Officials in southeastern Washington state went on alert Tuesday after reporting a cave-in of a tunnel containing radioactive materials at the Hanford Site, a deactivated nuclear weapons complex that has become one of the nation's most challenging nuclear cleanup sites.
No injuries have been reported, all cleanup employees are accounted for, and officials have not confirmed any release of radiation, according to the Hanford Emergency Operations Center. The center went into operation at 8:26 a.m. after workers discovered a 20-by-20-foot section of soil had collapsed over a tunnel.
By Tuesday evening, the operations center posted a notice on its website: "Officials continue to monitor the air and are working on how they will fix the hole in the tunnel roof. They are looking at options that would provide a barrier between the contaminated equipment in the tunnel and the outside air that would not cause the hole in the tunnel's roof to widen."
The collapse appears to have occurred where two tunnels, made of wood and concrete, connect near the site's Plutonium Uranium Extraction Facility. The facility, called Purex, reprocessed fuel for the nation's nuclear weapons program between 1956 and 1990.
"The Department of Energy informed us this morning that a tunnel was breached that was used to bury radioactive waste from the production of plutonium at the Hanford Nuclear Reservation," Washington Gov. Jay Inslee said in a statement, adding that the White House had contacted his office about the situation. "Federal, state and local officials are coordinating closely on the response, and the state Department of Ecology is in close communication with the U.S. Department of Energy Richland Office."
The tunnels "house sealed rail cars containing packaged contaminated materials," U.S. Sen. Maria Cantwell (D-Wash.) said in a statement. "We need to understand whether there has been any environmental contamination resulting from the subsidence at these tunnels."
About half a dozen cleanup employees were evacuated from the immediate area of the collapse, and more than 4,700 other workers at the Hanford Site were at one point ordered to shelter inside in case any radiation was released, according to emergency officials.
By Tuesday afternoon, all nonessential employees had been cleared to leave the area and were sent home for the day, with no decisions announced on whether normal work would resume Wednesday.
The site is about seven miles northwest of the town of Richland, population 53,000, which has not been affected. Federal officials have instituted a five-mile no-fly zone around the site up to 5,000 feet in altitude, which is lower than that typically flown by commercial airliners.
Officials are still on the scene investigating.
The Hanford complex produced the plutonium for the world's first nuclear explosion, in New Mexico, and also for the atomic bomb that devastated Nagasaki, Japan, in 1945. The facility went on to produce plutonium for decades, producing hundreds of billions of gallons of liquid waste that was poured or buried in the ground.
5:15 p.m.: This article was updated to report that officials are studying how to repair the cave-in without causing the hole to become larger.
3:15 p.m.: This article was updated to report that non-essential employees at the Hanford facility had been cleared to leave the area and were sent home for the day.
12:45 p.m.: This article was updated with details on the tunnel cave-in and quotes from Jay Inslee and Maria Cantwell.
10:15 a.m.: This article was updated with background on the site.