FILE--In this July 9, 2014, file photo, a sign warns of radioactivity near a wind direction flag indicator at the "C" tank farm on the Hanford Nuclear Reservation near Richland, Wash. An emergency has been declared Tuesday, May 9, 2017, at the Hanford Nuclear Reservation after a portion of a tunnel that contained rail cars full of nuclear waste collapsed. Randy Bradbury, a spokesman for the Washington state Department of Ecology, said officials detected no release of radiation and no workers were injured.  (AP Photo/Ted S. Warren, file)
FILE--In this July 9, 2014, file photo, a sign warns of radioactivity near a wind direction flag indicator at the "C" tank farm on the Hanford Nuclear Reservation near Richland, Wash. An emergency has been declared Tuesday, May 9, 2017, at the Hanford Nuclear Reservation after a portion of a tunnel that contained rail cars full of nuclear waste collapsed. Randy Bradbury, a spokesman for the Washington state Department of Ecology, said officials detected no release of radiation and no workers were injured. (AP Photo/Ted S. Warren, file) Credit: Ted S. Warren

RICHLAND, Wash. — The collapse of an underground tunnel containing radioactive waste that forced workers at the Hanford Nuclear Reservation to shelter in place is the latest incident to raise safety concerns at the sprawling site that made plutonium for nuclear bombs for decades after World War II.

Officials detected no release of radiation Tuesday and no workers were injured, said Randy Bradbury, a spokesman for the Washington Department of Ecology.

No workers were inside the tunnel when it collapsed, causing soil on the surface above to sink 2 to 4 feet over a 400 square foot area.

The tunnels are hundreds of feet long, with about 8 feet of soil covering them, the U.S. Department of Energy said.

The anti-nuclear group Beyond Nuclear said the incident helped show “radioactive waste management is out of control.”

Democratic U.S. Sen. Maria Cantwell of Washington said worker safety must be the priority.

“My thoughts are with the first responders who are working to assess the situation on the ground,” she said.

Worker safety has long been a concern at Hanford, which is located about 200 miles southeast of Seattle.

Washington Attorney General Bob Ferguson filed a lawsuit last fall against the Energy Department and its contractor, Washington River Protection Solutions, contending vapors released from underground nuclear waste tanks posed a serious risk to workers.

Ferguson said that since the early 1980s, hundreds of workers have been exposed to vapors escaping from the tanks and that those breathing the vapors developed nosebleeds, chest and lung pain, headaches, coughing, sore throats, irritated eyes and difficulty breathing.

Lawyers for the Energy Department have said no evidence has been provided showing workers have been harmed by vapors.