D Reactor

D Reactor
Name	D Reactor
Country	United States
Location	Benton County, Washington
Coordinates	46°22′N 119°26′W
Operator	Manhattan Project / United States Atomic Energy Commission
Construction	1943
Commission	1944
Decommission	1967
Type	Graphite-moderated, water-cooled plutonium production reactor
Fuel	Uranium metal
Coolant	Columbia River
Moderator	Graphite

D Reactor

D Reactor was one of the plutonium production reactors built at the Hanford site in the state of Washington (state) during World War II. Constructed as part of the Manhattan Project and later managed by the United States Atomic Energy Commission, it contributed to the United States' early nuclear weapons program and Cold War plutonium production. The facility's engineering, operations, environmental legacy, and role in nuclear history link it to a broad set of people, places, institutions, and events in twentieth-century science and geopolitics.

Design and construction

D Reactor was designed under direction of engineers and scientists associated with the Manhattan Project, including teams from DuPont, the United States Army Corps of Engineers, and the Metallurgical Laboratory. Sited on the Hanford Site near Richland, Washington, construction involved coordination with the Bonneville Power Administration for electrical supply and with the United States Navy for logistics. The facility's concrete structures and process systems paralleled contemporaneous reactors such as B Reactor and C Reactor, reflecting design decisions debated among figures from Los Alamos National Laboratory, Oak Ridge National Laboratory, and the Argonne National Laboratory. Labor for construction drew on regional workers, contractors referenced in War Production Board mobilization, and civil engineering practices promulgated by the American Society of Civil Engineers.

D Reactor's layout included a large graphite moderator core, charge face, and discharge face, built within a heavy shielding structure reminiscent of designs used in Chicago Pile-1 experiments. Cooling systems were integrated to use water from the Columbia River, necessitating civil works coordinated with Benton County, Washington authorities and compliance with prevailing wartime construction standards influenced by the National Defense Advisory Commission.

Operation and production

During World War II and the immediate postwar period, D Reactor operated to irradiate natural uranium slugs to produce plutonium isotopes destined for the weapons programs of the United States Department of War and later the Department of Defense. Reactor operation relied on procedural controls developed in collaboration with scientists from Los Alamos National Laboratory, including protocols for criticality safety influenced by experience at Hanford Engineer Works and Oak Ridge. Production runs were scheduled around chemical separation campaigns at the nearby B Plant and T Plant, linking reactor output to reprocessing conducted by teams drawn from the Atomic Energy Commission workforce.

Operational history included routine outages for maintenance, fuel handling performed by trained staff associated with the General Electric and Westinghouse Electric Company practices of the era, and responses to operational anomalies that informed regulatory development at the Nuclear Regulatory Commission successor agencies. D Reactor's plutonium feedstock contributed to inventories stored or transferred under policies shaped by the Truman administration and military planning in the early Cold War.

Reactor technology

D Reactor used graphite as a neutron moderator and heavy concrete biological shielding, a configuration shared with early production reactors such as X-10 Graphite Reactor and Chalk River Laboratories designs. The reactor was water-cooled, drawing coolant from the Columbia River and returning effluent under flow regimes managed with input from hydraulic engineers who had worked on projects like the Grand Coulee Dam. Fuel elements were metallic uranium slugs clad in aluminum, assembled following metallurgical guidance from researchers connected to Metallurgical Laboratory studies and industrial partners including DuPont metallurgy groups.

Instrumentation and control systems reflected mid-twentieth century electronics and instrumentation technologies developed by companies such as General Electric and influenced by standards emerging from the Institute of Electrical and Electronics Engineers. Safety systems and criticality management evolved from early practices at Chicago Pile-1 and lessons learned at sister reactors, informing later reactor physics work at Argonne National Laboratory.

Environmental and health impacts

Operations at D Reactor, like other Hanford reactors, produced radioactive releases and chemical discharges that affected the local environment, particularly the Columbia River ecosystem and areas around Richland, Washington. Radiological and toxicological concerns engaged experts from the Public Health Service, research conducted by scientists at University of Washington, and later epidemiological studies connected with the Centers for Disease Control and Prevention. Worker exposures and community impacts prompted investigations by entities such as the National Institutes of Health and legislative attention from members of United States Congress representing Washington (state).

Contamination pathways included airborne emissions, liquid effluents, and subsurface migration to soil and groundwater monitored by the Environmental Protection Agency and documented in reports produced for the Department of Energy, successor to the Atomic Energy Commission in federal oversight of legacy sites.

Decommissioning and remediation

D Reactor was shut down and placed into transition under policies of the Atomic Energy Commission and later the Department of Energy. Decommissioning activities involved decontamination, entombment of reactor structures, and long-term stewardship planning developed with input from contractors, including firms experienced in nuclear site cleanup like those who worked at Rocky Flats Plant and Savannah River Site. Remediation strategies incorporated radiological characterization, removal of hazardous materials, and construction of engineered barriers influenced by standards promulgated by the Environmental Protection Agency and guidance from the National Academy of Sciences.

Community outreach and regulatory compliance required coordination among local governments, tribal nations in Columbia Basin territories, and federal agencies, culminating in site management plans that remain part of broader cleanup efforts across the Hanford Site overseen by the Department of Energy.

Legacy and historical significance

D Reactor stands as a key element of the Manhattan Project industrial complex and the United States' early nuclear weapons infrastructure, connected historically to events such as the Trinity test and the bombing of Hiroshima and Nagasaki through its role in plutonium production. Its technical contributions informed reactor physics, industrial-scale plutonium production, and postwar nuclear policy debated in forums involving the Atomic Energy Commission, United States Congress, and scientific institutions like American Physical Society. The site's environmental legacy has influenced policy and research in radiological protection, remediation technology, and public health, engaging historians at institutions such as University of Chicago and archivists preserving records within National Archives and Records Administration collections.

Category:Hanford Site