RICHLAND (AP) — 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.

Washington state Department of Ecology spokesman Randy Bradbury says officials detected no release of radiation Tuesday and no workers were injured.

Officials say no workers were inside the tunnel when it collapsed, causing soil on the surface above to sink 2 to 4 feet (half to 1.2 meters) over a 400 square foot (37 square meters).

Worker safety has long been a concern at Hanford, which is located about 200 miles (322 kilometers) southeast of Seattle.

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