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Gilles Armand - One of the best experts on this subject based on the ideXlab platform.

  • In Situ Investigation of the THM Behavior of the Callovo-Oxfordian Claystone
    Rock Mechanics and Rock Engineering, 2020
    Co-Authors: Nathalie Conil, Manon Vitel, Carlos Plua, Minh Ngoc Vu, Darius Seyedi, Gilles Armand
    Abstract:

    The thermo-hydro-mechanical behavior of the host rock is essential while designing an underground Radioactive Waste Disposal repository, and in particular, while considering the long-term safety of the facility. In 2000, the French National Radioactive Waste Management Agency (Andra) started constructing an underground research laboratory located in the Meuse Haute Marne to carry out a research program aiming to demonstrate the feasibility of constructing and operating a Radioactive Waste Disposal facility in the Callovo-Oxfordian claystone, and to optimize its implementation. To study the thermo-hydro-mechanical effects of the early thermal phase on the clay host rock of a deep repository, Andra has performed various in situ heating tests; one of them is called the TED experiment. The aim of the TED experiment was to measure the evolution of the temperature and pore pressure fields around several heaters and to back-analyze the thermo-hydro-mechanical properties of the Callovo-Oxfordian claystone. Thermal conductivity and heat capacity values were determined based on the back-analysis of the in situ measurements and compared to those measured on samples. The in situ experimental data and numerical model confirm the anisotropic behavior of the claystone. The TED experiment results demonstrate the ability of current models to predict the evolution of temperature and pore pressure in the far field of Disposal cells.

  • main outcomes from in situ thermo hydro mechanical experiments programme to demonstrate feasibility of Radioactive high level Waste Disposal in the callovo oxfordian claystone
    Journal of rock mechanics and geotechnical engineering, 2017
    Co-Authors: Gilles Armand, Nathalie Conil, F Bumbieler, R De La Vaissiere, J M Bosgiraud
    Abstract:

    Abstract In the context of Radioactive Waste Disposal, an underground research laboratory (URL) is a facility in which experiments are conducted to demonstrate the feasibility of constructing and operating a Radioactive Waste Disposal facility within a geological formation. The Meuse/Haute-Marne URL is a site-specific facility planned to study the feasibility of a Radioactive Waste Disposal in the Callovo-Oxfordian (COx) claystone. The thermo-hydro-mechanical (THM) behaviour of the host rock is significant for the design of the underground nuclear Waste Disposal facility and for its long-term safety. The French National Radioactive Waste Management Agency (Andra) has begun a research programme aiming to demonstrate the relevancy of the French high-level Waste (HLW) concept. This paper presents the programme implemented from small-scale (small diameter) boreholes to full-scale demonstration experiments to study the THM effects of the thermal transient on the COx claystone and the strategy implemented in this new programme to demonstrate and optimise current Disposal facility components for HLW. It shows that the French high-level Waste concept is feasible and working in the COx claystone. It also exhibits that, as for other plastic clay or claystone, heating-induced pore pressure increases and that the THM behaviour is anisotropic.

Bumbieler F. - One of the best experts on this subject based on the ideXlab platform.

  • Thermo-hydro-mechanical simulation of a full-scale steel-lined micro-tunnel excavated in the Callovo-Oxfordian claystone
    2019
    Co-Authors: Tourchi Saeed, Vu Minh-ngoc, Vaunat Jean, Gens Solé Antonio, Bumbieler F.
    Abstract:

    The paper presents an interpretation of the full-scale ALC1604 in situ heating test carried out in Callovo-Oxfordian claystone (COx) in the Meuse/Haute-Marne underground research laboratory (MHM URL). The MHM URL is a site-specific facility planned to study Radioactive Waste Disposal in the COx. The thermo-hydro-mechanical (THM) behaviour of the host rock is significant for the design of the underground Radioactive Waste Disposal facility and for its long-term safety. When subjected to thermal loading, the Callovo-Oxfordian claystone of low permeability (~10-20-10-21 m2) exhibits a strong pore pressure response that significantly affects the hydraulic and mechanical behaviour of the material. The observations gathered in the in situ test have provided an opportunity to examine the integrated thermo-hydro-mechanical (THM) response of this sedimentary clay. Coupled THM numerical analyses have been carried out to provide a structured framework for interpretation, and to enhance understanding of THM behaviour of COx. Numerical analyses have been based on a coupled theoretical formulation that incorporates a constitutive law specially developed for this type of material. The law includes a number of features that are relevant for a satisfactory description of the hydromechanical behaviour. By performing the numerical analysis, it has been possible to incorporate anisotropy of material parameters and of in situ stresses. The performance and analysis of the in situ tests have significantly enhanced the understanding of a complex THM problem and have proved the capability of the numerical formulation to provide adequate predictive capacity.Postprint (published version

  • Thermo-hydro-mechanical simulation of a full-scale steel-lined micro-tunnel excavated in the callovooxfordian claystone
    CIMNE, 2019
    Co-Authors: Tourchi S., Vaunat J., Gens A., Vu M. N., Bumbieler F.
    Abstract:

    The paper presents an interpretation of the full-scale ALC1604 in situ heating test carried out in Callovo-Oxfordian claystone (COx) in the Meuse/Haute-Marne underground research laboratory (MHM URL). The MHM URL is a site-specific facility planned to study Radioactive Waste Disposal in the COx. The thermo-hydro-mechanical (THM) behaviour of the host rock is significant for the design of the underground Radioactive Waste Disposal facility and for its long-term safety. When subjected to thermal loading, the Callovo-Oxfordian claystone of low permeability (~10-20-10-21 m2) exhibits a strong pore pressure response that significantly affects the hydraulic and mechanical behaviour of the material. The observations gathered in the in situ test have provided an opportunity to examine the integrated thermo-hydromechanical (THM) response of this sedimentary clay. Coupled THM numerical analyses have been carried out to provide a structured framework for interpretation, and to enhance understanding of THM behaviour of COx. Numerical analyses have been based on a coupled theoretical formulation that incorporates a constitutive law specially developed for this type of material. The law includes a number of features that are relevant for a satisfactory description of the hydromechanical behaviour. By performing the numerical analysis, it has been possible to incorporate anisotropy of material parameters and of in situ stresses. The performance and analysis of the in situ tests have significantly enhanced the understanding of a complex THM problem and have proved the capability of the numerical formulation to provide adequate predictive capacity

Nathalie Conil - One of the best experts on this subject based on the ideXlab platform.

  • In Situ Investigation of the THM Behavior of the Callovo-Oxfordian Claystone
    Rock Mechanics and Rock Engineering, 2020
    Co-Authors: Nathalie Conil, Manon Vitel, Carlos Plua, Minh Ngoc Vu, Darius Seyedi, Gilles Armand
    Abstract:

    The thermo-hydro-mechanical behavior of the host rock is essential while designing an underground Radioactive Waste Disposal repository, and in particular, while considering the long-term safety of the facility. In 2000, the French National Radioactive Waste Management Agency (Andra) started constructing an underground research laboratory located in the Meuse Haute Marne to carry out a research program aiming to demonstrate the feasibility of constructing and operating a Radioactive Waste Disposal facility in the Callovo-Oxfordian claystone, and to optimize its implementation. To study the thermo-hydro-mechanical effects of the early thermal phase on the clay host rock of a deep repository, Andra has performed various in situ heating tests; one of them is called the TED experiment. The aim of the TED experiment was to measure the evolution of the temperature and pore pressure fields around several heaters and to back-analyze the thermo-hydro-mechanical properties of the Callovo-Oxfordian claystone. Thermal conductivity and heat capacity values were determined based on the back-analysis of the in situ measurements and compared to those measured on samples. The in situ experimental data and numerical model confirm the anisotropic behavior of the claystone. The TED experiment results demonstrate the ability of current models to predict the evolution of temperature and pore pressure in the far field of Disposal cells.

  • main outcomes from in situ thermo hydro mechanical experiments programme to demonstrate feasibility of Radioactive high level Waste Disposal in the callovo oxfordian claystone
    Journal of rock mechanics and geotechnical engineering, 2017
    Co-Authors: Gilles Armand, Nathalie Conil, F Bumbieler, R De La Vaissiere, J M Bosgiraud
    Abstract:

    Abstract In the context of Radioactive Waste Disposal, an underground research laboratory (URL) is a facility in which experiments are conducted to demonstrate the feasibility of constructing and operating a Radioactive Waste Disposal facility within a geological formation. The Meuse/Haute-Marne URL is a site-specific facility planned to study the feasibility of a Radioactive Waste Disposal in the Callovo-Oxfordian (COx) claystone. The thermo-hydro-mechanical (THM) behaviour of the host rock is significant for the design of the underground nuclear Waste Disposal facility and for its long-term safety. The French National Radioactive Waste Management Agency (Andra) has begun a research programme aiming to demonstrate the relevancy of the French high-level Waste (HLW) concept. This paper presents the programme implemented from small-scale (small diameter) boreholes to full-scale demonstration experiments to study the THM effects of the thermal transient on the COx claystone and the strategy implemented in this new programme to demonstrate and optimise current Disposal facility components for HLW. It shows that the French high-level Waste concept is feasible and working in the COx claystone. It also exhibits that, as for other plastic clay or claystone, heating-induced pore pressure increases and that the THM behaviour is anisotropic.

T M Krishnamoorthy - One of the best experts on this subject based on the ideXlab platform.

  • probabilistic safety assessment model for near surface Radioactive Waste Disposal facilities
    Environmental Modelling and Software, 1999
    Co-Authors: Ramesh Nair, T M Krishnamoorthy
    Abstract:

    Abstract A probabilistic safety assessment model has been developed for assessing the performance of near surface Disposal facilities for low-level Radioactive Waste. Two modes of Disposal such as single dump and multiple dump are considered in the model. The model is composed of four components: source term, repository failure, geosphere transport and radiological assessment. The source term contains low-level Radioactive Waste equivalent to 50 GWe.y energy production (1 GWe.y=3.2×1016 J of electrical energy production) either disposed at an instant or distributed over 50 years. The endpoints of assessment are expressed as radioactivity release rate, radionuclide concentration in ground water, radiation dose to a member of the critical group through drinking water pathway and total risk to critical group due to Disposal practice. Sensitivity analysis is carried out to identify the critical parameters, which have maximum effect on the assessment endpoints. Uncertainty analysis, based on random selection of all main parameters, is also carried out to identify the effect of overall variation of parameters used in the model in relation to a reference level. The reference level delivers a maximum annual effective dose of 1.2×10−2 mSv to a member of the critical group after about 1.25×102 years of Disposal mostly from 129I, the long-lived and less sorbing radionuclide. The corresponding risk to the public due to the Disposal practice (9.0×10−7 y−1) is found to be lower than that due to natural background radiation. The most critical parameters as indicated by the sensitivity analysis are the distribution coefficient of radionuclides, seepage velocity in the unsaturated zone between the facility and the water table, dispersivity in ground water and thickness of the unsaturated zone. The uncertainty analysis shows that 129I is the critical radionuclide delivering maximum dose in most cases though it constitutes a low percentage in the low-level Radioactive Waste inventory. The annual effective doses derived from the uncertainty analysis fall in a log normal distribution with a geometric mean of 3.6×10−2±3.9 mSv and the most probable annual effective dose to a member of the critical group works out to be 2.8×10−4 mSv.

M Jorda - One of the best experts on this subject based on the ideXlab platform.