Patent Number: 041742931
Section: summary

In recent years there has been a large scale increase in the number of water-cooled nuclear reactors both in the United States and abroad. This has created a large problem in that such reactors create large quantities of radioactive solutions of aqueous wastes. The water molecules contained in such wastes often contain the element tritium which in and of itself poses environmental hazards. Further, such aqueous waste solutions may contain radioactive isotopes of elements such as cesium, iodine, and the like, which have relatively low vaporization temperatures. Safety requires that such wastes be stored in leak-proof containers over long periods of time to prevent damage to the environment. Due to the large volume of such wastes, disposal methods must be economical if nuclear power is to survive in competition with fossil fuel plants. In British Pat. No. 938,211, issued to Rudolph Albert on Oct.2, 1963, entitled "Improvements in Methods of Solidifying Watery Atomic Waste", there is disclosed a process whereby aqueous solutions of atomic waste waters are used as the water, for the hydration of a mixture of alumina cement with or without aggregate added thereto; the water-cement mixture is thereafter allowed to set up, and is later baked at a temperature of about 1200.degree. C. for several hours, allowed to cool and thereafter impregnated with plastics, paraffin and/or other materials to reduce the possibility of the radioactive wastes entrained therein from leaking out. The temperatures employed in this process boils off excess water from the concrete mixture and will cause many of the radioactive elements contained therein to vaporize, thus requiring apparatus to prevent such vapors from reaching the atmosphere. This thermal requirement greatly increases the cost of the process and reduces the production rate of the plant. It is an object of this invention to provide an efficient, economical process for incorporating aqueous solutions containing radioactive elements at temperatures below 99.degree. C., into a solid substantially non-compressible, non-leachable body. SUMMARY OF THE INVENTION A process for disposing of aqueous solutions containing radioactive wastes whereby the waste solution is dispersed in situ throughout a mass of powdered portland cement, said cement being placed in a leakproof container and is densified tnerein to a bulk density ranging from about 1.3 to about 1.8 grams per cubic centimeter and a practice size ranging from about 120 mesh to about 400 mesh; the amount of water dispersed in the powdered cement being in a weight ratio thereto of from about 15 weight percent to about 30 weight percent based upon the weight of the powdered cement so used; sealing the container containing the cement with the aqueous solution dispersed therein to prevent evaporation of the aqueous solution contained therein during cement curing, thereafter impregnating the cured cement in said container with a mixture of a monomer and polymerization catalyst and polymerizing the monomer impregnated in said mixture in situ within the cured cement body, thereafter storing the container containing the polymer-impregnated cement in a storage facility suitable for storing such containers. Throughout the process the temperature of the cement body containing the aqueous solution containing the radioactive waste material is maintained at a temperature below 99.degree. C. In the preferred embodiment of this invention, we maintain the cement-aqueous solution mix at a temperature below 90.degree. C. throughout the processing. While cooling mechanisms can be employed if it is desired to make very large bodies of cement in accordance with this process, none are needed when the body is formed within conventional 55 gallon industrial drums and type II portland cement is used. No mixing apparatus is required to work the mixture of cement and aqueous solution but rather the water is dispersed in situ within a quiescent body of the densified powdered cement in the container through porous tubes strategically placed throughout the powdered cement. These tubes may be left in the cement after processing. The impregnation of the concrete with monomer and catalyst is accomplished simply by covering the entire surface of the cured cement within the container with a mixture of monomer and polymerization catalyst and allowing the monomer-catalyst solution to seep down thru and completely impregnate the concrete body in the container.