DECOVALEX

DEvelopment of COupled models and their VALidation against EXperiments

The DECOVALEX project is an international research and model comparison collaboration, initiated in 1992, for advancing the understanding and modeling of coupled thermo-hydro-mechanical (THM) and thermo-hydro-mechanical-chemical (THMC) processes in geological systems. Prediction of these coupled effects is an essential part of the performance and safety assessment of geologic disposal systems for radioactive waste and spent nuclear fuel. The project has been conducted by research teams supported by a large number of radioactive-waste-management organizations and regulatory authorities. Research teams work collaboratively on selected modeling test cases, followed by comparative assessment of model results between different models. Through this collaborative work, in-depth knowledge has been gained of coupled THM and THMC processes associated with nuclear waste repositories, as well as the suitability of numerical simulation models for their quantitative analysis. More »

DECOVALEX-2015: The Current Project Phase (2012-2015)

Brief Summary
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DECOVALEX -2015 is the current and 6th project phase and runs from 2012 through 2015. Modeling teams from 10 international partner organizations participate in the comparative evaluation of five modeling tasks involving complex field and/or laboratory experiments in Switzerland, France, Japan, and Czech Republic. Together, these tasks address a wide range of relevant issues related to engineered and natural system behavior in argillaceous and crystalline host rocks. More »

Task A: The SEALEX Experiment
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A view of the SEALEX experiment

The main objective of Task A is to study the sealing systems efficiency, and in particular to identify conditions (technical specifications, design, construction, defects…) that will control the performance of swelling clay-based sealing systems over the long-term. For this purpose, Task A is based on a ‘test-case’, the SEALEX project, which is being performed in the Tournemire Underground Research Laboratory, run by IRSN (Institut de Radioprotection et de Sûreté Nucléaire), in France. More »

Task B.1: HE-E Heater Test
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Installation of HE-E Heater Test

Task B1 is geared towards the understanding of Thermo-Hydro-Mechanical (THM) processes in a bentonite buffer and an argillaceous host rock. It is based on the performance of 1) the HE-D in situ heating test (rock only), 2) laboratory column tests on bentonite pellets and 3) the HE-E in situ heating experiment (integrating buffer materials and host rock), the final objective of the Task. The two in situ experiments were performed at the international Mont Terri rock laboratory in Switzerland (www.mont-terri.ch). More »

Task B.2: Horonobe EBS experiment
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Horonobe EBS experiment

The purpose of Task B2 is to examine the coupled thermal-hydraulic-mechanical (optional chemical) processes in the full scale in-situ engineered barrier system (EBS) experiment to be conducted at the Horonobe underground research laboratory in Japan. The Horonobe EBS experiment demonstrates Japanese engineered barrier system concept for the high level radioactive waste (vitrified waste) in a sedimentary rock supported with concrete lining. A test pit in the gallery floor contains an electric heater to represent the high level waste that is enclosed by a bentonite buffer. More »

Task C.1: THMC Processes in Single Fractures
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Fracture surface topography for the novaculite experiment (dimensions in mm).

The purpose of Task C1 is to examine the Thermal-Hydraulic-Mechanical-Chemical coupled processes operating within single fractures through the construction of appropriate mathematical models that are constrained by two sets of laboratory experiments. These experiments consider flow of pressurised water through highly characterised artificial fractures in novaculite (quartz) and granite under mechanical loading and variable temperatures, with chemical analysis of the resulting effluent. More »

Task C.2: Bedrichov Tunnel Test Case
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Picture: (1) Tunnel in the boundary of bored and blasted part, (2) Example of 3D model with 2D fractures.

Task C2 is a study of water flow, tracer transport, and reactive transport in a granite massif, based mainly on the tunnel inflow (flow rate and quality) measured in the Bedrichov Tunnel in the Czech Republic . The main issue is inhomogeneity of water flow, i.e., the heterogeneous distribution of water as a result of conduits of different size/scale (faults, fractures), and relation of water quantity and flow velocity (or residence time). An additional topic is the uncertainty evaluation from calibration and blind prediction steps with partial data sequences and from cross-validating with different models/data (hydraulics, tracers, and reaction). More »

Current Partner Organizations

Logo Link Organization
link BGR
Federal Institute for Geosciences and Natural Resources
Germany
link CAS
Chinese Academy of Sciences
link DOE
Department of Energy
USA
link ENSI
Swiss Federal Nuclear Safety Inspectorate
Switzerland
link IRSN
Institut de Radioprotection et de Sûreté Nucléaire
France
link JAEA
Japan Atomic Energy Agency
Japan
link KAERI
Korea Atomic Energy Research Institute
Republic of Korea
link RWM
Radioactive Waste Management
UK
link NRC
Nuclear Regulatory Commission
USA
link SURAO
Radioactive Waste Repository Authority
Czech Republic
link UFZ
Helmholtz Centre for Environmental Research
Germany