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Post by nocky2 on Dec 16, 2010 23:27:27 GMT
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Post by elvisuk on Dec 17, 2010 1:22:49 GMT
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Post by tuesdaymine on Dec 20, 2010 11:55:59 GMT
 213 
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Post by elvisuk on Dec 20, 2010 14:27:16 GMT
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Post by tuesdaymine on Dec 21, 2010 12:57:38 GMT
215
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Post by elvisuk on Dec 21, 2010 14:22:24 GMT
216
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Post by tuesdaymine on Dec 28, 2010 21:59:52 GMT
217
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Post by elvisuk on Dec 29, 2010 2:16:43 GMT
218
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steve
New Member
Posts: 9
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Post by steve on Jan 7, 2011 15:32:27 GMT
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Post by Lynnrose on Jan 7, 2011 17:30:20 GMT
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Post by elvisuk on Jan 7, 2011 19:21:51 GMT
221
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Post by Lynnrose on Jan 7, 2011 21:27:54 GMT
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Post by elvisuk on Jan 8, 2011 1:31:49 GMT
RT-223 - RhythmTrak Drum Machine
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Post by Pete on Jan 8, 2011 12:22:38 GMT
224.Hi
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Post by elvisuk on Jan 8, 2011 14:53:14 GMT
300px-An-225_Mriya
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Post by tuesdaymine on Jan 9, 2011 15:31:12 GMT
226
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Post by elvisuk on Jan 9, 2011 15:36:41 GMT
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Post by nocky2 on Jan 9, 2011 17:29:21 GMT
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Post by elvisuk on Jan 9, 2011 19:23:38 GMT
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Post by tuesdaymine on Jan 10, 2011 11:38:26 GMT
230 x
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Post by elvisuk on Jan 10, 2011 14:50:18 GMT
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Post by tuesdaymine on Jan 12, 2011 14:20:20 GMT
;D 232
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Post by elvisuk on Jan 12, 2011 15:50:18 GMT
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Post by nocky2 on Jan 12, 2011 17:55:19 GMT
Arado 234.  |
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Post by elvisuk on Jan 12, 2011 19:40:05 GMT
Uranium-235
is an isotope of uranium making up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238 it is fissile, i.e. it can sustain fission chain reaction. It is the only fissile isotope that is a primordial nuclide or found in significant quantity in nature.
Uranium-235 has a half-life of 700 million years. It was discovered in 1935 by Arthur Jeffrey Dempster. Its nuclear cross section for slow thermal neutrons is about 1000 barns. For fast neutrons it is on the order of 1 barn.[1] Most but not all neutron absorptions result in fission; a minority result in neutron capture forming uranium-236. The fission of one atom of U-235 generates 202.5 MeV = 3.244 × 10−11 J, i.e. 19.54 TJ/mol= 83.14 TJ/kg.[2] Heavy water reactors, and some graphite moderated reactors can use unenriched uranium, but light water reactors must use low enriched uranium because of light water's neutron absorption. Uranium enrichment removes some of the uranium-238 and increases the proportion of uranium-235. In nuclear weapon design, highly enriched uranium containing 40% or greater U-235 is sometimes used in the secondary stage in place of natural or depleted uranium. Primary stages today most commonly use plutonium but when uranium is used, it is even more highly enriched in U-235.
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Post by tuesdaymine on Jan 13, 2011 15:21:49 GMT
236
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Post by elvisuk on Jan 13, 2011 15:42:45 GMT
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Post by tuesdaymine on Jan 14, 2011 12:01:57 GMT
238
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Post by elvisuk on Jan 14, 2011 14:29:46 GMT
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Post by tuesdaymine on Jan 15, 2011 14:42:24 GMT
240
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