Sludge levels in a buried single-shell tank at the Hanford site in Washington are dropping at a rate of 150 to 300 gallons per year, the Department of Energy acknowledged Friday.
The source of the drop within tank T-111 has not been confirmed, the DOE said in a release. Nearby monitoring wells have not detected an increase in radionuclides. Nonetheless, the agency is considering its response to the potential leak in the World War II-era tank containing 447,000 gallons of highly contaminated sludge.
Energy Secretary Steven Chu personally notified Washington Gov. Jay Inslee of the situation before the announcement, according to a statement from the governor's office.
"I am alarmed and deeply concerned by this news. This was a problem we thought was under control, years ago, when the liquids were pumped from the tanks and the sludge was stabilized. We can't just leave 149 single-shell tanks with high-level radioactive liquid and sludge siting in the ground, for decades after their design life," Inslee said. "Fortunately, there is no immediate public health risk. The newly discovered leak may not hit the groundwater for many years, and we have a groundwater treatment system in place that provides a last defense for the river. However, the fact that this tank is one of the farthest from the river is not an excuse for delay. It is a call to act now."
The tank in question is among 177 at the Hanford site adjacent to the Columbia River. Its pumpable liquids were removed in 1995, leaving thicker sludges behind. According to the governor's office, this is the first documented loss of fluids from a Hanford tank since the site completed interim stabilization in 2005.