Staff Reports
WC Monitor
3/07/2014
The state of Hanford’s aging double-shell tanks, which are intended to store waste for the foreseeable future until it can be processed for disposition, came under new scrutiny this week, after the Department of Energy announced that more waste has been found to be leaking between the shells of the site’s oldest double-shell tank and the release of construction reviews performed on other tanks. Hanford tank farms contractor Washington River Protection Solutions notified DOE this week that waste appears to have been found in a third location in the annulus of Tank AY-102, according to JD Dowell, deputy manager of the DOE Office of River Protection. DOE confirmed in October 2012 that Tank AY-102 had waste in two places between its shells. “We just further believe this reinforces the need to pump this tank. We are really concerned,” said Jane Hedges, the director of the Washington State Department of Ecology’s Nuclear Waste Program. The state had criticized DOE in January for its plan to monitor the waste but take no action unless conditions worsened. The state asked for a plan to pump waste from the tank, which DOE already was scheduled to deliver at the end of this week.
WRPS workers spotted the new waste during a bi-weekly inspection of the largest known pool of dried waste in the tank’s annulus. A video camera lowered down a riser showed a shadow in a place previously thought to be bare. When a video camera was lowered down the riser closest to that spot, the new dried waste was found. The area had appeared to be clear in September 2012 when video was shot using the same riser, according to DOE. The newest pool of dried waste is estimated to cover an area about 7 feet by 21 inches and is less than an inch deep. It’s about 31 feet from the largest pool of dried waste, which is 25 feet long and about the same width and depth. The other waste site has a footprint similar in size to the newest one.
DOE has directed WRPS to do another complete inspection of the tank’s annulus, which was last done in September 2012. The inspection is expected to take several months as video cameras are sent down multiple risers in a radioactive environment. DOE can only say now that “there is a change of conditions” in the tank annulus. It does not know if there are multiple leaks from the inner shell or, as some Hanford officials believe is more probable, one leak coming into the annulus in different places. The inner shell sits on a ceramic refractory between the bottom of the inner and outer shells. The refractory has ventilation slots for cooling air and also pathways that allow waste to escape to the base of the circular annulus. No waste is believed to have escaped into the soil beneath the tank.
Reviews Show Other Tanks Had Construction Issues
Meanwhile, Sen. Ron Wyden (D-Ore.) late last week released a set of reports he said raise new concerns over the ability of Hanford’s other double-shell tanks to store waste for the long-term. The reports outline the results of construction reviews performed on some of Hanford’s other double-shell tanks, of which there are a total of 28 at the site. The reviews, which use historical documents to reconstruct how the tanks were built, call for enhanced inspection of some of the 28 tanks. DOE will be doing more frequent visual inspections of all 28 tanks in response to the findings of the construction reviews, said Tom Fletcher, DOE assistant manager of the Hanford tank farms. The review of the newest tank farm, built in the 1980s, still is in progress.
The reviews finished to date conclude that while there were continuing construction difficulties, none of the tanks had as troubled a construction history as Tank AY-102. Wyden sent a letter to Energy Secretary Ernest Moniz late last week calling for DOE to provide a plan within 45 days to respond to what he believes are increased safety and operational risks associated with construction flaws. He wants the plan to include an assessment of long-term options, such as constructing more waste storage tanks. However, Rep. Doc Hastings (R-Wash.) said there is no new threat to the environment and that new storage tanks are not a panacea for Hanford waste issues. It’s important to keep Tank AY-102 in perspective with other Hanford projects, including building the Waste Treatment Plant, emptying single-shell tanks and cleaning up contaminated groundwater, he said.
DOE earlier concluded that the interior leak in Tank AY-102 was the result of both construction difficulties and also the combination of waste stored in the tank. The waste at the bottom of Tank AY-102 did not have a corrosion inhibiting chemical added to it. In addition, large amounts of waste that generated high levels of heat were added to the tank, which also made corrosion of the tank’s metal more likely. However, none of the other double-shell tanks have that same combination of high heat waste and waste without a corrosion inhibitor, Fletcher said. DOE began video inspections of the six double-shell tanks it believed to be at the highest risk of a leak after it became clear in 2012 that Tank AY-102 had an interior leak. No leaks were found in those tanks and Hanford workers are continuing visual inspections of the remainder of the tanks. Inspections had been done every five to seven years, but because of the construction review reports DOE will have the inspections increased to every three years, Fletcher said.
Various Issues Seen at Different Tank Farms
Tank AY-102, which was built in 1969, had 36 percent of its welds rejected after an inspection and some welds were redone as many as four times before they passed a radiography examination. When the AN Tank Farm was built, the weld rejection rate decreased. However, a weld rejection rate of 9 percent to 20 percent leaves cause for concern, the construction review said. Weld and other construction issues at the farm “leave room for uncertainty of long-term tank integrity,” according to the review, but the overall condition of the farm following construction was judged to be better than that of the earliest double-shell tank.
Other construction difficulties were outlined for different tank farms. For instance, some tanks in the SY Tank Farm had bulging in both of their shells, and that was addressed by adding grout underneath the bulges to support the inner shells. However, construction practices improved with thicker steel used in tanks after the first one was built. At the SY Tank Farm, the thickness of the bottom of the inner shell was increased from three-eighths to one-half inch and the steel in the bottom of the outer shell was increased from one-fourth to three-eighths-inch thick. “All tanks had some levels of construction challenges, but all were accepted or repaired and put into service,” Fletcher said. The number of rejected welds is an indicator of construction difficulties rather than the quality of the completed tank, since the problem welds were fixed, he said.
Senator Accuses DOE of ‘Stonewalling’
But Wyden’s take on the reviews is that at least six tanks holding 5 million gallons of waste have construction flaws similar to those at Tank AY-102. An additional 13 double shell tanks, holding 12 million gallons of waste, also may be compromised, he said. DOE led the people of the Pacific Northwest to believe that construction difficulties were a problem isolated to Tank AY-102, he said. “Now we know that is not necessarily the case,” he said. “This kind of stonewalling is absolutely unacceptable.” The information in the reviews completed as long as seven months ago could have been helpful to Washington Gov. Jay Inslee and Oregon Gov. John Kitzhaber, both of whom have called for new storage tanks to be built, Wyden said. Congress also should have been informed. “To make good policy judgments you have got to have good information,” he said. Wyden said he is not joining the call for new tanks to be built, but believes all information should be available to make that decision.
The Washington State Department of Ecology is studying the construction reviews, which it had not seen before, and at first glance it does not appear they change the state’s understanding of tank issues, said Jaime Smith, spokeswoman for Inslee. But it is “deeply troubling” the reports were not received, she said. DOE spokesman Erik Olds said there was no intent to withhold information. “The evaluation of Hanford’s double-shell tanks—including the historical reviews, video inspections, and extent of condition evaluations—is an ongoing process,” he said. The reviews are stamped “Approved for Public Release.”
DOE also should have identified the tank vulnerabilities in a framework document released in September that discussed possible solutions to getting the waste treated for disposal, Wyden said. Not doing so was “indefensible,” he said. His worries are heightened by DOE’s failure to release any firm schedule for starting or operating the Waste Treatment Plant to treat the waste and remove waste from Hanford tanks, he said. “Given the information now available concerning the state of the Hanford tanks, it is essential that DOE quickly come forward and present the region with a genuine plan for dealing with these growing risks,” Wyden said in his letter to Moniz. “It is time for the department to stop hiding the ball and pretending that the situation at Hanford is being effectively managed.” Hastings said it is no secret that Hanford tanks were never designed to last forever. “It is also no secret that it is critical for the federal government to be aggressive when it comes to work at the Waste Treatment Plant and the tank farms,” he said.
