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This report summarizes the knowledge base on the iron-enriched basalt (IEB) waste form developed at the Idaho National Engineering Laboratory (INEL) during 1979-1982. The results presented discuss the applicability of IEB in converting retrieved transuranic (TRU) waste from INEL's Radioactive Waste Management Complex (RWMC) into a vitreous/ceramic (glassy/rock) stable waste form suitable for permanent disposal in an appropri_te repc_sitory, such as the Waste Isolation Pilot Plant (WIPP) in New Mexico. Borosilicate glass (BSG), the approved high-level waste form, appears unsuited for this application. Melting the average waste-soil mix from the RWMC produces the IEB composition and attempting to convert IEB to the BSG composition would require additions of substantial B20 3,Na, and SiO2 (glass frit). IEB requires processing temperatures of 1400 to 1600°C, depending upon the waste composition. Production of the IEB waste form, using Jouleheated melters, has proved difficult in the past because of electrode and refractory corrosion problems associated with the high temperature melts. Higher temperature electric melters (arc and plasma) are available to produce this final waste form. Past research focused on extensive slag property measurements, waste form leachability tests, mechanical, composition, and microstructure evaluations, as well as a host of experiments to improve production of the waste form. Past INEL studies indicated that the IEB glass-ceramic is a material that will accommodate and stabilize a wide range of heterogeneous waste materials, including long rived radionuclides and _;crap metals, while maintaining a superior level of chemical and physical performance characteristics. Controlled cooling of the molten IEB and subsequent heat treatment will produce a glass-ceramic waste form with superior leach resistance. Recommended future work includes studies on 1) the retention and dissolution of TRU oxides in the IEB slag in solid solution with zirconia or equivalent, 2) the disposition af the high vapor pressure metals, including Cs, Pb, and Hg, 3) the controlled cooling process necessary to obtain the appropriate fine-grained crystalline structure necessary for minimum leaching of radionuclides and toxic substances, 4) processing with plasma-torch and/or arc-heated melters in an attempt to overcome process temperature-related problems experienced with the Jouleheated melter, and to detect at lab scale any r'_'_;or: processing problems.

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