Karl Herchenroeder
RW Monitor
01/22/16

A Vermont Department of Health official said Monday that groundwater monitoring crews on a few occasions in recent months have found contaminated samples near the Vermont Yankee nuclear power plant, but further investigation determined no public health risks.

Radiological Health Chief Bill Irwin said crews both from Vermont and plant owner Entergy have identified contaminated samples in separate instances, dating back to a 2010 tritium leak and 2014 discovery of a strontium-90 sample. The state agency conducts routine groundwater testing each month and will continue to do so until the plant is released for unrestricted use. That could mean testing for another 60 years, as the plant, which shut down in December 2014, has entered into SAFSTOR, which allows the facility to sit until its designated trust fund accrues enough interest to cover the cost of decommissioning.

“We have had a number of these incidents, and fortunately in every case actions have been taken to not only continuously characterize the environment, so that we know it’s not getting worse, and in some cases to document that the conditions have actually improved,” Irwin said, “but in every case, no risk to public health has been identified.”

Still, the department has concerns about area groundwater as decommissioning progresses, Irwin said, adding that officials want to make sure nothing goes undetected. Irwin said the department believes soil surrounding the facility contains radioactive material resulting from fallout from the plant stack, other air mediums, and spills that may have occurred. The groundwater, as it passes through these soils, can pick up radioactive materials that show up in groundwater samples.

“They are predictors of what may be found in the groundwater,” Irwin said, adding that the department needs to know if these materials are moving off-site.

Potential for the latter would mean cleanup challenges during decommissioning. Irwin said the general flow of groundwater is from the west of the plant, where residents live, down gradient to the Connecticut River. When groundwater mixes with the river, the material is diluted significantly, but gradual buildup would still harm animals, plants, and sediments, Irwin added.

“We can compare new samples, both water and other environmental medium, to see if changes are occurring,” Irwin said. “What we hope to see is no change and for that reason, no effect to public health.”

In August 2014, state officials discovered strontium-90 samples in groundwater within the boundaries at Vermont Yankee. This was the second discovery of a radioactive isotope at the site, following the 2010 identification of a tritium leak. Officials noted that the highest measurement of Sr-90 concentration was below the EPA’s drinking water threshold.

“The water is not available for consumption, the levels detected are well below the EPA’s safe drinking water threshold, and there is no immediate risk to health,” the state said at the time.