I have been blogging lately about the railroad tunnel cave in at the Hanford Nuclear Reservation. The ceiling of an old railroad tunnel containing highly radioactive railway cars and contaminated waste spontaneously collapsed. The U.S. Department of Energy had been warned for decades that the intense radiation was weakening the structure of the tunnel and that a cave in was inevitable.
It turns out that Hanford is not the only national nuclear waste site that is having problems with underground nuclear waste storage. It has just been reported that there has been a cave in at the Idaho National Laboratory (INL) during excavation of nuclear waste.
The accident occurred in the nuclear landfill called the Subsurface Disposal Area (SDA) at the INL. The site contains radioactive waste from nuclear research at the INL during the 1950s. During the 1950s and 1960s, the site received nuclear waste from nuclear weapons research and development at the Rocky Flats nuclear weapons plant near Denver, Colorado. Spent nuclear fuel was also sent to the SDA from commercial power reactors for decades.
Eventually the State of Idaho sued the Federal government to stop the shipments of spent nuclear fuel and to clean up the SDA. The Federal government is bound by a legal agreement signed in 1995 to remove all transuranic waste from the INL. Transuranic wastes include plutonium, americium and other highly radioactive elements that lie above uranium in the periodic table and are man-made.
An excavator was digging inside a large building at the ninety seven acre SDA when the side of the pit collapsed. The entire two acre excavation site is enclosed in a soft-sided building designed to prevent any escape of any radioactive materials. At the time of the collapse, the depth of the excavated pit was about twenty one feet.
The operator of the excavator stayed inside his sealed cabin for an hour and a half while his crew made sure that it would be safe for him to climb out of the pit. The excavator cab has its own air supply and the rest of the crew working at the site have respirators to protect them from airborne radioactive particles.
Ed Simpson is with Fluor Idaho, the contractor hired to clean up the Subsurface Disposal Area. He reported that there was no radiation released into the environment and that no one was injured in the accident. He said “Our crews had been exhuming waste for about 30 minutes when a portion of the pit wall where the excavator was operating sloughed off and the excavator slid into the pit. We’re working on a path to remove the excavator from the edge of the pit and basically make some additional enhancements to protect the operators and the excavators from this point forward.”
Flour Idaho procedures call for excavators to never be closer to the side of the pit they are working on than two feet. The excavator that slid into the excavation was more than four feet from the edge of the pit before it collapsed so correct procedures were being followed. Fluor Idaho is studying the cause of the accident and may revise their procedures to stay further from the edge of a pit being excavated.
