Basic Research Needs for Geosciences - Energetics Meetings and ...

APPENDIX 1: TECHNICAL PERSPECTIVES RESOURCE DOCUMENT• Incorporate low-probability, high-impact events into performance assessment analyses• Incorporate alternative conceptual models into uncertainty assessments• Develop appropriate model abstractions• Perform comprehensive simulations on the system levelMathematical and computational challenges are also associated with these modeling needs (seeDOE 2006c for more detailed discussions).6. Geological criteria for site selectionIn siting repositories, it is important to select a hydrological and geochemical environment thatensures low solubility and high retardation of radionuclides. The needed repository capacity isclosely coupled with the waste inventory, future use of spent fuel with advanced fuel cycles, andthe national energy policy on reprocessing and recycling. Both options should be considered: thepotential siting of additional repositories in different geological media, and the potentialexpansion of capacity of existing sites with different design configuration optimized with thenatural surrounding. There is a need to develop criteria and to identify site characterization needsand approaches for future geologic repositories based on previous experiences and newdevelopments.NUCLEAR WASTE HISTORICAL BACKGROUND—ADDITIONAL INFORMATIONThe U.S. has had a longstanding and ongoing technical and policy discussion on the importanceof geologic disposal to nuclear waste management. To place the technical aspects of geologicdisposal in the proper context, it is useful to review the history of the technical and policydiscussions. This is discussed in some detail below. Much of this discussion is taken directlyfrom Office of Technology Assessment (1985). The reader is also referred to Cotton (2006) for amore recent, thorough review of this subject.High-level radioactive waste was first produced in the United States on a large scale in thewartime effort of the early 1940’s to produce plutonium for atomic weapons. Spent fuel fromdefense reactors was routinely reprocessed to recover uranium and plutonium, and liquid highlevelwaste from reprocessing was stored in storage tanks at federal facilities—first at Hanford,Washington, and later at Savannah River, South Carolina, and Idaho Falls, Idaho. It was assumedthat disposal could take place later, possibly at these same sites.In 1954 the Atomic Energy Act opened the nuclear power industry to private enterprise, and thefirst contract for a commercial reactor was issued two years later. Unlike defense reactors,commercial reactors were designed primarily to produce electricity. Spent fuel discharged fromcommercial reactors was stored in water-filled basins at reactor sites, pending development of acommercial reprocessing facility.The Atomic Energy Commission (AEC) first addressed the problem of waste disposal in 1955when it asked the National Academy of Sciences (NAS) how to structure research to establish ascientific basis for the waste management program. Under the assumption that the waste to bedisposed of would be dissolved at relatively low concentrations in liquid, NAS stated in its 1957report (National Research Council 1957) that disposal was technologically feasible and thatstable salt formations appeared to be the most promising repository medium. Such formationswould theoretically prevent transport of liquid and would become self-sealing in the event ofBasic Research Needs for Geosciences: Facilitating 21 st Century Energy Systems Appendix 1 • 43