LACEY TOWNSHIP - A leak at the Oyster Creek Generating Station contains tritium, a radioactive form of hydrogen, and officials have lowered power at the plant to make repairs.

Oyster Creek, the nation's oldest continuously operating nuclear power plant, is now working at about 50 percent capacity, according to spokesman David Benson.

There is no threat to public or employee safety, Benson and the Nuclear Regulatory Commission said. The tritium has not spread into any public water supplies and is contained on the site, Benson said.

The levels of tritium found in this latest leak, which was first identified Monday, are higher than those found in an April leak.

The tritium levels have been 10 million picocuries per liter of water, higher than the 5 to 6 million picocuries per liter of tritium identified in the leak found in April, he said. By comparison, anything above 20,000 picocuries per liter is considered unsafe for drinking water.

"We are addressing this leak aggressively even as we speak," Benson said.

Exelon, the company that owns Oyster Creek, hasn't decided whether to fully shut down the plant to make repairs, Benson said.

The plant notified New Jersey's Department of Environmental Protection within nine minutes after a water sample from the leak tested positive for tritium, he said.

According to a report released Wednesday morning by the NRC, the leakage appears to come from a 6-inch aluminum transfer line that is used to transport water from condensation. It is leaking at a rate of less than 20 gallons per minute.

To operate properly, the plant needs the aluminum line to be in good condition. However, the plant may be able to make temporary repairs and not have to shut down the plant while those repairs are made, according to Neil Sheehan, a spokesman for the NRC.

The preliminary report from the NRC suggests the leakage is passing through the condenser building wall, which is about 4 feet thick. Staff at Oyster Creek have excavated around the wall and found leakage coming from that area. This suggests that the leak is located inside the wall, Sheehan said.

The aluminum pipe is surrounded by a sleeve, so plant personnel would be able to make repairs to the pipe without excavating the wall, according to Sheehan.

The piping in question was replaced in 1994 and last inspected in 2007.

"It's not as though this is piping that hasn't received attention," Sheehan said.

Oyster Creek is required to stop the leak as soon as possible.

This is the second leak to contain tritium that the Oyster Creek plant has faced in 2009. The leak in April occurred within days of the plant's operating license being renewed for another 20 years.

Assemblyman Brian E. Rumpf, R-Ocean, Burlington, Atlantic, was pleased that the plant acted appropriately in reporting the leak and immediately attempting to fix it. However, the assemblyman previously pressed the NRC to be more open with documents related to the previous leak at Oyster Creek.

Sheehan said that the documents have been withheld because of concerns from Exelon that the documents could contain private information.

"This begs the bigger question of why (the leaks are) happening," Rumpf said Wednesday.

New Jersey environmentalists who protested the relicensing pointed to the fact that this is the second leak this year.

"This clearly demonstrates that plant should not have been relicensed for another 20 years," said Jeff Tittel, director of the New Jersey Sierra Club, in a statement released Wednesday. "The plant is unsafe, and the NRC is more concerned about protecting Exelon than public health and safety."

"We know that Oyster Creek is unsafe and unreliable," said Matt Elliott, clean energy advocate for the group Environment New Jersey. "That gets proven every time it leaks. At what point do we pull the plug on this dinosaur's life support and move full-speed ahead toward cleaner, safer, renewable technologies?"

The nuclear plant has a capacity of 619 megawatts, enough to generate electricity for about half a million homes in New Jersey. About 450 people are employed at the plant, not including security personnel, according to Exelon's Web site.

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