Plans to make Grand Gulf Nuclear Station the nation’s single most powerful reactor could be presented as soon as next week to the Nuclear Regulatory Commission, Entergy spokesman Mara Hartmann said this morning.

If approved by the NRC, the upgrade is scheduled for February 2012 during regular maintenance outages, pending federal approval. Entergy expects the expansion will take at least a few weeks, but has no definitive timetable. NRC is expected to take 11 months to review the data.

Approval by federal nuclear regulators will increase output by 13 percent, from 1,265 megawatts to 1,443 megawatts, Entergy Mississippi officials have said. The Claiborne County plant will produce enough electricity to power an additional 53,000 homes around the clock for the life of the plant after the upgrade, officials said.

The expected output is about 9 percent higher than the most productive reactor at Arizona’s Palo Verde plant, though that facility’s three reactors generate more electricity overall, at more than 4,000 megawatts.

Average monthly usage per household typically is measured at about 1,000 kilowatts. Costs of the upgrade would be dispersed among the facility’s joint owners, which include Entergy subsidiaries in Arkansas, Louisiana and New Orleans. For individual customers, bills will rise slightly the first year after the upgrade, then become savings by 2017, according to the state Public Utilities Staff. Precise costs from month to month depend on the price of natural gas, which is the source for about 60 percent of Entergy’s power.

About 1,000 to 1,500 temporary jobs in construction, engineering and technical areas will be added as a result of the upgrade, company officials have said. Hotel bookings in Vicksburg spiked more than 10 percent during the spring due to contract workers employed on the project.

Grand Gulf was started up in 1985 after an 11-year construction period and uses a controlled nuclear reaction to generate heat to boil water. The resulting steam is piped under pressure to a turbine, which spins to generate electricity that goes onto a grid with power from other plants. The upgrade intensifies the process — more steam through a faster, more efficient generator.