MONTPELIER -- Vermont Yankee officials revealed Friday that while cleaning up after a leak of radioactive tritium, they found another, more potent radioactive isotope in soil near where the leak occurred.
Strontium-90, a byproduct of nuclear fission that has been linked to cancer and leukemia, was confirmed at the Vernon nuclear plant in a report received by plant owners Monday.
Vermont Yankee spokesman Larry Smith revealed the discovery in an e-mail update about the tritium remediation late Friday. He said the substance hasn't been found in any groundwater and plant officials believe they've removed all the soil containing it. He said there was no threat to public safety or health.
"We believe we've removed it all," Smith said. "It's out of the ground, we've removed it. We're doing follow up soil samples."
Vermont Health Commissioner Dr. Wendy Davis didn't return a call seeking comment Friday night. A message left after hours on her cell phone wasn't immediately returned.
The discovery comes as the plant removes soil contaminated by radioactive tritium. That leak was first reported Jan. 7 and was reported fixed March 25.
The tritium leak occurred in two separate underground pipes inside a concrete tunnel that allowed tritium-containing water to overflow a floor drain and seep through an unsealed concrete wall joint. The drain, which would normally take the water to processing inside the plant, was clogged with
The source of the strontium-90 contamination was not known.
Raymond Shadis, technical consultant to the anti-nuclear group the New England Coalition on Nuclear Pollution, said it could have migrated from the reactor to the ground outside through airborne leaks, waterborne leaks, poor handling of low-level radioactive waste or through leaks in a condensate storage tank.
"The problem with all this is (plant owner) Entergy's almost knee-jerk attempt to bound it -- to say it's an isolated incident, it's in this one area, we're going to contain it and wrap it up and put it away," Shadis said. "None of that is credible to anyone who's ever done site remediation at a nuclear power plant."
Strontium-90 is similar to calcium in that, when ingested, it tends to deposit in bone and blood-forming tissue, according to the U.S. Environmental Protection Agency. Internal exposure is linked to bone cancer, cancer of the soft tissue and leukemia.
It has been discovered at other nuclear power plants found to leak tritium, including the Indian Point nuclear plant in Buchanan, N.Y.