Dayton, Ohio — where all nuclear bomb blasts begin

Timothy R. Gaffney is a retired Dayton Daily News staff writer who works to promote the area’s aviation heritage.


Mound Science and Energy Museum

1075 Mound Road, Miamisburg. Located on the former Mound Laboratory site, the museum preserves the history of the Mound and its various missions. Website:

National Museum of the U.S. Air Force, Wright-Patterson Air Force Base

The museum displays the Boeing B-29 bomber Bockscar that dropped the “Fat Man” atomic bomb on Hiroshima. The exhibit includes actual but inert “Fat Man” and “Little Boy” type bombs. Website:

A recent underground blast that North Korea claims was an experimental hydrogen bomb is a disquieting reminder that Dayton’s story of aviation heritage has a cautionary side.

Dayton is justifiably proud that its two most famous sons, Wilbur and Orville Wright, invented the airplane in their West Third Street bicycle shop and built America’s first airplane factory, also along West Third. Dayton International Airport reminds travelers that Dayton is “where every flight begins.”

But in that same West Third Street corridor, between the site of the Wrights’ bicycle shop and their factory, is another historic site: the place where every nuclear bomb blast begins.

Several countries have tested hydrogen bombs, and a few have produced H-bomb arsenals. But the path to the H-bomb begins with mastery of the smaller and simpler atomic bomb. During World War II, scientists working in Dayton played a crucial role in producing the all-important initiator for the bomb.

Dayton’s atom-bomb heritage began with two research chemists, Charles Thomas and Carroll Hochwalt, who formed Thomas and Hochwalt Laboratories in Dayton in 1926. A string of creative new products prompted the Monsanto Chemical Company to buy the firm, making it the company’s Central Research Department with Thomas as its director.

In 1943, the Army turned to Monsanto for help with the Manhattan Project, the secret program to build an atomic bomb. It was a two-track program to develop both a uranium bomb and a superior but more complex plutonium bomb.

Each bomb used a different kind of initiator to kick-start the atom-splitting process that causes a nuclear blast, but both depended on the same key ingredient: polonium-210, a highly radioactive metal that was also extremely rare. Nobody knew how to produce it in useful amounts.

Monsanto handed the problem to its Central Research Department in Dayton. Thomas and Hochwalt formed what became code-named the Dayton Project.

With no time to build new facilities, they scouted existing properties for a usable project site. Dayton was already teeming with wartime work, so few places were available. The project ended up in four scattered locations, called units, and a warehouse.

Unit 1, the research department’s headquarters, was at 1515 Nicholas Road.

Unit 3 was a schoolhouse known as the old Bonebrake Seminary at 1601 West First St. The Dayton school board was using it as a warehouse. Monsanto leased it in October 1943 and quickly turned it into a lab. The unit grew as support buildings went up. It just so happened that Unit 3’s research work, so crucial to making an atomic bomb, took place just half a mile from where the Wright brothers had invented the means to deliver it.

Unit 4 was the wealthy Talbott family’s lavish private sports complex, known as the Runnymede Playhouse, at Runnymede Road and Dixon Avenue in Oakwood. By May of 1944, it was an operating polonium production plant.

The Dayton Warehouse, used for biological and environmental sample analysis and research, was at 601 E. Third St. (Unit 2, east of Ohio 741 south of Dayton, was an unrelated Monsanto rocket-fuel project.)

The Dayton Project employed up to 200 people by the end of 1945, but Daytonians knew nothing about it. So secret was their work that project members couldn’t tell their spouses, and military members were forbidden to wear uniforms. Despite posted guards and barbed wire fences, the units themselves drew little attention: secret wartime projects were common by then.

The Dayton Project succeeded in the form of two — and so far, the only — nuclear weapons to be used in war. The first was the “Little Boy” uranium bomb that fell on Hiroshima on Aug. 6, 1945. The second was the more advanced “Fat Man” plutonium bomb used against Nagasaki on Aug. 9. Each inflicted horrific damage. Whether atomic bombs were the only way to end the war remains a subject of debate, but end the war they did: Japan surrendered less than a week later.

What nobody in the Dayton Project knew was that they had developed the polonium process not only for America’s nuclear weapons program, but also Russia’s.

George Koval was the son of Jewish Russian emigrants who was drafted into the Army, where his scientific talents led to his assignment as a health physics officer for the Manhattan Project. He worked first at the Oak Ridge site in Tennessee and later at the Dayton Project.

Koval was also a Moscow-trained Soviet mole, having spent years in Russia — a part of his past he somehow managed to conceal.

Koval was one of several Soviet spies who penetrated the Manhattan Project, according to news reports. But his Dayton espionage was most crucial because it yielded the technical details on how to use polonium in bombs and how to make it. The polonium secrets shaved years off the Soviet Union’s bomb program, and its first test in 1949 shocked Western powers.

Koval slipped back to Russia in 1946 and died in obscurity in 2006. His work as a spy only came to light in 2007, when Russian President Vladimir Putin awarded him the posthumous title of Hero of the Russian Federation.

After the war, the Army moved initiator production from Los Alamos to Dayton, where it continued at Unit 3 on West First Street until 1949.

Meanwhile, the Army built a new production plant — a massive, bombproof complex built into a hill overlooking downtown Miamisburg. What became known as the Mound Laboratory was the first permanent facility in America’s nuclear weapons complex.

Mound’s missions and size grew throughout the Cold War, but the Department of Energy phased out its Mound work in the 1990s. Today, the 306-acre site is the Mound Business Park.

Dayton’s crucial role in the Manhattan Project isn’t well known, in part because its polonium work remained deeply secret for many years. Much of its physical presence literally disappeared as contaminated structures were demolished and sent to radioactive waste sites, and what remains is deteriorating in obscurity. When Congress created the Manhattan Project National Historical Park in December 2014, it left Dayton out.

But Dayton’s atomic legacy lives on in every nuclear bomb. What began here could yet end civilization or continue to preserve it through nuclear deterrence. North Korea’s nuclear program makes the ultimate outcome even more uncertain. How this story of aviation heritage ends won’t be written until the last nuclear warhead is retired — or exploded.

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