Some fundamental understandings of Zn-injection water chemistry on material corrosion in pressurized water reactor primary circuit

The optimization of water chemistry in pressurized water reactor(PWR) primary circuit is one of the most effective ways to achieve both safety and economy for operating PWR nuclear power plants(NPPs). Special attention has been paid to fundamental research and engineering application of Zn-injection water chemistry(ZWC) in PWR primary circuit in recent years in China due to the rapid development of nuclear power. The present paper mainly reports the status of PWR NPPs in China and some fundamental understandings of ZWC on material corrosion. Effects of temperature(T), pH at T value, Zn concentration, Zn-injection sequence and lasting time on electrochemical corrosion behavior, oxide film characteristic and stress corrosion cracking(SCC) susceptibility of nuclear-grade austenitic alloys were investigated. A modified point defect model was used to discuss the effects of ZWC on the oxide films in high-temperature pressurized water. Some water chemistry parameters in PWR primary coolant system are proposed for mitigating corrosion and SCC of nuclear-grade austenitic alloys.