Caracterización termo-hidro-mecánica y geoquímica de materiales de confinamiento en almacenamientos de residuos radiactivos

Convenio ENRESA/CIEMAT

2022-2026

Colaboración entre ENRESA y CIEMAT con el objeto de desarrollar un proyecto de investigación sobre la caracterización y evolución de las propiedades térmicas, mecánicas, hidráulicas y geoquímicas de materiales utilizados como barrera de ingeniería de instalaciones relacionadas con el almacenamiento de residuos radiactivos de alta actividad. Dentro de esta colaboración se han realizado trabajos relacionados con los siguientes proyectos/actividades:

• Estudio de los procesos que tienen lugar en la interfase metal/bentonita (en conexión con el proyecto EURAD-ACED)
• Estudio en ensayos de laboratorio del comportamiento hidro-mecánico, mineralógico y geoquímico de los materiales de barrera bajo temperaturas superiores a 100°C (en conexión con el proyecto EURAD-HITEC)
• Estudio del transporte de gas en materiales de barrera (en conexión con el proyecto EURAD-GAS)
• Participación en ensayos a gran escala llevados a cabo en el laboratorio subterráneo de Mont Terri (e.g. HE-E, SANDWICH)
• Estudio en ensayos de laboratorio del comportamiento a largo de plazo de la bentonita en condiciones del almacenamiento y las repercusiones sobre su microestructura y su capacidad de homogeneización

https://www.ciemat.es/cargarAplicacionNoticias.do?identificador=2519&idArea=-1

Influence of temperature on clay-based material behaviour

Commission of  the European Communities, Euratom research and training programme 2014-2018 grant agreement No 847593

2019-2023

https://www.ejp-eurad.eu/implementation/influence-temperature-clay-based-material-behaviour-hitec

Most repository concepts consider that the temperature at the surface of the canisters should be below 100°C. However, the nuclear waste management agencies have realised that being able to tolerate higher temperature, whilst still ensuring an appropriate performance, would have significant advantages (e.g. shorter above-ground cooling times, more efficient packaging, fewer disposal containers, fewer transport operations, smaller facility footprints, etc.). In this context, the European project EURAD includes a work package devoted to the “Influence of Temperature on Clay-based Material Behaviour” (HITEC), which evaluates whether or not elevated temperature limits (of 100-150°C) are feasible for a variety of geological disposal concepts and aims to determine where the buffer safety functions start to be unacceptably impaired. In the framework of this project the Group will:

• Determine the water retention curves of buffer materials at high temperature, with focus on the low suction range (Fig. 1).
• Perform thermo-hydraulic tests in cells under high temperature, following the evolution over time of water intake, pressure, relative humidity, temperature. This activity will support the modelling work of UPC (Universitat Politècnica de Catalunya).
• Assess the modifications induced over time by the thermal gradient and hydration on the bentonite physico-chemical, chemical and mineralogical characteristics. This will be performed in collaboration with UAM (Universidad Autónoma de Madrid).

The Group is also in charge of the coordination of the State of the Art report.

Fig. 1. Setup for the determination of water retention curves at high temperatures

• Villar, M.V., Armand, G., Conil, N., de Lesquen, Ch., Herold, Ph., Simo, E., Mayor, J.C., Dizier, A., Li, X., Chen, G., Leupin, O., Niskanen, M., Bailey, M., Thompson, S., Svensson, D., Sellin, P., Hausmannova, L. 2020. D7.1 HITEC. Initial State-of-the-Art on THM behaviour of i) Buffer clay materials and of ii) Host clay materials. Deliverable D7.1 HITEC. EURAD Project, Horizon 2020 No 847593. 240 pp.

In several disposal concepts, the potential for migration of free gas containing radionuclides to the biosphere is an important issue. Experiments in the FORGE project revealed complex mechanisms and emphasized the importance of the mechanical control exerted by the porous material on gas transport. How gas can migrate, which radionuclides are associated with it, and what perturbations induced by gas could affect barrier integrity and performance are questions that must be ansewered.

In this context, the European project EURAD includes a work package devoted to the “Mechanistic understanding of gas transport in clay materials (GAS)”, which will provide data and develop process-level models to improve mechanistic understanding of transport processes, both in natural and engineered clay materials, and including couplings with mechanical behaviour and impact on the clay properties. In particular, it aims to determine, for each identified gas transport regime, the conditions under which that regime is possible; both in clay materials representative of the host rock, as in the components of the EBS. In the framework of this project the Group will:

• Adapt the gas permeability apparatuses to include the measurement of RH/T in the gas flow.
• Perform tests in cells under high gas transport rates, in compacted samples saturated with water from Spanish EBS clay, for different boundary conditions.
• Determine the break-trough gas pressure of EBS Spanish clay, in isochoric cells, for several dry densities.
• Identify the conditions under which different regimes of gas transport are possible and assess the modifications induced on the bentonite barrier performance by gas transport, if any. This activity will support the modelling work of UPC (Universitat Politècnica de Catalunya).

https://www.ejp-eurad.eu/implementation/mechanistic-understanding-gas-transport-clay-materials-gas

The sealing ability is essential for the engineered clay (bentonite) barriers in all geological repository concepts. The overall objective of the Beacon project is to develop and test the tools necessary for the assessment of the mechanical evolution of an installed bentonite barrier and the resulting sealing ability of the barrier. It will require a more detailed understanding of material properties, of the fundamental processes that lead to homogenisation and of the role of scale effects, as well as improved capabilities for numerical modelling. The barrier can be initially inhomogeneous (Fig. 2) or become inhomogeneous over time. CIEMAT’s work focuses on the conceptual understanding of the evolution of bentonite fabric and microstructure upon hydration and the factors affecting them. To this aim, different kinds of laboratory tests have been designed and set up:

• Hydration tests in isochoric cells to analyse the fabric and microstructure evolution of initially inhomogeneous bentonite, using in conjunction compacted blocks and pellets (Fig. 3).
• Tests in transparent cells to obtain qualitative information about the texture evolution of initially inhomogeneous bentonite upon hydration.
• Hydration tests with initially inhomogeneous materials, such as those mentioned above but following relative humidity and pressure evolution inside the bentonite (Fig. 4).
• Tests to check the water content and volume changes of bentonite under suction control and limited axial swelling, considering the influence on them of the existence of gaps, initial dry density and suction.

Fig. 2.Conceptual design of an engineered barrier composed of bentonite blocks and pellets (www.nagra.ch). 

Fig. 3. Appearance of samples composed of bentonite pellets (bottom) and blocks (top) after different periods of hydration under constant-volume conditions. 

Fig. 4. Hydration cell to test bentonite block/pellets assemblages with measurement of water intake, lateral pressure, relative humidity and pore pressure. 

• Villar, M.V., Iglesias, R.J., Gutiérrez-Álvarez, C., Carbonell, B., Real, E., Brea, N. 2022. Laboratory tests on bentonite homogenisation performed by CIEMAT: Saturation of block/pellets systems (Project BEACON). Informes Técnicos CIEMAT 1509. Madrid, 110 pp. https://www.ciemat.es/portal.do?NM=3&IDM=223
• Villar, M.V., Gutiérrez-Álvarez, C., Campos, G. 2022. Laboratory tests on bentonite homogenisation performed by CIEMAT: Gap filling (Project BEACON). Informes Técnicos CIEMAT 1510. Madrid, 72 pp. https://www.ciemat.es/portal.do?NM=3&IDM=223

Compacted bentonite will be one of the engineered barriers in the KBS-3V repository concept for spent nuclear fuel in Finland. Mineralogical alteration of the bentonite buffer due to thermal, hydraulic, and chemical gradients may impair the safety functions of the engineered barrier. These alteration processes include loss of montmorillonite mass, cementation due to the precipitation of secondary minerals, alteration of cation exchange capacity (CEC), and dissolution of accessory minerals. Hence, there is a need to reduce conceptual and modelling uncertainties to a low level. To this end, POSIVA is conducting research to assess the long-term mineralogical alteration of the buffer under partially and fully water saturated conditions. The focus is on conditions that are specific to the future repository at Olkiluoto in terms of groundwater composition, bentonite type, or initial and boundary thermal and hydraulic conditions. Within this framework, an experimental campaign is on-going at CIEMAT since autumn 2016, in collaboration with Amphos 21, to study the long-term (5 years) geochemical evolution of compacted bentonite under partially saturated conditions.

Fig. 5: Thermo-hydraulic cells for the Minalben project. 

• Villar, M.V., Cuevas, J., Melón, A.M., Gutiérrez-Álvarez, C., Ruiz, A.I., Ortega, A., Iglesias, R.J., González, A.E., Brea, N., Fernández, R., Real, E. 2021. Project Minalben. Report on postmortem analyses of samples from cells running for 2.5 years (C3, C4 and C5). Technical Report CIEMAT/DMA/2G219/1/21. Madrid, 86 pp.

• Villar, M.V., Gutiérrez-Álvarez, C., Iglesias, R.J., Melón, A.M., Martín, P.L., Barcala, J.M., Cuevas, J., Ruiz, A.I, Ortega, A., Fernández, R. 2019. Project Minalben. Final report on dismantling and postmortem analysis of cells C1 and C2. Technical Report CIEMAT/DMA/2G219/1/19. Madrid, 89 pp.

Caracterización termo-hidro-mecánica y geoquímica de materiales empleados en almacenamientos de residuos radiactivos

Convenio Marco CIEMAT /ENRESA 2/6/2004. Anexo XLII

2016-2020

Colaboración entre ENRESA y CIEMAT con el objeto de desarrollar un proyecto de investigación sobre la caracterización y evolución de las propiedades térmicas, mecánicas, hidráulicas y geoquímicas de materiales utilizados como barrera de ingeniería o como sustrato geológico de instalaciones relacionadas con el almacenamiento de residuos radiactivos, tanto de baja como de alta actividad, profundizando en la comprensión de los procesos que tienen lugar en estos materiales. Dentro de esta colaboración se han realizado trabajos relacionados con los siguientes proyectos/actividades:

• ATC – sustrato geológico.
• FEBEX-DP: caracterización ampliada respecto a lo considerado por el consorcio FEBEX-DP descrito más abajo.
• Estudio en ensayos de laboratorio del comportamiento a largo de plazo de la bentonita en condiciones del almacenamiento (en relación con el proyecto BEACON) y colaboración en proyectos llevados a cabo en el laboratorio subterráneo de Mont Terri (HE-E, SANDWICH).
• Trabajos en argilitas utilizadas como roca almacén (Opalinus, Ypresian) en diferentes laboratorios subterráneos europeos.

As a continuation of the FEBEXe project described below, a new consortium was formed to undertake the final excavation and dismantling of the FEBEX in situ test (Fig. 23, Fig. 16), which was accomplished in 2015 after 18 years of operation, and the postmortem analysis of all the different elements and interpretation and modelling of the experiment. In addition to the members of FEBEXe (SKB, CIEMAT, POSIVA and NAGRA) six additional partners joined the consortium: NDRA, BGR, Obayashi, RWM, SURAO, US-DOE/LBNL.

The Group coordinated the physical characterisation of the bentonite performed on site (Villar et al. 2016, Fig. 6, Fig. 7) and the THM-C characterisation of the bentonite performed in different laboratories appointed by the consortium partners (Villar 2017, Fig. 8).

Fig. 6. Drilling of core samples for onsite determinations (left) and onsite laboratory for water content and dry density determinations (right). 

Fig. 7. Contour plots for the bentonite barrier water content after 18 years operation around the heater (left) and in an area outside the heater influence (right). 

Fig. 8. Change of effective gas permeability with increasing confining pressure in samples from section S47. 

• Villar, M.V. 2018. Desmantelamiento del ensayo FEBEX-DP: una simulación en condiciones naturales del concepto español de almacenamiento de residuos de alta actividad en funcionamiento durante 18 años. Estratos 120: 44-51. ENRESA.
• Villar, M.V., Iglesias, R.J., Abós, H., Martínez, V., de la Rosa, C., Manchón, M.A. 2016. FEBEX-DP onsite analyses report. NAB 16-012. 106 pp.
• Villar, M.V. 2017. FEBEX-DP Postmortem THM/THC Analysis Report. Technical Report NAB 16-017. 147 pp.
• Villar, M.V., Iglesias, R.J., Gutiérrez-Álvarez, C., Carbonell, B., Campos, R., Campos, G., Martín, P.L., Castro, B. 2018. FEBEX-DP: Thermo-hydro-mechanical postmortem analysis of bentonite performed at CIEMAT. Technical report CIEMAT/DMA/2G216/2/16. NAB16-024. Madrid, 134 pp.
• Villar, M.V., Carbonell, B., Martín, P.L., Gutiérrez-Álvarez, C., Barcala, J.M. 2018. Gas permeability of bentonite samples of the FEBEX Dismantling Project (FEBEX-DP). Informe Técnico CIEMAT 1431. Madrid, 89 pp.
• Campos, G., Villar, M.V. 2018. Water retention curves of bentonite samples of the FEBEX Dismantling Project (FEBEX-DP). Informe Técnico CIEMAT 1432. Madrid, 44 pp.

Proyecto de investigación sobre los parámetros de migración del emplazamiento del almacén temporal centralizado de Villar de Cañas: respuesta termohidromecánica y geoquímica del sustrato geológico del emplazamiento y su incidencia en la seguridad a largo plazo.

Convenio Marco CIEMAT /ENRESA 2/6/2004. Anexo XXXVII

2012-2015

Este proyecto abordó el estudio del substrato geológico del emplazamiento del almacenamiento temporal centralizado (ATC) en Villar de Cañas (Cuenca), en concreto de los aspectos relacionados con el comportamiento termo-hidro-mecánico y geoquímico de los materiales geológicos y de los parámetros que condicionan y permiten establecer la respuesta de los mismos al impacto térmico y mecánico de la instalación. Se trabajó con testigos de sondeo realizados en el emplazamiento propuesto, una cuenca sedimentaria terciaria formada por conglomerados, areniscas, lutitas, yesos y calizas (Fig. 9). Se realizó una caracterización de materiales de la Segunda Unidad Neógena (esencialmente lutítico-limosa y, sobre todo, yesífera) que incluyó los siguientes aspectos (Fig. 10):

• Caracterización de los materiales del subsuelo en condiciones representativas: humedad, densidad del sólido, límites de plasticidad, peso específico y distribución granulométrica.
• Análisis de la capacidad de hinchamiento y la presión de hinchamiento.
• Determinación de las curvas de retención.
• Medida de la conductividad térmica.
• Determinación de la mineralogía y geoquímica.
• Análisis petrofísico (distribución de tamaño de poros, superficie específica)

Con los resultados obtenidos se establecieron tres litotipos dentro de la formación Lutitas Superiores de Balanzas (la más estudiada y de mayor interés geotécnico), distinguiéndose inicialmente por su apariencia tres: LBSmic, LBSmac y LBSlut (Fig. 11). El contenido de yeso disminuye del primero al último, mientras que el contenido de filosilicatos y la capacidad de cambio catiónico aumenta. La distribución granulométrica también es diferente, disminuyendo el porcentaje de fracción arena del primero al último y aumentando el de fracción arcilla, a la vez que aumenta la plasticidad. En cuanto a la capacidad de hinchamiento, es baja para el litotipo LBSmic y presenta los valores más altos para el LBSlut.

Fig. 9. Geological cross- section of the Tertiary of Villar de Cañas synclinal with the location of some sampled boreholes (WSW-ENE) (Inypsa-Eptisa 2013).

Fig. 10: Example of sampling in laboratory of a core sample.

Fig. 11: Identified lithotypes in the Lutitas Superiores de Balanzas formation: LBSmic, LBSmac and LBSlut (from left to right).

• Villar, M.V., Iglesias, R.J., Campos, G., Gutiérrez-Alvarez, C. 2016. ATC: Caracterización básica y termo-hidro-mecánica del sustrato. Informe Final. Informe Técnico CIEMAT/DMA/2G214/3/16. Madrid, 114 pp.
• Fernández, A.M., Sánchez-Ledesma, D.M., Melón, A.M., Robredo, L.M., Labajo, M.A., Sánchez, M., Clavero, M.A., González, A.E., Rey, J.J., Gutiérrez-Nebot, L. 2016. Síntesis geoquímica, mineralógica y petrográfica del sustrato geológico del ATC: Características de las unidades litoestratigráficas LBS, YB, LBI y UI en el entorno de Villar de Cañas (Cuenca). Informe final. Informe Técnico CIEMAT/DMA/2G214/1/2016. Madrid, 150 pp.
• Campos Egea, R. 2016. ATC: Caracterización petrofísica. Informe Final. Informe Técnico CIEMAT/DMA/2G214/2/16. 53 pp.
• Campos, G., Villar, M.V. 2018. ATC: Curvas de retención de muestras del sondeo SG-125. Informe Técnico CIEMAT/DMA/2G218/6/18. Madrid, 41 pp.

Caracterización sistema poroso AGP de CO2

Plan Nacional 2011: PROYECTOS DE INVESTIGACIÓN FUNDAMENTAL NO ORIENTADA. 3154-11

2011-2015

La inyección de CO2 en formaciones geológicas se plantea como una de las soluciones más viables para la reducción de gases con efecto invernadero a la atmósfera. Esta solución conlleva la investigación de los procesos que tendrán lugar en el almacenamiento una vez inyectado el gas y es en este contexto de investigación donde se planteó este proyecto. Se encuadró en una de las áreas de acción prioritarias de la ANEP, el cambio climático y mitigación del calentamiento global.

El objetivo del proyecto era la caracterización del sistema poroso de la formación geológica Utrillas, como posible roca almacén en un AGP de CO2, contribuyendo al conocimiento de los mecanismos de movilidad/retención del gas en el reservorio, tras la inyección de CO2 en una formación detrítica saturada.

• R. Campos, I. Barrios y J. Lillo. 2015. Experimental CO2 injection: Study of physical changes in sandstone porous media using Hg porosimetry and 3D pore network models. Energy Reports 1 (2015) 71–79.

The main aim of the project PEBS (Long-term Performance of the Engineered Barrier System) was to evaluate the sealing and barrier performance of the EBS with time, through development of a comprehensive approach involving experiments, model development and consideration of the potential impacts on long-term safety functions. The experiments and models covered the full range of conditions from initial emplacement of wastes (high heat generation and EBS resaturation) through to later stage establishment of near steady-state conditions, i.e. full resaturation and thermal equilibrium with the host rock. These aspects were integrated in a manner that led to a more convincing connection between the initial transient state of the EBS and its long-term state that will provide the required isolation of the wastes. The project intended to provide a more complete description of the THM and THM-C (thermo-hydromechanical-chemical) evolution of the EBS system, a more quantitative basis for relating the evolutionary behaviour to the safety functions of the system and a further clarification of the significance of residual uncertainties for long-term performance assessment.

CIEMAT contributed to several workpackages of this project. In particular the Group performed laboratory infiltration tests at room temperature to support the large-scale EB project (Mont Terri, Fig. 12), continued running the FEBEX mock-up test and the GAME geochemical mock-ups, and designed and started laboratory THM tests with different materials (Fig. 13) to support the large-scale test HE-E (Mont Terri, Fig. 12).

Fig. 12: Lay-out of the Mont Terri underground laboratory showing the location of tests EB (number 8) and HE-E (number 9). More information at https://www.mont-terri.ch/en/experiments/the-most-important-experiments.

Fig. 13. Thermo-hydraulic tests in cells with buffer materials used in the HE-E in situ experiment

• Palacios, B., Rey, M., García-Siñeriz, J.L., Villar, M.V., Mayor, J.C., Velasco, M. 2013. Engineered Barrier Emplacement Experiments in Opalinus Clay: “EB” Experiment. As-built of dismantling operation. PEBS Deliverable D2.1-4. Madrid, 95 pp.
• Villar, M.V. Campos, R., Gutiérrez-Nebot, L. 2014. EB experiment. Laboratory post-mortem analyses report. EC Contract 249681 PEBS. PEBS Deliverable 2.1-7. Technical Report CIEMAT/DMA/2G210/01/2014. Madrid, 34 pp.
• Johnson, L., Gaus, I., Wieczorek, K., Mayor, J. C., Sellin, P., Villar, M.-V., Samper, J., Cuevas, J.A., Gens, M., Velasco, M., Turrero, M.J., Montenegro, L., Martin P.-L., Armand G. 2014. Integration of the Short-term Evolution of the Engineered Barrier System (EBS) with the Long-term Safety Perspective (Deliverable D4.1 of the PEBS Project). Nagra Arbeitsbericht NAB 14-79. Wettingen, 85 pp.
• Villar, M.V., Martín, P.L., Romero, F.J., Gómez-Espina, R., Iglesias, R.J., Gutiérrez-Rodrigo, V. 2015. HE-E Experiment: Laboratory test in a THM cell with the Sand/Bentonite mixture. Mont Terri Project TN 2015-43. Madrid, 28 pp.

The FORGE project was a pan-European project with links to international radioactive waste management organisations, regulators and academia, specifically designed to tackle the key research issues associated with the generation and movement of repository gasses. Of particular importance are the long-term performance of bentonite buffers, plastic clays, indurated mudrocks and crystalline formations. Experimental data were brought forth to reduce uncertainty relating to the quantitative treatment of gas in performance assessment. FORGE addressed these issues through a series of laboratory and field-scale experiments, including the development of new methods for up-scaling allowing the optimisation of concepts through detailed scenario analysis. CIEMAT focused on the experimental study at laboratory scale of gas transport in bentonite, Opalinus clay and concrete. To this aim a laboratory for gas testing was designed and set up, and different experimental procedures and protocols were implemented (Fig. 14, Fig. 15). Part of the results of this project gave place to the Ph.D. thesis of Vanesa Gutiérrez-Rodrigo.

Fig. 14. Different lay-outs of the gas testing laboratory during FORGE project. 

Fig. 15. Detail of one of the gas transport experiments in operation during FORGE. 

• Villar, M.V., Martín, P.L., Romero, F.J., Gutiérrez-Rodrigo, V. & Barcala. J.M. 2012. Gas and water permeability of concrete. Informes Técnicos CIEMAT 1261. Octubre 2012. CIEMAT, Madrid, 45 pp.
• Villar, M.V. & Romero, F.J. 2012. Water retention curves of Opalinus clay. Informes Técnicos CIEMAT 1262. Octubre 2012. CIEMAT, Madrid, 33 pp. DOI: 10.13140/RG.2.2.17689.72808
• Villar, M.V.; Gutiérrez-Rodrigo, V.; Martín, P.L.; Romero, F.J. & Barcala, J.M. 2013. Gas transport in bentonite. Informes Técnicos CIEMAT 1301. Madrid, 63 pp. DOI: 10.13140/RG.2.2.14334.28489
• M.V. Villar, F.J. Romero, P.L. Martín, V.Gutiérrez-Rodrigo, J.M. Barcala. 2015. Gas transport in Opalinus clay. Informes Técnicos CIEMAT 1378. Madrid, 40 pp. DOI: 10.13140/RG.2.2.28594.91846

The FEBEX experiment was the research subject in three subsequent European research projects: FEBEX, FEBEX II and NF-PRO (see below), under the leadership of Enresa (Spain). Starting in 2008, a consortium of four partners (SKB, CIEMAT, POSIVA and NAGRA) was brought together and continued running the in situ experiment (Fig. 16) and CIEMAT’s mock-up (Fig. 17) as part of Grimsel Phase VI under the name FEBEXe (extension). This consortium was joined by KAERI in 2013.

Fig. 16. FEBEX in situ test 2002-2015

Fig. 17. FEBEX mock-up at CIEMAT, running since 1997

Caracterización de materiales de confinamiento de base hormigón/arcilla.

Convenio Marco CIEMAT /ENRESA 2/6/2004. Anexo XX

2009-2013

Caracterización del material de cobertera y el hormigón del C.A. El Cabril

Convenio Marco CIEMAT /ENRESA 2/6/2004. Anexos XIII y XX

2006-2009

ENRESA diseñó un ensayo a gran escala para definir la cobertera a largo plazo de las plataformas Norte y Sur del Centro de Almacenamiento de El Cabril para su clausura (Fig. 18). Se trata de una cobertera multicapa que contribuya a la reducción de la erosión, la eliminación de aguas superficiales, la protección frente a la biointrusión, la minimización de la permeabilidad para limitación de aguas infiltradas y el drenaje de las infiltraciones. La caracterización por parte del CIEMAT de los materiales del ensayo de cobertera incluyó la determinación de propiedades hidráulicas, mecánicas, térmicas y eléctricas. Además, se realizó la caracterización hidráulica y térmica del hormigón de las celdas de almacenamiento (Fig. 18). En una segunda fase la caracterización se amplió con la realización de ensayos de evaporación a escala de laboratorio en columnas de los diferentes materiales utilizados en el ensayo de cobertera y en el hormigón de las celdas de almacenamiento; así como a la caracterización de rocas arcillosas provenientes de laboratorios subterráneos (Callovo-Oxfordian clay del laboratorio de Bure, Francia, y Opalinus Clay del laboratorio de Mont Terri, Suiza). Los ensayos de evaporación en hormigón se utilizaron para calibrar modelos de flujo multifase en colaboración con la UPC (Chaparro et al. 2015).

Fig. 18. El Cabril liner layers test and concrete storage cells (ENRESA). 

Fig. 19. Experimental setups for performance of evaporation tests in cover materials and concrete.

• Villar, M.V.; Martín, P.L. & Barcala, J.M. 2009. Caracterización del material de cobertera y el hormigón del C. A. El Cabril. Caracterización termo-hidro-mecánica. Informe Técnico CIEMAT/DMA/2G205/03/09. Madrid, 55 pp. Agosto 2009.
• Villar, M.V. 2011. Resultados de los ensayos de caracterización de los materiales de cobertera. Informe Técnico CIEMAT/DMA/2G208/06/11. Madrid, 20 pp.
• Chaparro, M.C., Saaltink, M.W. & Villar, M.V. 2015. Characterization of concrete by calibrating thermo-hydraulic multiphase flow models. Transport in Porous Media 109(1): 147-167. DOI: 10.1007/s11242-015-0506-9

The principal objective of the Integrated Project NF-PRO was to establish the scientific and technical basis for evaluating the safety function "containment and minimisation of release" of the near-field of a geological repository for high-level radioactive waste and spent fuel. To this end, NF-PRO investigated dominant processes and process couplings affecting the isolation of nuclear waste within the near-field and applied and developed conceptual and mathematical models for predicting the source-term release of radionuclides from the near-field to the far-field. Results and conclusions of experimental and modelling work were integrated in performance assessment. NF-PRO was structured in five Research and Technology Development Components (RTD Components) each representing a major near-field sub-system. In particular, the group participated in RTD Components 2 (chemical processes taking place in the Engineered Barrier System, EBS), 3 (thermo-hydromechanical (THM) evolution of the EBS) and 4 (characteristics and the evolution of the excavation disturbed zone, EDZ).

• Villar, M.V. 2004. Thermo-hydro-mechanical characteristics and processes in the clay barrier of a high level radioactive waste repository. State of the art report. Informes Técnicos CIEMAT 1044. CIEMAT, Madrid, 75 pp.
• Villar, M.V.; Fernández A.M. & Melón, A.M. 2009. Mont Terri Ventilation Test Phase II. Water retention curves determined on argillite samples taken before and after an in situ Ventilation Phase. Informes Técnicos CIEMAT 1170.  Madrid, 34 pp. Junio 2009. DOI: 10.13140/RG.2.2.35096.08960
• Villar, M.V. & Gómez-Espina, R. 2009. Report on thermo-hydro-mechanical laboratory tests performed by CIEMAT on FEBEX bentonite 2004-2008. Informes Técnicos CIEMAT 1178. Madrid, 67 pp. Agosto 2009. DOI: 10.13140/RG.2.2.10087.55208

The project's main objective was to validate experimentally a constitutive model for unsaturated soils behaviour proposed by Robles & Elorza [2003] and to determine its practical limits of applicability. To accomplish this CIEMAT carried out an experimental study under triaxial saturated and unsaturated conditions on a silty clay soil. At the same time, UPM developed a tool for the automatic calibration of the parameters of the model with the experimental data. Frédéric Lambert, from INSA-Rennes did his final internship in the framework of this project.

Fig. 20. Schematic design and appearance of the triaxial equipment with controlled suction (from left to right).

• M.V. Villar, A. Udías, I. Cañamón & J. Robles. 2006. Estudio experimental de la deformabilidad de un material geológico: caracterización inicial e identificación de parámetros. Informes Técnicos CIEMAT 1080. CIEMAT, Madrid, 45 pp. Junio 2006. DOI: 10.13140/RG.2.2.23509.32480

The CIEMAT/CIMNE agreement took place in the context of the participation of CIMNE and ENRESA in the project Temperature Buffer Test (TBT), performed by ANDRA and SKB at the Äspö Hard Rock Laboratory (Sweden). The TBT project was a full-scale test for high-level radioactive waste disposal aiming at improving the understanding of the THM behaviour of buffers with a temperature around and above 100°C during the water saturation transient. The French organisation Andra run this test in cooperation with SKB (Svensk Kärnbränslehantering AB). Two electrical heaters simulating the waste containers were placed in an 8-m depth and 1.8-m diameter vertical hole drilled in granitic rock (Fig. 21). The heaters were surrounded by compacted MX-80 bentonite. The participation of CIEMAT consisted in the performance of laboratory tests to support the THM modelling work carried out by CIMNE, specifically the determination of the water retention curves of the bentonite at high temperatures and the performance of laboratory-scale thermo-hydraulic tests simulating the conditions of the bentonite in the large-scale in situ tests (Fig. 22). This work was part of the Ph.D. thesis of Roberto Gómez-Espina (https://dialnet.unirioja.es/servlet/tesis?codigo=258183).

Fig. 21. Design of the TBT experiment (Äkesson, M. 2012. Temperature Buffer Test. Final Report. SKB TR-12-04

Fig. 22. Experimental setups designed for the project. 

• M.V. Villar, R. Gómez-Espina & P.L. Martín. 2006. Behaviour of MX-80 bentonite at unsaturated conditions and under thermo-hydraulic gradient. Work performed by CIEMAT in the context of the TBT project. Informes Técnicos CIEMAT 1081. CIEMAT, Madrid, 45 pp. July 2006. DOI: 10.13140/RG.2.2.30062.92482
• Gómez, R. & Villar, M.V. 2010. Geochemical and mineralogical changes in compacted MX-80 bentonite submitted to heat and water gradients. Informes Técnicos CIEMAT 1199. Marzo 2010. Madrid, 33 pp.
• Gómez-Espina, R. & Villar, M.V. 2013. Modificaciones en la bentonita MX-80 compactada sometida a tratamiento termo-hidráulico. Informes Técnicos CIEMAT 1290. Madrid, 85 pp.

The Prototype Repository project was a full-scale test of the KBS-3 concept for high-level radioactive waste disposal conducted at the Äspö Hard Rock Laboratory (Sweden) focusing on the engineered barrier system performance but comprising also canister deposition, backfilling and plug construction. Electrical heaters simulating the waste containers were placed in six vertical holes. The MX-80 bentonite was used as sealing material around the heaters. CIMNE, as a subcontractor to ENRESA performed part of the THM and THMC modelling of the clay barrier behaviour. To support this modelling work, and specifically to improve the knowledge of the hydro-mechanical behaviour of the clay, CIEMAT –under direct contract with ENRESA– carried out the a laboratory thermo-hydro-mechanical characterisation of the MX-80 bentonite.

• Villar, M.V. 2005. MX-80 bentonite. Thermo-hydro-mechanical characterisation performed at CIEMAT in the context of the Prototype Project. Informes Técnicos CIEMAT 1053. CIEMAT, Madrid, 39 pp. Febrero 2005.
• M.V. Villar, R. Gómez-Espina & P.L. Martín. 2006. Behaviour of MX-80 bentonite at unsaturated conditions and under thermo-hydraulic gradient. Work performed by CIEMAT in the context of the TBT project. Informes Técnicos CIEMAT 1081. CIEMAT, Madrid, 45 pp. July 2006. DOI: 10.13140/RG.2.2.30062.92482
• Gómez, R. & Villar, M.V. 2010. Geochemical and mineralogical changes in compacted MX-80 bentonite submitted to heat and water gradients. Informes Técnicos CIEMAT 1199. Marzo 2010. Madrid, 33 pp.
• Gómez-Espina, R. & Villar, M.V. 2013. Modificaciones en la bentonita MX-80 compactada sometida a tratamiento termo-hidráulico. Informes Técnicos CIEMAT 1290. Madrid, 85 pp. DOI:

The project aimed at assessing the integrity with respect to gas migration of the engineered barrier system of low/intermediate-level nuclear waste repositories, since a large amount of gas may be produced by anaerobic corrosion and microbial degradation of metallic materials and organic wastes. The project consisted of a large-scale silo excavated at the Grimsel Test Site (Switzerland), small mock-ups, a series of laboratory tests, and the development of models of gas migration through the engineered barriers and into the geosphere. The experiments performed at CIEMAT were designed to enhance the understanding of gas migration processes through a Kunigel bentonite/sand mixture for a given range of well-defined experimental conditions. The boundary and initial conditions (e.g. initial water saturation, confining pressure) matched those of the mock-up and in-situ experiments as closely as possible.

• Martín, P.L.; Villar, M.V.; Barcala, J.M. & Campos, R. 2000. GMT/IR 99-07: Material Tests on Specimens of Kunigel VI Bentonite/Sand (20/80) Mixture. Informe Técnico CIEMAT/DIAE/54141/1/00. NAGRA Project Report 00-09. Wettingen (CH), 31 pp.

Desarrollo y aplicación de métodos para el seguimiento del impacto sobre las aguas subterráneas del vertido de lodos mineros. El caso Aznalcóllar

1999-2000

CICYT-FEDER 1FD97-1867

Efectos sobre suelo y acuíferos del vertido de las Minas de Aznalcóllar

1998-1999

FEDER-CICYT-1FD97-0765

La avenida de aguas ácidas y lodos piríticos que se produjo como consecuencia de la rotura de la balsa minera de Aznalcóllar causó un considerable incremento en el contenido metálico de los suelos de la zona afectada del Guadiamar a causa de la infiltración directa de las aguas cargadas en metales pesados, y de los sulfuros de granulometría muy fina que constituían la carga sólida, a través de los poros del suelo, las fracturas existentes en el mismo y otras irregularidades en la superficie del suelo. Una vez retirados los lodos, el CIEMAT realizó una campaña para muestrear columnas de suelos representativos del área afectada y se realizó su caracterización física, geoquímica y mineralógica como apoyo a los ensayos de sorción/desorción.

• Alonso, C.; Antón-Pacheco, C.; Barettino, D.; Cabrera, F.; Fernández, A.M.; Fernández, J.E.; García-Gutiérrez, M.; Giráldez, J.V.; Girón, I.F.; López Pamo, E.; Moreno, F.; Ordóñez, R.; Pelayo, M.; Rivas, P; Vanderlinden, K.; Villar, M.V. 2001. Los suelos de Guadiamar: estudios de caracterización y de la evolución de los suelos contaminados por el lodo. Boletín Geológico y Minero 112: 163-197. Número Especial: Ayora, C.; Barettino, D.; Carrera, J.; Manzano, M. & Mediavilla, C.(eds): Las aguas y los suelos tras el accidente de Aznalcóllar.

The RESEAL project aimed at demonstrating the sealing of a borehole and a shaft in plastic clay on a representative scale. The main objective of the project was to demonstrate that a seal of bentonite avoids preferential migration of water, gas and radionuclides along the seal/host rock interface and through the excavation disturbed zone. The project included the selection and characterisation of sealing materials (see reports in this section), the development of the seal installation technique, the monitoring of the horizontal borehole and the shaft sealing tests performed at the HADES Underground Research Facility (https://www.euridice.be/sites/default/files/editor/RESEAL.pdf) in Mol (Belgium) and the modelling of the main processes and phenomena observed during the tests.

• Villar, M.V. 1999. RESEAL Project. Topical Report on Laboratory Tests. Version 1. Informe Técnico CIEMAT/DIAE/54121/2/99. Madrid, 33 pp.
• Villar, M.V.; Imbert, Ch.; Billaud, P.; Touzé, G.; García-Gutiérrez, M. ; Mingarro, M. ; Van Geet, M.; Maes, N.; Aertsens, M. & Volckaert, G. 2005. A large in situ demonstration test for repository sealing in an argillaceous host rock – phase II. RESEAL II. Final report on laboratory tests (WP1). September 2000 – May 2005. EC contract FIKW-CT2000-00010. SCKCEN-ER-1. CIEMAT/DMA/M2147/1/05. 05/MVGe/P-32. Mol (B), 88 pp.

Full-scale Engineered Barrier Experiment in crystalline host rock

2000-2003: FEBEX II

Commission of  the European Communities Contract No FIKW-CT-2000-00016 / ENRESA

https://cordis.europa.eu/project/id/FIKW-CT-2000-00016

1995-1999: FEBEX I

Commission of  the European Communities Contract No FI4W-CT95-006 / ENRESA

https://cordis.europa.eu/project/id/FI4W950006

To demonstrate the feasibility of the Spanish geological repository concept for crystalline rock, ENRESA started in 1995 the project FEBEX (Full-scale Engineered Barrier EXperiment), which also studied the behaviour of the near field of a nuclear waste repository, in particular of the engineered barrier (ENRESA 2006). The project was organised in four interrelated parts: a large-scale test under natural conditions performed at the Grimsel Test Site (Switzerland); a large-scale mock-up test performed at CIEMAT under controlled conditions (Figure 23); a series of laboratory tests designed to obtain parameters to model the behaviour of the materials and the study of processes; and the part devoted to the development, verification and validation of models of the behaviour of the repository system.

Fig. 23. Esquema general del ensayo in situ realizado en el laboratorio subterráneo de Grimsel y del ensayo en maqueta llevado a cabo en CIEMAT como parte del proyecto FEBEX (ENRESA 2006)

• Cuevas, J.; Villar, M.V.; Martín, M.; Cobeña, J.C.; Leguey, S. & Rivas, P. 2000. Thermo-hydro-geochemical tests in small cells. Version 1. Informe Técnico CIEMAT/DIAE/54111/4/99, FEBEX 70-IMA-M-0-5 v1. EC Contract FI4W-CT95-006. Madrid, 46 pp.
• Lloret, A.; Villar, M.V. & Pintado, X. 2002. Ensayos THM: Informe de síntesis. Informe Técnico CIEMAT/DIAE/54520/1/02. Madrid, 98 pp.
• Lloret, A.; Villar, M.V. & Romero, E. 2004. Final report on THM laboratory tests. Informe Técnico CIEMAT/DIAE/54520/3/04 (70-UPC-L-7-13). Barcelona, 146 pp.
• Villar, M.V., A.M. Fernández, P. Rivas, A. Lloret, D. Daucausse, E. Montarges-Pelletier, K. Devineau, F. Villieras, E. Hynková, Z. Cechova, L. Montenegro, J. Samper, L. Zheng, j.-c. Robinet, A.  Muurinen, H.P. Weber, L. Börgesson, T. Sandén, J. Verstricht. 2004. Task 141: Post mortem bentonite analysis. Informe Técnico CIEMAT/DIAE/54520/4/04 (70-IMA-M-6-7 v.0 y v.1). Madrid, 169 pp.
• Villar, M.V. 2004. Thermo-hydro-mechanical characterisation of the bentonite of a simulated HLW repository after five years operation (in situ test of the FEBEX Project). Informes Técnicos CIEMAT 1049. CIEMAT, Madrid, 61 pp. DOI: 10.13140/RG.2.2.30220.21123
• Enresa 2006. FEBEX Full-scale Engineered Barriers Experiment, Updated Final Report 1994-2004. Publicación Técnica Enresa 05-0/2006, Madrid, 590 pp.

Generación y transporte de gas en las barreras de ingeniería

Acuerdo de Investigación y Desarrollo Tecnológico CIEMAT/ENRESA 97-176

1997-1999

Este proyecto constituyó la iniciación del grupo en el área del conocimiento y comprensión de los fenómenos relacionados con el transporte del gas en la bentonita, utilizada como material de barrera y a través del almacenamiento de RRAA. Los objetivos eran múltiples: diseñar equipos capaces de medir la permeabilidad al gas en diversas condiciones de contorno; describir los protocolos a utilizar para la medida de los parámetros de transporte; proporcionar la información requerida para determinar los posibles efectos sobre las funciones de la barrera; y la necesidad de incorporarlos en el diseño del almacenamiento y los cálculos de seguridad.

• Martín, P.L.; Villar, M.V.; García, M.; Yllera, A.; Barcala, J.M. & Casero, D. 1998. Transporte de gases en la bentonita. Informe final 1997-1998. Informe Técnico CIEMAT/DIAE/54123/2/98. Madrid, 152 pp.