Method for Modeling Regional Scale Deformations and Stresses Around Radioactive Waste Depositories in Bedded Salt.

摘要

When heat producing nuclear waste is placed in mined drifts, the surrounding geology is disturbed to some extent. Primary concerns on a regional scale may include fracture of brittle stratigraphic layers bounding water bearing strata, surface upheaval or subsidence, and disturbance of other nearby mining operations. This study presents a structural analysis method which may serve as a base for answering questions of this sort. The analysis method is presented with the use of a generic but very specific problem. A depository in bedded salt is chosen for analysis and a cylinder of earth 0.8 miles deep by 3.0 miles in diameter is modeled. Sandstone, shale, and bedrock are modeled as linear elastic media. The rock salt is modeled with an elastic, secondary creep model. Drifts which are backfilled with crushed salt are modeled with a simple volumetrically creeping model which accurately captures the subsidence due to drift closure. Following a slight initial subsidence, the results show a maximum surface rise of 0.46 m at 90 years with eventual subsidence of 0.18 m after thousands of years at a point directly above the depository center.