The reactor is part of the Manhattan Project National Historical Park at Hanford but continues to be owned by DOE, which provides the tours. Registration will open at noon Wednesday, July 3, for ...

Washington Gov. Jay Inslee sits at the controls for Hanford’s historic B Reactor in July 12, 2024. It was his first look inside the reactor, part of the Manhattan Project National Historical Park.

Washington Gov. Jay Inslee sits at the controls for Hanford’s historic B Reactor in July 12, 2024. It was his first look inside the reactor, part of the Manhattan Project National Historical Park.

The B Reactor at the Hanford site was the world’s first full-scale nuclear reactor. Here, scientists and engineers pioneered the technology behind nuclear reactors.

Tucked away in the desert at the Hanford site northwest of Richland is the historic B Reactor, the world’s first full-scale nuclear reactor built during World War II to develop the atomic bomb.

The B Reactor altered the course of World War II and changed global electricity sources, environmental restoration technology, science and medicine, said Michele Gerber, a Hanford historian.