Deep Borehole Storage of Nuclear Waste using MMW Technology

Deep borehole disposal of high level nuclear waste has been acknowledged by most experts as the best and safest method to permanently dispose the large volumes/ tons of such waste that have been generated (military and civilian) and surface stored over many decades at various sites around the country. Surface storage of such materials is not ideal. The cost of the required wells (drilling and completion) is estimated at $20-$40 million each and hundreds of such wells are needed for the volumes of waste amassed to date. Methods to lower cost and add additional layers of sealing barriers are desired as this disposal program advances. High energy millimeter wave (MMW) technology, in the 20 to 300 GHz frequency range that was developed for fusion energy research, can be efficiently transported through boreholes over long distances, to over 5 kilometer (16,500 feet) in depth, and can drill into hard crystalline rock formations. The impacted rocks (e.g. granites and basalts) will melt and form a solid, dense, impermeable glass melt seal in the wellbore for permanent entombment of any waste below. A new MMW drilling capability can drill smaller diameter, deeper boreholes to allow the use of higher vitrification waste loadings, reducing waste volumes and have a multiplicative effect on reducing the entire cost of nuclear waste disposal from processing to disposal. Phase I will include analysis of this approach and bench test experiments including at least one rock melt demonstration using a 10 kiloWatt (kW) MMW source to form a rock-melt plug/ seal in a pre-drilled rock bore. In addition, high temperature furnace melt tests on various materials will form the basis for later comparative testing to the standard cement. Phase II will further demonstrate MMW melting with the goal to determine the most optimal conditions to create solid impermeable melt plugs from various rock, metal and other materials. Furnace tests will be expanded to melt different materials for further improvements. Strength and permeability tests on the melt specimens are planned to compare to cements and other materials. Commercial Applications and Other Benefits: Commercialization of this technology can proceed rapidly after limited testing with a higher powered MMW source to confirm the findings from Phase II of this project. Commercial applications using the higher powered units include mining and tunneling through hard rock, drilling and lining wellbores, even very deep geothermal wells, hydraulic fracturing shales and geothermal granites, as well as permanently sealing nuclear wastes in deep rock vaults.