Entergy finds huge radiation jump
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By Susan Smallheer Staff Writer - Published: February 6, 2010
VERNON — The Department of Health said late Friday that Entergy Nuclear workers found the highest concentrations yet of the radioactive isotope tritium at Vermont Yankee, this time in a drainage pit close to a highly contaminated groundwater monitoring well.
William Irwin, radiological health chief for the Department of Health, said the pit tested positive for 2.7 million picocuries per liter of tritium.
While the radioactive water was not in groundwater and was inside the reactor complex, Irwin said the high tritium levels were almost identical to the levels of tritium found in reactor cooling water, indicating a leak.
Irwin said it was possible the underground piping that drains into the pit or moves the water to a system for treatment could be leaking.
Entergy Nuclear workers will look at that piping for the source of the radioactive plume at the Vernon reactor, according to Robert Williams, Entergy Nuclear spokesman.
The level of radioactive contamination in the new well that shows the highest contamination in groundwater at the Vernon site continued to climb.
That well tested at just less than 775,000 picocuries per liter Thursday. It climbed to 834,000 picocuries per liter Friday, according to Irwin and Williams.
Arnie Gundersen, a nuclear engineer from Burlington who acts as a consultant to the Vermont Legislature, said the 2.7 million picocurie level in the sump pit wasn't out of the ordinary in such a drainage system.
But he said the 2.7 million picocurie reading could easily drop to the 775,000 to 840,000 picocurie level after being filtered through soil.
Williams said the significance of the discovery of the high concentration of tritium was that it could mean Entergy is getting closer to the source of the leak.
Williams said the high concentration of tritium "was not unexpected" in the underground drainage pit, which he described as a concrete vault at the bottom of the advanced off-gas building.
He said Vermont Yankee personnel now have 10 monitoring wells in service, and four new ones were being prepared for sampling.
Williams said a pump that moves the water from the pit to the rad waste building had been removed from service and an investigation of the sump was under way.
Williams again stressed there have been no elevated levels of tritium in drinking water wells, and that it posed no danger to the public. While tritium is a known carcinogen, it has to be ingested or inhaled in a gas form.
Both Williams and Irwin said excavation is planned for the area and a new monitoring well is being considered in the area to gather additional information.
susan.smallheer@rutlandherald.com
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