Byline: The Register-Guard

Nearly three decades after the Three Mile Island disaster, Sen. John McCain is proposing an American nuclear renaissance.

As part of a weeklong focus on energy security, the presumptive Republican presidential nominee said Wednesday that he wants 45

That would be a significant increase, but not as massive as it seems at first glance.

Currently, there are 104 reactors in this country, and they supply a fifth of the nation's electricity; many of the new plants proposed by McCain would replace existing ones. That's because no new nuclear plants have been built in the United States since the 1970s, and many of the facilities still operating are nearing the end of their useful lives.

As are a growing number of Americans, McCain embraces nuclear power as a clean, safe alternative to traditional energy sources that emit greenhouse gases. It's an unqualified enthusiasm that brings to mind Homer Simpson's memorable prayer thanking God "for nuclear power: the cleanest, safest energy there is. Except for solar, which is just a pipe dream."

If McCain is elected president, he will attempt to end a long-standing American aversion to nuclear generated power, which sets this country apart from the rest of the world.

In contrast with the United States, France gets nearly 80 percent of its power from nuclear plants and has a robust building program, as do Japan and Finland. Britain is encouraging companies to build new reactors, and Italy recently lifted the ban on nuclear plants it imposed after the Chernobyl meltdown in the former Soviet Union two decades ago. Across the world, more than 100 new plants are either in the planning or construction stages, roughly half of them in rapidly developing nations such as China and India.

The United States should be in no rush to join the parade. Despite McCain's glowing assessment and the urgent need to reduce greenhouse gas emissions, nuclear power still has serious shortcomings.

Modern nuclear plants are certainly safer than their Chernobyl-era predecessors, but accidents remain a problem. The Union of Concerned Scientists recently reported that 41 U.S. reactors have been shut down at least 51 times for more than a year because of safety problems.

While security has been improved since Sept. 11, nuclear plants remain worrisome targets for terrorists. They are also sources of waste that can be used to create weapons-grade plutonium.

Meanwhile, the question of how to dispose of the radioactive waste from existing U.S. reactors, much less the new facilities proposed by McCain, remains unanswered. Radioactive waste from nuclear plants can remain highly toxic for thousands of years, and no permanent storage facilities have been built in the United States - or anywhere else in the world. Congress long has struggled to build a U.S. disposal site at Yucca Mountain in Nevada, but relentless opposition by Senate Majority Leader Harry Reid promises to delay its opening for another decade - and perhaps longer.

It's also unclear that nuclear power can play a timely role in fighting climate change. Because many of the new nuclear plants proposed by McCain would replace existing ones, it would take many more than the 45 new plants that he proposes by 2030, or the 100 he proposes in the long term, to achieve major reductions in emissions of greenhouse gases.

Nuclear plants also take large amounts of time and money to build. Current licensing and testing requirements would delay construction for at least five years, and new nuclear plants require investments of between $5 billion and $10 billion - investments that Wall Street is unlikely to make without huge federal taxpayer subsidies.

McCain's Democratic opponent, Sen. Barack Obama, has a more realistic and safer view of nuclear power. While he acknowledges nuclear power may prove necessary to meet aggressive climate goals, he says it should not be expanded until the challenges of cost, safety, disposal and nuclear proliferation have been addressed.

The head of a French nuclear energy company recently declared that "nuclear is not the devil anymore." He may be right, but it is no angel, either. Not yet, anyway.