Transport and deposition of halide in alkali metal-stainless steel systems, (1)

Deposition behavior and solubility of sodium iodide in sodium-stainless steel system was studied with using capsules placed vertically under a large temperature gradient. The stainless steel capsule loaded with 20 g of reactor grade sodium containing sodium iodide was heated at its upper part and cooled at its bottom to establish the temperature gradient along the capsule tube and to precipitate and accumulate the iodide onto the capsule bottom, and was quenched to fix the iodide in solidified sodium after the diffusing run. Distributions of the iodide in the sodium in radial and axial directions were obtained as a function of temperature during the run. A partition value of the iodide between the core sodium and its periphery was calculated from the radial distribution in the sample in unsaturated regions. The solubility of the iodide in sodium was determined from the axial distribution in the core sodium samples. Heat of adsorption obtained from the partition value and the solubility determined with this method are in reasonable agreement respectively with the data reported by Allan. (author)