Transport and Deposition of Metals in Sodium-Stainless Steel Systems, (V)An Experiment on Thermal Diffusion of Zinc, Antimony and Cesium in Liquid Sodium

摘要

Thermal diffusion constants were determined over a temperature range of 400°700°C in liquid sodium alloyed with trace amounts of zinc, antimony or cesium.Purified sodium containing a radioisotope of one of the three solute metals was filled by suction in a capillary made of stainless steel. The capillary was then carefully seal-welded to prevent the sodium from oxidation; the sealed capillary was placed along the core of a heat conductor rod; a steady linear temperature gradient was produced along its length by heating its head and cooling its foot. After a predetermined period of this thermal diffusion run, the capillary was quickly chilled to solidify the sodium and sectioned into pieces.The specific radioactivity observed in the sodium in the sectioned piece were plotted in log-log scale against the absolute temperature prevailing in the piece during the thermal diffusion run, and the thermal diffusion constant was obtained from the inclination of the straight lines drawn through the plots. All three solute metals were found to have become enriched in the lower temperature region. The measured thermal diffusion constants were respectively 2.1 for zinc, 1.7 for antimony and 1.6 for cesium.