ABSTRACT
On-line corrosion monitoring methods have been applied extensively for system condition diagnosis, material degradation resistance evaluations, and water chemistry optimisation in Taiwan’s boiling water reactor (BWR) and pressurised water reactor (PWR) nuclear power plants. Electrochemical corrosion potentials (ECP) in Chinshan and Kuosheng BWR water circulation loops are measured to evaluate the extent of ECP protection provided by hydrogen water chemistry (HWC). On-line crack advance surveillance equipment can continuously monitor the effectiveness of HWC in mitigating stress corrosion cracking (SCC) of stainless steel components. In the Maanshan PWR, ECP measurements in secondary systems are used both as a sensitive diagnostic tool for system oxygen abnormalities and as a reference for hydrazine concentration control. On-line monitors are installed for service water loops to detect the corrosion behaviour of materials in the system under different water chemistry conditions. In decontamination processes, on-line corrosion monitors are also implemented to ensure the integrity of systems and components. In addition, a pipe-thinning monitor is installed in Maanshan plant to continuously monitor the thickness reduction of carbon steel (CS) components during normal plant operation. On-line corrosion monitors have proven to be very useful tools within the nuclear power monitoring systems currently installed and have fulfilled their specific purpose in the operation of Taiwan’s power plants. This chapter will provide a general description of on-line corrosion monitoring systems developed and currently installed in Taiwan and their mode of operation.
