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The American Physical Society has recognized the Graphite Reactor, located at the Department of Energy’s Oak Ridge National Laboratory, as an APS historic site. APS President Young-Kee Kim presented a plaque commemorating the recognition on Monday, Nov. 4, the 81st anniversary of the reactor’s first achieving criticality in 1943.

The APS citation reads: The X-10 Graphite Pile was the second nuclear reactor in the world to achieve criticality. It produced substantial quantities of plutonium for the Manhattan Project during World War II and later synthesized medical isotopes. Physicists Clifford Shull and Ernest Wollan used the X-10 Graphite Pile to pioneer neutron diffraction experiments for which Shull won a share of the 1994 Nobel Prize in Physics.

“We welcome the APS’s recognition of the Graphite Reactor’s legacy,” said ORNL Director Stephen Streiffer. “The X-10 Pile was built out of wartime necessity by a team of the leading scientists of the day. It served for two decades as a facility for groundbreaking scientific research and radioisotope production, setting the standard of excellence and achievement ORNL observes to this day.”

The day’s events included an expert panel discussion, titled “The Significance of the Graphite Reactor,” and moderated by ORNL Deputy for Science and Technology Susan Hubbard. Panelists delved into the significance of the Graphite Reactor and its impact on the missions that ORNL still fulfills today.

Panel members included:

The APS previously recognized ORNL’s Holifield Radioactive Ion Beam Facility as a . The Graphite Reactor’s historic landmark status has also been recognized by the Department of the Interior (in 1965) and the American Neutron Society (in 1992). ORNL's Mickey Wade initiated the process that culminated in the APS historic site designation.

“Pile” is an early term for a nuclear reactor. The Graphite Reactor was initially known as the “X-10 Pile” or “Clinton Pile” in reference to the nearby town. Its construction followed Enrico Fermi’s successful Chicago Pile (CP-1) chain reaction experiment at the University of Chicago in December 1942. The next step in the Manhattan Project quest to produce plutonium for a weapon was to construct pilot plants for a reactor and chemical separations facility, for which the Oak Ridge X-10 site was selected.

The Graphite Reactor achieved critically on Nov. 4, 1943, a scant nine months after ground was broken on the site. The reactor ultimately produced gram quantities of plutonium for the Manhattan Project effort. By the close of World War II the reactor had shifted to research missions that included Wollan and Shull’s seminal neutron scattering research, the production of radioisotopes for myriad uses and studies on how materials and organisms respond to irradiation — all new and groundbreaking fields of science.

The reactor served science until Nov. 4, 1963, when it was shut down exactly 20 years after it came online. Eugene Wigner, one of the primary theoreticians and designers of the Graphite Reactor and ORNL’s first scientific director, received the Nobel Prize for Physics the same year.

Today the Graphite Reactor serves as a museum, preserved in its 1963 state, and is through the American Museum of Science and Energy in Oak Ridge. For more information on this history of ORNL, please visit the .

Oak Ridge National Laboratory is managed by UT-Battelle for the Department of Energy’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit . – Bill Cabage

Click of Oak Ridge National Laboratory's main campus.

Click of ORNL's historic Graphite Reactor.

Click of the Graphite Reactor.