The Department of Energy did not start emptying waste from a Hanford double-shell tank with an interior leak by Monday as ordered by the state of Washington.
However, DOE and the state have been in settlement discussions regarding Tank AY-102 since July, said John Price of the Washington State Department of Ecology at a Hanford Advisory Board meeting Thursday in Pasco.
"We think DOE is very motivated to work with us because we are past the Sept. 1 date," Price said. "We're also very motivated because we issued an order, so we are very hopeful we will reach some kind of an agreement."
The state, a Hanford regulator, issued an order in March setting the deadline for starting to empty waste in the tank. DOE was not moving quickly enough to empty the tank since officials determined in October 2012 that waste was leaking from the interior shell into the space between the shells, according to the state.
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Tank AY-102 is the oldest of Hanford's double-shell tanks, which are used to hold radioactive and hazardous chemical waste emptied from Hanford's older and leak-prone single-shell tanks until the waste can be treated for disposal. The waste is left from the past production of plutonium for the nation's weapons program.
DOE filed an appeal to the state's order in April with the State Pollution Control Hearing Board, asking that the state order be halted. The state objected, and DOE withdrew its appeal, Price said.
The inner shell of the tank appears to be leaking about 30 ounces of waste per week, said JD Dowell, deputy manager of the DOE Hanford Office of River Protection, at the advisory board meeting.
"I will not say it is static," he said. "We are seeing a small change, but we are not seeing a significantly dynamic evolving leak."
The waste is believed to be leaking from the inner shell and traveling through air channels in the structure the inner shell sits on above the outer shell. The air channels help provide cooling for the waste, but officials are not seeing temperature changes, Dowell said.
DOE had proposed earlier this year emptying no waste from Tank AY-102 sooner than March 2016. Pumping liquid waste out of the tank immediately was technically feasible, but presented a risk because the liquid helps cool the waste, DOE said.
DOE proposed waiting to remove any liquid waste until it also had equipment ready to pump the sludge beneath the liquid in the tank. The sludge generates heat as it radioactively decays, and heat can increase corrosion rates in the tank and contribute to generating potentially flammable hydrogen gas.
Any action to remove liquid waste also might affect the rate at which the inner shell leaks, DOE said.
However, the state argued that delaying the start of waste removal not only violated the law but also would put the environment at increased risk. It said enough liquid -- 96 inches -- could be left in the tank to help cool it until sludge removal also begins, which the state has ordered by Dec. 1, 2015.
This spring, the tank had about 55 inches of sludge topped with about 235 inches of liquid waste. There is no evidence that waste has leaked from the outer shell into the soil around the underground tank.
In another legal matter between DOE and the state, an agreement to continue dispute resolution on amending Hanford's court-enforced consent decree expires today. DOE earlier notified the state that it was at risk of missing most of the remaining deadlines in the consent decree.
The deadlines cover emptying some single-shell tanks and for constructing and starting operations of the vitrification plant to treat the waste.
The agreement that expires today was the second extension of dispute resolution and a third extension is a possibility. If the agreement is not extended, either party can seek court involvement.
-- Annette Cary: 509-582-1533; email@example.com; Twitter: @HanfordNews