RATTLEBORO, Vt., Dec. 4 — Some people here never liked the Vermont Yankee nuclear plant, worrying about accidents and radioactive waste. Others always thought it was a reliable, cheap and clean source of electricity. Over 30 years of arguing, they had mostly run out of new things to say and bored the general public with their arguments. But that was before Sept. 11.

Now discussions about Vermont Yankee, and other reactors around the Northeast, are drawing big crowds. There were 600 people here on Monday night, in the auditorium of Brattleboro Union High School, not counting the 20 federal, state and local officials on stage to answer their questions. They were at it for four hours, and a while longer in the parking lot.

"This is a small town, in a small state," said Representative Bernard Sanders, who convened the meeting, marveling at the turnout. "People are very, very concerned."

Last month there were hearings near the Pilgrim plant, in Plymouth, Mass.; the Seabrook plant, in the New Hampshire town of the same name; and the undamaged reactor at Three Mile Island, near Harrisburg, Pa.

There was also a hearing near the Maine Yankee plant, in Wiscasset, Me., which was shut down five years ago, but where radioactive spent fuel is still stored. Next week in White Plains, a committee of the Westchester County Board of Legislators plans a hearing on whether to revoke approval of the emergency plan for the Indian Point reactors. A hearing about the dangers of spent fuel is planned for the Shearon Harris plant in North Carolina.

"Sept. 11 has been the biggest challenge to nuclear power since Chernobyl," said David Lochbaum, a nuclear engineer at the Union of Concerned Scientists, a nonprofit group that frequent criticizes government oversight of nuclear safety. "Congressmen who have had very little interest in nuclear power in the five years I've been at U.C.S. are suddenly competing with each other to examine security issues at the plants."

Although it is not clear how seriously local governments or members of Congress can threaten the future of licensed reactors, the industry hardly welcomes the discussion.

Until Sept. 11, the outlook for the nation's 103 nuclear power plants was improving. The years since the 1986 accident at Chernobyl have been mostly quiet, with no significant unusual radiation releases in the United States, and rising reliability. Reactors were beginning to look more attractive given the increasing demand for electricity. Several have recently won 20-year extensions on their 40-year licenses, and others have met the first challenge of deregulation of the electricity business, having sold at prices higher than analysts expected.

But since Sept. 11, public officials have mused publicly about whether a nuclear plant would withstand the crash of a jet any better than the World Trade Center did, and the technology's opponents have found a wider audience.

"We have handed our enemies a radiological weapon, a target of opportunity," said Ned Childs, one of dozens of people who spoke at the hearing last night. Mr. Childs lives in Dummerston, Vt., 10 miles from the plant in Vernon.

State officials have voiced the same concern. Kate O'Conner, chairwoman of the Vermont Terrorist Task Force, said Sept. 11 had prompted Gov. Howard Dean, who is a doctor, to seek a stockpile of a drug to protect the public against radiation-induced thyroid cancer, something that has been debated nationwide for 20 years.

The industry does not relish the attention. At the Nuclear Energy Institute in Washington, Angelina Howard, a spokeswoman for the industry's trade group, said some people in New York and New England had always shown "skittishness" about nuclear power. But elsewhere, she said, there were anecdotal reports that more tourists were stopping by the visitor centers at the plants, or at least those centers that were still open after Sept. 11.

"When the public has a concern and they go look into it, usually they come off feeling better about it," she said. Opinion polls commissioned by her organization show growing approval of nuclear power since Sept. 11, Ms. Howard said.

The Nuclear Regulatory Commission has defended the design of the plants. Hubert J. Miller, the commission's administrator for the Northeast, said that while Vermont Yankee's designers did not have an attack by a Boeing 767 in mind when they designed it, the building is "very robust," and that nuclear plants are among the strongest buildings of any kind.

Defending Vermont Yankee's security preparations is somewhat harder. On Aug. 23, it was the plant's turn for a mock attack by federal agents playing terrorists, and the evaluators found so many deficiencies that they graded the plant "yellow," in a grading system that runs green, white, yellow and red. It was the lowest grade in the industry.

But Mr. Miller said the problems had been corrected.

At the town meeting, calls for conservation and renewable energy drew applause, although this being Vermont, at the mention of windmills, one strong voice shouted, "They're bird killers."

Ross Barkhurst, the chief executive of the Vermont Yankee Nuclear Power Corporation, stood his ground on reasons of safety and economics. Speaking of wind power, he said: "As long as we have the ability to compete, bring it on. Right now my best friend is the renewable energy we have in the state — it costs about two and a half times what mine does."

Public officials here and elsewhere have described the risk of terrorist attack on a reactor, especially by big planes, as remote, though some members of the public doubt the government's ability to pick what the next target might be.

"I know the opinion of many of you is that the best thing to do is not to have a plant down here," said Edward von Turkovich, the director of Vermont Emergency Management, to loud applause. But he added, "We're going to coexist with a plant. The best thing to do is to have a plan in place."