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 (Graphite Reactor) 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.