A nuclear pioneer’s work on safer, cheaper, inexhaustible nuclear power is still inspiring nuclear environmentalists.
by Robert Hargraves
Physicist Alvin Weinberg worked on the Manhattan Project and later co-invented the pressurized water nuclear reactor. As Director of Oak Ridge National Laboratory he led development of liquid fuel reactors, including walk-away-safe liquid fluoride thorium reactors with inexhaustible fuel. Today such cheap, safe, clean energy has the potential to economically displace worldwide coal burning, inspiring many efforts to implement Weinberg’s achievements.
Alvin Weinberg was a Chicago product, born there in 1915, educated in Chicago schools, attending the University of Chicago, earning BS, MS, and PhD degrees in physics. Ironically, his master’s thesis dealt with the infrared absorption spectrum of CO2, presaging his later efforts to warn of global warming. His PhD work in cell metabolism taught him about diffusion, which turned out to be applicable to neutron diffusion, of interest to the Manhattan Project.
Obtaining his PhD in 1939 he joined the University Chicago Metallurgical Laboratory, conducting work for the nascent Manhattan Project. There he rubbed shoulders with physicists Edward Teller, Leo Szilard, and Nobel-prize-winners Arthur Compton, Eugene Wigner, and Enrico Fermi.
Fermi led the project to demonstrate the first nuclear chain reaction. Neutrons from fission of uranium-235 needed to be slowed down to have a good chance of fissioning more uranium-235 before escaping. Collisions with carbon atoms slowed neutrons, so Fermi designed a lattice of graphite and uranium, separated so that the slowing took place outside the uranium, where the neutrons might be absorbed by uranium-238.