Millstone seeks source of leak of radioactive element

December 29, 2007

http://www.newsday.com/news/local/wire/connecticut/ny-bc-ct--millstoneleak1229dec29,0,1966240.story

WATERFORD, Conn. (AP) _ Millstone Power Station is trying to find the source of a leak of tritium, a radioactive element that was first discovered leaking a month ago at the nuclear power complex.

Pipes that scale a water storage tank at the Unit 3 reactor at Millstone may be leaking water laced with small amounts of tritium, a byproduct of the fission process. It's a naturally occurring form of hydrogen found in reflective watch faces, road signs and other items.

Tritium is a low-energy isotope that emits a weak form of radiation and does not travel far through the air, though it can be absorbed in the skin.

Millstone owner Dominion has ruled out the reactor core and the spent fuel pool as sources of the tritium leak, which was first discovered Nov. 27.

The company is focusing on pipes that travel along the outside of a tank.

"We've looked in other places and found no (leak) of tritium, and that's the only place nearby that could be the source," Pete Hyde, a spokesman for Dominion, said.

Dominion has hired a contractor that will begin work next month to examine pipes and drill wells to determine how far, if at all, the tritium leak has spread.

The radioactive element is bubbling up in low levels in groundwater beneath a foundation drain sump well where water collects after it is drawn from the reactor, Hyde said.

So far, the leak has not spread in groundwater to any of 41 monitoring wells at Millstone, said Hyde and Neil Sheehan, a spokesman for the Nuclear Regulatory Commission.

Levels of the isotope at Millstone exceed drinking water standards set by the U.S. Environmental Protection Agency, but are far below standards for water not intended for drinking, Sheehan said.

Sheehan characterized the leak as minor but said similar leaks over the past few years _ at the Braidwood Station in Illinois and Indian Point in New York _ prompted the industry to respond more rapidly to tritium leaks with voluntary reporting to federal regulators.

Officials are concerned that continued leaks of water laced with tritium could migrate through the groundwater and eventually off site into neighboring residents' wells.

The state Department of Environmental Protection is paying attention to Millstone's work, and the inability so far to isolate the leak, DEP spokesman Dennis Schain said. Staff from DEP's radiation division have been at Millstone, discussing the matter with Dominion officials, he said.

"We're definitely watching it and are in touch with (Dominion) on their findings," he said.

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