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Soma, Yasutaka; Komatsu, Atsushi; Ueno, Fumiyoshi
Corrosion, 78(6), p.503 - 515, 2022/06
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)The effects of electrochemical potential (ECP) on water chemistry within a crevice are of critical importance for understanding stress corrosion cracking (SCC) of Fe-Cr-Ni alloys in high temperature water. In this study, the effects of ECP on the electrical conductivity of a solution within a Type-316L stainless steel crevice (
) have been studied in 288
C and 8 MPa water containing 10 ppb Cl
as major anionic species. In situ measurements of in a rectangular crevice with a gap of 15 
m and a depth of 23 mm have been conducted using small sensors installed at different crevice depths. An increase in ECP from -0.49 V (vs. standard hydrogen electrode) to -0.12 V resulted in an increase in from 12 Scm
to 160 Scm at a distance of 21 mm from the crevice mouth. The increase in reached a maximum at about 0.15 V (about 300 Scm) and then tended to decrease with increasing potential. Finite element model analysis taking into account the electrochemical reaction quantitatively reproduced this behavior. It is considered that Cl is the major anionic species transported into the crevice at relatively low potentials, and that increases monotonically with increasing ECP. On the other hand, when ECP exceeds around 0 V, a sufficient amount of HCrO
generated by transpassive dissolution also transported into the gap. Since this chemical species is highly oxidizing, unlike Cl, it is assumed that it reacts with metal cations to oxidize and precipitate them, thereby lowering conductivity.
Sato, Tomonori; Yamamoto, Masahiro; Tsukada, Takashi; Kato, Chiaki
Zairyo To Kankyo, 64(3), p.91 - 97, 2015/03
In the boiling water reactors (BWRs), reactor cooling water is maintained in high purity condition by controlling of a deionizing and deaerating apparatus, however H
O contains by water radiolysis. In order to determine the corrosive condition in high-temperature pure water containing HO, the electrochemical impedance spectroscopy was performed in this study. To simulate BWR condition precisely, the measurements were performed without any electrolyte. The obtained impedance responses were changed with the HO concentration. The solution resistance and polarization resistance were determined by the equivalent circuit analyses. The conductivity was determined by the obtained solution resistance and the calculation of the current flow between the working electrode and the counter electrode by the 3-demensional finite element method. The value, 4.4
10
S/cm, was obtained as the conductivity of the pure water at 288C. The reciprocal of the obtained polarization resistance increased in proportion with HO concentration. This indicates that the corrosion current density was determined by the diffusion limiting current density of HO. The diffusion coefficient of HO at 288C was determined using the relationship between the reciprocal of the polarization resistance and HO concentration. The obtained diffusion coefficient was 1.510
cm
/s. This is about twice larger than that of the reported value of O.
Tanaka, Tadao; Yamamoto, Tadatoshi; Kato, Shohei; *
Nihon Genshiryoku Gakkai-Shi, 33(4), p.373 - 380, 1991/04
Times Cited Count：2 Percentile：31.86(Nuclear Science & Technology)no abstracts in English
; ; ; ; *; *
EIM-82-24, p.9 - 18, 1982/00
no abstracts in English
