Sodium Vapor Deposition, on Simulated Model of LMFBR Rotating Shield Plug Annulus, (I)

Abstract

Experimental study was made to investigate the controlling factors on the vapor deposition rate on reactor operational shield plug annulus, which is exposed to the vapor entrained cover gas during reactor operation. Two simulated test assemblies having annuli were made for this purpose and were installed into a small test vessel. In the experiment, the average deposition rates on the annular walls of the test assemblies were measured for various pool temperatures, and their dependents upon such parameters as pool temperature, Ts (or the saturated vapor pressure Ps at pool surface), cover gas pressure Pg , and temperature drop ΔTa across cover gas, were studied. The results revealed that the dominant controlling factor was the vapor pressure Ps at pool surface. Dependent of the average deposition rate φbard. upon the above parameters was simply expressed by: φbard=BσpsDsΔTG , where, σs is the saturated vapor concentration at pool surface, Ds , the vapor diffusion coefficient, and B the proportional constant. To these experimental results, the previously published evaporation rate data and the theoretical evaporation rate equation based on Epstein & Rosner's theory were reviewed. Then correlation between the deposition and the evaporation rates was discussed.