For the first time, Hanford officials admit that radioactive waste has traveled deep under leaky storage tanks and may have reached the groundwater.
“According to new measurements, we’ve determined it’s coming from the tanks,” said Guy Schein, U.S. Department of Energy spokesman.
“We couldn’t say before whether it was coming from the tanks or from cribs and ponds next to the tank farm,” Schein said.
The wastes are dangerous discards from nearly 50 years of bomb-making.
The leaks don’t pose an immediate threat to workers or the public, officials said.
But the highly toxic tank wastes could reach the Columbia River within 25 to 250 years, according to a range of estimates.
The new findings add urgency to Hanford’s program to empty the old single-shell tanks of their highly radioactive liquid contents.
Radioactive Cobalt 60 has been found 100 to 125 feet in a borehole in BY Tank Farm far deeper than previously reported.
Also, radioactive Technetium 99 and chromium may have reached groundwater in the SX Tank Farm, the Energy Department said Friday.
Cobalt 60 emits beta and gamma rays and loses half its radioactivity in five years. Technetium 99 takes 210,000 years to lose half its strength. Chromium is a metal that can cause cancer and ulcers.
A Seattle environmental group complained the contamination was not disclosed last month at public hearings on a cleanup plan for Hanford’s waste tanks.
“This was a classic cover-up and attempt to mislead the public,” said Gerald Pollett of Heart of America Northwest.
That’s not true, Schein said.
Hanford managers didn’t know about the cobalt and technetium contamination until last week, he said.
“None of this information was available for any of the public meetings” last month, Schein said.
Scientists also discovered a cesium contamination problem in the SX tank farm earlier this year.
Cesium has a half-life of 30 years. It emits beta and gamma radiation and is hazardous to muscle tissue, bone and bone marrow.
An expert panel met in early June and recommended more testing to track contaminants.
Hanford officials plan to submit a plan to the Washington Department of Ecology next month for a formal study of groundwater contamination in the SX Tank farm.
Some 67 of Hanford’s 149 single shell tanks have leaked or are suspected leakers.
So far, 115 tanks have been pumped. Some 5.1 million gallons of drainable liquids remain.
“We’ve eliminated a potential problem when that’s done. The only thing left in the tanks will be salt cake and sludge,” Schein said.
Hanford officials’ candor on tank farm issues has been roundly criticized over the past decade.
Several reports have concluded Hanford officials often minimized or simply ignored information on tank hazards - including leaks to the ground.
In 1990, Hanford managers acknowledged that 800,000 gallons of cooling water could have leaked from one tank in the 1960s during a tank rupture - when 5,000 gallons had previously been reported.
The tank could have leaked more than 1 million gallons over a 10-year period, according to a 1991 General Accounting Office report.