The level of waste between the shells of Hanford’s oldest double-shell tank held steady Tuesday as preparations were made to start pumping it back into the inner shell.
The Department of Energy said Tuesday it hoped to start pumping waste from the space between the shells soon and also to resume retrieving waste from the tank.
On Sunday at least 3,000 gallons of waste leaked into the space between the shells as work was underway to empty the tank, which previously had leaked about 70 gallons of waste from its inner shell over several years.
“Monitoring and inspections show no visual or chemical indications that waste has leaked into the environment from the tank,” DOE said in statement Tuesday.
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Sen. Ron Wyden, D-Oregon, called on Energy Secretary Ernest Moniz on Tuesday to immediately convene an independent panel to look at double-shell tank conditions.
“I do not believe that these determinations can be left to the department and its site contractors,” Wyden wrote in a letter to Moniz.
Previous analyses of this tank and other double-shell tanks have raised numerous design and construction concerns.
Sen. Ron Wyden
“Citizens in the Northwest need to be assured that there is no immediate danger from the conditions in Tank AY-102 and from any continuation of retrieval operations,” he said.
Wyden has criticized DOE’s double-shell tank program in the past and wants to reassess the risk of failures for Hanford’s 27 other double-shell tanks.
“Previous analyses of this tank and other double-shell tanks have raised numerous design and construction concerns and the exact cause of the original AY-102 leaks has never been determined,” he wrote in the letter.
He pointed out that the double-shell tanks, built between 1969 and 1986, were supposed to be much safer than Hanford’s 149 leak-prone single-shell tanks. The oldest of the single-shell tanks were built during World War II.
After the leak from the inner shell of Tank AY-102 was confirmed, a DOE review of the tank’s construction concluded that “construction difficulties and trial-and-error repairs left the primary tank bottom with residual stresses that could not be foreseen by the designers. These provided a fertile incubator for sustained corrosion to take place.”
The combination of the waste stored in the tank also contributed, generating high levels of heat that made corrosion more likely.
The Washington State Department of Ecology said there is no indication of a risk to the public at this time.
The state of Washington is requiring DOE to empty enough waste from the tank to learn more about the leak.
DOE also had a study conducted of the construction records of the other tanks, concluding that construction issues were not as serious as at Tank AY-102. But weld and other construction issues in some of the tanks leave some uncertainty about their long-term integrity.
Wyden said in 2014 that six tanks in addition to Tank AY-102 have construction flaws that could increase the risk of leaks and that 13 more have construction problems that will shorten their lifespan.
DOE confirmed Tuesday that it had received Wyden’s letter and was reviewing it.
Hanford has had a panel of independent experts focused on tank integrity — the Tank Integrity Expert Panel — since 2004. It includes experts from national laboratories, industry and academia who look at data collected by ultrasonic testing to detect thinning of metal, videotaped footage shot inside the tanks and waste sampling results.
In addition, a separate panel was assembled to focus just on Tank AY-102.
The Washington State Department of Ecology released a statement Monday saying there was no indication of a leak from Tank AY-102 to the environment or a risk to the public at this time.