In the wake of new tests that show elevated levels of tritium, a radioactive isotope of hydrogen, in two monitoring wells at the Vermont Yankee nuclear power plant in Vernon, Gov. Peter Shumlin announced on Feb. 1 that the state will create an oversight panel to keep tabs on Entergy Corporation's management of the plant.
As part of a new probe, an Entergy hydrogeologist will share data with experts from New Hampshire, Vermont, Massachusetts, and the Nuclear Regulatory Commission on Feb. 10.
The two monitoring wells that have tested positive for very low concentrations of tritium (between 1,000 and 9,000 picocuries per liter, well below the EPA standard of 20,000 pc/L) are located 200 feet and 100 feet, respectively, from tritium contamination that was discovered at the nuclear power plant a little more than a year ago.
At no point, officials say, has public health been at risk as a result of the leaks. Larry Smith, spokesman for Vermont Yankee, said a new source of tritium is “not unexpected.”
“We don't understand why we're seeing it,” Smith said. “We're not saying it's a leak. We don't know that, and we're investigating it.”
Entergy notified the Shumlin administration about the new tritium discoveries last month. The results were from tests conducted in December. The corporation's radioactive sensing equipment broke down in the interim.
The governor noted that Entergy didn't mention the problem when officials testified before the Public Service Board recently.
“We have a responsibility to all Vermonters that we operate a nuclear power plant that is not leaking tritium or other radioactive substances into the ground,” Shumlin said.
“This is the second January in a row that we've been stuck with this challenge,” he said. “I intend as governor to work together with the commissioner to ensure we get straight talk and transparency; have a plan to get to the bottom of it; have a more active relationship with Entergy to ensure we're getting accurate information in a timely fashion.”
On Jan. 28, Dr. Harry Chen, the commissioner of the Vermont Department of Health, sent a letter to Entergy insisting that the company send the state split samples of water from monitoring wells. The department is missing “hundreds” of samples, some of which date back to September, he wrote.
“Obviously, I am concerned, No. 1, that this aging plant continues to show signs of a lack of reliability by yet another leak or a plume that is moving in directions north,” Shumlin said. “No. 2, by a lack of transparency by Entergy Louisiana in communicating to Vermont the challenges we're facing in terms of the aging plant and reliability that should be a concern to all Vermonters. They're certainly a concern to me.”
Shumlin outlined a three-point plan for the Department of Public Service to address the tritium problem at Vermont Yankee.
• First, the governor has charged Liz Miller, the commissioner of the Department of Public Service, with appointing nuclear experts to a Reliability Oversight Committee. The panel will advise the department about Vermont Yankee reliability and “other issues that come up” as the state moves toward closing the plant in 2012.
• Secondly, the state will expect daily updates on tritium levels in monitoring wells from Entergy to the Department of Public Service and the Department of Health, Shumlin said. The Nuclear Regulatory Commission has called for a similar testing regimen.
• Finally, Shumlin has demanded that Entergy give the DPS an emergency plan that explains to how “they're going to get to the bottom of this will be formulating a plan to get to the bottom of this latest leak.”
Shumlin said these steps are necessary because “Entergy Louisiana does not do business the way Vermonters do business.”
“That's been my experience,” Shumlin said. “I have not seen any behavior that suggests that they've decided to do business differently.”
Since last January, Entergy Corp., based in Louisiana, has excavated tons of soil. It also continues to remove tritiated water (now up to 316,000 gallons) from the contamination plume that flows from the plant, which is on the west bank of the Connecticut River. The river, which separates Vermont from New Hampshire, flows south to Massachusetts.
The source of the original leak was an underground piping tunnel system connected to the Advanced Off-Gas (AOG) Building. Last year, readings from monitoring wells in the plume area were in the millions of picocuries.
The origin of the new leak has yet to be determined, but several officials say it's likely coming from buried pipes that carry radioactive waste.
Bill Irwin, radiological chief for the Vermont Department of Health, says there are three possible sources for the new tritium findings in the two monitoring wells. The water from the plume, which he said is flowing south and east toward the river, could be moving north toward test wells GZ6 and GZ24S, along a pipe way; or the hydrology of the site could be forcing the water west and north. Both those scenarios seem unlikely, in his view.
“Something (could be) acting as a conduit or a channel where (tritiated water) might move up against an obstacle because it can't travel east to west,” Irwin said.
Irwin described GZ24S as a “sentinel well,” one that Entergy uses to identify a leak in “one or more buried piping lines” coming from the radioactive waste building.
“There's more evidence … of the possibility of other pipes that contain radioactive fluids that run near GZ24S, and somewhat near GZ6, that may be the leaking underground pipes everyone has expressed concern about,” Irwin said.
Until this latest sample, Irwin said, all attention was focused on the plume. Now, he said, the state is looking at this second set of sources. “That's in fact why GZ24S was sited where it is,” Irwin said. “It's a sentinel well. It's next to some drain lines carrying radioactive liquids. A sentinel well will be the means by which Entergy identifies a leak in one or more of those buried piping lines.”
Neil Sheehan, a spokesman for the Nuclear Regulatory Commission, agrees with this assessment. He said that the initial evidence indicates the tritium is not coming from the plume. The outline of the contamination area has been carefully drawn based on “dozens and dozens” of tests performed by Entergy, Sheehan said.
“The fact that those wells between the plume and GZ24 and GZ6 have not indicated contamination supports the theory this is not coming from the pre-existing (plume),” Sheehan said.