Karl P. Cohen

Karl Paley Cohen (February 5, 1913 – April 6, 2012) was a physical chemist who became a mathematical physicist and helped usher in the age of nuclear energy and reactor development. He began his career in 1937 making scientific advances in uranium enrichment (isotope separation) as research assistant to Harold Urey, who discovered deuterium–the heavy isotope of hydrogen. Cohen worked within the Columbia group of physicists that included Harold Urey, Enrico Fermi, Leo Szilard, Isidor Isaac Rabi, John R. Dunning, Eugene T. Booth, A. Von Gross and others)–all pioneers of nuclear energy.

In 1942, the Manhattan Engineer District Project was established at Columbia University, and research began on various approaches for separating out the fissionable uranium isotope, U-235. Cohen developed the theory for the now-universal method of centrifugal isotope separation for enriching uranium, but was deeply involved also with the theory of gaseous diffusion, and literally wrote the book about both methods.

Cohen and Urey were convinced that the Uranium Committee had made the wrong choice in 1942 by picking gaseous diffusion instead of centrifuges to produce U-235 for the atom bomb, and thus extended the war by a year. In 1944, Cohen left Columbia and went to work for Standard Oil Development Company to advise on nuclear energy.

Edward Teller’s autobiography ''Memoirs'' reflects positively on Cohen and Urey's centrifuge method for producing U-235 when he writes: “What if we had the atomic bomb a year earlier? The easiest and least expensive method of separating isotopes, a method used throughout the world today, is based on a centrifuge procedure that Harold Urey proposed in 1940. General Leslie Groves chose the diffusion method instead. Karl Cohen, Urey’s able assistant during that period, believes that Groves’ decision delayed the atomic bomb by a year. If Dr. Cohen is right, atomic bombs of the simple gun design might have become available in the summer of 1944 and, in that case, would surely have been used against the Nazis. Atomic bombs in 1944 might have meant that millions of Jews would not have died, and that Eastern Europe would have been spared more than four decades of Soviet domination.”

In 1948, Cohen became technical director for H.K. Ferguson's Atomic Energy Division, which was building the Brookhaven, Long Island, nuclear reactor. By 1952, Cohen was a founder, vice president and operating manager of Walter Kidde Nuclear Laboratories (WKNL), a privately funded research facility formed to commercially develop nuclear power. The lab's principal contract was with the Atomic Energy Commission for R&D on reactors, and it established many industry standards, especially regarding slightly enriched uranium and water moderated reactor concepts.

Cohen's long association with General Electric began in 1955, at first as a consultant, then as a manager involved with advanced engineering, advanced products, breeder reactor development, and operational planning. In 1973 Cohen was appointed Chief Scientist of G.E.'s commercial nuclear department. After his retirement in 1978, Cohen consulted for companies such as G.E., Boeing, and Exxon, and organizations such as the Institute for Energy Research, Scientists and Engineers for Secure Energy and the Electric Power Research Institute. Cohen also continued to be active on committees, at conferences, and in more informal peer review of technology and policy papers. He also taught intermittently at Stanford during this time, and donated his papers to the Stanford Library (M1798, Karl Cohen Papers). Karl Cohen died of natural causes in 2012. His last published paper was in ''Science'' in 2002, but due to his vast knowledge of the field, he continued to be a source of information on nuclear energy and nuclear policy for several years after the paper.

Cohen had a dream of bringing safe, abundant and affordable energy to the world. His paper published in 1992 in the ''International Journal of the Unity of the Sciences'', Volume 5, Number 3 entitled "A Promise Unfulfilled" argues that before the potential of nuclear fission as a limitless source of energy for earth's societies can be reached, there must first be disarmament and nuclear weapons must be destroyed. Provided by Wikipedia