Model for fuel-sodium interaction

A model of sodium-fuel interaction, referred to as TRACONA-BUEE, has been developed. The fuel particles are assumed to be introduced in the interacting zone within a finite mixing time, according to a given function (not necessarily linear). The equations for heat transfer inside fuel particles are those of Cho and Wright (transient conduction for phase A and quasi-steady state heat transfer for phase B). During phase B several options for heat transfer from fuel to sodium can be assumed (no transfer, transfer proportional to the volume fraction of liquid sodium, given duration of transfer, etc...) Two versions are available : a spherical one (EPISCOPOS) and an axial one (TEXAS). For application to the JEF experiments a model of heat losses along the cold column had to be introduced into TEXAS. It was found that the phenomenon is essentially governed by the heat losses. The velocity of the cold sodium in the column presents marked maxima and minima. The agreement with experiment is satisfactory. (auth.)