On 9 May 2017, the Hanford Nuclear Reservation in southeast Washington state declared a state of emergency after part of a storage tunnel collapsed, prompting workers there to take cover:

Officials are responding to reports of a cave-in of a 20 foot section of a tunnel that is hundreds of feet long that is used to store contaminated materials. The tunnel is located next to the Plutonium Uranium Extraction Facility, also known as PUREX, which is located in the center of the Hanford Site in an area known as the 200 East Area. There is no indication of a release of contamination at this point, Crews are continuing to survey the area for contamination. All personnel in the vicinity of the PUREX facility have been accounted for and there are no reports of injuries.

The segment of tunnel that fell evidently houses rail cars filled with radioactive waste, according to a Department of Energy spokesperson:

The damage was more serious than initially reported, and the take-cover order was expanded to cover the entire facility after response crews found a 400-square-foot section of the decommissioned rail tunnel had collapsed, she said.

The Associated Press reports that there are no injuries:

There were no workers inside the tunnel when it collapsed. But nearby Hanford workers were evacuated and others who were farther away were told to remain indoors, the U.S. Department of Energy said.

The accident occurred at a facility known as PUREX, located in the middle of the sprawling Hanford site, which is half the size of Rhode Island, Bradbury said.

Hanford is located near Richland, about 200 miles southeast of Seattle.

The closed PUREX plant was part of the nation’s nuclear weapons production complex.

Hanford is the largest depository of radioactive waste, containing 56 million gallons of it, mostly in underground tanks. In the past, rail cars full of radioactive waste were driven deep into the tunnels and then simply buried there. The United States is in the process of dismantling and decommissioning the site.