Deposition of Nickel and Cobalt Ions on Heated Surface under Nucleate Boiling Condition

The depositionof Ni and Co ions on a heated surface of simulating fuel rods has been studied in water at atmospheric and 70 atm pressures during nucleate boiling. The effects of various factors, including heat flux of the heated surface, concentration of coexisting iron oxide (αFe2O3 and concentration of Ni and Co ions, on their deposition rate have been investigated. The model for iron oxide deposition which is based on microlayer evaporation and drying out phenomena in the nucleate boiling bubble was shown to be applicable to the deposition of Ni and Co ions. That is, dW/dt=K.Q.C/L, where dW/dt is the deposition rate, K the deposition rate coefficient, Q the heat flux, C the ion concentration, and L the latent heat of vaporization. The K value of Ni ion is about 0.1 and independent of iron oxide concentration. On the hand, the K value of Co ion increases with iron oxide concentration and seems to approach that of iron oxide concentration and seems to approach that of iron oxide (0.3). The Co ion deposit...