Modelling heat and moisture transport in the ANDRA/SKB temperature buffer test

The present paper regards heat and moisture transport in the barrier of the temperature buffer test (TBT) large-scale experiment. TBT includes two individually powered 1500 W heaters, vertically positioned on top of each other in a KBS-3 type disposal pit with 0.5 m of compacted MX80 bentonite in between. The experiment is run at high temperatures and with controlled hydraulic boundary conditions. This, and an extensive instrumentation of the barriers, makes the TBT experiment particularly suited for modelling and for testing and evaluation of different modelling approaches. This is in particular true for the two horizontal sections at the heater mid-height levels, where radial arrays of densely spaced thermocouples allow for accurate direct monitoring of the temperature development and for monitoring of the saturation development with indirect interpretation methods. Examples of early predictions, given by a number of modelling teams using different codes and different approaches, are presented in the paper. Comparisons are made between different sets of modelling results and measurements.