BACTERIA GO NUCLEAR

Another age-old process is now being used on low-level nuclear wastes. Let me warn you from the very beginning that there can never be a microbial process to deactivate the radiation of nuclear wastes. Radioactivity is a nuclear phenomenon which has nothing to do with the electrons orbiting the nucleus of an atom; yet it is these electrons (and even then only the outer shells) that are in-volved in chemical reactions, including the chemistry of the proteins forming genes, enzymes, DNA, etc. You cannot kill anybody by piercing a voodoo doll.

Nevertheless bacteria can be called in for a significant volume reduction of low-level wastes (LLW). In the case of power plants, LLW consist mostly of rubber and plastics, since they include mostly such items as gloves, overalls, cables, galoshes, etc. that have been soiled by radioactive dust (radiation alone will not make them active, unless it is neutron radiation). At present only the Fin-nish nuclear plant at Loviisa uses the method, which is known as anaerobic digestion, and does not essentially differ from compost-ing and other ways of processing manure in a digester as used all over the world for centuries to produce methane or just to convert the manure to more convenient fertilizer. The "anaerobic" means that the process takes place without access to air, or more precise-ly, to oxygen. The LLW are carried through the bioreactor by a water stream, where natural bacteria will break them down and reduce their volume by at least 90%. The total radioactivity, of course, remains undiminished; in fact, since the NRC defines LLW by specific activity (curies per kg), I suppose one must take care not to be too successful, or the LLW will be turned into HLW without adding one microcurie of radioactivity.

[More: Biotechnology: An Introduction, $3.85 from ACSH, 1995 Broadway, 16^th fl., New York, NY 10023; "Cleaning up with biotechnology," EPRI J., Sept. 1988; Genetic codes and engineering, recent editions of encyclopedia; bioreactors: O. Kitani, C. W. Hall, Biomass Handbook, Gordon & Breach, New York 1989.]