Dayton, OH (U.S. National Park Service)

3 people wearing respirators and protective clothing work in large gymnasium that is empty except for 20 50-gallon metal drums. A fire burns in one of the drums. — Runnymede Playhouse or Unit IV was in the wealthy Dayton suburb of Oakwood on the Talbott Family Estate.
Mound Science & Energy Museum Association & Mound Cold War Discovery Center.

Article written by Jaclyn Miller, Site Manager of the Mound Cold War Discovery Center with Dayton History.

Dayton, Ohio is known for cash registers, Cheez-It crackers, pop top cans, and being the Birthplace of Aviation. However, the city has another important but widely unknown accolade on its long list of innovations and inventions: the scientific work done during the top-secret Dayton Project. The work done throughout the city in the 1940s culminated in the polonium initiators used in the atomic bombs developed by the Manhattan Project during WWII.

The Dayton Project, a subsidiary of the Manhattan Project, got its start in 1943 when Dr. Charles Allen Thomas, the Director of Monsanto Chemical Company’s Central Research Department, met with General Leslie Groves. After several meetings, Monsanto (and Dr. Thomas) was tasked with studying the chemistry and metallurgical properties of polonium to be used in the initiators. This work was to be done in Dayton, Ohio.

Polonium was discovered by Marie and Pierre Curie in 1898 and was named after Marie Curie’s home country of Poland. Through various tests and studies, the Curies realized that pure polonium was much more radioactive than uranium. Polonium-210, an isotope of polonium, was used in the initiators because it can be artificially produced, emits lots of energetic alpha particles, and has other characteristics that make it ideal to work with.

A group of more than 50 people. Women sit on the ground in the first 2 rows. Men are either seated or standing behind the women. — Unit IV continued as the production location through the end of the war but once again, the Dayton Project was outgrowing their facilities.
Mound Science & Energy Museum Association & Mound Cold War Discovery Center

The scientists and staff of the Dayton Project started their work at Monsanto Central Research Department or Unit I which was located near Downtown Dayton. The project quickly outgrew the facility so Units II, III, IV, and a warehouse were added throughout the city and a nearby suburb.

For most of the project, Unit I was used as “preliminary organization and personnel recruiting.” Unit II was known as the Monsanto Rocket Propellant Lab. Work done here was unrelated to the Dayton Project, but they needed to use the building for storage as the Dayton Project progressed.

Bonebrake Theological Seminary, Unit 3
Mound Science & Energy Museum Association & Mound Cold War Discovery Center

Bonebrake Theological Seminary was rented by Monsanto from the Dayton Board of Education to house Unit III. It was used for all polonium research and development from October 1943 until the project outgrew the facility.

Runnymede Playhouse, where Unit IV was located, is perhaps the most well-known of the Dayton Project Sites. It was in the wealthy Dayton suburb of Oakwood on the Talbott Family Estate. Runnymede was a large private recreational building used by the Talbott family to entertain friends and extended family. Dr. Thomas may have been familiar with the facility because he married one of the Talbott Daughters, Margaret Stoddard Talbott, in 1926. The playhouse was built in 1927. The Production Group within the Dayton Project moved to Runnymede in June 1944. By June 1945, they were producing 35 curies (7 milligrams) of polonium-210 every week and shipping it to Los Alamos.

Balding white male wearing a suit. Text includes Charles Allen Thomas, Project Director 1973-1975. — Charles Allen Thomas, Project Director, 1943-1945
Mound Science & Energy Museum Association & Mound Cold War Discovery Center

Unit IV continued as the production location through the end of the war. Due to the postwar demand, it was decided that a permanent facility was needed. The Dayton Project started with 43 personnel in 1943. By 1948 it had 843 personnel. This is when the planning phases of Unit V and VI began. Unit V, located in Miamisburg, Ohio, was called Mound Laboratory after the large conical earthen mound built by the Adena Culture that was near the site. Construction started in 1946. Mound Laboratory opened in 1948, with the polonium processing work starting in February 1949. Ken Foster, who retired from Monsanto / Mound, wrote “I was privileged to act as escort for one of the transfers operations. Trays of specimens were suitably packed, placed in one of the AEC autos, and we drove the load from Oakwood to Miamisburg, keeping in touch all the way by radio with the guard station at Mound.”

Unit VI or Scioto Laboratory in Marion, Ohio, was built as a backup to Mound Laboratory. The plant was in operation from 1949 through 1954 but was on cold standby. In 1953, it was decided the site was no longer needed and shutdown began. Mound Laboratory, however, operated from 1948 through 2003 as an integrated research, development, and production facility that supported the United States’ nuclear weapons, energy, and space programs. Mound’s contributions to science can be seen even today, through its technology and innovations that are still in use. For example, the radioisotope thermoelectric generator (RTG) that was invented by two Mound Scientists is getting a lot of attention as private companies are trying to use it travel to space. RTGs provide power to spacecrafts.

A lot of Mound’s history can also be seen at the Mound Cold War Discovery Center. The Discovery Center shares and preserves the history of Mound Laboratory, including the Dayton Project, with the public. Visitors can walk through the exhibits for free or set up a guided tour or educational program for a small fee. A fun fact about the Discovery Center is that it is located in one of the old Mound Lab Buildings (Building 102) that remains on the Mound Site. Plan a visit to the Mound Cold War Discovery Center.