Power production at Grand Gulf Nuclear Station remained halted this morning after a feedwater pump tripped Monday.

Loss of water pressure sufficient for the Claiborne County facility to produce electricity prompted the shutdown, Entergy Nuclear spokesman Suzanne Anderson said this morning.

Protocol requires that power be increased gradually until the plant can go back on the grid, Anderson said. The plant, the only nuclear-fired plant in Mississippi, was operating at 10 percent of its startup power, according to the Nuclear Regulatory Commission’s daily status report update. Anderson said the 672 workers were on site today, about 30 percent more than a typical day because of the shutdown.

“Repairs were made safely yesterday,” Anderson said. “Right now, we’re looking to ramp up slowly.”

The failure, which occurred at 4:35 p.m. Monday, was the first unplanned shutdown of operations at the reactor since 2008 when there were four such shutdowns. Entergy’s power grid is served by multiple generating plants, and the shutdown had no effect on service to consumers.

Federal regulators are expected to present the findings of Grand Gulf’s 2009 inspection report this month, Anderson said.

A $574 million upgrade to the plant’s power generating capacity — making it the nation’s largest single nuclear reactor — was approved by the Mississippi Public Service Commission in October. An OK from the NRC is expected by the end of 2011 and major work is set to begin in 2012, plant officials have said.

Plans for a second reactor at the facility were put on hold in 2009 due to cost estimates to build its core.

Customers in Mississippi, Louisiana and Arkansas receive electricity from the $3 billion plant, completed in 1985 following an 11-year construction period.

Contact Danny Barrett Jr. at dbarrett@vicksburgpost.com