MONTPELIER, Vt. (AP) — When the federal Nuclear Regulatory Commission announced last week that it would grant the Vermont Yankee nuclear plant a 20-year extension on its operating license, the plant’s supporters won a fresh and strong talking point toward improving the reactor’s political fortunes in Vermont.

Only hours later, the devastating earthquake and tsunami in Japan set off a disaster at reactors of the same design and vintage as Vermont Yankee. Politically, the trouble-plagued plant’s chances appeared doomed.

“I don’t think they had a pulse last week, but we’ve picked out the casket now,” said Rep. Tony Klein, chairman of the Vermont House committee that oversees Vermont Yankee, said of the plant’s political prospects in the state.

Nuclear politics is unusually raw in Vermont, the only state with a law calling on its legislature to give the OK before regulators give the state’s approval for the license extension.

But across the country, the nuclear industry is coming under new scrutiny, with questions being raised about whether a big dose of bad news about the technology might cool the ardor for a renaissance in the industry.

“The timing could not be worse,” said Richard Levick, CEO of Levick Strategic Communications, a Washington-based firm that advises companies on how to handle public-relations crises. “We saw the American nuclear industry really starting to reposition itself for growth. At best this is a short-term setback.”

The government has already offered $18.5 billion in loan guarantees for new nuclear plant construction, and President Barack Obama, a strong supporter of building new reactors, has asked in his recently proposed budget for $36 billion more.

Of the money already allocated, $8 billion is earmarked for a new plant in Georgia, due for a groundbreaking later this year. Obama and other supporters say they expect the twin reactors planned near Waynesboro, Ga., will be the first of a new fleet of reactors that will help the nation wean itself from imported oil and other carbon-emitting fossil fuels.

On Monday, four days after announcing his agency’s green light for the 20-year license extension at Vermont Yankee, NRC Chairman Gregory Jaczko told reporters at the White House he did not want to speculate about whether U.S. reactors would be able to withstand a disaster as severe as the one that struck Japan.

For critics of the industry, that’s a big problem.

Just as Japan did not plan for an earthquake as powerful — and a tsunami as large — as what struck the Fukushima reactors, no one can plan for a future unknown disaster that might hit a U.S. nuclear plant, said Arnold Gundersen, a former nuclear industry engineer who has advised the Vermont Legislature on nuclear issues.

“What we thought was impossible last week is now commonplace this week,” he said. “The chance of a single meltdown was one in a million and now we’ve having three in five days.”

Gundersen said a report he helped write for a legislative oversight committee in 2009 concluded that Vermont Yankee did not meet current standards for ability to withstand an earthquake.

Vermont Yankee is one of three nuclear plants in New England that have still-unresolved applications seeking permission to run for an additional 20 years beyond their original 40-year licenses. The Vermont reactor’s fate is unresolved only at the state level.

Legislative leaders say they have no plans to reopen an issue they regard as resolved last year when the state Senate voted 26-4 to block the state Public Service Board from issuing Vermont Yankee a state permit to operate after 2012. Senate President John Campbell said he was afraid Vermont Yankee’s owners may try to continue operating even without a state permit, which he said would make it a “rogue nuclear plant.”

House Speaker Shap Smith said there’s no point in bringing the matter up in his chamber given the Senate’s strong opposition. But he said House lawmakers also have strong misgivings, especially about plant owner Entergy Corp.’s failure to fill a projected shortfall in Vermont Yankee’s decommissioning fund and make plant upgrades recommended by a legislative oversight panel.

The NRC also is reviewing renewal applications from the Pilgrim plant in Massachusetts, the Seabrook plant in New Hampshire, Indian Point in New York and Davis-Besse in Ohio. Vermont Yankee’s is the 63rd renewal application it has approved, against no rejections.

Vermont Yankee is a General Electric boiling-water reactor with a GE Mark 1 containment dating from the early 1970s — the same as the Fukushima reactors. Vermont Yankee spokesman Larry Smith said the plant was designed to withstand a magnitude-6.2 earthquake, slightly larger than the strongest recorded earthquake to hit the region, a magnitude-6 temblor centered in East Haddam, Conn., in 1791.

As the crisis in Japan worsened, U.S. nuclear industry officials were scrambling to reassure the public. New Orleans-based Entergy Corp., which owns Vermont Yankee, Pilgrim and Indian Point among other plants, issued a statement saying “lessons will be learned and translated to even greater safety and effectiveness to meet the challenges of the most adverse and unexpected events, creating stronger public confidence in U.S. nuclear programs.”

It said the NRC has required U.S. plants be built to withstand the worst historical natural disasters in their regions, with extra safety margins added in.

But Richard Brodsky, a former long-time New York legislator and lawyer who has done battle with Indian Point on a range of issues, argued in an interview Tuesday that the NRC has been no tougher a regulator than the Securities and Exchange Commission and other federal agencies that allowed the financial meltdown of 2008 to happen.

“We had a meltdown there. That was the phrase that was used — a financial meltdown,” Brodsky said. At the Fukushima reactors in Japan, “We are facing a literal meltdown today.”