Applications of iron-enriched basalt to TMI radioactive waste disposal

Iron-enriched basalt (IEB), a man-made analogue to natural basalt, has been investigated as a dissolution and immobilization medium for Three Mile Island (TMI) radioactive wastes. The research has focused on the ability of IEB, a glass-ceramic whose principal constituents are SiO2, Fe2O3 + FeO, and Al2O3, to contain TMI zeolites, resins, and core debris; and on the practical aspects of producing IEB on a large scale using a joule-heated melter. The retention of cesium and strontium during high-temperature processing of IEB and the leach rate of these species from IEB in 363 K deionized water have been investigated. Simulated TMI core debris (UO2, zircaloy, and stainless steel) have been successfully dissolved in IEB by using an air bubbler to accelerate the dissolution process. Large-scale IEB castings (10 kg and 75 kg) incorporating simulated TMI wastes have been prepared using a 250 kg capacity joule-heated research melter. Subjecting the castings to a controlled cooling produced fine grained monoliths with almost no microcracks. 6 figures