U.S. President Barack Obama caused viewers to do a double take when he called for a boost in nuclear energy in his recent State of the Union address.

But while many praised the proposal, opponents doubted the plan would come to fruition.

"To create more of these clean energy jobs, we need more production, more efficiency, more incentives," said the president. "And that means building a new generation of safe, clean nuclear power plants in this country."

THREE CHALLENGES

Opponents, however, took the issue with high costs, safety concerns and the possibility of weapons proliferation.

"While the nuclear power industry promotes nuclear energy as a response to global warming and therefore foresees a 'nuclear renaissance' about to take place, I believe that these three major and interrelated challenges to the industry will seriously hinder its practical implementation," said Paul Walker, director of security and sustainability at Global Green USA, an environmental group founded by former Soviet President Mikhail Gorbachev.

According to Global Green, there are around 104 power plants in the U.S., generating around 20 percent of the country's electricity and accounting for 16 percent of global energy output.

But Walker said he did not see nuclear power rising much above that level and current figures could decline because of the decade-long process for building new nuclear power facilities.

Fears of triggering weapons proliferation may hinder a nuclear renaissance in the United States, although experts have expressed differing opinions over the issue.

Some contend that while creating a nuclear explosion is easy, many nations do not possess the electronics and engineering capabilities to deliver a nuclear device to its target.

Storage space for nuclear waste may also be running out, as the Congress is prohibiting the proposed storage site at Yucca Mountain in Nevada, requiring plant operators to store dangerous nuclear waste on-site at plants, raising public health and homeland security concerns.

SAFETY CONCERN

Safety is another concern. There have been two major nuclear plant accidents in the world -- Chernobyl and Three Mile Island -- and as a result of the latter no nuclear facility has been built in the United States since 1979.

But the Soviet-era power plant in Chernobyl was the result of major design deficiencies, violations of operating procedures and the absence of a safety culture, according to the World Nuclear Association.

Some experts said Chernobyl used an old design and outdated safety features that would not likely be licensed today, and contended the accident was fluke unlikely to re-occur.

But it takes only one accident to spur panic, the fallout of which could halt nuclear power expansion, some analysts said.

"WRONG MESSAGE"

In addition to those risks, some said both Obama and the former Bush administration had sent the wrong message about nuclear power to other countries.

Charles Ferguson, president of the Federation of American Scientists, said certain criteria should be put in place before a country ventured into a nuclear power program -- "safety, security and safeguards," he said.

And nuclear power may not be the best option for all countries, he said, adding that natural gas may be a viable low-carbon alternative for some.

Still, most environmental organizations that released statements on Obama's State of the Union address praised the president's message, which, though, was mostly for pushing the Senate to pass a climate bill.

One exception was Greenpeace, saying in a statement that it was "disappointing to hear the president promote coal, offshore drilling, and nuclear power, since these forms of dirty energy are expensive distractions that stall the fight against climate change."

But organizations like the Environmental Defense Fund, Alliance for Climate Protection, League of Conservation Voters, Natural Resources Defense Council, National Wildlife Federation were among the groups that voiced their support of the president's address.

Ferguson of the Federation of American Scientists said he foresaw no large grassroot movements such as those that followed the Chernobyl and Three Mile Island catastrophes, although there might be more public debates next year when new nuclear facilities would apply for licensing.

Still, Walker of Global Green USA said nuclear power was in the long run unlikely to impact U.S. energy supplies. While 15 applications for 24 new nuclear power plants have been filed with the U.S. government since 2007, none of these is currently under construction, he noted.

And the financial markets are wary of taking on such high risk investments, he added.

Estimates indicate that it will take more than 300 billion U.S. dollars to replace current nuclear power plants, and the storage of nuclear waste will add another 100 billion dollars or more, he said.

Ferguson, however, said an increase in the number of U.S. nuclear power plants could create a windfall of high paying jobs not only for the college educated but also for highly skilled blue collar workers, such as welders, electricians and fire inspectors.

Workers could be trained at vocational schools or community colleges, which could certify students within a two-year time frame to work at nuclear energy facilities, he said.

And while those job possibilities could heighten Washington's interests in nuclear power in this worst economy since the 1930s, some political analysts said Obama's statements were meant to win Republican support for his climate change bill. But Democrats may find the president's nod to nuclear power hard to swallow, analysts said.