ColumbiaStation.jpg

Steam rises from Energy Northwest's Columbia Generating Station, the region's only commercial nuclear reactor, near Richland, Wash., in a 2003 file photo. (The Associated Press)

A nuclear plant in Richland, Washington, was shut down last weekend after cold weather caused a malfunction in Bonneville Power Administration equipment connecting the plant to the region's electrical grid.

The Columbia Generating Station, the only nuclear station in the region, has been inoperative since Sunday morning, said Mike Paoli, a spokesman for Energy Northwest, which operates the plant. The station lost use of a 500-kilovolt line because of the malfunction, forcing an automatic safety shutdown, Paoli said.

After the outage, crews discovered a leak in the plant's high-pressure cooling system, a standby system that cools the nuclear reactor core in event of an emergency. The leak was unrelated to the outage, Paoli said.

The system leaked water and was a "minor maintenance issue," Paoli said. The leak was fixed by Tuesday night, Paoli said.

Dave Lochbaum, the director of the Nuclear Safety Project, a nuclear watchdog group run by the Union of Concerned Scientists, agreed the leak was a minor problem. The cooling system is not needed when the plant is already shut down, he said.

A report filed with the Nuclear Regulatory Commission said the leak was not an emergency but the plant could not operate until it was fixed.

Though the leak is repaired, the plant will not resume operations until the BPA takes corrective action to prevent the equipment from malfunctioning again, Paoli said.

It will likely be a few days until the plant is operating again, Paoli said.

-- Samantha Matsumoto

@SMatsumoto55, 503-294-4001