Yankee may have found leak
|
|
Toolbox
By Susan Smallheer STAFF WRITER - Published: February 27, 2010
VERNON – The source of the radioactive leak at the Vermont Yankee reactor may have been located, traced back to cracked underground pipes discovered early Friday morning in a drain system, both the state Department of Health and the Nuclear Regulatory Commission said.
And both said other radioactive isotopes, ordinarily found in reactor water, were found in the excavation trench near the suspected source of the leak, which has contaminated about a half dozen groundwater wells at the reactor with tritium.
"This could be a significant development, but they are far from done," said Neil Sheehan, spokesman for the Nuclear Regulatory Commission.
Entergy Nuclear announced Jan. 7 that tritium had showed up in a monitoring well on the banks of the Connecticut River, and since then the contamination has grown and increased.
Sheehan said that cobalt-60, zinc-65, manganese-54 and cesium-137 were all found in the soil near the cracked pipes, although he said later Friday that cesium-137 was found in a different location.
Meanwhile, the Public Service Board said it would open an investigation into whether Vermont Yankee "should be required to cease operations" or if its state certificate of public good should be revoked.
The Conservation Law Foundation and the New England Coalition have been pushing to close down Vermont Yankee because of the tritium leak, which they say poses an immediate threat to the Vermont environment.
Sandra Levine, staff attorney for the Conservation Law Foundation, said that even if the tritium leak has been identified, Yankee still should be shut down.
"It's still significant. Entergy continues to violate the law, their discharges into the Connecticut River is in violation of their license to operate. But the board wants to look beyond the leak, into the management of Vermont Yankee," she said.
The board said that despite the federal pre-emption on most nuclear issues, including safety, it had the power to modify or revoke Entergy Nuclear's certificate of public good if its operation was no longer in the public good, either because of the leak or misstatements Entergy executives have made to state regulators, including the Public Service Board. The board said it would also consider possible penalties against Entergy.
"It is well-established that the board retains significant authority in other areas of traditional state regulation," the board noted. Those areas include land use, economic issues and reliability.
The possible source of the leak has been identified as two cracks in underground pipes in the plant's advanced off-gas system. Two different pipes, one concrete and the other plastic pipe, both showed "significant" cracks, according to the Department of Health.
The cracks were discovered around 5 a.m. Friday during the excavation efforts by Entergy Nuclear of the advanced off-gas pipe tunnel, which carries a two-inch drain line.
There were cracks in the concrete as well as the PVC pipe that surrounds and carries the drain line into the tunnel, according to Sheehan, spokesman for the NRC.
Sheehan said there were three factors leading state and federal officials to think the two cracks may be the source of the tritium. A steam leak in the pipe tunnel was found last week and fixed. It had leaked water into the tunnel, and the regular drain line in the tunnel was plugged with debris, he said, leading to standing water in the tunnel that could have escaped to the groundwater via the cracks.
He said the monitoring wells near the tunnel have had the highest tritium levels, either in excess of 2.6 million picocuries or about 1 million picocuries, but since the steam leak had been fixed, the tritium levels were declining. He said that could also be a result of fluctuating groundwater levels as well.
Larry Smith, spokesman for Entergy Nuclear, said that a "pathway" had been identified in the concrete that encased the off-gas drain line that could have allowed leakage.
"It is important to note that no active process leakage was observed this morning when the condition was identified," said Smith, who took a more cautious approach.
Smith said soil samples had been taken, but so far no results were ready. However, both the Department of Health, which got its samples from Entergy, as well as the NRC confirmed the existence of the new radionuclides.
He noted that officials from both the Department of Health and the NRC were on the scene and monitoring the investigation.
He said that while a majority of the concrete pipe tunnel had been exposed for inspection, the full excavation was expected to be completed later Friday.
He said that an "integrity" test, designed to trace leakage paths to the ground, would be performed today using de-mineralized water.
susan.smallheer@rutlandherald.com
13