TVA’s application to build new nuclear reactors in North Alabama was rendered “fatally deficient” last month when the utility resurrected plans to also finish the two original nuclear units at the same site, three environmental groups said Friday.

The Blue Ridge Environmental Defense League and two related anti-nuclear groups — Bellefonte Efficiency and Sustainability Team and the Southern Alliance for Clean Energy — petitioned the U.S. Nuclear Regulatory Authority to suspend TVA’s request to build two new reactors at its Bellefonte nuclear site.

In a 13-page filing to the NRC, the environmental groups said the application from TVA and its partner, NuStart Energy Development LLC, did not justify operating up to four reactors at Bellefonte, where critics already question whether more power plants could cause thermal pollution and endanger wildlife.

“The environmental impact statement was written only for the two new units and the cumulative impact of possibly having four units at the site was not even considered,” said Louise Gorenflo, a leader in the Bellefonte Efficiency anti-nuclear group.

But TVA said its application for the new reactors met all environmental standards and was not significantly altered by its announcement in August of plans to possibly resurrect the construction permit for two previously scrapped reactors at Bellefonte.

“We are exploring the feasibility of additional units, but we have not made any decision yet,” TVA spokesman Gil Francis said.

The NRC’s Atomic Safety and Licensing Board is considering a request from TVA and NuStart, a consortium of nuclear utilities, for a combined operating license for the new reactors at Bellefonte. The NRC panel agreed Friday to conduct another hearing on four of 19 challenges raised by anti-nuclear groups to the Bellefonte application.

Ken Clark, a spokesman with the Nuclear Regulatory Commission, said the government was in the early stages of reviewing requests to reinstate construction permits for the unfinished Bellefonte reactors and possibly to build two more reactors at the plant.

“It’s all under consideration,” he said.

TVA began construction in 1974 of two reactors at its Bellefonte site in Hollywood, Ala. But building on those units was halted in 1988 — and the construction permit for the original units abandoned in 2006 — after TVA determined it would be too costly to finish the incomplete units.

Last year, TVA and NuStart filed a license application to build two next-generation nuclear reactors at Bellefonte under a more streamlined licensing process. But because of rising material costs, TVA asked the NRC in August also to reinstate the construction permit to finish the original units as a possible alternative to building the new reactors.

Lou Zeller, a legal representative for the three environmental groups, said the NRC shouldn’t allow TVA to alter its application by doubling the number of potential units it may build at Bellefonte.

“Their stop-start approach to nuclear power is no excuse,” he said.

The Associated Press contributed to this story.