July 26, 2008
Vermont Yankee Fence Line Dose Up 30 Percent
By Bob Audette, Brattleboro Reformer, Vt.
Jul. 26--BRATTLEBORO -- Radiation levels measured at the fence line of Vermont Yankee nuclear power plant were 30 percent higher in 2007 than in 2006.Despite the 30 percent increase, the report stated the highest fence line measurement recorded by the Vermont Department of Health was less than 18 millirem.
"At no time has Vermont Yankee posed a measurable risk to public health," said Health Commissioner Wendy Davis.
Although radiation levels were found to be higher than in previous years, they are still below the health department's regulatory limit of 20 millirem per year, a limit that is more protective than any other state or federal agency, said Bill Irwin, the chief of radiological health for Vermont's Department of Health.
"We are talking about very low levels of exposure and dose," he said. "Public exposure at those levels and the doses that do come from those exposures are unlikely to contribute measurably to risk."
With a carcinogen such as ionizing radiation, there is no way to eliminate all risk short of not having any exposure at all.
Still, he said, "The amount of risk is very small if it can be measured at all."
The NRC limit for exposure to all sources of ionizing radiation is 100 millirems a year.
"Because Yankee exists here we have lower limits for everywhere around the plant," said Irwin. "We also have to have a much more robust surveillance system."
The 30 percent
increase in direct gamma radiation around the plant was attributed to a power uprate in 2006 from 520 to 650 megawatts, according to the annual report.
Also blamed for the increase were a pair of corrosion-control procedures -- injecting hydrogen into and adding noble metals to the reactor cooling system.
The increase was predicted during hearings to review Entergy's request to increase power output at the plant.
This year, the department applied a conversion factor to its measurements to more precisely calculate the amount of radiation that could be absorbed by a person who is exposed, according to the press release.
In addition, said Irwin, the department did away with its "plus-or-minus-five" uncertainty factor. Getting rid of the factor puts Vermont Yankee on notice, he said.
"The report clearly specified to Vermont Yankee that there is no allowance about our limit any longer. It should be very clear at 18 millirems and a hard and fast limit of 20 millirems and no adjustment on the basis of plus or minus five there's not a great deal of margin for compliance."
Those opposed to Yankee's continued operation said the conversion factor is only being used to give Vermonters a false sense of security.
"Anytime you have a 30-percent increase it should be of concern, especially to those people who live nearby," said Bob Stannard, spokesman for Citizen Awareness Network.
If the state had not applied its conversion factor to its measurements, the high reading of 18 millirems would have been around 23 millirems.
Stannard called this "moving the benchmark."
The department is not trying to fool anyone with the conversion factor, said Irwin.
"We're trying to be transparent and open," said Irwin. "If we wanted to, we could have simply put the final numbers in there. We could have said nothing about using dose conversion factors."
It may be many years before we know what the real effect is of the uprate, said Stannard.
"How long does it take," said Stannard. "We'll have to wait 20 years and then decide it was a bad idea."
In addition to keeping track of radiation levels around the power plant in Vernon, the department also conducted an analysis of the health of people who live near Yankee with respect to radiation-related illness.
"The analysis concludes that there is no statistically significant difference between those who live in the six towns near Vermont Yankee and those who live elsewhere in Windham County or elsewhere in Vermont," stated a press release accompanying the report.
Epidemiological studies are based upon death certificates, said Maggie Gundersen, a paralegal who has worked on nuclear safety issues. Her husband Arnie was recently appointed to a three-person panel overseeing a state evaluation of the power plant.
"People with cancer leave Windham County to be treated elsewhere. If they die elsewhere, they are not in the Windham County statistics," she said. "I have not seen any U.S. or Canadian studies that accurately track and monitor the health effects of radiological isotopic releases from operating nuclear power plants. Without that concrete statistical data, any conclusion is meaningless because it is not based upon sound scientific and medical analysis."
The increase in radiation levels due to the uprate was the only significant change in the more than 1,300 measurements the department takes of air, water, milk, soil, vegetation, sediment and fish taken at the site boundary and in the six surrounding towns, according to the report.
"The state health department's conclusions on radiation releases from the plant are consistent with the data we have seen," said Neil Sheehan, spokesman for the NRC. "The federal limit for radiation exposure for a member of the public at a plant's fence line is 25 millirems per year. That would mean someone standing at the fence line for the entire year. These limits are conservatively set and protective of public health and safety. The levels recorded by the state fall below these thresholds."
Before the power uprate, only six dosimeters were used to measure radiation at the site boundary. Since then, 20 have been added. Another 45 are located throughout Vernon and Windham County, including the Vernon Elementary School and 10 other locations nearby. Thirty-four background dosimeters are located in the six Vermont towns in the emergency preparedness zone around Yankee.
One detector at the plant had a reading of 47 millirems. The high reading is due to the fact the device is located on the river side of the plant and is placed relatively close to the reactor, said Irwin.
Vermont Yankee also has its own dosimeters and other equipment for measuring releases.
"We have worked closely with the state department of health and the national lab as they developed a scientifically valid means of determining the level of radiation present over the long term," said Rob Williams, spokesman for Yankee. "The data clearly shows that our operations are within the state limits which are the most stringent limits set for any plant in the country."
Bob Audette can be reached at [email protected] or 802-254-2311, ext. 273.
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Copyright (c) 2008, Brattleboro Reformer, Vt.
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