A part of a tunnel at the Hanford nuclear waste site in Washington State collapsed, leading to concerns that the incident could have caused a radiation leak.

The underground tunnel contained rail cars that were filled with radioactive waste, forcing the site's officials to order an evacuation of some workers.

Hanford Nuclear Waste Site Tunnel Collapse

In the early morning of May 9, Hanford management ordered employees to take cover and secure ventilation. They were also told to avoid eating or drinking.

The directive was sent out because crews discovered that a 20-foot section of one of the underground tunnels in the site had caved in. The collapsed tunnel caused soil on the surface above it to sunk by 2 feet to 4 feet over an area of 400 square feet.

The collapse was found by workers as part of a routine inspection. The reason behind the incident is still unknown, though Department of Energy spokesman Mark Heeter noted that there has never been a tunnel collapse at Hanford.

Heeter said that it is still too early to determine the cause of the collapse, with the investigation to only begin once that tunnel is safe enough for people to enter again.

Another spokeswoman for the Department of Energy said that there were almost 5,000 employees at the Hanford site at the time of the incident, spread out across the 586-square-mile facility. There were less than a dozen employees near the tunnel that collapsed.

Officials said that by early afternoon of the same day, non-essential employees were cleared to go home. Crews then started preparations to fill the hole left behind by the collapsed tunnel with clean soil. They are now working to fix the hole in the roof of the tunnel and are looking to install a barrier to contain the radioactive waste.

A massive cleanup that started in the 1980s is still ongoing at Hanford, with the project expected to be completed by 2060. The cleanup costs over $2 billion annually and over $100 billion over its lifetime.

Previously, plutonium to be used for nuclear weapons was manufactured at Hanford. Now, the site is the biggest depository of radioactive defense waste in the United States, with about 56 million gallons mostly stored in 177 tanks located underground. The facility is twice the size of Singapore.

Is There A Radiation Leak?

Washington State Department of Ecology spokesperson Randy Bradbury laid concerns of a possible radiation leak to rest, saying that officials detected that no radiation was released by the tunnel collapse. In addition, no workers were injured or exposed to radiation.

However, tests are still continuing, with radiation levels constantly being monitored through the help of robotic equipment.

Heeter said that the greatest threat presented by plutonium is airborne contamination. While there is so far no evidence of such a thing, he assured that the Department of Energy has methods to contain the contamination in case the problem arises.

Advocacy group Hanford Challenge executive director Tom Carpenter, meanwhile, said that the tunnel collapse should serve as a "wake-up call," as the facility continues to age, but the radioactive waste it contains remains very dangerous.

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