Given the high cost to empty and treat Hanford's radioactive tank wastes, the government should consider leaving more waste in the underground tanks, according to a new Government Accountability Office report.
The report also challenges the Department of Energy to find ways to reduce costs for retrieval and final disposal of high-level radioactive wastes, saying they could be more costly than justified by the reduction in risk.
The estimated price tag to empty Hanford's underground tanks of radioactive waste and treat it are rapidly escalating and could be from $86 billion to more than $100 billion -- rather than the $77 billion that DOE estimates, according to the report. The study was prepared at the request of the House Appropriations Subcommittee on Energy and Water Development.
Cost escalation is the result of a range of issues, including the difficulties Hanford workers have had in emptying the leak-prone tanks of millions of gallons of waste, questions about how well vitrification plant technology will work and a decision not to send treated wastes to Yucca Mountain, Nev., for disposal, the report says.
DOE disagreed with the increased cost estimate. It pointed out that GAO's predictions of cost and schedule problems at the Rocky Flats, Colo., nuclear site had not materialized. It also argued DOE has shown it could successfully treat radioactive waste at several of its other nuclear sites.
But the report countered that DOE had not yet faced a tank waste challenge of the magnitude at Hanford, both in the volume of waste and the complex variety of chemical and radioactive elements that are mixed in the tanks.
Hanford has about 53 million gallons of high-level radioactive waste left from about 40 years of processing plutonium for the nation's nuclear weapons program. That waste are stored in underground tanks, including 142 leak-prone single-shell tanks and 28 newer double-shell tanks.
DOE is working to empty the single-shell tanks and transfer the waste to the limited space in the double-shell tanks until it can be treated at the vitrification plant to prepare it for permanent disposal.
Hanford workers have emptied tanks at the rate of about one a year since 2003, finding the work to be more difficult than expected.
The GAO report says Hanford will need to retrieve waste at the rate of five to seven tanks a year when the vitrification plant starts turning the waste into a stable glass form. If not, the plant will not be able to operate continuously and costs will rise.
DOE is legally required to empty 99 percent of the waste in the tanks or to empty each tank to the limits of technology before the tanks can be closed. The retrieved waste would be treated for disposal.
But the report says, "More than half the experts we spoke with said that the 99 percent figure has no scientific basis, and several recommended that DOE conduct a comprehensive risk assessment of residual tank waste."
As workers try to get the last waste out of each tank, the cost rises.
"DOE has estimated that the cost of retrieving the last 15 percent of the waste can equal or exceed the cost of removing the first 85 percent," the report says.
DOE originally estimated retrieving waste would average about $7.6 million per tank. But the report says costs for retrieving waste from the first seven tanks averaged about $34 million per tank.
If DOE does not find ways to reduce expenses, the costs in terms of effort, money and worker exposure to hazards "might be out of proportion with the risk reduction achieved," the report said.
The GAO also pointed out that as costs are rising for the work, the risks are declining. All but 2 percent of the radioactivity in the tanks comes from strontium 90 and cesium 137, which decay to half of their radioactivity in about 30 years.
In 100 years about 90 percent of the radioactivity in the tanks will have dissipated and within 300 years, 99.8 percent will disappear, the report says.
However, about 2 percent of the radioactivity in the tanks is from elements such as iodine-129, which needs more than 15 million years for half of its radioactivity to decay. The tanks also contain large volumes of hazardous chemical waste added during processing that will remain dangerous for thousands of years.
DOE faces other technical uncertainties, including whether key treatment technologies at the vitrification plant will work, the report says.
"Unless DOE successfully resolves these uncertainties, it could face problems, such as facility shutdowns, facility modifications and retrofitting, or significant cost increases and delays in completing Hanford's tank waste cleanup activities," according to the report.
DOE is researching ways to make sure the vitrification plant will operate as planned, including by operating large test facilities with materials that simulate radioactive waste. If DOE can solve technical issues to allow more high-level waste and less glass-forming materials to be used to produce the glassified logs at the vitrification plant, the number of waste canisters and costs would be reduced.
However, there still remains the question of what to do with the glassified waste now that the Obama administration has ruled out sending it to Yucca Mountain. That means Hanford will need capacity for at least temporary storage of the treated waste.
-- Annette Cary: 582-1533; acary@tricityherald.com; More Hanford news at hanfordnews.com.
