Mound Site Process History Summary

Prepared by Floyd R. Hertweck, Jr. (May 2000)


The Dayton area’s link to the Second World War era War Departments Manhattan Engineer District, and to the Manhattan Project and to the Cold War began during the Second World War with the Dayton Unit Operations in 1943. mound-museum-hill2The work at the Dayton Units actually contributed to the development of the initiator used in the Trinity Test at the Alamogordo Bombing Range in New Mexico in July 1945, and in the Fat Man device that was dropped on Nagasaki later in 1945.


The Dayton Units consisted of various locations in the Dayton, Ohio area that were utilized for research and development in polonium. The Dayton Units (including Unit III or Bonebreak Theological Seminary, Unit IV or Runnymeade Playhouse, and the Warehouse) were operated in support of the Manhattan Project, sharing in the research and development of initiators for the atomic bomb. The Dayton Unit III was instrumental in the development of the atom bomb during the Second World War, and Dayton Unit III, IV, and the Warehouse were involved in research and development activities in the Post War period, and in the early Cold War years immediately following the War.

Construction of the Mound site was begun in 1946, under the Manhattan Engineer District of the War Department. Completion of the site, and the start up of production of polonium initiators began under the Atomic Energy Commission. The site became operational in 1948. Mound was the Nations first Post-War Atomic Energy Commission site to be constructed.

As indicated in War Department and early Atomic Energy Commission documents, Mound was established to consolidate and to continue the polonium-related work being done at the Dayton Units. Work at Mound evolved and grew to include additional radionuclides (e.g., radium and actinium, thorium, plutonium) the research in and the manufacture of explosives for initiators in weapons, the development of radio isotopic thermoelectric generators, and other non-nuclear research and development activities.

Perspective on Mound Processes and Mission Activities

The Dayton Units operations and the Mound operations that followed in 1949 were initially heavily involved in research with and the manufacture of polonium based initiators, ultimately in support of the Cold War. As early as late 1949 work began on other radionuclides, and in the ensuing years, Mound was also heavily involved in the manufacture and testing of:

  1. Detonators and explosives that were used as initiators and other explosive actuated devices for nuclear weapon component production
  2. Tritium recovery
  3. Power sources for the space industry
  4. Research with radionuclide
  5. Other weapons and nuclear related research and development activities

All of these activities are also linked to the Cold War, including the space industry, which was a race to conquer space between the Soviet Union and the United States.

As such, the facility has played a significant role in the Cold War, being instrumental in the propagation of nuclear weapons and armaments through its activities in the manufacture and research related to radionuclides and in it’s activities related to the development of non-nuclear initiators.

Mound has also piloted and/or worked with radionuclides for peacetime, with peacetime use for power sources, stable isotope separation, research with fossil fuels, technology exchange, and other research and development with other programs that have benefited industry and the government.

Mound has also played a significant role in the private sector with various programs. These programs have included Mound being a producer of rare and stable gases used by private industry, research related to the fossil fuels, through nuclear fuel programs, by supporting research at other sites and at universities, and so on. Mound also has played a significant role in this country’s space program with the Radioisotopic Thermoelectric Generator Program.

Summary of the 50-Year Mound Plant Production Summary

The first Mound program polonium research and development investigated the chemical and metallurgical properties of polonium-210 and its applications as an initiator, including the fabrication of neutron and alpha sources for weapons initiators and for non-weapons use.

The major post-polonium mission related activities at Mound have included: (1) research, development, engineering, production, and surveillance of components for weapons programs; (2) separation, purification, and sale of stable isotopes; and (3) Department of Energy programs in nuclear safeguards and waste management, heat source testing, and fusion fuel systems.

Polonium Production And Research

In a nuclear weapon, polonium provides a catalyst for the reaction that detonates the plutonium. The plutonium it self will not initiate the chain reaction necessary to achieve detonation, and requires a neutron source that gives off neutrons faster than the plutonium. In earlier nuclear weapons, the initiator was a beryllium metal and polonium mixture where the polonium gave off alpha particles that irradiated the beryllium. Irradiated beryllium gives off the necessary neutrons to initiate the chain reaction in the plutonium.

The Polonium-210 operations were terminated at Mound in June 1972.

POST POLONIUM ACTIVITIES: RADIUM AND ACTINIUM- Because of polonium’s relative short half-life, the AEC realized it would be necessary to frequently change the polonium in the initiators. Because of this, the AEC began exploring alternate fuels for the initiator. One element of interest was actinium-227. In response to this interest, the AEC charged Mound with activities related to the development and research in actinium. These activities started with small scale studies in 1949 in R Building, and later were expanded to larger scale production operations in SW Building (1950), biologic studies in B Building, and personnel and environmental monitoring in I Building. The efforts related to actinium research ceased in the early-1950s. Mound also conducted early work with polonium 208.

POST POLONIUM ACTIVITIES: OTHER RADIONUCLIDES- During the period from 1950 to 1963, laboratory investigations involving uranium, protactinium-231, and plutonium-239 were conducted as part of the National Civilian Power Reactor Program. The purpose of this program was to develop nuclear reactors suitable for the production of power or heat for civilian use. The mission at Mound was to acquire data on some of the proposed fuel systems.

POST POLONIUM ACTIVITIES: STABLE ISOTOPE PROGRAMS- Separation of the stable isotopes of noble gases began in 1954. Non-radioactive isotopes of helium, neon, argon, krypton, and xenon were separated and purified in a separate building (HH). The non-radioactive isotopes of carbon, nitrogen, and oxygen were separated by low-temperature distillation at Los Alamos National Laboratory and shipped to Mound for further processing. Enrichment of sulfur-34 in sulfur compounds was also performed. These isotopes were distributed as part of the Stable Isotope Inventory Program.

The isotopes developed in these processes had a variety of applications in agriculture, biochemistry, biology, medicine, and the nuclear industry. As an example, Helium-3 is used in the manufacture of neutron detectors, and in the dilution refrigeration systems used in extremely low temperature cryogenic investigations. Carbon-12, carbon-13, nitrogen-14, nitrogen-15, oxygen-17, oxygen-18, and calcium isotopes are used as tracers in biological and agricultural research and as diagnostic tools in medicine.

POST POLONIUM ACTIVITIES: RADIOISOTOPIC THERMOELECTRIC GENERATOR PROGRAM- In 1954, the radioisotopic thermoelectric generator fueled with polonium-210 was invented at Mound by scientists Ken Jordan and John Birden. This invention used heat from radioactive decay of polonium-210. The first Space Nuclear Auxiliary Power (SNAP) generator, SNAP 3 fueled with polonium-210, was demonstrated in 1959. However, use of polonium-210 in space application proved to be impractical.

The development of plutonium-238 heat sources was started at the Mound in 1961. Since their development, these units have been used on a variety of space missions including navigational satellites, weather satellites, several of the Apollo lunar missions and deep space missions such as Voyager I and II. The most recent and final missions for which Mound supplied the radioisotope thermoelectric generators have been the Galileo mission to study Jupiter and its moons, the ULLYSSES mission to study the polar regions of the sun and lastly, the Cassini mission to study Saturn and its moons. These units supplied both thermal and electrical energy to support spacecraft operations.

POST POLONIUM ACTIVITIES: EXPLOSIVES AND DETONATORS RELATED RESEARCH AND DEVELOPMENT- By 1957, Mound was assigned a new mission to develop, produce, and provide surveillance of detonators for military applications. Development of explosive timers in 1959 led to their being manufactured at Mound starting in 1963. The development and manufacture of ferroelectrical transducers and firing sets components that control initiation of detonators began at Mound in 1962. These detonators were installed in explosive timers, firing sets, and switches developed and manufactured at the facility and shipped to other Department of Energy production and design sites for use in the assembly of nuclear weapon components and for use in testing programs.

POST POLONIUM ACTIVITIES: TRITIUM PROGRAMS- The first of several programs requiring tritium-handling technology was initiated at Mound in 1958. Through the years the plant developed extensive capabilities for handling and studying tritium and tritium compounds in support of the nuclear weapons production program and for non-weapon applications.

POST POLONIUM ACTIVITIES: MOUND IN TRANSITION- In the early 1970s, national attention and concerns about the environment and the conservation of resources mounted. In response to these concerns, Mound expanded its programs in environmental monitoring and waste management, as well as continuing its ongoing activities in detonator surveillance; energy-related activities; separation, purification, and worldwide sales of noble gas isotopes; the development of measurement technologies for nuclear materials; and, RTG fabrication and testing.

Because of environmental concerns Mound implemented programs for the decontamination and decommissioning of facilities. In 1989, Mound was named to the Environmental Protection Agency’s, National Priorities List. Mound was placed on this list following EPA’s evaluation of the site, noting the necessity of cleanup of volatile organic compounds around the site and the contamination of the Miami-Erie Canal due to the settling of plutonium-238 in the canal bed following a 1969 waste transfer line break.

Current Site Uses

The Mound mission has shifted and evolved through time, paralleling the evolution of defense related industry through the Cold War period. During that time, Mound had also, developed capabilities to support non-weapons activities and missions. As noted above, programs at Mound have included the development of nuclear and non-nuclear weapons components, research into the use of radionuclides for both weapons and non-weapons purposes, production of noble gases, fossil fuels research, and other programs.

In 1977, the Mound name was changed to the Mound Facility. Despite this name change, the plant site continued in its multifaceted role in support of the nuclear complex, the development of non-nuclear weapons components, and in non-weapons related programs, until its mission was changed in 1994.

In 1994, all production at Mound, with the exception of the RTG Program officially ceased, and the mission was changed to shutdown of operations, site cleanup, and the transition of reusable buildings and processes to the Mound Development Corporation (MDC). The Heat Source/RTG work continued until the Cassini mission was completed in 1998. After the Cassini mission was complete, the Heat Source/RTG program was officially transferred in 2003.

Cleanup and environmental restoration was completed in 2007. Current use of the site is for commercial development and placement of local businesses through the Mound Development Corporation (MDC).

Process History Summary Table

The table that follows includes a list of many of the major programs, operations, activities and missions that have taken place at Mound since 1949.

These projects and activities listed noted by the project name or by a description of the project. The dates of operation are approximate dates. The table follows:

Mission Or Program Name Period of Operation
Polonium 210 Program 1949-1974
Radium-226/Actinium Program 1949-1953 and 1955-1959
Analytical Operations Programs

  • Environmental Monitoring
  • Personnel Monitoring
Biological Studies Program

  • Polonium 210 Studies
  • Actinium 227 Studies
  • Polonium 208 Studies
Instrumentation, Electronics & Techniques Research 1949-1994
Reactor Waste Decontamination Research Program

  • Fused Salts Project (Mid-1950s)
  • Bismuth Phosphate Wastes
  • Tributyl Phosphates Wastes
  • Purex Process Wastes
Polonium-208 Research Project To Separate Polonium 208 and 209 1950-1952
Project To Determine Physical Properties Of Uranyl Sulfate Heavy Water For Oak Ridge
Raw Materials Research And Production (Uranium Extraction From Phosphates, Shale, Slag) 1952-(e.g., early 1950s?)
Thermal Diffusion Project Mid-1950s
Lithium Programs

  • Livermore Project
  • Laboratory Scale Operation
  • Development Of Analytical Methods
1950s-1960s (intermittent)
Tritium Operations

  • Production
  • Disassembly And Waste Disposal
  • Analysis
  • Development Of Nuclear Components
Thorium-232 Refinery (Monex) Operations 1955
Decontamination & Decommissioning Process Development

  • Polonium-210
  • Radium-226/Actinium-227
  • Plutonium-238 4. More
Thorium-230 (Ionium) Programs 1956
Explosives/Detonator Related Operations

  • 1957- Detonator Production and Surveillance on LASL Detonators Begins
  • 1958-Plastics Production Facility Operational
  • 1959- Detonator Development Function Established
  • 1959-Detonator Production of LLNL Detonators Begins
  • 1960-Explosive Timer Development Begins
  • 1962- Weapon Component Disassembly and Surveillance Facility Operational
  • 1962- Method to Thermally Stabilize PETN Developed
  • 1962- Production of Explosive Timers Begins
  • 1962- Productiuon of Ferroelectric Transducers Begins
  • 1962- Production of Explosive Firesets Begins
  • 1962-Fabrication of Sandia Detonators Begins
  • 1972-Lead Responsibility For the Design /Fabrication of Product Testers
  • 1972-Components For CDU Firesets Produced
  • 1974-Development of Ceramic Components for Detonator and Igniter Application Begins
  • 1974-Development of Pyrotechnic Powder Blends Begins
  • 1975-Ceramic And Pytotechnic Facilities Operational
  • 1975-Moldable Ceramic Material Developed
  • 1975-Production of Advanced Electronic Product testers Begins
  • 1976-Consolidated Thermites Developed
  • 1977- Project To Develop Consolidated Thermites
  • 1978- Became Lead Department Of Energy Laboratory For Ceramics Production
  • 1980-Plastic Bonded Explosives First Produced at Mound
  • 1981- New Cobalt Perchlorate (CP) Explosives Characterized
  • 1985- Components Produced Using Flat Cable Tape
  • 1986-Development of MSAD/LLNL components
  • 1990-Decision to close Mound announced by the Department of Energy
  • 1994- Final WR Explosive Components Shipped from Site
Neutron And Alpha Sources Production

  • 1949 to 1962-Polonium-210
  • 1949 to 1971-Plutonium-239
  • 1956 to 1962-Neptunium-237
1949 to 1962
Plutonium-238 Operations Mid 1950s-1978
  • Plutonium Research And Development
  • Plutonium 238 RTG Systems Development
Mid 1960s-Late 1970s
  • Pressed Plutonium Oxide Sphere Fabrication
  • Plutonium-Molybdenum Cermet Production Process
  • Plutonium Metals Production Process
Early 1960s-1978
Protactinium-231 Programs Early 1950s-1979
(intermittently )
Reactor Fuels Program

  • 1953-Civilian Power Reactor Program
  • Mid-1950s-Homogenous-Type Reactor Fuels
  • 1953-Aircraft Nuclear Propulsion Project
Rare Isotopes Programs 1956-1983
Stable Isotopes Programs 1957-1996
RTG Support Project Programs

  • The Snap Program
  • The Heat Pipe And Poodle Programs
  • The Swimsuit Heater Program
  • Pacemaker Program
  • Pioneer Program
  • Artificial Heart Program
  • Viking Program
  • Voyager Program
  • Galileo Program
  • Ulysses Program
  • Cassini Program
  • Light Weight Radioisotopic Heater Units
Container Testing Program Later 1960s
Cotter Concentrate Processing Programs Early 1970s-Late 1970s
Fossil Fuel Energy Programs

  • Study Radioactive Constituents In Western Coal For The U.S. Environmental Protection Agency
  • Characterization Of Devonian Oil Shale
  • In-Situ Coal Gasification Monitoring (West Virginia)
Late 1970s 1976 1977 1979
Environmental Monitoring And Compliance Program 1949-2007
Waste Management Programs 1949-2007
Operation Of The Californium Multiplier Neutron Radiography Facility 1977-1995
Program To Design, Construct, And Test A Tritium Storage And Delivery System For Princeton University 1978-1979
University Of Rochester Fusion Project. 1978
Environmental Restoration Program 1989-2007
Support Staff Operations And Activities Programs 1949-2007
Technology Transfer Program Late 1980s to 1994
Project For The Study Of Solar Energy And Fossil Fuel For Long-Term Energy Independence Late 1970s
Mound Metrology Program  1966-1994
Back to Top