By Dorothy Davis
Entergy Vermont Yankee officials notified the Vermont Department of Health Friday about a positive tritium sample from the Construction Building well. The well, once used for drinking water, was decommissioned in March of 2010. The positive sample measured a tritium concentration of 1,040 picocuries per liter (pCi/L), which is well below the allowable limit for drinking water set by the Environmental Protection Agency’s 20,000 pCi/L.
The tritium positive sample was extracted at a depth of 200 to 220 feet while contractors were conducting packer testing. Packer testing is utilized to spotlight specific fractures in the bedrock to assessthe water within them.
Another sample from the Construction Building well extracted at a depth of 300 to 320 feet tested at less the lower limit of detection of tritium (generally less than 500 pCi/L). This finding prompted testing to be immediately stopped to allow for an investigation into the possibility that the testing equipment or the process itself cross-contaminated the well. The Vermont Department of Health had requested a split sample from the Construction Building well for all packer testing sites.
In January, the Vermont Yankee Power Station notified the Vermont Department of Health that samples collected in November of 2009 from a ground monitoring well on the site contained tritium, signaling an unintended release of radioactive material. An investigation was launched; and in February, it was discovered that a pair of steam pipes inside the Advanced Off-Gas (AOG) pipe tunnel were badly corroded and leaking nuclear steam. This event was followed by an additional leak at the AOG drain, which occurred as the system was being restarted following a scheduled refueling outage.
The testing being conducted at the Construction Building well last week is part of ongoing investigative, monitoring and corrective actions being conducted in response to the leaks of nuclear material that occurred in November 2009 and May 2010. Although the reported levels of tritium Friday are well below regulatory standards and do not pose a risk to public health and safety, the finding could have a significant impact on the future of the Vermont Yankee plant, whose license is set to expire March 21, 2012.
Entergy filed with the Nuclear Regulatory Commission in 2006 for a 20-year license renewal for Vermont Yankee and was still awaiting a decision from regulators when Vermont senators voted 26-4 last winter in a landmark decision against Entergy’s request. Although license renewals for nuclear power reactors are overseen by the U.S. Nuclear Regulatory Commission, Vermont is the only state to have a law that also requires approval from the Legislature.
According to reports published by the Vermont Department of Health, samples from the Vernon Elementary School and numerous private residences off-site near the plant have not shown tritium levels greater than the lower limit of detection, nor have they measured any other nuclear power plant-related radioactive materials since the tritium investigation began in January.
Nuclear News: Entergy detects tritium in another Vermont Yankee well
By Dorothy Davis