SUBSURFACE DISPOSAL AT THE WASTE ISOLATION PILOT PLANT

One category of radioactive waste is finally being placed into the Waste Isolation Pilot Plant (WIPP) in southeastern New Mexico. Subsurface disposal experience abroad, as well as international analogue studies, helped validate permanent isolation in massive salt as a very suitable option for eliminating threats to our health, safety, and the environment. Salt is dry, impermeable, and easy to mine. Geologically old salt demonstrates by its continued presence the lasting stability of its tectonic and hydrologic environment. Viscoplastic rock salt deformation (creep) heals short-lived fractures and closes excavations tightly around the waste. Drift and shaft seals ensure short-term isolation, while the host rock itself provides long-term confinement. Compared with the risk of continued temporary storage at or near the surface, permanent deep subsurface disposal remains the superior choice. Operating the WIPP is therefore the cornerstone in cleaning up our nation’s radioactive waste legacy.