Electrochemical corrosion potential modeling in the primary heat transportcircuit of the Chinshan boiling water reactor under the condition of hydrogen water chemistry with noble metal coating
Tk. Yeh et F. Chu, Electrochemical corrosion potential modeling in the primary heat transportcircuit of the Chinshan boiling water reactor under the condition of hydrogen water chemistry with noble metal coating, J NUC SCI T, 37(12), 2000, pp. 1063-1074
The technique of noble metal treatment, such as noble metal coating (NMC) o
r noble metal chemical addition, accompanied by a low level hydrogen water
chemistry, is being employed by a number of nuclear power plants around the
world fur mitigating intergranular stress corrosion cracking in the vessel
internals of their boiling water reactors (BWRs). A computer model DEMACE
was expanded and employed to assess the effectiveness of NMC throughout the
primary heat transport circuit (PHTC) of a BWR. The effectiveness of NMC w
as justified by the electrochemical corrosion potential (ECP) and crack gro
wth rate (CGR) predictions. In calculating the ECP, enhancing factors for t
he exchange current densities of redox reactions available from recently pu
blished data, were employed. The Chinshan BWR was selected as a model react
or. According to the modeling results, it was found that the effectiveness
of NMC in the PHTC of a BWR could vary from region to region at different f
eedwater hydrogen concentrations. For the selected BWR: NMC was predicted t
o be of little benefit when the feedwater hydrogen concentration reached 0.
9 ppm or over. In particular, the NMC technique proved to be beneficial in
reducing ECP and CGR along the PHTC even if the BWR was operated under norm
al water chemistry.