and a krypton-xenon spectrum typical of U fission." Conditions for such reactions are highly unlikely today, with abundances of uranium 235 at the site being far higher in the past. On top of this ...

Central to this phenomenon was the concentration of uranium-235 (U-235), a naturally ... down the neutrons released from fission so they can sustain a chain reaction at a controlled rate.

Like uranium 235, element 94 would be an incredibly ... achieved a controlled and sustained nuclear fission chain reaction. During the last months of the war, a small group of scientists working ...