A new draft study shows importing radioactive waste for disposal at Hanford would significantly increase pollution in ground water beneath the nuclear reservation, according to the Washington State Department of Ecology.
The state long has opposed the Department of Energy sending radioactive waste to Hanford for disposal. But the draft Hanford Tank Closure and Waste Management Environmental Impact Statement that's open for public comment puts some numbers to that assertion.
"We're cleaning up Hanford of some of the constituents we care most about and then recontaminating it with off-site waste to above the acceptable level from a cancer risk standpoint or a safe drinking water standpoint," said Suzanne Dahl, tank waste treatment section manager for the Department of Ecology.
Under some scenarios that appear likely, the amount of certain long-lived radioactive isotopes that would be imported and buried at Hanford would account for as much as 90 percent of the releases of that isotope to the environment, according to the state. Some of the worst contamination could occur 1,000 or more years from now.
The draft study prepared by DOE looks at sending 107,000 cubic yards of radioactive waste, some mixed with hazardous chemicals, to Hanford for disposal. However, DOE officials agreed as part of a settlement agreement of a state lawsuit not to import that waste until the Hanford vitrification plant is fully operational to treat the waste. That's scheduled for 2022.
But importing waste could then again become an option.
In the summary of the 6,000-page draft study, DOE writes that "receipt of off-site waste streams that contain specific amounts of certain isotopes, specifically iodine 129 and technetium 99, could have an adverse impact on the environment."
It suggests two alternatives: Robust treatment of the waste such as turning it into glass before burying it at Hanford, or limiting or restricting disposal of waste with those isotopes.
Iodine 129 and technetium 99 are of concern because both spread readily in ground water rather than clinging to soil and also are long-lived. Isotopes of cesium and strontium are more prevalent in the waste proposed to come to Hanford, but half of the radioactivity of those isotopes decays in about 30 years.
In contrast, 212,000 years are required for half of the radioactivity of technetium 99 to decay and 15.7 million years are required for half of the radioactivity of iodine 129 to decay.
Under current proposals, imported waste would not be processed at Hanford. It could go straight to a lined landfill in central Hanford, such as the Integrated Disposal Facility which also is planned to hold some Hanford tank waste.
The 53 million gallons of waste now held in Hanford's underground tanks will be separated into low-activity radioactive waste and high-level radioactive waste to be turned into a stable glass form at the vitrification plant for long-term disposal.
National law requires high-level waste to be disposed of at a national repository deep underground, such as the one previously proposed for Yucca Mountain, Nev., but glassified low-activity waste would be buried in a central Hanford landfill.
Tank waste from Hanford would have 48.2 curies of iodine that would be immobilized in glass primarily from the low-activity waste. The proposed imported waste would add an additional 15 curies of iodine, which under current plans would not be immobilized in glass.
About 1,800 curies of technetium 99 would be expected from off-site sources, compared with 29,700 curies of technetium from Hanford tanks that would be immobilized primarily in the low-activity waste glass.
Radioactive iodine releases from the Integrated Disposal Facility would peak 1,000 or 2,000 years in the future at 18 picocuries per liter. The drinking water standard is 1 picocurie per liter.
"When you look at the ground water releases from the Integrated Disposal Facility, it goes up significantly when you have off-site waste," Dahl said.
About 90 percent of the radioactive iodine that would be released from the landfill would come from waste imported to Hanford, and about 75 percent of the radioactive technetium released from the landfill would come from waste imported to Hanford, according to the state.
That's assuming of all the low-activity tank waste is treated at the vitrification plant, rather than through alternate methods the state does not support, such as bulk vitrification.
"It is so significant it is hard to imagine it would be acceptable to be disposed of at Hanford," Dahl said. "Certainly it would have to be significantly mitigated, and they may not be able to mitigate that far."
Washington voters in 2004 approved Initiative 297, which would have blocked sending more radioactive waste to Hanford until waste already there had been cleaned up. It was found unconstitutional, however, and never became law.
-- Annette Cary: 582-1533; email@example.com; More Hanford news at hanfordnews.com.