Walter Zinn

Walter Henry Zinn (December 10, 1906 – February 14, 2000) was a Canadian-born American nuclear physicist who was the first director of the Argonne National Laboratory from 1946 to 1956. He worked at the Manhattan Project's Metallurgical Laboratory during World War II, and supervised the construction of Chicago Pile-1, the world's first nuclear reactor, which went critical on December 2, 1942, at the University of Chicago. At Argonne he designed and built several new reactors, including Experimental Breeder Reactor I, the first nuclear reactor to electrically power a building, which went live on December 20, 1951.

Early life Walter Henry Zinn was born in Berlin (now Kitchener), Ontario, on December 10, 1906, the son of John Zinn, who worked in a tire factory, and Maria Anna Stoskopf. He had an older brother, Albert, who also became a factory worker. writing his Doctor of Philosophy thesis on "Two-crystal study of the structure and width of K X-ray absorption limits". This was subsequently published in the Physical Review.

To support himself, Zinn taught at Queen's University from 1927 to 1928, and at Columbia from 1931 to 1932. He became an instructor at the City College of New York in 1932. While at Queen's he met Jennie A. (Jean) Smith, a fellow student. They were married in 1933 and had two sons, John Eric and Robert James. In 1938, Zinn became a naturalised United States citizen.

The Army leased a of the Cook County Forest Preserves known as "Site A" to the Manhattan Project, and "the Country Club" to the hundred or so scientists, guards and others who worked there. Zinn was placed in charge of Site A, under Fermi. Chicago Pile-1 was disassembled and rebuilt, this time with a radiation shield, at Site A. The reactor, now known as Chicago Pile-2, was operational again on March 20, 1943. Within a few months, Fermi began designing a new reactor, which became known as Chicago Pile-3. This was a very different type of reactor. It was much smaller, being only in diameter and high. It was power by 120 uranium metal rods, and moderated by of heavy water.

The other branch of reactor development at the Argonne National Laboratory, and the one closer to Zinn's heart, was the fast breeder reactor. At the time it was believed that uranium was a scarce resource, so it would be wise to make the best use of it. The breeders were designed to create more fissile material than they consumed. AEC Chairman Gordon Dean described it as a major milestone in nuclear history.

The BORAX Experiments were a series of destructive tests of boiling water reactors conducted by Argonne National Laboratory in Idaho. The BORAX-1 test was conducted under Zinn's supervision in 1954. He had the control rods removed to demonstrate that the reactor would shut down without trouble, and it immediately blew up with a loud bang and a tall column of dark smoke, a turn of events that he had not anticipated. He shouted to Harold Lichtenberg to put the control rods back in again, but Lichtenberg pointed out that one was already flying through the air. Zinn later had to testify on the experiment before the Joint Committee on Atomic Energy.

Later life After leaving the Argonne National Laboratory in 1956, Zinn moved to Florida, where he founded his own consulting firm, General Nuclear Engineering, He served as a member of the President's Science Advisory Committee from 1960 to 1962, and a member of the General Advisory Committee of the AEC and its successor, the Energy Research and Development Administration, from 1972 to 1975.

Over the years Zinn received multiple awards for his work, including a special commendation from the AEC in 1956, the Atoms for Peace Award in 1960, the Enrico Fermi Award in 1969, and the Elliott Cresson Medal from The Franklin Institute in 1970. In 1955 he was elected as the first president of the American Nuclear Society (ANS).

Zinn's wife Jean died in 1964.

Walter H. Zinn Award Since 1976, the American Nuclear Society's Operations and Power Division, has annually presented the Walter H. Zinn Award to recognize an individual "for a notable and sustained contribution to the nuclear power industry that has not been widely recognized."