The age of atomic energy could be said to have begun, literally, with the wave of a wand. On September 6, 1954, President Dwight D. Eisenhower, who was vacationing in Denver, passed a pole with a gleaming tip over a cabinet full of electronic equipment. This “neutron wand” supposedly sent a signal that was then conveyed to an unmanned power shovel, twelve hundred miles away, in Shippingport, Pennsylvania. The shovel lurched forward and scooped up three tons of dirt, breaking ground for the country’s first commercial nuclear power plant. “My friends, through such measures as these, and through knowledge we are sure to gain from this new plant we begin today, I am confident that the atom will not be devoted exclusively to the destruction of man, but will be his mighty servant and tireless benefactor,” the President said.

Illustration by TOM BACHTELL

The Eisenhower Administration subsequently did just about everything it could to promote nuclear energy; in 1955, the President went so far as to propose that the United States build a reactor-powered ship that would cruise around the world and act as a floating P.R. campaign. (The ship was constructed but was mothballed after eight years, owing to high operating costs.) Even so, the hazards of commercial nuclear power could not be entirely ignored. Private companies were willing to insure nuclear plants only up to sixty-five million dollars, which was estimated to be just a tenth of what a major accident, in 1956 dollars, would cost, and utility companies weren’t interested in building plants without coverage. Then Congress stepped in and—metaphorically, this time—waved another wand. The Price-Anderson Act, approved in 1957, in effect created a government-run insurance pool for the industry.

In the half century since, the risks of nuclear power have alternately preoccupied Americans and been ignored by them. Concern spiked after the partial meltdown at Three Mile Island, outside Harrisburg, Pennsylvania, in 1979, and again after the disaster at Chernobyl, in 1986. It then receded, picked up once more after 9/11, and receded again, to the point where many in the industry had begun to speak of a “nuclear renaissance.” Just last month, President Barack Obama, who has advocated “building a new generation of safe, clean nuclear power plants,” called for thirty-six billion dollars in federal-loan guarantees for new reactors. Now it looks as if the renaissance will have to be postponed.

The still unfolding catastrophe at Japan’s Fukushima Daiichi power station differs from previous crises in that it began with a natural disaster, or, really, two. The station was designed to withstand a powerful earthquake and also to resist a tsunami. But it seems not to have been designed to cope with an earthquake combined with a tsunami, even though earthquakes are generally what cause tsunamis. What many have described as a “one-two” punch left the complex without its normal power supply (electricity from the grid) and also knocked out its backup power supply (a set of diesel generators), a condition known as a “station blackout.” The station has six reactors, three of which were operating at the time of the quake; the others were off-line. The operational reactors—Nos. 1, 2, and 3—automatically shut down, but a reactor core, even after shutdown, generates a huge amount of heat, and must be continuously cooled. When the cooling systems at all three units failed, a series of escalating crises ensued: explosions and, it appears, partial meltdown of the reactor cores. With radiation levels soaring, workers couldn’t complete crucial tasks. At the time of writing, a complete meltdown at one or more of the reactors was still deemed to be a risk. Japanese officials seemed particularly alarmed by conditions at No. 3, which uses a form of fuel, known as MOX, that contains plutonium.

Meanwhile, as the cores in Nos. 1, 2, and 3 began to overheat, different, but potentially no less catastrophic, problems arose at Nos. 3, 4, 5, and 6, in the aboveground pools where spent fuel rods are stored. Spent fuel also requires cooling, and cooling water apparently boiled away in No. 4, leaving the rods exposed and, according to some reports, burning intermittently. A spent-fuel pool can hold many more fuel-rod assemblies—and thus much more radioactive material—than a reactor core. And while a reactor core is isolated by thick layers of steel and concrete, a spent-fuel pool is largely unshielded. Concerns about the situation at No. 4 prompted U.S. officials to advise Americans to stay at least fifty miles away from the plant.

Every time there’s an accident, proponents of nuclear power point out that risks are also associated with other forms of energy. Coal mining implies mining disasters, and the pollution from coal combustion results in some ten thousand premature deaths in this country each year. Oil rigs explode, sometimes spectacularly, and so, on occasion, do natural-gas pipelines. Moreover, burning any kind of fossil fuel produces carbon-dioxide emissions, which, in addition to changing the world’s climate, alter the chemistry of the oceans. Among those who argue most passionately for nuclear power these days are some environmentalists, who see the uncertain threat that it presents as preferable to the certain harm of climate change. An objective comparison might indeed suggest that a well-designed and vigorously regulated nuclear power plant poses less danger than, say, a coal-fired plant of comparable size. Such a comparison, however, ignores the fact that the regulation of nuclear power in the U.S. still relies on wand-waving.

Consider the prospect of a terrorist attack. After 9/11, it would seem only prudent for nuclear plants to be prepared for an assault by a large, well-armed group. But the Nuclear Regulatory Commission, in revising its security rules, decided not to require that plants be able to defend themselves against groups carrying the most dangerous sort of weapons, even though these were just the sort of weapons the N.R.C.’s staff had concluded that terrorists could be expected to possess. (The exact weapons in question are classified information.) According to a study by the Government Accountability Office, the N.R.C. appeared to have based its revised rules “on what the industry considered reasonable and feasible to defend against rather than on an assessment of the terrorist threat itself.”

Or consider the requirement, instituted in response to the accident at Three Mile Island, that emergency-evacuation plans be drawn up for a ten-mile zone around all nuclear plants. As anyone who has driven through Westchester County knows, the idea that the area around the Indian Point plant, in Buchanan, New York, could be safely evacuated after an accident is, to say the least, implausible. (More than three hundred thousand people live within ten miles of the plant, and nearly twenty million live within fifty miles.) Nevertheless, the N.R.C. believes that Indian Point has a workable evacuation plan, and is contemplating relicensing the plant for twenty years.

Or, finally, consider the problem of spent fuel. After several decades and billions of dollars’ worth of studies, the U.S. still does not have a plan for developing a long-term storage facility for radioactive waste, much of which will remain dangerous for millennia. (The Obama Administration rejected the idea of creating a repository at Yucca Mountain, in Nevada, but has yet to put forward or, it seems, really consider an alternative.) Instead, spent-fuel rods are stored at each of the country’s hundred and four nuclear power plants. More than two dozen reactors in the U.S. have aboveground storage pools similar to those that have failed at Fukushima—the only difference is that the American pools contain far more waste than their Japanese counterparts. In a conference call with reporters the other day, David Lochbaum, a nuclear engineer and the director of the Nuclear Safety Project of the Union of Concerned Scientists, called the risks currently posed by spent-fuel pools in the U.S. “about as high as you could possibly make them.”

As the disaster in Japan illustrates, so starkly and so tragically, people have a hard time planning for events that they don’t want to imagine happening. But these are precisely the events that must be taken into account in a realistic assessment of risk. We’ve more or less pretended that our nuclear plants are safe, and so far we have got away with it. The Japanese have not. ♦