Chemical treatment and cement fixation of radioactive wastes

The treatment of radioactive wastes is necessarily different from treatment of other industrial wastes because of the very nature of the material. The radio active characteristics of the contami nants cannot be changed. Radioactive isotopes cannot be stabilized by oxida tion as cyanides are oxidized to innocu ous compounds ; they cannot be reduced to less hazardous nuclides in the manner that hexavalent chromium is reduced to trivalent chromium. Only time has any effect on this kind of contamina tion. Because the contaminants cannot be destroyed, there are only two ways to handle these wastes?concentrate and contain or dilute and disperse. In the case of waste management at Los Alamos Scientific Laboratory (LASL), the former method has been chosen. The " half-life' ' is the term used in the description of radioisotopes to indicate the rate of disintegration. It represents the length of time required to reduce the activity by one-half. This time varies from microor milli seconds for many fission products to 28 yr for strontium-90 and 30 yr for cesium-137, two of the more important contaminants, to 25,000 yr for pluto nium 239, which is the principal con taminant at LASL, to 4.5 bil yr for natural uranium, which presents a very minor problem in water pollution. There are three types of radiation emitted by unstable nuclides?alpha,