FEBEX-DP Postmortem THM/THC Analysis Report.

Abstract

FEBEX (Full-scale Engineered Barrier Experiment in Crystalline Host Rock) was a research and demonstration project that was initiated by Enresa (Spain). The aim of FEBEX (Full-scale Engineered Barrier Experiment) was to study the behaviour of components in the near-field for a high-level radioactive waste (HLW) repository in crystalline rock. The project was based on the Spanish reference concept for disposal of radioactive waste in crystalline rock (AGP Granito): the waste canisters are placed horizontally in drifts and surrounded by a clay barrier constructed from highly-compacted bentonite blocks (Enresa 1995).This report is intended for documenting the activities carried out and the main results obtained by different laboratories in the analyses performed with bentonite samples retrieved from the FEBEX in-situ test and sent to them. The following contributions of the different organisations are summarised, compared and evaluated in this report: • 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. NAB 16-24. Madrid. • Fernández, A.M., Sánchez-Ledesma, D.M., Melón, A., Robredo, L. M., Rey, J.J., Labajo, M., Clavero, M.A., Carretero, S. & González, A.E. (2018): Thermo-hydro-geochemical behaviour of a Spanish bentonite after of the FEBEX in situ test at the Grimsel Test Site. Technical report CIEMAT/DMA/2G216/03/16. NAB 16-25. Madrid, 256 pp. • Romero, E., Alvarado, C., Lloret, A. & Mirsalehi, S. (2017): Laboratory tests on the post mortem hydro-mechanical characterisation of FEBEX bentonite. CIMNE-UPC-GEOLAB, 62 pp. • Dueck, A., Nilsson, U. & Åkesson, M. (2016): FEBEX-DP, Hydro-mechanical analyses of the bentonite buffer. Clay Technology AB, 33 pp. • Cuevas, J., Ruiz, A.I., Ortega, A. & Fernández, R. (2016): Bentonite laboratory program and report. Contribution to (3) mineralogical and geochemical characterization: S45, mineralogy, crystal-chemistry. UAM, Madrid, 30 pp. • Plötze, M. (2015): FEBEX DP Bentonite characterization. IGT Report CL 1053/1. 15 pp. • Plötze, M. (2017): FEBEX DP Bentonite characterization. IGT Report CL 1053/2. 13 pp. • Kaufhold, S., Dohrmann, R. & Ufer, K. (2016): FEBEX Experiment – Geochemistry and Mineralogy. 20 pp. • Sakaki, T. (2016): FEBEX-DP: In-situ measurement of thermal conductivity of bentonite blocks during dismantling and a comparison with CIEMAT laboratory results. Nagra AN 16-05 (included in NAB 16-68). 25 pp. Kawamoto, K. (2016): Microfocus X-Ray Computerized Tomography on selected FEBEXDP samples at Saitama University. Internal Report. • Zheng, L., Voltolini, M. & Birkholzer, J. (2017): Characterization of the microscopic structure of bentonite samples: Quantitative characterization of the fracture network in the FEBEX samples via Synchrotron X-ray MicroCT. In: Zheng L., Rutqvist J., Xu H., Kim K., Voltolini M., Cao X. 2017. Investigation of coupled processes and impact of high temperature limits in argillite rock: FY17 Progress. Lawrence Berkeley National Laboratory, June 23, 2017, SFWD-SFWST-2017-000040, LBNL No. 2001014. • Cervinka, R. & Kolomá, K. (2016): Determination of CEC and exchangeable cations on sample B-S-36-3. Technical Report XY/2015. Prague, 14 pp. These reports are collectively stored in a Nagra internal report (Kober 2018), except for the detailed studies performed at CIEMAT, which are included in the two additional NABs mentioned above. The current report is organised in the following chapters, in which the results obtained by the different laboratories are presented together and compared: • Three introductory chapters, including this one, a chapter on the material considered by the different laboratories as reference one (the FEBEX bentonite) and a chapter identifying which samples were analysed as well as the state in which they were received by the laboratories. • A chapter on the physical state of the bentonite (water content and dry density), its microstructure (texture, pore size distribution) and the physico-chemical properties related to them (surface properties, suction and water adsorption capacity). • A chapter on the mineralogical and geochemical characteristics of the solid bulk and fine fractions of the bentonite and of its pore water, as analysed using different techniques. • A chapter on the thermo-hydro-mechanical properties of the bentonite, analysed in situ (thermal conductivity) and in the laboratory, both in the "as-retrieved" and in "remoulded" samples. • A final chapter discussing the results obtained concerning the three areas identified above and drawing some conclusions. • An Annex including the numerical data obtained by the different groups organised in tables, except CIEMAT's results, which are included in the documents NAB 16-24 and NAB 16-25.