Washington's KING-TV reports that a portion of a tunnel that transports trains carrying radioactive material collapsed early on Tuesday morning, with officials warning workers at the facility to take emergency precautions. We talk to our United States correspondent.
It was discovered during "routine surveillance", according to the Energy Department.
The Purex (Plutonium Uranium Extraction Plant) separations facility at the Hanford Works is seen in an undated aerial photo. Workers in the area have been evacuated after about eight feet of earth collapsed into an old railroad tunnel near a processing facility.
No broader warnings were issued for workers in other parts of the facility or civilians in surrounding areas, said the spokeswoman, who stressed the precautionary nature of warnings issued to workers.
The building has been vacant for almost twenty years, but it remains highly contaminated. "Collapse of the earth covering the tunnels could lead to a considerable radiological release". It is located about 200 miles southeast of Seattle and is half the size of Rhode Island. "There are various projects in this site and occasionally there is spread of contamination". They rest on reinforced concrete footings.
"Officials continue to monitor the air and are working on how they will fix the hole in the tunnel roof", the Hanford Emergency Information site announced.
Hours later, the U.S. Energy Department said an undisclosed number of non-essential workers were being sent home.More news: Eric Trump denies alleged statements on Russian funding
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The two tunnels were used at the beginning of the 1950s to store contaminated equipment and the cave-in apparently took place in an area where the two join together.
Mostly decommissioned, Hanford has been a subject of controversy and conflict between state and local authorities, including a lawsuit over worker safety and ongoing cleanup delays.
Hanford for decades made plutonium for the nation's nuclear weapons arsenal.
Hanford for decades made plutonium for nuclear weapons and is now the largest depository of radioactive defence waste that must be cleaned.
In the past, rail cars full of radioactive waste were driven deep into the tunnels and then simply buried there.
It said responders on the scene were reporting that soil had slid on top of the tunnel in an area 20 feet by 20 feet (six meters by six meters).