The Hanford nuclear reservation is investigating the possibility that one of its double-shell tanks, thought to be a safe nuclear waste storage facility, might be leaking radioactive waste.
A highly radioactive segment of gunk — measuring two-feet by three-feet by a few-inches — was found between the inner and outer hulls of Tank AY-102 in central Hanford, said Cheryl Whalen, a Hanford cleanup section manager for the Washington Department of Ecology.
The tank is one of 177 underground tanks that Hanford currently uses to store its 53 million gallons of radioactive fluids, sludges and gunk. One hundred forty nine of these are single-shell tanks, at least 67 of which are already suspected of leaking at least 1 million gallons of nuclear waste into the ground since the 1990s. Waste that is likely seeping slowly toward the Columbia River.
Still, this is the first time that highly radioactive material has been found between the two hulls of a double-shell tank, which have a minimum design life of 20 years.
"This changes everything. It is alarming that there is now solid evidence that a Hanford double-shell has leaked," said Tom Carpenter, director of the watchdog organization Hanford Challenge in a press release. "These tanks were supposed to last another 40 years, but that thinking has been superseded by this new reality."
To neutralize the threat of radioactive waste seeping into the water table, Hanford has been pumping it from the single-shell tanks to the younger and more secure 40-year-old double-shell tanks. From there, the waste will eventually be glassified in a neighboring complex, which is currently still under construction.
Though Whalen said small amounts of radioactive liquid have been found before between the hulls of double-shell tanks, none of those discoveries were remotely as radioactive as the amount detected in early August. She speculates that the recently-discovered lump may not be entirely made up of radioactive material: Many other double-shell tanks have similarly-shaped non-radioactive globs between their hulls, left over from the tanks' construction. Whalen thinks that the recently-discovered lump may be one of those, coated with dripping radioactive fluids.
So far, none of the double-shell fluids have penetrated the outer hull to reach the ground, she said.
While a leak in the inner hull is suspected, the DOE has not yet confirmed that it has actually occurred. The agency will need to collect and analyze more samples from the highly-radioactive gunk in order to be sure.
Under Hanford's long-range plan, all of its nuclear waste would be transferred to the double-shell tanks until it can be turned into glass by a yet-to-be-finished glassification plant. The plant is slated to begin operation in 2019, and the entire glassification process would be finished by 2048. Recently though, doubts have emerged about the feasibility of a 2019 start date.
"This new evidence gives urgency to the suggestion that the [Federal Department of Energy] build more tanks. We always knew the double-shell tanks would leak. We just did not know when. We have the first. How many will be leakers in another 40 years? The only good news here is that waste from this tank leak was not in liquid form, and is apparently not yet affecting the environment," Carpenter said.
Carpenter criticized the DOE for not making a public announcement about the roughly two-week-old discovery. "The era of secrecy and hiding problems is supposed to be over, but old habits die hard," he said.DOE's contractors first spotted the material on a routine video check in early August. They told DOE on Aug. 7, and the feds in turn told the state ecology department on Aug. 8, said DOE spokeswoman Laurie Gamache. "We notified the regulators right away," she said.
DOE plans to finish its follow-up studies by Sept. 30 to determine if extra radioactivity came from inside the 1-million-gallon tank, she said.