Tritium numbers continue to rise

BRATTLEBORO -- The highest level of tritium contamination found at Vermont Yankee nuclear power plant in Vernon was discovered Friday in the plant's pit sump, which is designed to collect and hold water from various sources in the plant.
A sample of water taken from the sump measured 2.7 million picocuries a liter of tritium, more than three times as high as tritium levels found, also on Friday, in a well just east of the plant's condensate waste storage tank.
The level of tritium found in that well measured 775,000 picocuries on Thursday. On Friday, that level had increased to 834,000 picocuries.
The pit sump is a concrete vault and is a component of the plant's off-gas system, which discharges collected water into the plant's radioactive waste building.
The elevated level in the pit sump was not unexpected, wrote Yankee spokesman Rob Williams, in an e-mail to the media, "because it contains piping that contains water with similar tritium concentrations."
Williams said the "Tritium Team" does not believe the sump itself is the source of tritiated water found in monitoring wells on the grounds of the power plant.
"However, the sump pump discharges into buried piping connected to the radwaste facility," he wrote.
That piping could be the source of the tritium leak, stated the Vermont Department of Health's daily update on the search for the source of the contamination.
Whether the buried piping related to the pit sump was revealed
________________________________________
Advertisement
________________________________________
during hearings before the Public Service Board last year is not known at this point, wrote Williams.
When the tritium leak was first identified, the state learned Entergy representatives hadn't revealed the extent of buried piping during the PSB hearings. In response to the revelation, Entergy supplied to the state a list of all underground pipes at the plant.
"Senior management is directing a comprehensive review to determine what information was provided (at the hearings), what caused the errors and to set the record straight," wrote Williams.
Because the elevated levels in the sump indicate Yankee engineers are getting closer to the source, investigators are focusing on that underground piping, wrote Williams.
Yankee engineers are planning to dig 12 feet down to the underground piping to determine, stated the DOH update, and a new well is being considered to further evaluate the area.
One possible source of the leak was ruled out on Friday when Yankee technicians succeeded in accessing the plant's heating, ventilation and air conditioning duct by boroscope, an optical device that is used to view areas that are inaccessible to people.
No water was found in the duct, a 78-inch concrete pipe that carries building exhaust from the reactor and from the radioactive waste, turbine and off-gas buildings to a 318-foot high ventilation stack.
The stack releases radioactive materials into the atmosphere at levels regulated by the federal government.
Since the contamination was revealed on Jan. 6, Yankee engineers have had seven new monitoring wells drilled and have four others being readied for sampling.
The new wells are being used to not only find the source of the tritiated water, but also to define the extent of the contamination.
In addition, drinking water samples have been taken on-site and off-site, including from two residential wells located near the plant, the Vernon Elementary School well and the Hinsdale, N.H., village well. All have tested negative for tritium.
The Environmental Protection Agency's maximum allowable level for tritium in drinking water is 20,000 picocuries.
While tritiated water hasn't been found in any drinking water samples, said Wendy Davis, DOH commissioner, "That does not decrease the urgency to figure out where it's coming from."
The monitoring well that was the first to test positive for tritium contamination is located between the power plant and the Connecticut River.
While samples taken from the river have shown "no detectable levels" of tritium, the state is not assuming tritium is not making it into the water, said Davis. Because of the flow of the river and the amounts of water passing the power plant, any tritium leaking into it might be too diluted to be measured.
The Tritium Team had also considered a pipe tunnel that is used for the collection and processing of radioactive waste as a third potential source of the tritium.
Standing water in the pipe tunnel had measured levels of 2.2 million picocuries of tritium on Jan. 13. While no other radioactive materials have been discovered in the wells, water in the pipe tunnel tested positive for cobalt-60, at 13,000 picocuries, and zinc-65, at 2,460 picocuries.
The source of the standing water in the pipe trench was determined to be condensation from a nearby tank, wrote Williams.
The levels of tritium discovered Friday, while alarming, are nowhere close to those discovered at Oyster Creek and Salem nuclear power plants, both in New Jersey, said Neil Sheehan, spokesman for the Nuclear Regulatory Commission.
Last year, tritium levels tested at 14.4 million picocuries at Oyster Creek, and at Salem the levels tested at 15 million picocuries.