The U.S. Department of Energy said last week that a second tunnel filled with radioactive waste is at high risk of collapsing at the Hanford site. Hanford is located in south-central Washington state and for decades made plutonium for nuclear weapons.
DOE said it completed an evaluation of Tunnels 1 and 2 associated with the Plutonium Extraction Plant (PUREX) at the old nuclear weapons production site, prompted by the May 9 collapse of Tunnel 1. The engineering report concludes that the PUREX tunnels do not meet current structural codes and standards.
The May 9 partial tunnel collapse was in part due to heavy rainfall several days earlier, as well as the environmental decay of the aging wood timber structural support beams in the tunnel.
On May 31, DOE said that Tunnel 1 will be filled with an engineered grout to stabilize the tunnel and the area will be covered with tarp.
Tunnel 2, built in 1964 of metal and concrete, contains 28 rail cars filled with nuclear waste along with giant storage vessels and other large equipment from plutonium production.
The report said Tunnel 2 may not be able to bear the weight of eight feet of soil on top of it and presents a high potential for localized collapse there is a high potential for the 53-year-old structure to collapse.
DOE and its contractor, CH2M HILL Plateau Remediation Co., have been ordered to submit a plan detailing hat corrective actions can be taken to prevent a Tunnel 2 collapse. That plan is due August 1.
Tunnel 2 was sealed in 1996 and has not been entered since, said Doug Shoop, Hanford manager for the Energy Department .
Hanford was built by the Manhattan Project during World War II and made the plutonium for the atomic bomb dropped on Nagasaki, Japan , at the end of the war, then went on to make about 60 percent of the nation's plutonium during the Cold War.
The site now contains the nation's greatest volume of radioactive defense wastes. Cleanup of the site is expected to last until 2060 and cost an additional $100 billion .
For more images of the PUREX tunnels, click here: