A counter current LBE-Water heat exchanger is investigated with the system code TRACE with emphasize on the water side. Due to the liquid metal coolant on the outer side of the heat exchanger the present boundary conditions for the water side (pressure, mass flux, heat flux, etc.) might be out of range of normal LWR application and need therefore additional validation. The review of the physical models of TRACE, mainly the ones for pool boiling, indicated that these models might not be applicable to the present heat exchanger design. Alternative pool boiling models have been implemented into TRACE, namely the ones of Forster-Zuber and of Labuntsov. The comparison shows that the heat transfer coefficient of the original model is about 30 % higher than with the alternative models but with a wall heat flux which is almost identical for the three models. This is caused by the much lower heat transfer coefficient on the LBE side which dictates the global heat transfer. The resulting wall temperature and the power which can be transferred from the hot LBE side to the water are lower for the alternative models. That indicates that with the standard model too optimistic results might be calculated.
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