| 1. |
- Chijimatsu, M., et al.
(author)
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Numerical study of the THM effects on the near-field safety of a hypothetical nuclear waste repository - BMT1 of the DECOVALEX III project. Part 1 : Conceptualization and characterization of the problems and summary of results
- 2005
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In: International Journal of Rock Mechanics And Mining Sciences. - : Elsevier BV. - 1365-1609 .- 1873-4545. ; 42:5-6, s. 720-730
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Journal article (peer-reviewed)abstract
- Geological disposal of the spent nuclear fuel often uses the concept of multiple barrier systems. In order to predict the performance of these barriers, mathematical models have been developed, verified and validated against analytical solutions, laboratory tests and field experiments within the international DECOVALEX III project. These models in general consider the full coupling of thermal (T), hydraulic (H) and mechanical (M) processes that would prevail in the geological media around the repository. For Bench Mark Test no. 1 (BMTI) of the DECOVALEX III project, seven multinational research teams studied the implications of coupled THM processes on the safety of a hypothetical nuclear waste repository at the near-field and are presented in three accompanying papers in this issue. This paper is the first of the three companion papers, which provides the conceptualization and characterization of the BMT1 as well as some general conclusions based on the findings of the numerical studies. It also shows the process of building confidence in the mathematical models by calibration with a reference T-H-M experiment with realistic rock mass conditions and bentonite properties and measured outputs of thermal, hydraulic and mechanical variables.
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| 2. |
- Millard, A., et al.
(author)
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Evaluation of Thm Coupling on the Safety Assessment of a Nuclear Fuel Waste Repository in a Homogeneous Hard Rock
- 2004
-
In: Coupled Thermo-Hydro-Mechanical-Chemical Processes in Geo-Systems — Fundamentals, Modelling, Experiments and Applications. - : Elsevier. ; , s. 211-216
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Book chapter (peer-reviewed)abstract
- An evaluation of the importance of the thermo-hydro-mechanical couplings (THM) on the performance assessment of a deep underground storage design has been made as part of the international DECOVALEX III project. It is a numerical study that simulates a generic repository configuration in the near field in a homogeneous hard rock. A periodic pattern comprises a single vertical borehole, containing a canister surrounded by an over-pack and a bentonite layer, and the backfilled upper portion of the gallery. The thermo-hydro-mechanical evolution of the whole configuration is simulated over a period of 100 years. The importance of the rock mass intrinsic permeability has been investigated through three values : 10 -17, 10 -18 and 10 -19 m 2. Comparison of the results predicted by fully coupled THM analysis as well as partially coupled TH, TM and HM analysis, in terms of several predefined indicators, enables us to identify the couplings, which play a crucial role with respect to safety issues. The results demonstrate that temperature is hardly affected by the couplings. In contrast the influence of the couplings on the mechanical stresses is considerable.
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| 3. |
- Millard, A., et al.
(author)
-
Numerical study of the THM effects on the near-field safety of a hypothetical nuclear waste repository - BMT1 of the DECOVALEX III project. Part 2 : Effects of THM coupling in continuous and homogeneous rocks
- 2005
-
In: International Journal of Rock Mechanics And Mining Sciences. - : Elsevier BV. - 1365-1609 .- 1873-4545. ; 42:5-6, s. 731-744
-
Journal article (peer-reviewed)abstract
- An evaluation of the importance of the thermo-hydro-mechanical couplings (THM) on the performance assessment of a deep underground radioactive waste repository has been made as a part of the international DECOVALEX III project. It is a numerical study that simulates a generic repository configuration in the near field in a continuous and homogeneous hard rock. A periodic repository configuration comprises a single vertical borehole, containing a canister surrounded by an over-pack and a bentonite layer, and the backfilled upper portion of the gallery. The thermo-hydro-mechanical evolution of the whole configuration is simulated over a period of 100 years. The importance of the rock mass's intrinsic permeability has been investigated through scoping calculations with three values: 10(-17), 10(-18) and 10(-19) m(2). Comparison of the results predicted by fully coupled THM analysis as well as partially coupled TH, TM and HM analyses, in terms of several predefined indicators of importance for performance assessment, enables us to identify the effects of the different combinations of couplings, which play a crucial role with respect to safety issues. The results demonstrate that temperature is hardly affected by the couplings. In contrast, the influence of the couplings on the mechanical stresses is considerable.
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| 4. |
- Nguyen, T. S., et al.
(author)
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Implications of Coupled Thermo-Hydro-Mechanical Processes on the Safety of a Hypothetical Nuclear Fuel Waste Repository
- 2004
-
In: Coupled Thermo-Hydro-Mechanical-Chemical Processes in Geo-Systems — Fundamentals, Modelling, Experiments and Applications. - : Elsevier. ; , s. 225-230
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Book chapter (peer-reviewed)abstract
- In Bench Mark Test no. 1 (BMT1) of the DECOVALEX III international project, we looked at the implications of coupled thermo-hydro-mechanical (THM) processes on the safety of a hypothetical nuclear waste repository. The research teams first calibrated their models with the results of an in-situ heater experiments to obtain confidence in the capability of the models to simulate the main physical processes. Then the models were used to perform scoping calculations for the near-field of the hypothetical repository, with varying degrees of THM coupling complexity. The general conclusion from the BMT1 exercise is that it would be prudent to perform full THM coupling analyses for two main reasons. First, several safety features might be overlooked with lesser degrees of coupling. Second, the ability to predict and interpret several physical processes, during the post-closure monitoring period, is important for confidence building and public acceptance. Such ability is attainable only with fully coupled THM models.
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| 5. |
- Chijimatsu, M., et al.
(author)
-
Building Confidence in the Mathematical Models by Calibration With A T-H-M Field Experiment
- 2004
-
In: Coupled Thermo-Hydro-Mechanical-Chemical Processes in Geo-Systems — Fundamentals, Modelling, Experiments and Applications. - : Elsevier. ; , s. 193-198
-
Book chapter (peer-reviewed)abstract
- Geological disposal of nuclear fuel wastes relies on the concept of multiple barrier systems. In order to predict the performance of these barriers, mathematical models have been developed, verified and validated against analytical solutions, laboratory tests and field experiments within the international DECOVALEX project. These models in general consider the full coupling of thermal (T), hydrological (H) and mechanical (M) processes that would prevail in the geological media around the repository. This paper shows the process of building confidence in the mathematical models by calibration with a reference T-H-M experiment with realistic rock mass conditions and bentonite properties and measured outputs of thermal, hydraulic and mechanical variables.
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