United States Department of Energy strategy for in-situ testing at candidate repository sites

Abstract

The United States Department of Energy is preparing to conduct in-situ testing as part of site characterization studies at three candidate sites for the first repository in accordance with the Nuclear Waste Policy Act of 1982 (PL 97-425). The Act established a siting process and an attendant schedule for the development of geologic repositories for the disposal of civilian high-level radioactive waste, transuranic waste, and spent fuel. The Department of Energy is required in that siting process to recommend three sites to the President for approval before beginning site characterization. The site characterization activities at each site will include additional testing from the surface, construction of an exploratory shaft or shafts, and large-scale in-situ testing of the host rock from underground workings at the proposed repository depth and/or other depths, as appropriate. Applicable regulations promulgated by the Nuclear Regulatory Commission (10 CFR Part 60) require a performance confirmation program, including in-situ monitoring, laboratory and field testing, and in-situ experiments, beginning with site characterization and continuing through construction and operation of the repository until closure. The Department of Energy is in the process of developing an overall strategy for in-situ testing in the geologic repository program that is consistent with the requirements of the Nuclear Waste Policy Act of 1982 and 10 CFR Part 60. This overall strategy calls for a five-phase program for in-situ testing. The first phase consists of pilot research projects in rock types similar to those under consideration for a geologic repository. Subsequent phases consist of site-specific in-situ testing, beginning with site characterization activities at three sites and continuing at the site selected for development as the first geologic repository through construction, operation, and closure of the geologic repository - a time period on the order of up to 100 years. The strategy is to initiate tests at each phase, where needed, to satisfy the information needs of the various stages of site selection, development and licensing; to continue, where appropriate, the same tests from one phase to the next in the five-phase program; and, to increase the scope, dimensional scale, time duration, and interactive processes considered in the testing over those tests performed at each previous phase. The testing at each phase will build upon the tests performed and the data collected in the preceding phases. The major finding at each phase will be the determination or 41confirmation, with increasing confidence and certainty at each successive phase, of the suitability of the site for a geologic repository which will meet applicable standards for public health and safety.