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Gold/Mining/Energy : Gold Price Monitor
GDXJ 98.59-2.8%Nov 13 4:00 PM EST
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To: Casaubon who wrote (36489)7/4/1999 11:16:00 AM
From: Zeev Hed  Read Replies (2) of 116759
 
Casaubon, the neutron capture by a U235 nuclide actually requires a "slow neutron" (also called thermal neutrons), otherwise it goes through the nuclide an is not captured. U238 by itself is not fissionable, but neutron capture creates Np239 which decays to fissionable Pu230 (the nuclear reaction that serves as the basis of "breeder reactors").

I do not think that one can define a single particle's (like a thermal neutron) temperature. Temperature is a statistical measure of the state of matter having a very large number of particles. If you raise the temperature of a mass of fissible (fissionable?) U235 you will not create fission, fission is ignited by neutrons occurring just "out there" and if the mass of the chunk you have is large enough, neutrons released by the first "accidental" fission reaction self sustain, because the neutrons are slowed down within the critical volume to "become thermal" and continue the reaction. But that process has nothing to do with extreme temperatures. U238, for instance is stable "against" fission, and it will not split when two U238 collide with each other (high temperature), the nuclei themselves will be kept apart by their respective "clouds" of outer electrons.

Zeev
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