Nuclear energy is often touted as the safe alternative to coal. Here in Knoxville about 20% of our energy comes from nuclear power plants. TVA currently operates five nuclear reactors at three sites on the Tennessee River. The two closest are Sequoyah, on Chickamauga Reservoir above Chattanooga, and Watts Bar, near the Watts Bar Dam.

All nuclear power plants routinely release small amounts of radioactive material into the air and water. The evidence is inconclusive as to whether these routine releases can harm people living nearby; some studies show no effect, while others find elevated rates of cancer or leukemia.

The greatest concern with nuclear plants, however, is the possibility of a major release of radionuclides, such as occurred at Chernobyl in 1986. Though American reactors are better designed than the Chernobyl reactor, they are not foolproof. TVA has had one near-meltdown (at Browns Ferry in 1975), and an American-built reactor at Three-Mile Island in Pennsylvania underwent a partial core melt in 1979. Accidents are not the only way in which radionuclides might be released. There is also the possibility of terrorist attack. Efforts have been made to quantify such risks, but they depend heavily on guesswork. All we can say for sure is that the probability of a major nuclear release is low, but not zero.

The damage from an event at Watts Bar or Sequoyah could be enormous. Signs along the roads near both plants mark the evacuation routes, grim reminders of the scramble that must ensue if the sirens sound. If an air release occurred at Sequoyah when the wind was blowing down the valley from the northeast, the cloud of radiation would move directly into Chattanooga twenty miles away. A southwest wind blowing up the valley could drop radiation from a Watts Bar release onto Knoxville and Oak Ridge sixty miles downwind. If the wind were blowing from the west, a major release from either plant would fall out largely in the Great Smoky Mountains. The extent of the damage would depend on many factors besides the wind—most crucially on the amount of radiation released. In the worst case, thousands of lives and homes, billions of dollars, and the health of much of the land of Southern Appalachia would be lost.

The other major problem with nuclear power generation is that it creates radioactive waste. This waste is classified as either low-level or high-level. Low-level waste consists of such objects as contaminated filters, cloth wipes, plastic shoe covers, tools, water purification devices, and various residues. It is shipped to special regional landfills, where it is simply buried. Much of the radiation decays away within a decade after disposal, though some persists for much longer.

High-level waste, which consists mostly of spent fuel rods, is another matter. TVA's five reactors produce about 115 metric tons of used fuel per year. High-level waste, when first removed from the reactor, is extraordinarily radioactive and must be handled with the utmost caution. Most of the radioactivity subsides within several months, but the waste remains deadly to humans for tens of thousands of years—longer than civilization has existed on Earth.

There is no practical way to make such waste non-radioactive. Other means of eliminating it, such as shooting it into space or injecting it deep into the earth, are too expensive or too dangerous. So storage is, for the present at least, the only acceptable option. Storage facilities must be safe from earthquakes, climate change, rising water tables, and so on, and must also be constantly guarded against terrorists, since high-level waste could be used to make weapons. Whether this can be done successfully over a period of tens of thousands of years is doubtful.

There is no permanent disposal facility for high-level nuclear waste anywhere in the world. The only place in the United States currently being considered for such a facility is Yucca Mountain, which is located on Shoshone tribal lands in Nevada. But the Yucca Mountain site is controversial, being surrounded by geological faults and volcanoes, one of which erupted as recently as five thousand years ago. Since 1857, there have been eight major earthquakes within 250 miles of the site.

Nuclear energy is cleaner than coal in many respects. Still, any technology that passes radioactive trash on to generations thousands of years into the future is morally bankrupt. If we don't know how to clean up our mess, but only how to shovel it under the rug (or under Yucca Mountain, as the case may be), we have no business making it in the first place.