BRATTLEBORO -- According to the Vermont Department of Health, a water sample taken from the Connecticut River just offshore from Vermont Yankee nuclear power plant in Vernon tested positive for tritium.
The sample, which was taken about six feet from the shore on Nov. 3, had a level of 1,120 picocuries per liter.
A sample analyzed by a laboratory contracted by Entergy, which owns and operates the plant, tested at 1,230 picocuries per liter.
The EPA limit for tritium in drinking water is 20,000 picocuries per liter.
According to Bill Irwin, chief of radiological health and safety for the Vermont Department of Health, no other radiological materials have turned up in the river or in groundwater samples taken at the plant and from off-site monitoring wells.
"The only radioactive materials we have identified so far have been consistent with the levels found everywhere from nuclear weapons fallout," said Irwin. "But we continue to take samples for other radioactive materials that might be from fallout or from nuclear power generation."
According to DOH's website, the water samples have been sent to a contract laboratory to be analyzed for hard-to-detect radioactive materials including strontium-90.
Confirmatory gamma spectroscopy and analysis for tritium will also be done.
"Our concern is that we continue to have the opportunity to evaluate the environment for further contamination and keep a close
According to a press release from Larry Smith, Yankee's director of communications, samples taken by Yankee on Nov. 7 and 10 showed no signs of tritium.
"The sampling result is not unexpected given the location of the sampling point and is consistent with the directional flow of groundwater below the plant site," wrote Smith in the press release, adding that tritium finding poses no risk to public health and safety.
The DOH made a similar assessment on its website.
"These low concentrations of tritium at the river's edge are immediately diluted by the greater volume of river water to the point that they cannot be measured," it stated.
Following the detection of tritium in groundwater at Yankee in late 2009, the state and Entergy have been tracking the progress of the contamination. Much of the contaminated water was extracted, though the most recent tests prove some of the contamination has been migrating to the river.
"The sample results confirm the Conceptual Site Model that indicates small amounts of tritium would eventually reach the river," wrote Smith.
Bi-weekly sampling of the river will continue in accordance with the Vermont Yankee sampling plan, he wrote.
In an e-mail to the Reformer, Neil Sheehan, spokesman for the Nuclear Regulatory Commission, said while this is the first time a sample taken from the river by Entergy has identified tritium, the NRC has long said the plume was moving toward the waterway.
"Because of the huge volumes of water in the river, a sample taken farther out in the river would not be expected to show that concentration of tritium and most likely would indicate tritium at background levels," he wrote, adding that any dose to members of the public from tritium in the river has already been analyzed and been found to be within allowable levels.
Earlier this year, in river water samples taken by Vermont DOH on July 18 and 25 and on Aug. 8, tritium was detected at levels of 534, 611 and 565 picocuries, just above the lowest limit of detectability, which is 500 picocuries.
However, in August, water samples taken from the river by the New Hampshire Division of Public Health Services showed no detectable traces of tritium.
At that time, Irwin said test results can differ from day to day. Tritium levels can be affected by the amount of water in the river and how quickly water is flowing, he said.
Bob Audette can be reached at firstname.lastname@example.org, or at 802-254-2311, ext. 160.