Ground was broken at Hanford in 2002 for a $17 billion vitrification plant - one of the federal government's most expensive construction projects - to separate much of the waste into high-level and low-level radioactive material.
In the past, rail cars full of radioactive waste were driven into the tunnels and then buried there, he said.
It might seem like this sort of thing would be noticed immediately, the worker said, but the tunnel may have actually collapsed days or weeks ago, and since there was no radiation release, it was only noticed during a regular site walk-around.
Officials in Hanford said in a statement, "There are concerns about subsidence in the soil covering railroad tunnels near a former chemical processing facility".
As part of a huge, ongoing cleanup, rail cars full of radioactive waste were driven into tunnels and buried, Bradbury said.
Hundreds of workers at a nuclear site in the U.S. state of Washington were ordered to take cover today after a storage tunnel filled with contaminated material partially collapsed, but there was no indication of a radioactive leak.
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.
The Hanford site was built during World War II and made plutonium for most of the US nuclear arsenal, including the bomb dropped on Nagasaki, Japan, at the end of the war. The U.S. Department of Energy said the collapse covered about 400 square feet (37.1 square meters) instead of the 16 square feet (1.4 square meters) first reported. We do know that access to the area where the alert was generated, 200 East Area, has been "restricted" and workers in potentially affected areas have been told to stay indoors. The source also said that crews doing road work nearby may have created enough vibration to cause the collapse, and that Vit Plant employees were in cover mode as well.
Hanford for decades made plutonium for the nation's nuclear weapons arsenal.
The sprawling Hanford site is about half the size of Rhode Island.