Officials mixed on latest Yankee find
By Susan Smallheer
Staff Writer | February 05,2010
VERNON – Levels of radioactive tritium mushroomed Thursday in a new monitoring well at the Vermont Yankee reactor, an indication the leak was coming from water that runs through the reactor itself, according to the Department of Health.
"These are very high concentrations," said William Irwin, radiological health chief for the Department of Health, who was at the reactor Thursday. "We're not dealing with a minor system. It's an important source that needs to be quickly found."
The new concentration, 774,825 picocuries per liter, is eight times any level previously reported, and comes from a new groundwater monitoring well near the reactor and turbine buildings, between the condensate storage tank and the advanced off-gas building.
The federal limit for drinking water is 20,000 picocuries per liter, and before Thursday, the highest reading was 80,000 picocuries in another new monitoring well Monday. Four wells and an underground trench for pipes show varying levels of radioactive contamination.
Irwin has been splitting his time between the reactor and Health Department headquarters since the leak was revealed on Jan. 7, when a monitoring well registered 14,000 picocuries per liter, a number that has steadily grown.
"Our opinion is that this is a significant finding and that finding represents a very serious risk until it's known quite clearly what the cause is," Irwin said.
"It's clearly important to recognize that tritium is a marker of potential other radionuclides, more serious radioisotopes," Irwin said. "This is a very serious situation."
The new well did not show any other radionuclides, he said.
Entergy Nuclear issued a press release midafternoon, after the Nuclear Regulatory Commission had released the test results. Entergy Nuclear said the high concentration was actually "good news," because it appeared plant engineers were getting closer to the source of the leak.
But Irwin took issue with those particular words.
"It's not good news. None of this is really good news. There is contamination of the environment and contamination of the groundwater, neither which should have happened," he said.
Irwin said tritium levels could be even more concentrated closer to the source, since the earth could be acting as a filter for the tritium, trapping the radioactivity.
Irwin said about 40 state employees from various departments are working on the response to the tritium leak.
"We have a very significant operation that's been put together to independently assess the environmental and health impacts," he said. The higher concentrations may help investigators narrow their search, he said.
Irwin said shutting down the reactor until the leak is located would actually be counter-productive. Many of the tests needed to find the leak are dependent on the plant's systems being fully pressurized, he said.
Irwin's assessment of the latest development in the tritium crisis at Vermont Yankee contrasted with word from the Nuclear Regulatory Commission.
"Although the number 774,825 is a very large number, it is still a very low level of tritium contamination and continues to present no public health and safety hazard and no detectable negative impact to the environment," wrote NRC spokesman Neil Sheehan in an e-mail.
Sheehan noted that no drinking water wells either at the reactor or in the town of Vernon showed tritium contamination, and tests have not picked up any measurable levels in the Connecticut River.
Rob Williams, an Entergy spokesman, estimated that the new well was 200 feet from the Connecticut River. The first well to show contamination is on the banks of the Connecticut River.
Irwin said state officials were still waiting for a hydrologist's assessment of the site, to learn how much water was flowing under Vermont Yankee, at what volumes and levels.
He said the Department of Health is doing its own tests of drinking water wells in the area, of the river, of water used for irrigation and feeding animals. So far, all drinking sources test free of tritium, he said.
Irwin said it wasn't necessarily inevitable that the radioactive contamination would spread. Of the two dozen or so commercial reactors with a tritium contamination problem, only the Braidwood plant in Illinois resulted in offsite contamination of drinking water.
Helping to limit the effects on drinking water wells is the fact that most are deep in bedrock. The monitoring wells are quite shallow, he said, between 25 to 30 feet deep.
He said the location of the high concentration well, coupled with the other three wells already contaminated, narrowed the focus of the investigators, but he said it was too soon to say which system was responsible.
He said potential systems include the feed water, condensate or radwaste systems.
He said initially there was a lot of interest in one of Yankee's radwaste trenches, but a well nearby showed no tritium.
Williams said about three dozen Entergy Nuclear employees are working under John Dreyfuss, Vermont Yankee's director of nuclear safety assurance, on finding the radioactive leak.
"A large number of people are working a lot of hours to try and find the source," said Irwin.