As tritium levels spike, so does the furor over contamination from Vermont Yankee.
On Feb. 6, tritium concentrations hit an all-new high in groundwater monitoring wells at the Vernon nuclear power plant. And since then, federal, state and officials from Entergy, the plant’s owner, have maintained that “elevated levels” of the radioactive isotope have not been found in the Connecticut River.
On Feb. 9, Wendy Davis, the state’s health commissioner, told David Gram of the Associated Press that it’s logical to assume tritiated water is leaching into the Connecticut River based on the amount of contamination and the flow of water from the Yankee site, which is located on the river bank.
The next day, William Irwin, radiological health chief for the Vermont Department of Health, reiterated in an e-mail that tritium has not been found at elevated levels in the river.
He wrote that samples of Connecticut River water tested in his laboratory have detected the presence of tritium in concentrations no higher than 500 picocuries per liter since the leak was discovered on Jan. 7. Irwin wrote that over the course of 40 years of monitoring, tritium readings of river water have never exceed 500 picocuries per liter, the lowest level at which it can be easily measured. Tritium exists in nature at about 10 picocuries per liter.
However, Irwin also cautioned lawmakers last week, “The fact that we are able to see very low concentrations in our laboratory, we cannot rule out that there is tritium in the Connecticut River. With the volume of the river, with the flow rate of the river, my suspicion is that it is there, we just cannot measure it.”
One of the monitoring wells on the Vermont Yankee site tested for a tritium contamination level of 2.5 million picocuries per liter on Monday. The federally accepted level is 20,000 picocuries per liter. Uldis Vanags, the nuclear engineer for the Department of Public Service, said the new reading is so close to the reactor water concentration level of tritium “that it’s probably from that.” No other reactor-related chemicals, such as the more highly radioactive Cobalt 60 and Strontium 90, have been identified by gamma spectroscopy, according to Rob Williams at Yankee.
“We do know,” Irwin said last week, “that tritium as a radioactive material is relatively low in its radio-toxicity, but clearly this is just a marker of other things that are there and other things that could affect the public and the environment.”
Irwin told lawmakers on Feb. 5 that Entergy hadn’t said yet that they would test the Connecticut River daily (tests have been run weekly), “but they said it was a good idea.” As of Monday, Vanags said Entergy officials had begun testing the river every day.
Irwin is concerned about nearby residents ingesting tritium from drinking water wells.”
The Health Department, meanwhile, monitors the river once a week, and it has stepped up testing of drinking water wells near the plant. Two of the wells being monitored are on farms as far as a mile away from the plant. The costs incurred by the department for additional testing will be paid for by Entergy, according to Irwin.
As the state Health Department’s radiological health chief, Irwin is concerned about nearby residents ingesting tritium from drinking water wells. “That’s actually a possibility here,” Irwin said. “The groundwater monitoring is not consumable water, but we don’t want the next sample to be in drinking water.”
Neil Sheehan, a spokesman for the Nuclear Regulatory Commission, said even if high levels of tritiated groundwater from Yankee leached into the river, it would still not affect public health because the dilution of the tritium in a large, swift-moving body of water such as the Connecticut River would be so great that it would be impossible to see the presence of tritium above 300 to 500 picocuries per liter.
“This is groundwater that is contained within the site at this point,” Sheehan said. “Members of the public aren’t exposed to this. Members of the plant aren’t exposed to this because this is not water that is being used for drinking water purposes. Therefore it doesn’t pose a threat to public health and safety. That doesn’t diminish the fact that we believe they need to do everything in their power to identify the source of the leakage, halt it and then come up with a plan to address any existing contamination.”
Sheehan said tritium is a “weak beta emitter” that behaves like water and that to “see any health effects you would have to ingest large quantities of it.”
“If you drank 2 quarts of water per day at that level (the federal limit of 20,000 pCi/L) you’d have to drink that amount for a year, and at the end of that you would see a dose of about 4 millirems of radiation exposure,” Sheehan said. “The average American gets about 360 millirems of radioation exposure from natural and manmade sources. So you’re talking about very low levels.” A millirem is a unit used to measure the effect of radiation on the human body.
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The assertion that tritium isn’t harmful to public health is cold comfort to Vermont and New Hampshire officials.
Vermont Gov. James Douglas has called for a time out on relicensing the 38-year-old nuclear power plant in Vernon for an additional 20 years until issues are resolved around the tritium leak, the investigation into Entergy’s misstatements about underground piping, decommissioning plans for the plant and a purchase power agreement with Entergy.
All five gubernatorial candidates for the Democratic ticket have called for the shutdown of Vermont Yankee. The House Energy and Natural Resources Committee has held extensive hearings over the last several weeks to ascertain the impact of tritium contamination at the plant on public health.
This week, New Hampshire officials have also stepped up calls for action. On Monday, Paul Hodes, a Democratic Congressman from New Hampshire running for the U.S. Senate, visited the Yankee site and insisted that his state be given more oversight of the plant. Last night, New Hampshire’s Democratic Gov. John Lynch also called for a Nuclear Regulatory Commission investigation into the tritium leak at Vermont Yankee and a probe into Entergy’s misstatements in testimony to the Vermont Public Service Board regarding the existence of underground piping at the plant.
Entergy Nuclear maintained Yankee did not have underground pipes until January when the tritium leak was discovered.
The scope of the tritium contamination at Vermont Yankee is not yet clearly defined, but Irwin wrote in an e-mail last night that the contaminated wells “create a corridor from the turbine building to the river that is about 200 feet wide by 400 feet long (somewhat larger than a 160’x360’ football field), and may be as deep as 10 feet.
Irwin says the tritium spike of 2.5 million picocuries per liter in a new monitoring well, GZ-10, on Monday is an indication that the source must be a system that operates with a high concentration of the radioactive material – such as the condensate storage tank or the Advanced Off-Gas System. He said it’s also possible tritium has been building up in soil near the well for a long time. On Friday, GZ-7, located near the Advanced Off-Gas Building and the Reactor and Turbine Buildings, registered a concentration of 834,000 picocuries per liter. Today, it hit 937,000 ppl.
“Many other systems and components are still being inspected, including the AOG tunnel, the AOG pit sump and the rad waste trench,” Williams wrote in an e-mail over the weekend.
In August 2009, the Legislature’s nuclear consultant Arnie Gundersen questioned Entergy’s assertion that there were no underground pipes at Vermont Yankee. He pointed to the Advanced Off-Gas System as one of the likely systems that included underground pipes at the plant.
Vanags would not comment on whether the pipes that are suspected to be the source of the leak are part of Advanced Off-Gas System Gundersen identified last summer, citing the ongoing investigation into Entergy’s testimony on the subject.
In any case, Irwin says the area for potential tritium contamination at the plant is “a large area with a lot of piping that needs to be inspected, and this will take some time.”
Irwin told the House Energy and Natural Resources Committee that there is a remote possibility the leak might never be found.”
How much time is anyone’s guess. Vanags, testifying as the nuclear engineer for the Department of Public Service, told lawmakers last week that it could take as long as six months to find the leak. Irwin told the House Energy and Natural Resources Committee that there is a remote possibility the leak might never be found.
In an interview, Vanags said identifying the leak is crucial. “Until they identify where it’s coming from, it’s hard to say what mitigation will take place,” He said Entergy is excavating in the identified area
this week, and today Yankee officials dug four feet around the Advanced Off-Gas drain line. By Saturday, crews are expected to have excavated a total depth of 10 to 15 feet.
“If they identify the leak, then they have to come up with a plan for how to mitigate it,” Vanags said. “It has to be done very carefully because it’s an operating plant.”
The Conservation Law Foundation, a nonprofit advocacy environmental group, has asked the Public Service Board to require Entergy to show why it’s necessary to run the plant until the leak is found. Foundation attorney Sandra Levine says operating a leaking plant defies common sense.
“It’s clear that the radiation is coming from the activity at the plant, so why isn’t the plant shutting down while those leaks are repaired?” Levine asks.
Irwin said that if shutting down the plant would stop the leakage, the Health Department would make that recommendation, but he said “the system needs to be pressurized to find the leak, and operating the reactor is the best way to do that.”
“If you shut down the reactor, you may not be able to find the leak,” Irwin said.
Levine argues, however that the plant could be pressurized with something other than radioactive material, which would likely require shutting down the plant.
“It’s clear that the radiation is coming from the activity at the plant, so why isn’t the plant shutting down while those leaks are repaired?” Levine asks. “It seems pure common sense to me that you don’t continue to operate a plant that’s leaking.”
So how does the contamination at Vermont Yankee stack up to the two dozen or so tritium leaks that have been found at nuclear power plants around the country? Last week, in testimony to the Vermont House Natural Resources Committee, Irwin told lawmakers this was one of the nation’s seven worst spills.
NRC spokesman Neil Sheehan confirmed that assertion on Friday. Tritium levels spiked to 14.4 million picocuries per liter at the Oyster Creek Generating Station in New Jersey last year, Sheehan said. At Indian Point Energy Center in New York, the tritium contamination level was 300,000 picocuries per liter, and the spill included other radioactive isotopes.
Sheehan said tritium contamination levels reached 5 million picocuries per liter at Oyster Creek Generating Station last year; about 8 million at Dresden Generating Plant in 2004; and about 15 million at the Salem Nuclear Power Plant in New Jersey in 2002.
Correction: Health Department official William Irwin confirmed on Friday that tritium occurs naturally in the environment at about 10 picocuries per liter, not 500 picocuries per liter as reported, and stated by Neil Sheehan of the Nuclear Regulatory Commission. Irwin’s equipment cannot detect tritium easily at such low levels. The federal standard for exposure is 20,000 picocuries per liter; the limit in California is set at 500 picocuries per liter. We regret the error.
