SPOKANE, Wash. (AP) — Fluctuations inside a huge tank of radioactive waste raised concerns on the Hanford Nuclear Reservation in Washington state over the weekend, and workers prepared Monday to pump out the area of the leak.
A federal contractor said the amount of nuclear waste that has been leaking between the two walls of the underground tank for several years grew dramatically this weekend.
None of the waste appears to have escaped from Tank AY 102 into the environment, the contractor, Washington River Protection Solutions, said.
But workers were trying Monday to determine why the waste that leaked between the tank walls rose by about 8 inches on Sunday and then dropped by half an inch.
Hanford is located near Richland, Washington, and for decades made plutonium for nuclear weapons, including the atomic bomb dropped on Nagasaki, Japan. The site contains a huge volume of radioactive waste that will cost billions of dollars and take decades to clean.
"We're continuing our checks of the tank to determine whether any material might be escaping from the tank itself," said Jerry Holloway of Washington River Protection Solutions, which manages the underground tanks for the U.S. Department of Energy.
Workers are making preparations to pump all of the waste from between the two walls of the tank back inside the tank, Holloway said.
"We see no indication of any release of material to the environment," Holloway said Monday.
The most dangerous nuclear wastes at Hanford are stored in 28 giant double-walled tanks similar to AY 102. There are also 149 older single-walled tanks that contain wastes.
Tank AY 102 is Hanford's oldest double-shell tank and since March was being emptied of its 750,000 gallons of radioactive waste because of the leak between the two walls, which is called the annulus. Less than 100 gallons of waste was estimated to have leaked into the annulus in recent years, drying in three separate patches.
But Hanford officials said that on Sunday an alarm in the annulus sounded, after the waste level rose to more than 8 inches deep. Several hours later the waste level in the annulus dropped by about half an inch.
Hanford workers found no waste outside the tank in the leak detection pit in an initial check Sunday, Holloway said.
Work to pump out the contents of the tank itself stopped when the increased leak into the annulus was detected.
Holloway said pumping equipment had already been installed in the annulus, which is about 2-feet wide, in case the levels of waste there increased over time.
Holloway said officials had expected that the leak into the annulus might be impacted by the pumping of the main tank space.