Publications
Nuclear Fuel Cycle (NFC) Technology and Policy Program
A Review of Geology-Related Aspects of Deep Borehole Disposal of Nuclear Waste
B. Sapiie and M. J. Driscol
MIT-NFC-TR-109 (August 2009)
Abstract
This report updates work carried out at MIT since 2003 on the conceptual design and performance assessment of deep borehole repositories for disposal of high level nuclear wastes.
The focus is on 40 to 50 cm diameter holes drilled into crystalline granitic bedrock using available oil/gas/geothermal industry technology. The holes are fully lined using grouted-in-place standard steel drillpipe. Newer features include reduction in maximum depth to 3 km, with a 1 km waste emplacement zone, and the use of graphite “sand” as a lubricating/thermally conducting infill between the waste canister string and borehole wall liner, to increase the prospects for retrievability. The reduced bottom-hole lithostatic pressure also helps avoid hole collapse; likewise, the reduced depth limits maximum hydrostatic pressure, should the borehole flood, to levels which will not crush the waste canister string. Finally, the shorter emplacement zone reduces the weight of the canister stack to values which will not crush the bottom-most canisters, with a significant factor of safety.
Since 2003 the main focus at MIT has been on disposal of separated minor actinides and troublesome fission products (e.g., Tc-99, I-129) as a strategy for facilitating conventional disposal in shallow mined repositories such as Yucca Mountain, and other such, worldwide.
Future R&D requirements are identified covering the entire spectrum of needs.
