Grand Gulf Nuclear Station earned favorable ratings from federal regulators for safety performance in 2009, based on an annual safety and preparedness inspection.

Mississippi’s only nuclear plant operated in a manner that preserved public health and safety, according to the Nuclear Regulatory Commission. For three-quarters of the year, inspections of the Claiborne County facility showed very low safety significance and all performance indicators at levels requiring no additional NRC oversight.

Those findings for the second, third and fourth quarters put the plant in the highest possible safety grouping in the NRC’s color-coded system. Colors start with green and descend to white, yellow or red in the order of safety significance in various ratings. Those areas include incident response, integrity of the barriers between radioactive fuel inside the reactor and the public, emergency planning and limiting radioactive exposure to workers.

A first quarter inspection showed a white-coded performance indicator, tied to an “additional supplemental inspection” in February 2009, according to the NRC’s letter to Entergy Operations Inc. The extra inspection was done as a result of the agency’s response to two shutdowns during the fourth quarter of 2008, when four occurred altogether. Equipment failure caused three of that year’s interruptions in power production, according to the NRC’s senior resident inspector when the 2008 assessment was released.

The unit is returning to full power after a feed-pump trip March 8 halted production of electricity, an incident that did not affect service to Entergy customers but is sure to affect next year’s federal inspection. Output had risen to 99 percent of capacity Wednesday.

Results of a separate survey dealing with safety culture at Grand Gulf and four other Entergy-operated nuclear plants in Louisiana, Arkansas and Nebraska will be discussed Wednesday at NRC regional offices in Arlington, Texas.

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