The long-term thermal-hydraulic-mechanical response of a generic salt repository for high-level nuclear waste is investigated using the TOUGH-FLAC simulator, developed at Lawrence Berkeley National Laboratory, and the FLAC-TOUGH simulator, developed at Clausthal University of Technology. Although these sequential simulators rely on the same flow and geomechanics software, they are based on different numerical schemes. One of the aims of using two different approaches to model the same scenario is to gain reliability on the results obtained. The two simulators include state-of-the-art constitutive relationships and coupling functions. The generic scenario studied assumes in-drift emplacement of the waste packages and subsequent backfill of the drifts with crushed salt. The Lux/Wolters constitutive model for natural salt is used. The simulations are two-way coupled and include the stages of excavation, waste emplacement, backfilling and post-closure. This work has been performed within the framework of a collaboration effort between Lawrence Berkeley National Laboratory and Clausthal University of Technology. Although the predictions presented in this paper cover a post-closure period of 100 years, it is intended to continue the benchmark until 100,000 years. The results obtained so far provide confidence in the capabilities of the two simulators to evaluate the barriers integrity over the long-term.

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