Search for leak continues at [Vermont] Yankee

BRATTLEBORO -- A former nuclear industry insider turned nuclear safety advocate said the inspection team looking for the source of a tritiated water leak might consider the condensate storage tank, which contains 500,000 gallons of water that is used for normal auxiliary feedwater pump supply.
Arnie Gundersen said in 1976, a spill of tritiated water occurred at the plant, which was then owned by the Vermont Yankee Nuclear Power Corporation. The source of the leak was determined to be the condensate storage tank.
The state's nuclear engineer, Uldis Vanags, told the Reformer in an e-mail that the source of the leak is only speculation at this point.
And, he stated, "It's too early to tell if the concentration of tritium is increasing, decreasing or stable ... until we identify the source and acquire more samples over time so there are more data points. I am hoping the source of the tritium can be identified quickly."
Yankee has hired a hydrologist as part of its investigation and is considering drilling more wells to search for any plume of tritiated water.
Gundersen told the Associated Press that the contaminated sample is a sign that there's a pipe or a tank leaking somewhere.
"It's highly unlikely that the highest concentration in the ground would happen to be at the monitoring well," he said, adding the tank could have leaked anywhere between 10,000 and 50,000 gallons a month "without anybody noticing."
Last week, a Yankee spokesman told the media that tritiated water had been found in a test well on the site of the nuclear power plant.
Though the amount of tritium found in the water was below the threshold established by the Environmental Protection Agency, Yankee personnel and inspectors from the Nuclear Regulatory Commission are investigating where the tritiated water is coming from.
The sample was taken from an on-site well in November. On Jan. 5 Yankee learned from an independent laboratory that the water was contaminated with 17,000 picocuries per liter. On Jan. 6, a second sample was taken, which had a level of 14,500 picocuries. The EPA's limit is 20,000 picocuries.
According to the Nuclear Information Resource Center, the average tritium level in U.S. water ranges between 3.2 and 24 picocuries.
The NRC translates one million picocuries of tritium per liter as the equivalent of 50 millirems a year
The average American receives about 360 millirems a year from natural sources such as radon, cosmic radiation and as a result of medical procedures.
Off-site monitoring wells maintained by the state have shown no contamination, said Bill Irwin, Vermont's radiological health officer.
Because water in condensate storage tank circulates through the reactor, it contains radioactivity, including high levels of tritium, said Neil Sheehan, spokesman for the NRC, but there are measures in place to prevent tritium from contaminating water supplies.
"The condensate storage tank at the plant rests on a concrete pad that is surrounded by a concrete berm," said Sheehan. "Any leakage from the tank should therefore be collected and not reach the groundwater."
Tritium testing is done by way of deep wells, which are sampled on a quarterly basis, storm drain systems, which are sampled on a monthly basis and the south storm drain system, which is sampled on a weekly basis.
In addition, ground water test wells are sampled and analyzed for tritium and other radionuclides are sampled on a semi-annual basis.
"Operations personnel also take a contaminated water inventory on a daily basis in order to determine any abnormal water usage or movement that might indicate a leak from the system," according to the 2006 letter from Entergy to the NRC.
Under industry guidelines, said Sheehan, the threshold for reporting contamination to plant stakeholders is set at a very low level.
"In all cases we quickly learn about tritium and other types of groundwater contamination," he said. "The companies do not hesitate to notify our resident inspectors of even the smallest levels of contamination."
In 2006, the NRC established the Liquid Radioactive Release Lessons Learned Task Force in response to incidents at Braidwood, Indian Point, Byron and Dresden nuclear power plants.
"Virtually all commercial nuclear power plants routinely release radioactive materials to the environment in liquids and gases," stated the report. "These releases are planned, monitored and documented. Although there have been a number of industry events where radioactive liquid was released to the environment in an unplanned and unmonitored fashion, based on the date available, the task force did not identify any instances where the health of the public was impacted."
NRC regulations require that the releases not result in a dose of greater than 3 millirems to any individual in an unrestricted area.
A person flying on a cross-country trip receives about 3 millirems of cosmic radiation.
Bob Audette can be reached at [email protected], or at 802-254-2311, ext. 273.