WASHINGTON — In the wake of the Chernobyl disaster and Three Mile Island scare nearly three decades ago, the environmental movement took up the cause against nuclear proliferation with the rallying cry, “No new nukes!”

But with rising energy prices and worries about global warming, some environmentalists are shifting their position on nuclear power, viewing it as a viable alternative to polluting coal-fired plants.

“All we’re doing is saying it’s on the table,” said Tony Kreindler, a spokesman for Environmental Defense Fund, a nonprofit environmental advocacy group. “Our fundamental position in all of this is really that the market should sort out what the best technologies are. Nuclear is certainly a possibility.”

Many environmental organizations, however, remain opposed to nuclear power, citing the high costs of getting reactors online and problems with disposing of radioactive waste. Other critics point out that nuclear reactors may become terrorist targets and that spent fuel can be reprocessed into nuclear weapons.

While all environmental groups agree on the need to curb emissions, opponents of nuclear power say the government subsidies and investments in the industry would be better spent on increasing efficiency in appliances or supporting emerging renewable energy technology, such as biofuels, solar and wind.

“I think we can get a lot bigger bang for the buck on energy efficiency,” said Marty Hayden, legislative director of EarthJustice, which opposes building new nuclear plants. “Moving renewables forward in the near-term is more important and should be where the money goes.”

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Polls indicate Americans are growing more supportive of the nuclear industry.

An August 2006 survey by Bloomberg and the Los Angeles Times found 61 percent of respondents said they support the increased use of nuclear power to slow projected global warming, while only 30 percent rejected it. Seventy-one percent of 18-to-29-year-olds supported nuclear energy, compared to 59 percent of respondents 30 and over.

A poll in January 2007 by United Press International and Zogby found 62 percent either “strongly agree” or “somewhat agree” that new nuclear plants should be built. No new nuclear reactors have been built in the United States since the 1979 accident at Three Mile Island in Pennsylvania.

“I think what we’re seeing is that as people are becoming more aware of the problems of air pollution and global warming, people are getting a lot more interested in nuclear as a solution,” said Jonathan Gilligan, a political science professor at Vanderbilt University who studies environmental policy.

That’s exactly how the nuclear industry is promoting itself, as Congress debates climate change legislation that could place carbon emissions caps on power plants.

Tennessee and Georgia lawmakers have been supportive of the industry, saying nuclear power plants produce almost no carbon dioxide, a greenhouse gas emitted by burning fossil fuels, such as coal.

Just over half of the country’s electricity is generated from burning coal, while nuclear generates about 20 percent.

“For decades, we moved away from nuclear. That has hurt our country,” said U.S. Sen. Bob Corker, R-Tenn., a member of the Senate Energy Committee. “We need to step up the pace as quickly as possible. I think we’re going to see a tremendous increase in nuclear usage, and fortunately Tennessee is positioned to be a major part of that.”

The Tennessee Valley Authority, which supplies much of the energy to Tennessee and Georgia and operates three nuclear plants, currently generates 30 percent of its electricity from nuclear power and has plans to increase that percentage by potentially bringing new reactors online.

Given the favorable political climate for nuclear power, many energy experts say the expansion of nuclear power appears inevitable.

“I personally would love to see wind and solar get adopted, but those technologies are a ways off,” Dr. Gilligan said. “Nuclear’s probably going to have to play a part in between until we can get those technologies viable.”