Workers at Hanford Vitrification Plant, the world’s largest radioactive waste treatment plant, were sent an alarming text alert Friday morning telling them to "take cover." The reason was that one of the site's tunnels was found to have steam coming out of it.

#Hanford Vit Plant employees at the jobsite are currently in a precautionary Take Cover, as directed by @RiverProtection. Official updates from DOE at https://t.co/hsGp4zaubi. Workforce safety is highest priority, and Vit Plant will remain in Take Cover until released by DOE. — Hanford Vit Plant (@HanfordVitPlant) October 26, 2018

According to Hanford Vit Plant's Twitter account, the measures at this point are precautionary. "Workforce safety is highest priority, and Vit Plant will remain in Take Cover until released by DOE," said a recent tweet.

No hazardous material

Meanwhile, a statement by Bechtel National, the firm responsible for designing, constructing and commissioning the plant for the US Department of Energy, said that, as of now, there is no indication of a release of hazardous material. However, the employees will remain in cover until further notice.

A take cover was called as a precautionary measure in the 200 East Area on #HanfordSite after steam was observed coming from PUREX Tunnel 2 during tunnel filling operations. There is no indication of a release of hazardous material. For more info visit https://t.co/o11YHxEAkB — Hanford Site (@HanfordSite) October 26, 2018

The Hanford Vit Plant, also known as the Hanford Nuclear Reservation, is located in the US state of Washington. It was built in the 1950s to produce plutonium for the US nuclear weapons arsenal until 1988 when it was turned into a burial ground for radioactive waste.

A problematic plant

The tunnel releasing the steam is one currently storing nuclear waste in railroad cars left over from the Cold War. It is reported to be in danger of collapsing and had required cement to be stabilized.

According to the Statesman Journal, the tunnel measures about 1,700 feet (518 meters) long and holds 28 rail cars with nuclear waste. Last year, another Hanford tunnel partially collapsed, however, no employees sustained any injuries and there were no airborne releases.

According to the Tri-City Herald, the event also marks the seventh time in 2018 that suspicious odors have been detected near the plant's tank farms. There were also a reported two incidents in February, two in June, one in September and two in October.

IE will continue to update this story as it unfolds.