There are three possible directions in the futher work on thermomechanical modelling of pebble beds, but the discussion with my supervisor is needed first. These ideas are seperated, but still in the same framework.

1. *Thermal contact conductance model, and its application in HELICA mock-up.*

The first simulation has been carried out. The influences have been estimated by current TCC model, while for beryllium pebbles, the pebble-wall interactions are more significant.

2. *Thermal conductivity of packed beds, with the consideration of temperature*.

The basic of this activity can be traced back to 1970s-1980s, a professor (Schlunder) in University of Karlsruhe developed one model (SZB) describing the solid-gas conductivity, which consists well with existing experimental data. But, there are many other important facts to be taken into account, such as the pressure effects developed by Chan and Tien. And in the late 90s, the DEM has been used in different cases, but the theoretical work can be reconsidered and can surely predict more gerneral problems.

3. *Failure analysis of packed beds, and analysis of single pebble compaction experiments*.

First case has been simulated to find out the difference between Hertz solution and exact multi contact situations. But the current results show that the comparison with experiments is not so well, and the reason should be found first. An research assistant is needed for this project for systematic simulation on contacts.

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