The Department of Energy should look into alternatives for building new waste storage tanks at the Hanford nuclear reservation, the Government Accountability Office recommended in a report released Tuesday.
The report raised questions about how much DOE knows about the condition of its underground waste storage tanks. If another double-shell tank corrodes and needs to be emptied, DOE could be out of space to securely hold the waste, the report said.
“The tanks at Hanford — both single-shell and double-shell — are in deteriorating condition and the schedule for addressing the problem is slipping inexorably into the future,” said Sen. Ron Wyden, D-Ore., in a letter to Energy Secretary Ernest Moniz on Tuesday. Wyden requested the GAO review.
Wyden asked Moniz in the letter for a schedule and plan for DOE to implement all of the report’s recommendations within 90 days.
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DOE is emptying waste from 149 leak-prone single-shell tanks into 28 newer double-shell tanks. The waste is left from the World War II and Cold War production of plutonium for the nation’s nuclear weapons program.
However, Hanford’s oldest double-shell tank, AY-102, has developed a leak between its shells and will be emptied.
The GAO recommendations call for a more complete assessment than DOE has so far completed of the extent to which Hanford’s other double-shell tanks may be at risk of developing similar interior leaks.
The report also calls for an updated plan for emptying Hanford’s single-shell tanks. The most recent plan dates from 2011 and does not take into account changed conditions.
DOE now knows that both single- and double-shell tanks are in worse condition than known in 2011.
In addition, work at the Hanford vitrification plant, being built to treat the stored waste for disposal has fallen further behind schedule. Some construction has halted until technical issues at the plant can be resolved.
The updated schedule for emptying tanks should consider the impact of the delays at the vitrification plant, the risks of continuing to store waste in aging tanks and an analysis of available double-shell tanks, the report said.
“Agreeing to recommendations is one thing. Implementing them is another thing entirely,” Wyden said in a statement. “The DOE’s watch-and-wait strategy for these tanks leaking nuclear waste into the soil is completely unacceptable.”
At least one of Hanford’s single-shell tanks, Tank T-111, is leaking waste into the soil. The GAO report says the waste is leaking at a rate of 640 gallons annually, which is more than the initial DOE report of up to 300 gallons a year but less than a 2013 DOE estimate that had the leak at nearly 1,000 gallons a year.
A series of DOE assessments of the single-shell tanks in 2013 and 2014 concluded that water is leaking into at least 14 of the single-shell tanks, including Tank T-111. It can enter through the risers that allow access to the tanks and through the joints at the edge of their concrete-tops, among other ways.
The additional water in the tank not only increases the liquid in the tanks that can leak into the soil but it can make it difficult to assess whether tanks are leaking by looking for changes in the volume of the tank. The water is adding from less than 10 gallons to more than 2,000 gallons of waste to individual tanks annually.
DOE finished pumping as much liquid as possible from all single-shell tanks in 2005 to reduce the risk of leaking. But likely because of the water intrusion, five single-shell tanks again have more than 50,000 gallons of liquid, an amount that DOE considers pumpable, according to the GAO report.
DOE has not committed to pumping more of the liquid waste from the tank, as Wyden wants. Instead, it will test this spring whether using an exhauster in single-shell tanks would evaporate off some of the liquid.
DOE already is short on space to empty waste from single-shell tanks into double-shell tanks with waste from Tank AY-102 scheduled to be emptied into one of the other 27 double-shell tanks.
“Additional leaks cannot be ruled out,” given the decades longer that the double-shell tanks will have to hold waste until it is treated and growing concerns about the integrity of double-shell tanks, the GAO report said.
“Given the current condition of the tanks, it is unclear how long they can safely store the waste,” the report said.
DOE determined that construction flaws in Tank AY-102 and the type of waste in the tank likely caused the inner shell to corrode and leak. But earlier this year a panel of experts concluded that the corrosion was more likely caused by water collecting beneath the tank during construction and a six-year outage of the ventilation system.
DOE has looked at whether the other 27 tanks also had construction flaws and has found problems to a lesser extent in at least 12 more of them. However, DOE needs also to assess whether the factors that led to corrosion in Tank AY-102 also are present in the other double-shell tanks, the GAO report said.
DOE will know more about the cause of the leak in Tank AY-102 when it is emptied and that will provide information on maintaining the other double-shell tanks, DOE told the GAO.
But that will not happen until March 2017, “an unacceptably long time from now,” according to Wyden.
As the tanks age, there will be an increasing risk of tank failure, the report said. The single-shell tanks were built as temporary storage from the ’40s to the ’60s and all have been used far longer than the 25 years planned. Four of the newer double-shell tanks also already have held waste longer than planned when they were designed.
DOE is required by law to empty double-shell tanks with interior leaks, but GAO officials were told that Hanford would have nowhere to move the waste from another leaking double-shell tank.
DOE now has no plans to build new tanks and estimates it would take about eight years before new tanks were built, licensed and ready to hold waste, the GAO report said. DOE has estimated the price of eight new tanks at $800 million.
The state of Washington already has asked a federal court to require DOE to build new storage tanks.
Representatives of local governments near Hanford have argued that money should go toward the end goal of treating the waste for disposal rather than more storage capacity. Central Hanford already is contaminated with an estimated 1 million gallons of waste that spilled or leaked before current leaks were discovered.
DOE told the GAO that it has stepped up its program to monitor tanks for leaks and also is taking steps to optimize the space available in double-shell tanks to hold more waste emptied from the single-shell tanks.
It has made improvements to the 242-A Evaporator and this fall used the facility to reduce the volume of waste by 750,000 gallons. It has plans to reduce the amount of waste by 3 million gallons more over the next three years. It also is making a technical case for allowing the double-shell tanks to be filled to a higher level.
DOE now has 5.3 million gallons of space left in double-shell tanks, not including space from evaporation campaigns and other efforts.
But space that must be held for an emergency, planned transfers from single-shell tanks and the waste that will be emptied from double-shell Tank AY-102 bring the remaining capacity down to 200,000 gallons, the report said. That’s not enough space if another double-shell tank with a capacity of 1.1 million gallons needs to be emptied.