is destabilized and the atom transmutates into two or more pieces. Uranium dioxide pellets that begin as UO2 end up as “spent nuclear fuel” containing forty-two different elements, from Zinc with an atomic number of 30 through Lutetium with an atomic number of 71. Much of the spent nuclear fuel is transmutated into heavy metals: Zirconium, Molybdenum, Technetium, Ruthenium, Rhodium, Palladium, and Silver. Some is transmutated into solid solutions: Iodine, Xenon, Cesium, Barium, Lanthanum, Cerium, and Neodymium.

Many of the atoms in this spent nuclear fuel don’t have the “right” number of neutrons; that is, they are radioactive isotopes. They are in an unstable configuration, waiting for a chance to discharge the extra neutrons in order to reach equilibrium. For any given atom, this chance occurs randomly, but at a predicable rate. Scientists measure the time it takes to reach equilibrium in terms of half-lives. Of particular concern to biological organisms are the readily absorbed isotopes: Iodine-131 with a half-life of eight days; Strontium-90 with a half-life of 29 years; and Cesium-137 with a half-life of 30 years. Exposure to these three are known to cause sickness and death.

As I study the physics of nuclear power plants, I am struck by how many ethical considerations there are. I am exasperated by the proponents of the nuclear industry who talk of “recycling” spent nuclear fuel, as if we could just clean it up and throw it back in the reactor; who talk of the abundance of Uranium on Earth, as if there is an inexhaustible supply just waiting to be scooped up; who dismiss the long-term consequences of nuclear waste, as if it were simply a short-term problem of finding a willing host for disposal; who gloss over the health problems of radioactive isotopes, as if the safe use of different isotopes in medical diagnostics, suggest that these isotopes are benign; who resort to the argument: “What else can we do?” as if no other form of non-fossil fuel energy could ever amount to much.