Determining Zeta Potential of Magnetite Particles in PWR Secondary Side Water Treated with Ammonia or Ethanolamine by Using Streaming Potential Technique

Magnetite (Fe₃O₄) particles originating from secondary side carbon steel tubing and components of a PWR plant can cause different harmful corrosion problems when they deposit onto the steam generator (SG) surfaces. Magnetite deposits situated on the steam generator tubes, tube support plates and other components create a favourable environment for corrosion as different impurities are enriched beneath the deposits. Deposits also hinder the water flow and heat transfer. The susceptibility to deposition can be evaluated by measuring the difference between the surface charge of magnetite particles and SG surfaces. The sign and the magnitude of the surface charge can be described with zeta potential. There are several methods for determining zeta potential but most of them are only available for room temperature measurements. In this study, streaming potential technique is used for determining the zeta potential of magnetite particles in secondary side PWR water adjusted with ammonia or ethanolamine to pHRT=9.8 as a function of temperature (RT to 260°C). These values are compared to values previously measured with pHRT=9.2. The room temperature values for ammonia adjusted measurement solution are also compared to values measured with commercial zeta potential measurement equipment.