Any fission reactor basically ... a more powerful reaction is possible with less fuel. There are three isotopes of uranium: U-238, U-235, and U-234. Uranium decays naturally, and highly active ...

If we imagine discrete critical masses of U-235 colliding—say, two subcritical hemispheres brought together rapidly—the reaction mimics the initial moments of a fission bomb before disassembly.

O. Hahn and F. Strassmann 1 have discovered a new type of nuclear reaction, the splitting into two smaller nuclei of the nuclei of uranium and thorium under neutron bombardment. Thus they ...