Unlike the Chernobyl disaster in Ukraine -- which will mark its 20th anniversary on April 26 -- no one died at Three Mile Island. But critics of atomic power raise concerns over potential terrorist threats to plants and say science has yet to provide an adequate solution for highly toxic nuclear waste.

Three Mile Island owner Exelon Corp. now wants to extend its operating licence as part of an industry programme to keep all 103 US nuclear reactors going beyond their standard 40-year licences.

New plants are also under consideration as companies hope to cash in on an expected 45 percent surge in electricity demand over the next 25 years and answer US government calls to diversify sources for the world's top energy consumer.

President George W. Bush has said America is "addicted to oil" and called nuclear power a clean, low-cost alternative. Industry groups say its use can reduce emissions of greenhouse gases, caused by burning coal and crude oil, and they point to polls suggesting growing public acceptance.

Yet for some people living near Three Mile Island, in the Susquehanna River area near the Pennsylvania state capital of Harrisburg, worries over a possible deadlier accident remain.

"How big is the explosion going to be? How are you going to get out?" Mario Lugo asked from the main street of Middletown, about 5 km (3 miles) north of the plant.

The 42-year-old airport maintenance worker said he has considered moving away because of his fear of an accident.

GROWING APPROVAL

Nationally, however, industry surveys suggest 70 percent of the public is comfortable with nuclear power, up from around 50 percent in the mid-1980s.

Approval rises to more than 80 percent among those living close to a nuclear plants, which pay high taxes to host cities, according to the Nuclear Energy Institute (NEI) lobbying group.

"The contribution to the tax rates to the city and counties is pretty significant, primarily through property taxes which are the main instrument for funding public schools," said Mitch Singer, an NEI spokesman.

Nuclear power generates 20 percent of US electricity, up from 3 percent in the early 1970s. Supporters point to France, which over the past 30 years has built 58 nuclear plants that provide around 78 percent of electricity, as a model.

Nuclear power is enjoying something of a rebirth -- 20 years after the explosion at Chernobyl seemed to herald its decline -- in a power-hungry world, worried about rising oil prices.

Last month, Russia and the United States called for the world to embrace nuclear power to guarantee stable supplies of energy and cut emissions of harmful greenhouse gases.

Selling the industry as safe has been tough, however, and companies have had to adapt to shifting concerns.

At Three Mile Island, operators now face rigorous training to prevent a repeat of the 1979 incident. No one was killed or injured during the accident, and subsequent tests show no rise in cancer rates, but confidence in nuclear safety fell.

Plants are pouring money into barriers, checkpoints, bullet-resistant guard towers and surveillance equipment following the Sept. 11 attacks.

A 3-metre-thick (10-foot) concrete wall stretches across Three Mile Island, preventing unauthorised vehicles from getting within about 200 yards of plant buildings.

"Public opinion has turned around," said Michael Gallagher, vice president of licence renewal projects for Exelon. "It was dark in the '80s but is now very bright. We have proved that we can operate the plants safely and efficiently."