A tunnel partly collapsed on 9 May at a US plutonium-handling facility at the Hanford Nuclear Reservation in Washington state, Reuters and other press organisations reported.
US Energy Secretary Rick Perry has been briefed about the incident. Workers were evacuated or took cover and turned off ventilation systems after damage was discovered in the wall of a transport tunnel about 270 km east of Seattle, officials with the Department of Energy's Hanford Joint Information Centre said.
Centre spokesman Destry Henderson said in a video posted on Facebook that the damage was more serious than initially reported, and the take-cover order was expanded to cover the entire facility after response crews found a 400-square-foot section of the decommissioned rail tunnel had collapsed. "The roof had caved in, about a 20-foot section of that tunnel, which is about a hundred feet long," he said.
However, there was no indication that workers or the public had been exposed to radiation, federal officials said "This is purely precautionary. No employees were hurt and there is no indication of a spread of radiological contamination,” Henderson said of the shelter order. Nevertheless, Tom Carpenter, the executive director watchdog organisation Hanford Challenge who spoke with workers at the site after the incident, said the tunnel collapse was worrisome and said evacuation was the correct call. He described Hanford as the most contaminated US site and said he expects total cleanup costs could reach $300-500bn.
Although Hanford is undergoing decommissioning, it has been a subject of controversy and conflict between state and local authorities, including a lawsuit over worker safety and ongoing cleanup delays. Work has been under way since the 1980s and costs more than $2.7bn a year. No used nuclear fuel is stored in the tunnel, Energy Department officials said. However, it contains rail cars full of radioactive waste. The cause of the collapse was not immediately known.
The accident occurred at the Plutonium Uranium Extraction (Purex) Facility located in the middle of the 1,300km2 site. Hanford was originally established to produce plutonium for nuclear weapons and is the USA’s largest depository of radioactive defence waste, including about 56 million gallons of waste, mostly in 177 underground tanks.
Washington Attorney General Bob Ferguson filed a lawsuit last autumn against the Energy Department and its contractor, Washington River Protection Solutions, alleging that vapours 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 vapours escaping from the tanks and that those breathing the vapours 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 vapours.