Rock Support For Nuclear Waste Repositories

INTRODUCTION The design of rock support for underground nuclear waste repositories requires consideration of special construction and operation requirements, and of the adverse environmental conditions in which some of the support is placed. While repository layouts resemble mines, design, construction and operation are subject to quality assurance and public scrutiny similar to what is experienced for nuclear power plants. Exploration, design, construction and operation go through phases of review and licensing by government agencies as repositories evolve. This paper discusses (1) the various stages of repository development; (2) the environment that supports must be de signed for; (3) the environmental effects on support materials; and (4) alternative types of repository rock support. Much of the information presented in this paper was derived from work conducted for Basalt Waste Isolation Project. Most of the information, however, would apply to other hard rock repositories. REPOSITORY DEVELOPMENT AND THE NEED FOR ROCK SUPPORT Repository development can be characterized by five general stages: exploration and design, excavation, waste emplacement, re trievability period, and backfilling. It is helpful to understand these phases of development to see where and when rock supports are required and how the design is verified. The description that follows is simplified. Details have been omitted, and future plans may not conform to this scenario.