The deposition of 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 (a-Fe.0 3 ) 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, dWjdt=K·Q·C/L, where dWjdt 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 other hand, the K value of Co ion increases with iron oxide concentration and seems to approach that of iron oxide (0.3). The Co ion deposited with iron oxide forms Co ferrite. Solubility of Co ferrite is small compared with that of Co deposits without iron oxide (CoO or Co (OH)2). The increase in the K value of Co ion with iron oxide concentration is attributed to the change in chemical form of Co deposits into more stable species not favoring Co release.

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Since chemical regeneration of condensate demineralizers produces a large quantity of radioactive liquid wastes, reducing the volume of such wastes has become a significant concern.In Japanese Improvement and Standardization BWR's, by installing a prefilter upstream from the condensate demineralizer, and improving construction materials and method of controlling water chemistry, the crud and ion load on the condensate demineralizer has been reduced.Since non-regenerated operation of the condensate demineralizer has been devised and tried on the No.2 Unit of the Fukushima Daini Nuclear Power Station (2F -2) with variable resin measurement during every scheduled outage and each fuel cycle. The result has been a reduction of the number of drums to be disposed of to 1/5 the previous number.

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The deposition of 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 (a-Fe.0 3 ) 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, dWjdt=K·Q·C/L, where dWjdt 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 other hand, the K value of Co ion increases with iron oxide concentration and seems to approach that of iron oxide (0.3). The Co ion deposited with iron oxide forms Co ferrite. Solubility of Co ferrite is small compared with that of Co deposits without iron oxide (CoO or Co (OH)2). The increase in the K value of Co ion with iron oxide concentration is attributed to the change in chemical form of Co deposits into more stable species not favoring Co release.