RICHLAND, Washington, May 9, 2017 (ENS) РThe U.S. Department of Energy Richland Operations Office declared an emergency at the Hanford Nuclear Reservation at 8:30 this morning after a cave-in of a 20-foot section of a tunnel hundreds of feet long that is used to store contaminated materials.

A former plutonium ¬†and nuclear weapons production site on the Columbia River in central Washington State, Hanford is the most contaminated nuclear site in the United States and the target of the nation’s largest environmental cleanup.

tunnel hole

Hanford activated its emergency center after a tunnel containing contaminated material collapsed. May 9, 2017 (Photo courtesy U.S. Dept. of Energy)

During a routine surveillance of the tunnel area this morning, a 20-foot-wide hole in the roof of the tunnel was observed,

The tunnel is located next to the Plutonium Uranium Extraction Facility, a former chemical processing plant also known as PUREX, located in an industrial area near the center of the Hanford Site, in an area known as the 200 East Area.

No contamination has been detected following the cave-in, and crews continued to survey the area for contamination all day.

All personnel in the vicinity of the PUREX facility are accounted for and there are no reports of injuries.

As a precaution, workers in the vicinity of the PUREX facility as well as the Hanford Site north of the southern entrance to the site were told to shelter in-place for a few hours.

The shelter in place order was lifted in stages from noon to 1:30 pm, and employees were sent home early.

Workers continue to monitor the area for contamination as a crew prepares to fill the hole created by the cave-in to stabilize the tunnel.

At and near the area of subsidence crews have deployed a TALON, a remote operated surveying device capable of radiological and industrial hygiene monitoring as well as capturing video footage. The TALON allows crews to safely survey potential areas of contamination from a distance of up to half a mile.

In the 1950s and 1960s two tunnels were constructed next to the Plutonium Uranium Extraction Plant to hold rail cars that were loaded with contaminated equipment and moved into the tunnels during the Cold War. The tunnels were constructed of wood and concrete and covered with eight feet of soil.

The approximately 360-foot-long tunnel where the cave-in occurred contains eight rail cars loaded with contaminated equipment. That tunnel feeds into a longer tunnel that extends hundreds more feet and contains 28 rail cars loaded with contaminated equipment.

The hole opened up in the shorter tunnel near where it joins the longer tunnel. The tunnels were sealed in the mid-1990s and are checked periodically.

Only personnel essential to minimum safe operations are reporting to work, and non-essential personnel for swing and graveyard shifts were told not to report for work Tuesday night.

Established in 1943 as part of the Manhattan Project, the site housed B Reactor, the first full-scale plutonium production reactor in the world. Plutonium manufactured at Hanford was used in the first nuclear bomb and in the bomb detonated over Nagasaki, Japan in 1945.

During the Cold War, the project expanded to include nine nuclear reactors and five large plutonium processing complexes, which produced plutonium for most of the more than 60,000 weapons built for the U.S. nuclear arsenal.

The weapons production reactors were decommissioned at the end of the Cold War. Decades of manufacturing left behind 53 million gallons (200,000 m3) of high-level radioactive waste stored within 177 storage tanks, an additional 25 million cubic feet (710,000 m3) of solid radioactive waste, and 200 square miles (520 km2) of contaminated groundwater beneath the site.

Today, Hanford hosts a commercial nuclear power plant, the Columbia Generating Station, and various federal government centers for scientific research and development.

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