

"Little Boy" bomb dropped on Hiroshima, made with uranium-235 from Oak Ridge

In 1943, after graduating from Washington and Lee University, Bill Wilcox landed a coveted job as a government chemist and was sent to a city that didn’t exist.

Oak Ridge, Tennessee, then known only as the Clinton Engineering Works, was conspicuously absent from any map. On 60,000 acres of farmland framed by the foothills of the Appalachian Mountains, it was one of the United States’ three secret cities—remote sites chosen by Manhattan Project director Gen. Leslie Groves, evacuated of their civilian inhabitants, and developed for the specific purpose of producing an atomic bomb. The men and women of the Clinton Engineering Works would help provide the material for the bomb. “I was told I would be working on uranium, and was sternly cautioned, ‘That’s the last time you will hear that word, and you must never speak it,’” Wilcox, now 87, recalled.

Wilcox’s experience was atypical of the 75,000 government workers and construction personnel who populated the gated district from 1942 to 1945. Many had never heard of uranium until August 6, 1945—65 years ago—when radio broadcasts and newspapers announced that the most powerful weapon ever created had been dropped on a city in Japan, ending the war 22 days later.

The Clinton Engineering Works opened its gates to the public in 1949, and was renamed Oak Ridge; today, its residents are keenly aware of their atomic heritage. The city is home to two of the most advanced neutron science research centers in the world, and the government is still the area’s major employer. But Oak Ridge has come a long way from the stretch of cultivated fields stippled with charmless industrial plants, prefabricated houses, and signs warning its denizens, “What you see here…when you leave here, let it stay here.” Trees that were planted in wartime have since grown tall, and the city is clean and well manicured. Still, the opportunities to celebrate its unique place in history are plentiful.

Visitors to Oak Ridge should start their journey at the American Museum of Science and Energy, which provides a wonderful overview of the city’s wartime past. Its exceptional exhibit includes an original 576-square-foot flat-top house—the type of dwelling a scientist or plant worker would have moved into with his family during the war years. The boxy prefab building, composed of three sections, was designed for quick assembly; at the height of the Manhattan Project, a house went up every 30 minutes.

Skidmore, Owings, and Merrill, the architecture firm commissioned to design the original communities within the Clinton Engineering Works, created several types of homes for Manhattan Project workers, including dormitories for single men and women. Many were made of cemesto, a mixture of cement and asbestos. House hunting was never an issue for new residents, who were assigned accommodations based on their position and rank. The houses were rented, not sold, and modifications were forbidden. Ten years after the war, the government put the houses up for sale. Bill Wilcox, now the Oak Ridge city historian, reports that 90 percent of those buildings are still in use throughout the city. Though homeowners have made changes—siding, eaves, paint—to distinguish their houses from the others, some Oak Ridge neighborhoods still retain an eerie, modular quality.

A short distance from the American Museum of Science and Energy is A. K. Bissell Park, home of the Secret City Commemorative Walk, a recent and charming addition to the city from its Rotary Club. Located in a beautiful garden, the walk is a memorial to the individuals who came to Oak Ridge during the war. Stroll along the figure eight–shaped path and take in the bronze plaques offering stories of wartime life. Though the work was intense, the young residents had fun, too. Many of them, like Wilcox, were just out of college; the average age in the community during the war was only 27. Tennis courts, then the only paved surface, doubled as dance floors. Residents remember the time as one of excitement, enjoyment, and devotion to a common cause.

Much of what originally brought people to Oak Ridge can still be seen: three of four plants used to produce material for the atomic bomb survive. These buildings are within 30 minutes of the city center, on what are today the sites of Oak Ridge National Laboratory, the Department of Energy East Tennessee Technology Park, and the Y-12 National Security Complex. On weekdays, the Department of Energy (DOE) operates a three-hour bus tour of these facilities, isolated in a 17-mile-long valley studded by parallel ridges—a major reason the spot was chosen for the Manhattan Project in the first place. If a catastrophic explosion occurred, the ridges would act as buffers between the plants.

Oak Ridge National Laboratory was established in 1948 from the facility codenamed X-10, where plutonium was extracted from irradiated slugs of uranium, and encompasses the original graphite reactor. The exterior and interior of the building that houses the reactor are, as they were then, army green. No longer in service today, the facility is a well-preserved throwback to the days when it produced radioisotopes. With no air conditioning or heating, windows at the top provided the only airflow. Inside, visitors can stare into the giant face of the graphite reactor, which is pocked with more than 1,200 openings into which workers once inserted uranium slugs with long rods. The dark control room, cluttered with knobs, switches, and analog clocks and controls, seems simple and ancient compared with today’s sleek technology.

From a nearby overlook, to the west on State Highway 58, you can see the original K-25 building—the plant where U-235, the fissionable uranium isotope, was separated from U-238, the heavier, more stable isotope, using a process called gaseous diffusion. It cost $500 million to build (the equivalent of more than $6 billion today), and when it was completed in 1945 it was one of the largest single-roofed buildings in the world.

Dormant since 1987, the enormous U-shaped structure has deteriorated and is currently being torn down. It contains original equipment, some of which is still classified. The demolition will cost more than $1 billion and will take several more years, at which time the area will be used for industries in the Department of Energy’s Eastern Tennessee Technology Park. However, the government plans to preserve K-25’s Gaseous Diffusion Process Building along with some of its equipment, so future generations can learn of K-25’s World War II—and Cold War—era contributions.

The closest a visitor can get to K-25 is via the Secret City Scenic Excursion Train, which follows a rail line that carried construction equipment and supplies in 1943 and 1944. Also visible on the route is a Tennessee Valley Authority substation from the 1940s, which helped generate the the massive amount of electricity required by the plants. The popular 12-mile roundtrip excursion runs the first and third Saturdays of summer months.

The city’s third remaining Manhattan Project plant, Y-12, is a bustling DOE facility that still manufactures, manages, and stores nuclear materials. Aside from the New Hope Center for visitors with a small exhibit hall, access is restricted. But it is remarkable to think that Oak Ridge’s legacy continues today. On this site, beginning in 1943, workers created weapons-grade uranium using a process called electromagnetic isotope separation. Those who knew they were working with uranium were instructed to call it by a code name, tuballoy. One local story tells of a Y-12 scientist who, after seeing newspaper reports that the uranium in the Hiroshima bomb had come from Oak Ridge, was finally able to speak the name of the secret he kept since he first came to Tennessee and ran through the laboratory hallway screaming, “Uranium! Uranium!”

That seems to be a common trait among the men and women who settled Oak Ridge: the eagerness to reveal, and preserve, the secrets of their atomic city.

Planning a trip? Visit the Oak Ridge Convention and Visitors Bureau for more information.