The Dayton Project was one of several sites involved in the Manhattan Project to build the first atomic bombs. Charles Allen Thomas, an executive of the Monsanto Company corporation, was assigned to extract and purify the polonium used in the neutron generating devices that triggered the nuclear detonation of the atomic bombs once the critical mass had been "assembled" by the force of conventional explosives.
Thomas established the project in the Runnymede Playhouse on the grounds of the Talbott family estate in a wealthy residential section of Oakwood, a suburb of Dayton, Ohio. The Playhouse was a leisure facility that included a ballroom, indoor squash and tennis courts as well as a stage for community theater. It was located at the intersection of Runnymede Road and Dixon Avenue. The Talbotts were among the heirs of the Delco (by then a part of General Motors) fortune. Before the war, Thomas worked as a chemist for Delco/GM and was married to Margaret Talbott. He promised his mother-in-law that he would return the building to the family intact after the war. He was unable to keep his promise because the building had become contaminated with radioactivity. The facility (also known as Dayton Unit IV) was in use for nuclear work until 1949 when Mound Laboratories was opened in Miamisburg, Ohio. The Playhouse was dismantled in 1950 and later buried in Tennessee.
The neutron generator used on the implosion design (such as the Fat Man bomb that was dropped on Nagasaki) was coded named "Urchin". It was composed of alternating layers of polonium-210 (Po-210) and beryllium separated by gold foil. The initiator, located in the center of the bomb, was carefully designed to ensure that during the implosion of the bomb core, the polonium and beryllium mixed. Once the elements mixed, alpha particles emitted by the polonium were absorbed by the beryllium causing it to emit neutrons. The precise timing of the neutron pulse was necessary to avoid pre-detonation of the bomb which would have resulted in a "fizzle" rather than the desired blast. In modern nuclear weapons a pulsed neutron emitting tube has replaced polonium/beryllium initiators, as polonium-210 has a relatively short half-life and thus would need to be replaced every few months.
In 2007 Russian president Vladimir Putin posthumously awarded Zhorzh Abramovich "George" Koval a gold star making him a hero of the Russian Federation for his work as the GRU spy "Delmar". Russian officials stated that the initiator for their Joe-1 bomb had been "prepared to the recipe provided by Delmar".
Koval was a US citizen born in Sioux City, Iowa in 1913 to parents of Belorussian origin. In 1932 his family returned to the Jewish Autonomous Oblast in the Soviet Union. In 1939 he was drafted into the Soviet Army, joining the GRU intelligence service. Koval returned to the US in 1940 and was drafted into the US Army in 1943. He was inducted into the Special Engineering Detachment of the Manhattan project. Koval was initially assigned to Oak Ridge where his job as a health physics officer gave him access to much of the plant. He began passing secrets relating to the production of polonium at Oak Ridge to his GRU handler code named "Clyde". In 1945 Koval was transferred to Dayton. Again his job as a health physics officer gave him wide access to the secret installation.
In 1946 he left the Army. Koval returned to the Soviet Union via Europe in 1948. In 1949 the Soviets detonated their first atomic bomb. The FBI did not begin to suspect Koval until the mid-1950s, long after he had left the US. In 2002 Vladimir Lota published "The GRU and the Atom Bomb" explaining Delmar's role. Koval died in 2006.
- DeBrosse, Jim (2004-12-05). "The Dayton Project". Dayton Daily News. p. A1. More than one of
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- Michael Walsh (May 2009). "Iowa-Born Soviet Trained". Smithsonian (Washington, D.C.: Smithsonian Institution): 40–47.