Richland — The Department of Energy is asking for a halt to a Washington order requiring it to begin emptying waste from a double-shell tank with an interior leak by Sept. 1.
It filed an appeal with the State Pollution Control Hearing Board over the order issued in March by the State Department of Ecology.
DOE is prepared to begin pumping waste if conditions warrant. But its concerned that the risk of pumping waste outweighs the benefits since the waste remains contained within the walls of Tank AY-102, DOE said in a statement Friday.
Not only could starting to pump waste soon create unsafe nuclear conditions, but it diverts resources from work to retrieve waste from leak-prone single-shell tanks. At least one of those tanks is leaking waste into the ground, according to DOE.
The work to empty the double-shell tank would require millions of dollars not in DOEs budget, it said.
The tank is Hanfords oldest double-shell tank and has held radioactive waste for more than 40 years.
DOE also is concerned that emptying Tank AY-102 would reduce the remaining space available in Hanfords 27 other double-shell tanks.
Double-shell tanks are nearing capacity because they are being used to store waste emptied from older single-shell tanks until it can be treated for disposal.
The state has argued that DOE has not moved quickly enough to empty the tank once officials determined in October 2012 that waste was leaking. That increases the risk that waste could leak into the soil beneath the tank or that leaking waste could clog a ventilation system within the tank, according to the state.
State regulations require DOE to begin removing the waste as soon as possible.
That is what DOE is proposing to do, but the work must be done in a way that ensures safe handling of the nuclear material in the 1-million-gallon capacity tank, DOE said in the appeal.
DOE has the infrastructure in place to remove liquid waste from the tank, but it does not want to start pumping liquid waste until it also is ready to remove the sludge beneath the liquid. The tank has about 850,000 gallons of waste about 55 inches of sludge topped with about 235 inches of liquid.
The liquid is needed to cool the sludge, which generates heat as it radioactively decays, according to DOE. The 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, according to DOE.
Based on the concerns DOE identified and feedback from the Defense Nuclear Facilities Safety Board, DOE prefers to continue with a risk-based approach until issues are better understood, DOE said in a statement Friday.
DOE has proposed adding infrastructure to remove sludge, but not removing any waste sooner than March 2016. It continues to closely monitor Tank AY-102, it said.
The state proposal requires DOE not only to start pumping liquid waste from the tank by Sept. 1 but also to start removing sludge by Dec. 1, 2015. Complete removal of enough waste to determine the cause of the leak is required by Dec. 1, 2016.
The state has said it is ordering that liquid be pumped only to 96 inches above the sludge initially to maintain safety. But that would allow about 350,000 gallons of liquid waste to be removed from the tank.
It also has ordered DOE to provide a contingency plan for safely managing any worsening conditions such as an increase in the rate of leaking or blockage of ventilation.
But DOE is arguing in the appeal that the Department of Ecology has overstepped its authority.
The state order requires actions that conflict with the safe handling of nuclear materials, said the appeal. The federal government has the sole authority to regulate nuclear materials and the state has authority only over hazardous chemicals, both of which are contained in the tank.
DOE also argued that the state order has many ambiguous and unclear statements, preventing DOE from fully understanding it.
DOE sent a letter to the state April 1 asking it to clarify 17 points in its order and saying that the state had some information wrong. Among questions were whether deadlines some to take effect in 30 days were based on working or calendar days.
DOE also asked for more information on what it meant by immediately and what a contingency plan should cover.
We are confident that the order is unambiguous and clear as it stands, the state replied April 8.
As the appeal was filed, Kevin Smith, manager of the DOE Hanford Office of River Protection, asked the state to resolve the matter without going to the hearings board.
I fully believe our organizations can work through these matters in a collaborative manner that will save time, preserve or improve our working relationship, and efficiently manage precious resources that would be better used in other more comprehensive pending matters that will affect our long-term future, Smiths letter said.
DOE has previously said Tank AY-102 is leaking between its walls because of the high heat waste in the tank, the lack of corrosion-inhibiting chemicals in the sludge at the bottom of the tank and difficulties with its construction. -- Annette Cary: 582-1533; email@example.com; Twitter: @HanfordNews