Hyperalkaline Plume in Fractured Rock (HPF) - Modelling

The modelling for the HPF experiment has been carried out by several international groups on both the in-situ and laboratory tests and a new model with uncertainty analysis was also developed.The modelling groups are from Spain (CSIC), France (ITASCA), Sweden (Chalmers University) and Switzerland (Nagra, PSI and Solexperts).

 

  • 2-D tracer transport modelling of the field experiment (PSI), and 2-D reactive transport modelling was carried out by CSIC and PSI.

     
  • 1-D reactive transport modelling of core infiltration experiment was carried out by ITASCA and CSIC.

     
  • Nagra, SOLEXPERTS and ITASCA were responsible for hydraulic modelling and interpretation of single-hole and cross-hole testing of shear zone before and during high-pH alteration.

     
  • Finally. A reactive transport model with uncertainty analysis and applications was developed by Chalmers University.
     

 

Results of the modelling
Core infiltration experiments.

The graph below shows the breakthrough of Ca, Al and Si from the laboratory core infiltration experiment compared with the results of the modelling. There is excellent agreement between the Ca and Al results over the 180 days of the experiment. The Si data is also in excellent agreement until around 90 days when the model begins to over predict the amount of Si passing through the core.

 

Modelling of flow rates
The second model of the core infiltration tests predicts how the water flow rate through the core will decrease during the infiltration of a cementitious fluid through the core. Again, excellent agreement can be observed between the measured and calculated values.

 

Modelling of final in-situ tracer test
Predictive modelling of the final in-situ tracer test has been used in planning of the final tracer test. The diagrams below show a prediction of the behaviour of uranine (a fluorescent dye), caesium (Cs),cobalt (Co) and europium (Eu). The tracers are injected at the left hand side and the dipole outlet is at the right hand side. Non-sorbing dyes are expected to spread relatively far, while strongly sorbing tracers such as Eu are expected to be sorbed very close to the injection borehole.


Cs, Co, Eu distribution after 30 days



Developing conceptual models from site investigations
(e.g. structural analysis, hydraulic data etc.)

 

The GTS underground facilities are also available to interested 3rd parties for underground testing and research. The GTS offers cost-effective access to a fully developed, well characterised underground research facility with round the year logistical support - please contact Dr. Ingo Blechschmidt, Head of the Grimsel Test Site, for further details.