Development of SCC Mitigation Method in BWR by TiO₂ Technique - 14391

The ECP measurements were conducted in order to investigate the effect of amount of TiO₂ deposition on the ECP under several water conditions without the UV irradiation. From the results, in the case of higher than 0.2 ppm of hydrogen in the feed water, the ECP at the region of PLR system can be lowered to less than about -0.2 V vs. SHE by the TiO₂ deposition of 10-15 μg/cm². TiO₂ deposition tests were conducted under simulated operating condition of BWR in order to investigate the TiO₂ deposition behavior in operating condition of BWR. The deposition rate and the release rate of TiO₂ particles under the turbulent flow in high temperature water were calculated from the deposition profiles of TiO₂ against time. The correlation between the deposition rate and the mass transfer coefficient k which is calculated from Sherwood relation was investigated. The effect of the shear stress on the release rate was investigated. Furthermore assuming that the On-Line TiO₂ injection is applied to BWR-5, amount of TiO₂ deposition on each of the components was calculated based on these experimental data. (authors)