X-10 Plant

The unassuming building numbered X-10 held the Graphite Reactor, built in only eleven months. After its first chain reaction it was yielding a third of a ton of irradiated uranium a day within two months, and by early spring 1944 it had produced the world's first grams of plutonium. It was a pilot for the Hanford reactors, and its plutonium went into the Fat Man bomb. It also gave the first electricity from nuclear energy and became the first reactor used to study the health hazards of radioactivity.

What the plaque says

X-10 Plant A Manhattan Project facility, the plutonium pilot plant was constructed in 1943 as a production model for the Hanford Engineering Works. The air-cooled graphite reactor "went critical," on November 4, 1943. The world's first radioactive isotope for medical use was produced here on August 2, 1946. The facility now serves as one of this country's national laboratories.

Where it stands

Worth the stop nearby

• American Museum of Science and Energy — 6.5 mi
  The Oak Ridge museum that opened in 1949, when the Manhattan Project city's gates opened, in a town whose Black workers were housed in the Gamble Valley hutments.
• Fort Southwest Point State Historic Park — 13 mi
  A reconstructed 1797 federal fort on a knoll at the meeting of the Clinch and Tennessee rivers, headquarters of Cherokee agent Return J. Meigs, a state park since July 2026.
• Historic Brushy Mountain State Penitentiary — 15 mi
  The coal-mining prison opened in 1896 after the Coal Creek War ended convict leasing, where James Earl Ray escaped in 1977, now a tourist site and distillery.
• Green McAdoo Cultural Center — 15 mi
  The 1935 school in Clinton that sent twelve Black students down Foley Hill to desegregate Clinton High School in August 1956, now a museum with bronze statues of the Clinton 12.

More markers nearby

• Oak Ridge — 3.7 mi
• Sam Rayburn — 3.8 mi
• K-25 Plant — 4.6 mi
• Freels Bend Cabin — 5.2 mi