.
A gamma ray laser might be possible but it wouldn't be very practical.
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IvX
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I meant the X-ray laser in the terms that a few decades back it was in the same state as a gamma laser today.
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