The Problem of Nuclear Waste Disposal

Nuclear waste disposal remains an unresolved problem for the nuclear power industry, and one that has been the subject of much deception.


| November/December 1978



anne and paul ehrlich - nuclear waste disposal

Anne and Paul Ehrlich warn that safe nuclear waste disposal requires a solution that will last hundreds of thousands of years.


PHOTO: MOTHER EARTH NEWS STAFF

The possibility of catastrophic nuclear power-plant "accidents" isn't the only reason why we and many other scientists are apprehensive about the spread of nuclear power. Perhaps an even greater danger exists in the radioactive wastes produced within the power generators themselves. Until a means of safely disposing of these materials is found, the production of "no risk" nuclear-generated electricity will be impossible.

Remember that most reactors split uranium 235 (U-235) nuclei to produce heat energy. That heat provides steam, which in turn spins generator turbines. However, when the uranium atoms split they create fragments (called "fission products"), and the nuclear waste disposal problem begins. The fragments, for example, contaminate the reactor's fuel rods so badly that the rods must be replaced about once a year. (This replacement is necessary because the fission products "poison" the chain reaction by absorbing neutrons without fissioning. The trapped neutrons are then unable to sustain the "atomic" reaction.)

Furthermore, because many of these fragments remain highly radioactive after they're formed, the fuel rods (in which most of the fragments become embedded) are also radioactively "hot" by the time they're removed from the reactors. These used rods, in fact, are so radioactive that they're normally stored at the power plants for a period of several months until some of their most dangerous contaminants have had a chance to decay into somewhat less harmful materials.

The spontaneous changes in nuclei that result in the emission of radioactivity, you see, always transform an atom into something else. If its chemical properties are altered, the atom becomes another element. On the other hand, if an atom's nucleus is changed but its chemical properties remain the same, a different isotope of the same element is formed.

Uranium 235, for example, decays in a long series of steps that include the radioactive isotopes radium 226, radon 222, and polonium 218. The end result, finally, is the chemically stable, non-"hot" element lead 206.

The process of this breakdown is statistically predictable, even though the instant at which a single nucleus will be spontaneously transformed isn't. For this reason, atomic decay is measured in "half-lives," which indicate the time needed for one-half of the billions of atoms in a small quantity of material to undergo this transformation.





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