Just as Grand Gulf Nuclear Station is emerging from a nearly four-month-long refueling outage and power upgrade, two dozen environmental groups have asked the Nuclear Regulatory Commission to halt a process to renew operating licenses at the Claiborne County plant and 16 others.

The groups want the plant to comply with a federal court ruling this month that the NRC revisit the issue of spent nuclear fuel.

Grand Gulf’s license expires in 2024, and an application to extend it an additional 20 years is expected to be finalized by September 2013.

In a statement Tuesday, Entergy Nuclear spokeswoman Suzanne Anderson said the plant’s license renewal remains on track.

“At this time, there is no reason to believe the court’s June 8 decision will impact the current license renewal schedule for Grand Gulf,” Anderson said.

In the decision, the U.S. Court of Appeals for the D.C. circuit threw out the so-called Waste Confidence Rule, used since 1984 by the NRC to license new reactors or re-license existing reactors for additional 20-year periods.

It held that highly radioactive fuel rods from reactors nationwide would be stored safely until a central repository was established.

In 2010, the Department of Energy abandoned efforts to license such a site at Yucca Mountain, northwest of Las Vegas, after a torrent of opposition from environmentalists and members of Congress over long-term emissions from the site. Since the 1990s, spent fuel rods have been stored on-site in deepwater pools.

The decision would require the NRC to analyze the impact of storing fuel rods for decades at a time while a more permanent repository is found, according to a release from Beyond Nuclear Inc., one of 22 groups and individuals who petitioned NRC to stop all license renewals until it wrote new guidelines on the matter. The Maryland-based organization identified Grand Gulf’s renewal proceedings as one it would attempt to intervene.

“This petition is to ensure that the environmental analysis directed by the court is meaningfully incorporated into the licensing of nearly 35 reactors in a number of states,” read part of the release.

Additional petitioners included the Blue Ridge Environmental Defense League and Public Citizen Inc., among others.

Other plants with pending renewals mentioned in the petition were Callaway Plant, in Missouri; Calvert Cliffs, in Maryland; Fermi Nuclear Power Plant, in Michigan; William States Lee III Nuclear Station, in South Carolina; Davis-Besse Nuclear Power Station, in Ohio; Turkey Point, in Florida; Comanche Peak Nuclear Plant, in Texas; Seabrook Station, in New Hampshire; Diablo Canyon Nuclear Plant, in California; Bell Bend Nuclear Plant, in Pennsylvania; Shearon Harris Nuclear Plant, in North Carolina; Levy County Nuclear Plant, in Florida; South Texas Project, in Texas; Bellefont and Watts Bar nuclear plants, both in Tennessee; and North Anna, in Virginia.

Entergy Nuclear stood by a key nuclear industry policy group’s stance, issued the day of the ruling. The D.C.-based Nuclear Energy Institute said it was “disappointed” by the court’s decision but did urge the NRC “to act as expeditiously” to start the environmental analysis identified by the court. “We also encourage the agency to reissue the rule as soon as possible,” the organization said.

This month, Grand Gulf began to wind down the refueling outage and power upgrade. More than 5,000 workers from 76 contracted companies and smaller subcontractors have worked to increase power generating capacity by 13 percent, which will make it the nation’s most powerful single reactor. Most recent estimates have put the cost of the project at $874 million.