Workers at Eastern Washington’s Hanford Site are trying to track down the source of radioactive contamination at an underground waste storage tank, one week after an internal leak sparked concern about a different tank at the facility.
Both double-walled tanks were put into service 45 years ago to hold radioactive and chemical wastes from plutonium production for the U.S. nuclear weapons program. Each tank is 75 feet wide and can hold a million gallons of waste.
One of the tanks, AY-102, has been the subject of concern for years. That’s where an alarm went off on April 17, when liquid waste and sludge leaked through the tank’s inner wall and built up to a depth of 8 inches in the space between the inner and outer walls.
That leak was cleaned up, and nearly all of the waste that was in AY-102 has been transferred to other storage tanks. But now the U.S. Department of Energy says air filter samples from the space between the walls in the other tank, AY-101, registered higher than normal levels of radioactive contamination this month.
“While these readings were higher than normal, they were well below the alarm level,” the Energy Department’s Office of River Protection said in a statement.
So far, visual inspections and detection instruments have shown no evidence of a leak in the tank’s inner wall, but workers at the Energy Department and its contractor for the tank farms, Washington River Protection Solutions, are continuing to look. “DOE is conducting engineering analysis and assessments to determine potential causes of the readings,” the department said.