CONCEPT FOR UNDERGROUND SITING OF SMALL NUCLEAR POWER PLANTS AT GRANITE DIMENSION-STONE QUARRIES

Rock masses with good to excellent geotechnical properties can be expected to occur at many granite dimension-stone quarries. Potentially, some could have volume, dimensions, discontinuity characteristics and groundwater conditions suitable to construct underground openings with spans of > 15 meters, century-scale stand-up times, and require minimal liners or ground support. If possible, then underground space for specialized applications could be created. An example would be bedrock chambers for nuclear power plants (NPPs) based on new-design, small modular reactors (SMRs). Past experience with small underground reactors and underground NPP conceptual design studies indicate that NPPs sited in bedrock-chambers could have several advantages compared to conventional surface-sited NPPs. Examples include reduced capital and life-cycle cost, increased margins of containment safety in case of radiation-releasing accidents, greater physical security against aircraft impact or terrorist attack, and improved protection against natural hazards such as earthquakes and severe weather. The concept would be to construct access tunnels or shafts from a quarry to a point where the overburden was approximately 100 meters or more and from there excavate an interconnected network of bedrock-chambers to house the SMRs. Use of modern underground excavation methods would maximize advance rates and minimize unit-cost. Layout options include subsurface or surface siting of the turbine-generator and auxiliaries. Produced nuclear waste could be stored in nearby bedrock chambers while awaiting reprocessing or direct disposal. Important site-specific issues include groundwater contamination risks and surface water availability. Candidate quarries, both in the U.S. and worldwide, could be evaluated and screened using existing information from original quarry exploration and development, subsequent operations, and using available engineering studies of the dimension stone and rock mass. Assuming favorable political, economic, environmental and other factors, prospective dimension-stone quarries could be explored and evaluated as to their suitability for underground siting of small NPPs.