SODDY DAISY, Tn -- Elevated levels of tritium have been discovered in a groundwater sample taken from one of two new onsite monitoring wells at the Sequoyah Nuclear Plant. According to Tennessee Valley Authority officials, these elevated levels pose no threat to the health and safety of the public.
"The newly installed groundwater monitoring wells were placed in an area known to have contained tritium that was previously reported," Sequoyah Plant Manager Paul Simmons said. "The health and safety of the public are our primary concern, which is why providing additional monitoring capability to the plant's groundwater wells is an important measure for protecting the community and the environment."
There are a total of 16 groundwater monitoring wells on the Sequoyah site. The highest level found in the sampling on Friday, Dec. 16, was approximately 23,000 picocuries per liter. A "curie" is the standard measure for the intensity of radioactivity contained in a sample; a picocurie is one trillionth of a curie.
None of the Sequoyah groundwater monitoring wells is used for drinking water or irrigation purposes and no potable water wells are downstream of where the tritium was found. Additionally, TVA confirmed no detectable levels of tritium in any sampling of the Tennessee River where the plant discharges water.
"Sequoyah voluntarily communicated to federal, state and local officials these elevated sample results due to TVA's own conservative decision-making process and in accordance with a groundwater protection initiative established by the nuclear industry in 2006, " Simmons said. "TVA is reviewing the new monitoring well sample results, determining the cause of these elevated levels and how they relate to the previously reported releases of tritium."
Tritium is a naturally occurring radioactive form of hydrogen that is produced in the atmosphere and is also a byproduct of the production of electricity by nuclear power plants.
The Environmental Protection Agency sets tritium drinking water limits at 20,000 picocuries, which is only slightly less than the elevated levels found in the new monitoring well at Sequoyah. To put this number into perspective, if a person drank two liters of water every day with this amount of tritium for a year, he or she would receive a radiation dose of about four millirem. In comparison, one X-ray from a dental exam will have a radiation dose of about 10 millirem. On average, Americans receive approximately 620 millirem of background exposure annually from natural and man-made radioactive sources.