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 ...

The concentration of U-235 in natural uranium resembled 3 per cent two billion years ... The reactor has to stop its operations: this occurred naturally after the reactor could not process fission ...

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 ...