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 Hematite
Newbee
 
Registered: 05/04/07
Posts: 153
Loc: Wisconsin
Last seen: 3 years, 2 months
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 Re: Mystery pic [Re: Ferris]
#8915056 - 09/11/08 07:42 PM (3 years, 8 months ago) |
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The uranium originated in granite that was weathering away to the west of where the dinosaur was buried, during the first uplift of the Rockies. Oxidized uranium is water soluble while reduced uranium is not. Groundwater carried the oxidized uranium from where it weathered in the mountains to where the dinosaur was buried, where it encountered a reducing environment-- possibly created by the slow decay of the dinosaur's soft tissues-- where it precipitated (pyrite also forms under reducing conditions). It is possible that some of the iron and sulphur originated in dinosaur tissues, or they could have ben carried in in groundwater as well.
This particular bone was about 1% uranium-- which I discovered is enough for it to sustain a chain reaction when bombarded by enough thermal neutrons, as in the core of a nuclear reactor.
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 Minstrel
Man of Science
Registered: 03/15/05
Posts: 1,974
Loc: Hogtown
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Re: Mystery pic [Re: Hematite]
#8915131 - 09/11/08 07:57 PM (3 years, 8 months ago) |
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>This particular bone was about 1% uranium-- which I discovered is enough for it to sustain a chain reaction when bombarded by enough thermal neutrons, as in the core of a nuclear reactor.
Really? Even though this 1% is natural U238 which cannot sustain a chain reaction? Doesn't U238 not release any neutrons when fissioning, and hence, cannot sustain it's own reaction? Doesn't it need to be U235, and even if that 1% was all U235, doesn't there need to be enough to cause criticality?
U238 will fission if hit with fusion neutrons, I know (as in a thermonuclear bomb's tamper/case), but those neutrons must come from an outside source.
I bet Seuss will know for sure.
Edited by Minstrel (09/11/08 08:04 PM)
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Ferris
PsychedelicJourneyman
Registered: 03/12/06
Posts: 11,529
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Re: Mystery pic [Re: Minstrel]
#8915201 - 09/11/08 08:12 PM (3 years, 8 months ago) |
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Bombarding the U238 with neutrons causes neutron absorption, temporarily converting the material to U239, which is a fissible isotope
EDIT: ah, I guess you understand that much
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Discuss Politics
Edited by Ferris (09/11/08 08:16 PM)
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Minstrel
Man of Science
Registered: 03/15/05
Posts: 1,974
Loc: Hogtown
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Re: Mystery pic [Re: Minstrel]
#8915277 - 09/11/08 08:24 PM (3 years, 8 months ago) |
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As I understand, it is the difference between fissile and fissionable. The former can chain react, the latter can't.
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Ferris
PsychedelicJourneyman
Registered: 03/12/06
Posts: 11,529
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Re: Mystery pic [Re: Minstrel]
#8915321 - 09/11/08 08:34 PM (3 years, 8 months ago) |
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 fissile. That's the word I was going for.
I suspect that you don't need a chain reaction to occur for power production, although I wouldn't quote me on that.
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Discuss Politics
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Hematite
Newbee
Registered: 05/04/07
Posts: 153
Loc: Wisconsin
Last seen: 3 years, 2 months
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Re: Mystery pic [Re: Minstrel]
#8915396 - 09/11/08 08:48 PM (3 years, 8 months ago) |
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Quote:
Minstrel said:
>This particular bone was about 1% uranium-- which I discovered is enough for it to sustain a chain reaction when bombarded by enough thermal neutrons, as in the core of a nuclear reactor.
Really? Even though this 1% is natural U238 which cannot sustain a chain reaction? Doesn't U238 not release any neutrons when fissioning, and hence, cannot chain react? Doesn't it need to be U235, and doesn't there need to be enough to cause criticality?
Seuss?
"Sustained chain reaction" was a poor choice of words, you're right. What I should have said is that when bombarded my slow neutrons, the bone produces enough of its own neutrons to boost substantially the rate of fission in it. When it came out of the reactor it was more loaded with fission products than could be explained by the reactor's neutron flux alone. So there was a chain reaction, but a self-quenching one.
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Hematite
Newbee
Registered: 05/04/07
Posts: 153
Loc: Wisconsin
Last seen: 3 years, 2 months
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Re: Mystery pic [Re: Ferris]
#8915437 - 09/11/08 08:56 PM (3 years, 8 months ago) |
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Quote:
Ferris said:
Bombarding the U238 with neutrons causes neutron absorption, temporarily converting the material to U239, which is a fissible isotope
EDIT: ah, I guess you understand that much
238 also can undergo fission directly, but neutron capture is more likely with slow (thermal) neutrons. 235 does not undergo fission with fast neutrons while 238 does.
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N2loma
Foaming Pipe Snake
Registered: 05/17/08
Posts: 925
Last seen: 2 years, 7 months
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Re: Mystery pic [Re: zouden]
#8935910 - 09/15/08 07:54 PM (3 years, 8 months ago) |
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bone?
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"So can you tell me what exactly does freedom mean/
If I'm not free to be as twisted as I wanna be" -Divide by Disturbed
Good Guitars Don't Cry
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Hematite
Newbee
Registered: 05/04/07
Posts: 153
Loc: Wisconsin
Last seen: 3 years, 2 months
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Re: Mystery pic [Re: N2loma]
#8935923 - 09/15/08 07:57 PM (3 years, 8 months ago) |
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Yes
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