Officials investigate possible new leak at Vermont Yankee

Posted
Saturday January 22, 2011

BRATTLEBORO -- Both the Nuclear Regulatory Commission and the Vermont Department of Health have indicated there may be a new leak of tritiated water at Vermont Yankee nuclear power plant in Vernon.

"It doesn't appear to have any connection to the original leakage from last year," Neil Sheehan, spokesman for the NRC, told the Reformer on Friday.

"It's evident that either groundwater can follow the human-made channels or it's another system or components that are leaking," Bill Irwin, chief of radiological health for Vermont DOH.

Both said the level of tritium in the ground water, 9,200 picocuries per liter, poses no danger to public health.

In January 2010, tritiated water was discovered leaking from a pipe tunnel in the Advanced Off-Gas system. The source of the leak was identified and stopped in March.

Larry Smith, director of communications for Yankee, said one of the 32 monitoring wells on site showed a new positive level. He said engineers do not have enough information to determine whether the leak is from a new source or from the previous leak.

"We have a reading we don't understand and are investigating to see what it means," Smith told the Reformer.

Six wells are located between the north edge of the original plume of tritiated water and the well that was identified on Friday, which is about 125 to 150 feet north of the plume, Sheehan said.

"As such, there would not appear to be a connection between the plume and the presence of tritium in this well," he said. "Therefore, this may indicate the presence of a different source of leakage, but investigation will be needed to determine the source."

The well, which was dug in November, had shown only minimal levels of contaminated water, less than 2,500 picocuries per liter, until Jan. 17, Irwin said. It is located in the vicinity of the radioactive waste building, which was one of the areas investigated when the January 2010 leak was discovered.

There might not be a new leak at all, Irwin said, because groundwater could be flowing along service water pipes that run north and south, bypassing the other wells.

However, "If it's a new leak, we need to determine what else may have leaked from those systems," he said.

Other radioactive materials such as cobalt-60, cesium-137 and strontium-90 could also be leaking into the soil, Irwin said.

The amount of tritium in the groundwater sample is well below the EPA safe drinking limit of 20,000 picocuries per liter, Sheehan said.

"We are continuing to review Vermont Yankee's groundwater contamination assessment and mitigation work," he said.

Since the source is unknown, technicians are investigating possible sources for any new leaks including four drain lines from the reactor and turbine building ventilation system and a drain line from the AOG Building, he said.

Entergy has applied to the NRC to continue to operate 20 years past its current license, which expires March 2012. In addition to NRC approval, Entergy must also receive a certificate of public good from Vermont. In February the Senate voted 26 to 4 against the plant's continued operation.

Governor Peter Shumlin, who has vowed to prevent the plant from being relicensed, said he was "very concerned about this change at the Vermont Yankee site. I look forward to quick and transparent action by Vermont Yankee."

Josh Stilts can be reached at jstilts@reformer.com, or 802-254-2311 ext. 273.


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