Comparison of two simulators to investigate thermal–hydraulic–mechanical processes related to nuclear waste isolation in saliferous formations

Abstract

a b s t r a c tWe investigate the capabilities of two simulators, TOUGH-FLAC and FLAC-TOUGH, to predict the longterm thermal-hydraulic-mechanical response of a generic salt repository for heat-generating nuclear waste. These simulators are based on sequential coupling and include state-of-the-art knowledge for saliferous materials. Their main difference is the sequential method used. We present a benchmark between LBNL and TU Clausthal. The scenario studied assumes heat and gas generation from the waste packages, and crushed salt backfill. The comparison of results is very satisfactory, providing increased reliability and confidence in the capabilities of the simulators to evaluate the geological and engineered barriers in the long-term.Published by Elsevier Ltd.

Modeling Coupled THMC Processes and Brine Migration in Salt at High Temperatures

“…The FLAC-TOUGH simulator has been implemented based on two different sequential methods (Lux et al 2014;Blanco Martín et al 2014d). In the first approach, the sequential undrained split method is used (Kim 2010).…”

Hydrous Mineral Dehydration Around Heat-Generating Nuclear Waste in Bedded Salt Formations

“…Following excavation of the drifts, the permeability of the DRZ is expected to evolve anisotropically due to fracture healing and viscoplastic creep that eventually leads to room closure; in the current work, permeability change in the DRZ is only caused by salt precipitation and dissolution. RoM backfill reconsolidation may affect the porosity structure and have important feedbacks on hydrological parameters, as investigated by multiple experiments and TM and THM models. ,,, …”

“…Numerical modeling of HGNW disposal in salt has been performed by multiple groups for WIPP and for other salt repositories worldwide, but simulation of the strongly coupled thermal, hydrological, mechanical, and chemical (THMC) processes have been done only at small spatial scales . Current state-of-the-art simulators for repository-scale simulations have been limited to incomplete coupling, e.g., only simultaneous coupling of THM processes to capture the viscoplastic reconsolidation behavior of salt, or only coupled THC processes to include the effects of porosity change from precipitation and dissolution across temperature gradients. ,− The THC model developed here does not include mechanical effects that lead to room closure and RoM reconsolidation. However, the modeled THC processes operating on short time scales may be important to the salt repository safety case because of impacts including different rates of reconsolidation of RoM backfill based on moisture content, , altered potential for corrosion of the waste canisters, gas generation, and a modified thermal regime (e.g., maximum temperatures reached) immediately surrounding the waste.…”

Modeling Coupled THM Processes and Brine Migration in Salt at High Temperatures

“…The model development of TOUGH-FLAC for salt has reached sufficient maturity for state-of-the-art applications on coupled THM processes in salt, and we have therefore been able to publish two new journal papers (Blanco Martin et al 2015a;2015b), which showcase the work and contribute to the stateof-the-sciences in the international salt research community.…”