ASCE Symposium on High-Level Nuclear Waste Repository Seismic Design, San Francisco, California, 19–20 August 1992
Authors: A. M. Richardson (AAI) and T. E. Blejwas (Sandia National Laboratories)
Yucca Mountain, the potential site of a repository for high-level radioactive waste, is situated in a region of natural and man-made seismicity. Underground openings excavated at this site must be designed for worker safety in the seismic environment anticipated for the pre-closure period. This includes accesses developed for site characterization, regardless of the ultimate outcome of the repository siting process. Experience with both civil and mining structures has shown that underground openings are much more resistant to seismic effects than surface structures, and that even severe dynamic strains can usually be accommodated with proper design. This paper discusses the design and performance of lined openings in the seismic environment of Yucca Mountain. The types and ranges of possible ground motions (seismic loads) are briefly discussed. Relevant historical records of underground opening performance during seismic loading are reviewed. Simple analytical methods of predicting liner performance under combined in situ, thermal, and seismic loading are presented, and results of calculations are discussed in the context of realistic performance requirements for concrete-lined openings for the pre-closure period. Design features that will enhance liner stability and mitigate the impact of the potential seismic load are reviewed. The paper is limited to pre-closure performance concerns involving worker safety because present decommissioning plans specify maintaining the option for liner removal at seal locations, thus, decoupling liner design from repository post-closure performance issues.