The World’s First Nuclear Reactor Hides in This Secret Washington Desert Facility

B Reactor National Historic Landmark, Washington

In an unassuming building along the Columbia River sits the world’s first full-scale nuclear reactor.

B Reactor didn’t just help end World War II – it launched the atomic age and changed the course of human history.

Today, this preserved Manhattan Project site lets you stand in the control room where scientists first harnessed the atom.

Fermi and DuPont Created Engineering Marvel in 11 Months

You can thank renowned physicist Enrico Fermi and DuPont engineers for this technological marvel.

They based the design on experimental work from the University of Chicago and tests at the X-10 Graphite Reactor at Oak Ridge National Laboratory.

Produced Plutonium for an Infamous Bomb

This massive facility in Hanford, Washington, produced the plutonium used in the “Fat Man” atomic bomb dropped on Nagasaki on August 9, 1945.

The B Reactor was one of three plutonium production reactors built in complete secrecy at Hanford during WWII. Most workers had no idea they were putting together the elements for the bomb that would drop over Nagasaki.

Japan surrendered just five days after the Nagasaki bombing, bringing the war to an end.

Columbia River Provided Critical Cooling at 75,000 Gallons Per Minute

You wouldn’t believe how much water it took to keep this thing from melting down – 75,000 gallons per minute pumped from the Columbia River.

There weren’t any moving parts inside the reactor, so the only sound during operations was millions of gallons of river water rushing through.

After cooling the reactor, this water went into settling basins to let radioactive materials decay before returning to the river.

This open-cycle cooling system wouldn’t be allowed in modern nuclear facilities.

40,000+ Workers Built Reactor in Remote Desert Location

Building this reactor required more than 40,000 workers in the middle of nowhere.

The Hanford Site covers 586 square miles – about half the size of Rhode Island. This was truly a global project, with uranium mined primarily in the Belgian Congo.

Several U.S. processing plants further refined uranium into billets, which were shaped into fuel slugs and sealed in aluminum jackets before being transported to the reactor.

Original Control Room Preserved with Vintage Control Panels

Today, you’ll see the actual control room where the operations took place.

It’s been preserved with the original control panels, gauges, and manual controls. It didn’t take many people to run this place – a typical crew numbered less than 20 people.

75,000 Graphite Blocks Slowed Neutrons in Nuclear Reaction

At its heart, B Reactor contained a massive core with 75,000 graphite blocks weighing about 2,000 tons. These blocks slowed down neutrons during the nuclear reaction process.

Early operation hit a snag with neutron absorption issues identified by physicist Chien-Shiung Wu. The reactor operated at 250 megawatts (thermal), which was unprecedented at the time.

As a result, the workers in the facility had to load 64,000 fuel slugs weighing around 500,000 pounds by hand into 2,004 process tubes.

Public Tours Started in 2009 After Decades of Cold War Secrecy

Tours began in 2009, and since then, people from all 50 states and more than 90 countries have checked it out. The Manhattan Project National Historical Park at Hanford welcomes up to 15,000 visitors yearly.

You’ve got two tour options: one visits the B Reactor itself, while another explores the area’s pre-Manhattan Project history.

Tours start at the visitor center in Richland with a 45-minute bus ride to the site.

2,004 Aluminum Tubes Created Iconic Honeycomb Pattern

The most recognizable feature of the B Reactor is its face with 2,004 aluminum tubes where uranium fuel was inserted, typically spent several weeks to a year in the reactor.

Every four to six weeks, workers pushed 10-20% of the irradiated uranium out the back into a water-filled storage basin.

After cooling for 2-3 months underwater, the material went to T Plant for plutonium separation. You can spot it’s distinct honey-comb pattern on tour.

Produced Nuclear Material for Cold War Arsenal Until 1968

After helping end WWII, B Reactor kept going, producing plutonium for America’s nuclear arsenal until its shutdown in 1968.

During the Cold War, the Hanford project expanded dramatically to include nine nuclear reactors and five plutonium processing complexes. These facilities produced material for most of the 60,000+ weapons in the U.S. nuclear arsenal.

Nuclear technology developed rapidly during this period, with Hanford scientists making major breakthroughs in reactor design and operation.

You Can Tour This Authentic Reactor

the free tours run from April through September, giving you a rare chance to see inside America’s first full-scale nuclear reactor. The park includes the B Reactor Building with its tall ventilation stack, visible in both historic and modern photos.

You’ll also find turn-of-the-century structures like a high school, bank, pump house, and fruit warehouse from agricultural towns the government took over in 1943.

It’s a National Historic Landmark

In 2008, B Reactor joined an elite club with places like Mount Rushmore and the White House as one of America’s most important historic sites.

National Historic Landmark status has been granted to fewer than 2,500 sites across the United States. In December 2014, Congress passed legislation making B Reactor part of the Manhattan Project National Historical Park.

The park became official on November 10, 2015, when the National Park Service and Department of Energy signed an agreement.