George Laurence

George LaurenceGeorge Laurence (1905-1987)

George Craig Laurence was born in Charlottetown, P.E.I. on January 21, 1905. He was educated at Dalhousie University in Halifax, Nova Scotia and later at Cambridge University in England where he earned a Ph.D. under the guidance of Ernest Rutherford at the Cavendish Laboratory. After graduating, Dr. Laurence joined the staff of the National Research Council of Canada (NRCC) in 1930 and became active in improving the measurement of radiation dosage in the treatment of cancer and in promoting safety from radiation exposure. He helped to develop radiation safety regulations for North America, co-authoring the first bulletin of the Radiological Society of North America’s Standardization Committee.

Pivotal in the Canadian nuclear power story was his pioneering work in 1940 on nuclear chain reactions after the discovery of nuclear fission in January 1939. He was the first person in the world to induce fission by neutrons in a very large quantity of uranium surrounded by carbon, to investigate the possibility that the fission chain reaction needed for a useful release of nuclear energy could be produced with these materials. Foiled by lack of funds, he was unable to obtain uranium or graphite of satisfactory purity to continue his work; however his initial studies enabled and encouraged Canada to enter into a scientific partnership with a distinguished group of British and European scientists to form the National Research Council’s Montreal Laboratory Division. George Laurence joined that group in 1942 as the senior Canadian scientist. With others, he assembled a sub-critical mock-up of the National Research Experimental (NRX) lattice and measured some of the constants needed for the design of the reactor.

Cutaway section of the Laurence “pile”, 1941-42
Cutaway section of the Laurence “pile”, 1941-42.

In 1945, Dr. Laurence moved to Chalk River where he continued his work on nuclear reactor design with the ZEEP, NRX and NRU units. During 1946–47 he served as scientific advisor to the Canadian delegation to the United Nations Atomic Energy Commission in New York. In 1950, when ideas for a distinctive Canadian nuclear power system were being developed, it was George Laurence who insisted that a non-breeder power plant suitable for Canadian requirements should be designed and constructed. That persistence paid off with the natural uranium reactor, cooled and moderated by heavy water, which became the Canadian nuclear power system.

In 1961, George Laurence left Atomic Energy of Canada Limited (AECL, now Canadian Nuclear Laboratories) to become the President of the Atomic Energy Control Board where he served as Chairman of the Reactor Safety Advisory Committee that advised on the health and safety of nuclear reactors and power stations.

George Laurence, one of Canada’s pioneering nuclear scientists, died in Deep River, Ontario on 7 November, 1987.

In 1966, the Canadian Association of Physicists awarded him its Medal for Achievement in Physics. In 1975, the Canadian Nuclear Association presented him with the W.B. Lewis Medal. In 1988, in San Diego, at the annual meeting of the American Nuclear Society a special plaque was awarded posthumously to Dr. G.C. Laurence.