This story was updated at 3:58 p.m. EST.

Vermont, New York and more than 20 watchdog groups say the Nuclear Regulatory Commission cannot conduct a court-ordered review of nuclear waste storage policies within two years.

The groups say the agency will need more than a decade to review the "waste confidence" rule that a federal court found deficient last year.

At issue is the court's finding last summer that the NRC failed to fully analyze the environmental effects of storing nuclear waste at sites across the country without a permanent repository in sight.

The court faulted the NRC for assuming a national repository would be built within the next 60 years, despite decades of political deadlock over the abandoned repository under Yucca Mountain in Nevada. The court then vacated both the agency's waste confidence decision and a separate storage rule (Greenwire, Aug. 7).

In response, the NRC began reviewing its policies and declared its intent to issue a final environmental impact statement and waste confidence rule by August 2014. The agency also decided to hold off on approving licenses for new nuclear plants or renewing the licenses of existing facilities, because the waste confidence rule underlies those decisions.

"We are confident that we can complete a thorough study and publish a comprehensive environmental impact statement to satisfy the court's requirements by September 2014," said Scott Burnell, a spokesman for the agency.

The nuclear industry also believes the timeline is adequate. The Nuclear Energy Institute said in a letter to the commission that it agrees with the two-year approach and the release of a final waste confidence decision and rule by September 2014. NEI also recommended the NRC assess storage with the assumption that a repository will be available up to 100 years after the licensed life of a reactor expires.

But the commission's two-year timeline has drawn the ire of states hosting nuclear reactors.

Vermont Attorney General William Sorrell (D) and New York Attorney General Eric Schneiderman (D) told the NRC last week that the timeline is too short, and risks of storing waste on-site must be fully understood because a repository won't be built or opened anytime soon.

"When NRC previously assumed and predicted that a permanent nuclear waste repository would be available by a date certain -- the latest of such dates being 2025 -- long-term safety and environmental problems associated with spent fuel pool use and on-site spent fuel storage were brushed aside as of minimal relevance," they wrote.

Two years provides only enough time to summarize existing, inadequate information about the dangers of long-term spent fuel storage, environmental groups said.

"The existing information is grossly inadequate to support any reasonable predictive findings about the safety of such long-term spent fuel storage," the groups wrote in comments to the NRC. "It will take a long time, potentially well over a decade, to collect the data needed to make scientifically valid impact analyses for high burnup fuel stored for long periods."

The groups have also pointed out that NRC staff members in the past have said it could take up to seven years to revise nuclear waste storage policies.

But Burnell said that projection "was for a different project looking at the potential environmental effects of spent fuel storage, a project that had low agency priority and just two staffers assigned to it part-time."

The NRC has assigned more than 20 full-time staffers to reviewing its waste confidence rule and can meet a two-year deadline, he said.