A few hundred gallons of highly radioactive wastes have leaked anew from an underground single-shell tank at Hanford.
That's a mere drop compared to the 1 million gallons that have leaked in the past 30 years.
In terms of danger, this leak is negligible. But it's a "canary in the coal mine" clue that a new environmental problem may be popping up at Hanford — rainwater seeping into old single-shell waste tanks, getting contaminated, and then leaking back into the soil.
This is the first new leak from a single-shell tank since 1995. State officals are worried that other new, yet-undiscovered leaks could be in other single-shell tanks. The big mystery is that almost all the fluids were pumped out of this tank, also in 1995.
"Washingotn state has zero tolerance on radioactive leaks," said Gov. Jay Inslee on Friday afternoon. He plans to meet soon with U.S .Secretary of Energy Steven Chu to discuss fix-it measures.
A U.S. Department of Energy press release said, "The Department will continue to work closely with the state of Washington, Congress and other key stakeholders" on this matter.
Since 1989, the state has legally clashed with DOE several times about the feds sticking to legal cleanup deadlines. Inslee hopes to avoid a lawsuit over the new leak situation. The state has a huge complicated contract — the Tri-Party Agreement — in which it and the U.S. Environment Protection Agency can legally enforce Hanford's cleanup.
The central Hanford reservation has 149 single-shell tanks and 28 newer double-shell tanks holding 53 million gallons of highly radioactive fluids, sludges, gunk and crusts. These "tank farms" are seven to 14 miles from the Columbia River. Sxity-seven of the single-shell tanks have been designated leakers or suspected leakers for decades. Hanford's tanks have design lives of roughly 20 years.
Hanford has pumped almost all the liquids from the single-shell tanks into the double-shell shells, finishing that task in 2005. The single-shell tanks still hold sludge, gunk and crusts, plus tiny pockets of fluids.
Tests were being conducted on several single-shell tanks to see whether rainwater was leaking into them through possible cracks, said Cheryl Whalen, cleanup section manager at the Washington Department of Ecology's Hanford office. Those tests showed a dip in fluid levels in Tank T-111, which is in the northwest corner of central Hanford's tank farms. Engineers extrapolated that drop into a leak of 150 gallons to 300 gallons annually for an undetermined numberr of years.
All 177 stainless steel tanks, ranging from 500,000 gallons to 1.2 million gallons in size, are buried beneath 10 to 20 feet of soil, All the testing and pumping are conducted through narrow pipes between the tanks' interiors and the ground's surface. The tanks are roughly 100 feet to 200 feet above the aquifer.
Past single-shell tank leaks have already hit the aquifer and are oozing at various speeds toward the Columbia River. Besides the 1 million gallons of highly radioactive wastes, Hanford has also put 440 billion gallons of slightly contaminated liquids into the ground with the plumes reaching the Columbia River decades ago. Roughly 180 square miles of Hanford's aquifer is contaminated, with about half of that being unsafe to drink. So far, the Columbia River's huge volume has diluted the contaminants. Drinking water has shown up as safe in Richland immediately downstream.
Pump-and-treat facilities and underground chemical barriers are scattered at strategic locations along the underground plume. A new pump-and-treat station was installed near Tank T-111 about one-and-a-half years ago, Whalen said.
The 530,000-gallon Tank T-111 -- one of the smallest tanks -- was built during World War II to received wastes from the world's first industrials-size nuclear reactor and its accompanying chemical plants at Hanford, which created plutonium for the Trinity and Nagasaki atomic bombs. Even though almost all the fluids have been pumped out, the presence of liquids is a clue that rainwater might be seeping into this tank and possibly others. Tank T-111 still contains 447,000 gallons of sludge and crusts.
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