The Vermont Health Department says for the first time it has found the radioactive isotope Strontium-90 in ground water at the Vermont Yankee nuclear plant in Vernon.
The levels found were below the Environmental Protection Agency's safe drinking water threshold and the water in the test wells is not used for drinking.
While the health department says there is no immediate risk to health, Commissioner Harry Chen says the discovery shows the need for the state to closely monitor the site now and in the future.
"This is more or less not surprising for a nuclear plant that's operated for 42 years, not surprising given the fact that there have been leaks and Strontium found in the soil,” he said. "I believe that (ongoing monitoring) is necessary and I think these results merely underscore that. I certainly would advocate for that with the state and the Legislature."
The water samples that turned up positive for Strontium-90 were collected in August and sent to the state's contract laboratory. In November, the lab reported to the state that four of the seven samples had Strontium-90 levels above the lower limit of detection. After consulting with the Nuclear Regulatory Commission, the health department had portions of the same samples sent to the Oak Ridge National Laboratory for additional, independent analysis.
On Jan. 25, Oak Ridge and the NRC verified the findings of the state's contract lab. The highest concentration of Strontium-90 from either lab was 3.5 picocuries per liter. The EPA's safe drinking water threshold is eight picocuries per liter.
Entergy Vermont Yankee spokesman Martin Cohn said the Strontium-90 levels were well below limits set by the plant's NRC license. He said Entergy agrees with the state that the contamination does not pose a public health risk.
'We will continue to monitor the groundwater as part of our licensure and as part of decommissioning," Cohn said.
Although the specific source of the Strontium-90 is unclear, the health department says it is likely due to past leaks and fallout at the plant.
Vermont Yankee shut down at the end of December and is now beginning the decades-long decommissioning process.