The failure of the Japanese reactors' backup cooling systems and the explosions that followed are likely to lead U.S. regulators to re-evaluate nuclear plant designs and safety. The heightened scrutiny could increase costs for new and existing reactors, and make it harder to raise money for new plants.
The crisis comes just as the U.S. nuclear energy industry is starting to build the first new reactors in a generation.
"This accident has the potential to tamp down any nuclear renaissance that we're poised to experience," said Tim Echols, a utility regulator in Georgia who supports expanded nuclear power.
Before the crisis, the U.S. nuclear industry was enjoying more public and political backing than it had in years -- 62 percent of the public, according to a Gallup poll done last year. That support grew out of concerns about greenhouse gases, a growing record of safe and profitable nuclear power production and volatile fossil fuel prices.
In Washington, nuclear energy was a rare issue on which the Obama administration and congressional Republicans agreed. President George W. Bush established an $18.5 billion loan guarantee program to help build new plants. President Obama wants to raise that to $54.5 billion. Obama has also included nuclear power in his plan for a clean-energy standard.
Nuclear power generation emits no carbon dioxide, a damaging greenhouse gas. And unlike wind or solar, nuclear reactors produce huge amounts of power, uninterrupted, for months. The 104 commercial reactors in the U.S. supply about 20 percent of the nation's electricity.
But only two of nearly three dozen nuclear plants that were proposed in the middle of the last decade remain on track to be built. Low electricity prices and the huge expense of building plants have contributed to the delay.
Industry analysts say few, if any, could be built without government loan guarantees, a low-carbon energy mandate, or both. That government help is predicated on support from a public that might have suddenly grown more fearful about the safety of nuclear power after the Japan crisis.
The two projects that appear to be furthest along, both with regulators and financing, are in the Southeast.
The Atlanta-based Southern Co. and its partners are seeking to build two more reactors at Plant Vogtle in Burke County, Ga.. And SCANA, based in Cayce, S.C., has proposed adding two reactors to its Plant Summer site in Jenkinsville, S.C.
Both utilities have said they expect to be granted operating licenses this year and insist their projects will proceed. The Nuclear Regulatory Commission is still evaluating both.