February 1940

February 1940

Otto Frisch and Rudolf Peierls, living in the United Kingdom, consider the possibility of fast fission in uranium-235. Based on a theoretical estimate of the fast fission cross section they estimate the critical mass of pure uranium-235 at "a pound or two", and that a large percentage could be fissioned before explosive disassembly. They also estimate the likely effects of the bomb, and possible assembly methods, as well as estimates of the feasibility of isotope separation. 

Date Range: 
1940CE Feb