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Entergy Mississippi was one step from rolling blackouts in frigid January

OFFLINE: During the coldest week in Mississippi, Grand Gulf Nuclear Station was off line. Photo by Entergy

On the coldest few days of the year, Entergy Mississippi had nearly run out of juice.

The utility was crippled by issues with its aging generation fleet and the regional transmission organization that it belongs to was down to the last step — buying expensive electricity from other utilities — before rolling blackouts began.

The company asked its 445,000 customers in the western part of Mississippi to reduce their usage during the cold snap, when temperatures dipped as low as 11 degrees in Jackson.

According to data from MISO, the RTO that Entergy joined, the demand on the grid in the South Region on January 17 was only 1.8 percent less than the record usage day on August 10, 2015.

The MISO South region includes Entergy, Louisiana utility Cleco, and Cooperative Energy (formerly South Mississippi Electric Power Association) in parts of Arkansas, Mississippi, Louisiana and Texas.

Plant outages in Louisiana were the biggest culprit in MISO South's struggles on January 17, as 57.1 percent of the missing generation capacity was from the Pelican State.

According to the same report, of the 17,000 megawatt capacity on the MISO grid in the South region, 3,551 megawatts were derated, which means a generation plant was not able to reach its full capacity rating because of equipment breakdowns or environmental concerns. Another 4,049 megawatts in generation capacity was down for planned maintenance, which means only 9,466 megawatts were fully available.

The biggest problem for Entergy was the unreliability of Grand Gulf Nuclear Station, which began a forced outage on January 8 that didn't end until January 17, when the plant was generating at 17 percent of its 1,440 megawatt capacity. The plant became operational in 1985.

Grand Gulf's reactor was scrammed on January 30, which means an emergency shutdown using the control rods was initiated. The report filed with the federal Nuclear Regulatory Commission says that an oscillation in the electricity-generating turbine of 30 megawatts precipitated the scram.

Grand Gulf was given an investigation report — which dated from investigations on November 5, 2015 and March 6, 2017 — by NRC officials on November 20 that highlighted several breaches of NRC rules that included:

  • An examination proctor deliberately compromised examinations by providing inappropriate assistance to contractor personnel.

  • Workers not conducting rounds to check plant equipment and condition.

  • Workers documenting that they'd completed the inspection rounds without having done so.

On March 14, the NRC and Entergy reached a deal in which the company will take steps to prevent willful misconduct at its seven nuclear plants.

The rest of the Entergy Mississippi generation fleet — with the exception of its two newest natural gas combined cycle plants in Hinds and Attala counties acquired through sale in 2012 and 2007 — is barely picking up the slack from Grand Gulf.

In 2016, the Attala and Hinds plants accounted for 64 percent of Entergy's non-nuclear generation output.

In 2015, the two plants accounted for 74 percent of Entergy's non-nuclear generation while in 2014 it was 67 percent. The pair accounted for 41 percent in 2013.

Entergy Mississippi has also bought capacity from its sister company in Arkansas in 2012 provided by its Independence coal-fired plant.

In 2016, the Arkansas plant's output provided to Entergy Mississippi made up 19 percent of its non-nuclear capacity, while in 2015 that figure was 17 percent.

In 2014, the Arkansas plant made up 31 percent of Entergy Mississippi's non-nuclear generation output, while in 2013 it was 26 percent.

The reason for the discrepancy between the production of the two newer plants and the rest of the fleet is age. Located in Vicksburg, Baxter Wilson facility's two generating units became operational in 1967 and 1972.

The Gerald Andrus natural gas plant in Greenville was completed in 1975.

The Rex Brown facility in Jackson has three natural gas units and one oil-fired unit and they were completed in 1951, 1959 and 1968.

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