Source of tritium leak at Oyster Creek still unknown

Federal and state inspectors are still trying to determine how the radioactive isotope tritium entered a concrete vault and a monitoring well at the Oyster Creek Nuclear Generating Station last week

Plant spokesman David Benson said the elevated levels of tritium did not pose any risk to the public.

"There is no danger," he said Monday. "We found this and we reported this as quickly as we found it. We are confident the tritium remains on plant property. Our investigation indicates the tritium is confined to a very small area inside the protected area of our plant."

Analysis of water samples taken from the plant's discharge canal and six of seven monitoring wells showed no detectable levels of tritium, Benson said.

But one 20-foot-deep monitoring well tested positive for tritium and showed levels up to 4.46 million picocuries per liter of water. A picocurie is one-trillionth of a curie, he said.

The tritium was discovered on April 15, seven days after the federal Nuclear Regulatory Commission renewed Oyster Creek's operating license for another 20 years. The 40-year-old plant is the oldest nuclear plant in the United States.

The affected monitoring well was last sampled on March 10, when no detectable levels of tritium were found, Benson said.

The tritium found in the concrete vault was discovered during routine environmental monitoring, he said.

It most likely entered the tank through underground electrical conduits that pass near a condensate storage tank and enter the vault, Benson said.

"They believe the leak may be coming from pipes associated with the condensate storage tank," NRC spokesman Neil R. Sheehan said. "That tank stores hundreds of thousands of gallons of water to be used in an emergency. You take water from the tank and pump it into the reactor, to keep the fuel covered."

Tritium is produced naturally in the upper atmosphere, in the environment at very low levels, during nuclear weapons explosions, as a byproduct in reactors that produce electricity, and in special production reactors, according to the federal Environmental Protection Agency's website.

Inspectors from the federal Nuclear Regulatory Commission were on-site early this week along with representatives from the state Department of Environmental Protection to determine the appropriate cleanup method, Benson said.

"Exelon is committed to cleaning up the area and locating the source," he said.

The NRC established a tritium task force several years ago. Plants are now required to report tritium leaks, which they didn't have to do in the past, NRC spokesman Neil R. Sheehan said.

"Now they do, which is a good thing," he said.

"We will be looking over their shoulders to ensure they are doing the right things," Sheehan said.

Oyster Creek officials reported the findings to the DEP within 15 minutes of receiving the results and to the NRC within four hours, Benson said.

"We want to be as transparent as possible," he said.