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Columbia Nuclear Plant Goes Off Line by Annette Cary The News Tribune, February 10, 2009

Columbia Generating Station automatically shutdown at 11:25 a.m. Sunday when monitoring equipment indicated a potential problem with systems that regulate steam flow across the blades of the main turbine.

The turbine drives the nuclear power plant's generator to produce electricity.

The plant northwest of Richland will remain shut down while crews investigate and repair the turbine control system, said Energy Northwest officials. That will take a minimum of two days.

The Bonneville Power Administration, which receives the power from the plant and sells it to retail customers across the Northwest, already has made arrangements to replace the electricity output from the plant, according to Energy Northwest.

The problem occurred during a routine test Sunday when a valve did not respond as expected and monitoring equipment automatically shut down the plant, said Rochelle Olson, Energy Northwest spokeswoman.

The hydraulic valve controls hydraulic fluid to a steam valve.

It's part of the same complex digital electro-hydraulic system that resulted in the 1,150-megawatt plant tripping off line in August. Then, one of many pipes in the system that regulates steam flow over the turbine blades dislodged from its fitting.

Before the shutdown, the plant provided power to the electrical grid for 80 days. It last had been shut down for planned maintenance in November.

The next scheduled shutdown is for refueling in May.