Papers by Author: Kyung Mo Kim

Abstract: The stress corrosion cracking (SCC) susceptibility of Alloy 600 MA, Alloy 600 TT, Alloy 800, and Alloy 690 TT were investigated in a deaerated 0.01 M solution of sodium tetrathionate using reverse u-bend test samples at 340 °C. The results showed that SCC occurred in all alloys, excluding Alloy 690 TT. The SCC susceptibility of the alloys increased in the following order: Alloy 690 TT, Alloy 800, Alloy 600 TT, and Alloy 600 MA. The SCC susceptibility decreased with an increase in the chromium content of the alloys. The results of the deposits and spectra taken from an energy dispersive X-ray system confirmed the existence of a reduced sulfur causing SCC.

Abstract: Several chemicals were studied to suppress the damage due to stress corrosion cracking (SCC) of steam generator (SG) tubes in nuclear power plants. The polarization curves showed that the electrochemical properties on the surface of Alloy 600 MA changed with the addition of inhibitors. The SCC tests were conducted by using a m-RUB specimen in a 10% NaOH solution at a temperature of 315°C. The effects on the SCC of the compounds, TiO2, TyzorLA and CeB6, were tested for several types of SG tubing materials. The test with the addition of TiO2 (P25) and CeB6 showed an effect in decreasing the SCC for the SG tubing material. However, CeB6 caused some more SCC for Alloy 800. The penetration property into a crevice of the inhibitors was investigated by using Alloy 600 specimens with different gap sizes and an AES analysis was performed on the oxide layer of the specimen.

Abstract: The stress corrosion cracking (SCC) susceptibility of Alloy 600 MA has been studied in deaerated 0.01 M sodium sulfate (Na2SO4) and sodium thiosulfate (Na2S2O3) solutions at 340°C. Pre-strained reverse U-bend (RUB) specimens are tested using a static-autoclave system. The specimens show an intergranular SCC and a higher resistance to SCC in a Na2S2O3 solution than in a Na2SO4 solution. The results of the deposits and surface analyses by using XRD and SEM/EDS confirm the existence of the sulfides. The SCC of Alloy 600 MA is associated with the reduced sulfur species and protective oxide film properties formed on the alloy surface in the Na2SO4 and Na2S2O3 solutions.