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.

Eight modelling teams are involved in Task B1. They are shown in the table below together with each team’s principle investigator, the funding organisation (F.O.), the country of origin and the code used in the framework of the Task:

Layout of the SEALEX in situ experiment


  • Investigation of the THM behaviour of bentonite barrier in the early non-isothermal resaturation stage and their THM interaction with Opalinus Clay.
  • Assessment of the evolution of a disposal system of high level waste in the early post closure period with emphasis on the thermal evolution, buffer resaturation, pore water pressure in the near field and the evolution of swelling pressures in the buffer.
  • Evaluation of the predictive capacities of different models. Model validation.
  • In situ determination of the thermal conductivity of bentonite and its dependency on saturation.
  • Proposal of a consistent parameter set common to the different modelling teams.


  • Step 1a: Opalinus Clay study: HE-D experiment; literature study; processes understanding and parameter determination.
  • Step 1b: Buffer material study: CIEMAT column cells; literature study; processes understanding and parameter determination.
  • Step 2: HE-E predictive modelling using as-built characteristics and true power load. Choice of 2D (axisymmetric, plane strain or combination) and 3D model geometries.
  • Step 3: HE-E interpretative modelling: based on observation data.
Figure 1: Tentative schedule for the different modelling steps

Study of THM processes in the host rock

This part is based on the performance of the in-situ HE-D heating test. The HE-D test was run in 2004-2005, including 340 days of heating. The temperature field was measured in the heating borehole (about 16 temperature sensors) and in the rock mass (about 23 temperature sensors). The associated pore water pressure and strain response of the rock mass was monitored in 11 piezometers and 2 extensometers (containing about ten strain measurement intervals each). This test is described by Wileveau (2005) and the HE-D was led by ANDRA (Agence nationale pour la gestion des déchets radioactifs).

Study of THM processes in the buffer materials

The buffer materials used in the HE-E in situ experiment are also characterized in the laboratory. Different column tests (Villar et al. 2012) with a height similar to the buffer material thickness in the HE-E are currently running. They are designed to mimick the boundary conditions prescribed at the heater side and at the Opalinus Clay side. Iso-thermal and non-isothermal infiltration tests are considered. The mechanical behaviour of the buffer materials will have to be derived from information available in the literature.

Study of the HE-E experiment

This part is based on the performance of the in-situ HE-E heating test. In the HE-E, heating started in July 2011 and is planned to go on at least until July 2014. The HE-E experiment was designed to be used as a modelling exercise to validate different THM formulations. The instrumentation in the HE-E consists in:

  • Temperature sensors in the heater to assist power control
  • Relative humidity sensors associated with temperature sensors in the buffer (at about 72 locations)
  • Relative humidity sensors associated with temperature sensors in the near rock mass (at about 20 locations)
  • Eight 2 metres long extensometers in the rock
  • Piezometers associated with temperature sensors in the rock mass (at about 20 locations).

The HE-E experiment is performed at the location of the previous VE experiment, which is described in Mayor et al. (2005) and Mayor and Velasco (2008) and in the final report of the previous DECOVALEX project (Garitte et al., 2012). Information about the HE-E experiment may be found in Gaus et al. (2011) and Teodori et al. (2011). The HE-E is an in situ experiment that is part of the PEBS (Performance of Engineered Barrier Systems) project, funded by the seventh framework project of the European Commission. The HE-E experiment is led by NAGRA.

3D virtual view of the HE-E experiment

Further Information

For further information, please contact the task leader, Benoit Garitte (benoit.garitte@nagra.ch)


  1. Garitte, B., Bond A., Millard A., Zhang C., English M., Mcdermott C., Nakama S., Gens A. 2012. Analysis of hydro-mechanical processes in a ventilated tunnel in an argillaceous rock on the basis of different modelling approaches. DECOVALEX-2011 project, final report of Task A (KTH).
  2. Gaus I., Wieczorek K., Mayor J.C, Trick T., Garcia, J.L., Schuster K. Garitte B. and Kuhlmann U. 2011. EBS behaviour immediately after repository closure in a clay host rock: the HE-E experiment (Mont Terri URL). Proceedings of the 14th Int. Conference on Environmental Remediation and Radioactive Waste Management ICEM’11.
  3. Mayor J.C., García-Siñeriz J.L., Velasco M., Gómez-Hernández J., Lloret A., Matray J.M., Coste F., Giraud A., Rothfuchs T., Marschall P., Roesli U., Mayer G. 2005. Ventilation Experiment in Opalinus Clay for the disposal of radioactive waste in underground repositories. Final Technical Publishable Report FIS5-2001-00015.
  4. Mayor, J.C. and Velasco, M., 2008. The Ventilation Experiment Phase II (Synthesis report). NFPRO Project W.P.4.3., Deliverable D 4.3.18.
  5. Teodori S.-P., Gaus I., Köhler S., Weber H.-P., Rösli U., Steiner P., Trick T., Garcià Siñeriz J.-L., Nussbaum C., Wieczorek K., Schuster K., Mayor J. C. 2011. Mont Terri HE-E Experiment: as-built report. Nagra Arbeitsbericht NAB 11-25.
  6. M.V. Villar, P.L. Martín, R. Gómez-Espina, F.J. Romero, J.M. Barcala. 2012. THM cells for the HE-E test: setup and first results. PEBS Report D2.2.7a. CIEMAT Technical Report CIEMAT/DMA/2G210/02/2012. Madrid, 34 pp.
  7. Wileveau Y. 2005. THM behaviour of host rock (HE-D experiment): Progress Report September 2003 – October 2004. Mont Terri Technical report TR 2005-03.