Summary Report for the WIPP (Waste Isolation Pilot Plant) Technology Development Program for Isolation of Radioactive Waste

摘要

The technology experiments have been managed in three broad categories: Thermal/Structural Interactions (TSI), Plugging and Sealing Performance and Design (PandS), and Waste Package Performance (WPP). The history and major progress in each of these areas is summarized in this report. The TSI program has established the fact that the WIPP salt creep rate, and therefore closure of WIPP rooms, is about three times more rapid than our best models predicted prior to the tests. Studies to resolve this discrepancy are well advanced; in the interim, good agreement between predicitions and observation is obtained by empirical adjustment of the elastic constants. The closure of backfilled waste room to about five percent void volume is predicted to take less than 100 years, the time during which active controls may be assumed to prevent human intrusion. The waste package program has revealed that migration of interstitial brine to excavations in the WIPP salt occurs at a significantly greater rate than assumed by earlier investigations. A satisfactory model to explain the data utilizes darcy flow in very low permeability salt which is driven by a pore pressure gradient caused when the excavation creates an atmospheric pressure boundary. This model, coupled with room closure predictions and backfill design using a salt/bentonite clay mixture, indicates that the rate of brine seepage will not result in a fluid or slurry state in the room, but rather in a compacted solid. 373 refs., 20 figs., 9 tabs. (ERA citation 13:035860)