uranium metal highly enriched in uranium-235
|isotope mass||235.0439299 u|
|excess energy||40914.062 ± 1.970 kev|
|binding energy||1783870.285 ± 1.996 kev|
|decay mode||decay energy (mev)|
|isotopes of uranium |
complete table of nuclides
uranium-235 (235u) 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 a fission chain reaction. it is the only fissile isotope that is primordial and found in relatively significant quantities in nature.
uranium-235 has a half-life of 703.8 million years. it was discovered in 1935 by arthur jeffrey dempster. its fission cross section for slow thermal neutrons is about 584.994 barns. for fast neutrons it is on the order of 1 barn.
most but not all neutron absorptions result in fission; a minority result in neutron capture forming uranium-236.