Electroless palladium or nickel-phosphorus plating for fouling mitigation in high-temperature water systems

As a method to mitigate fouling at the venturi flowmeter of pressurized water reactors, electroless nickel-phosphorus (Ni-P) plating and palladium (Pd) plating were conducted on AISI 304L stainless steel specimens and evaluated through a series of performance tests, including static corrosion testing, adhesion testing, and water loop testing using mock-up venturis. As expected from the zeta potentials, no iron oxide particles deposited on the surface of the plated specimens. The Ni-plated specimens exhibited localized corrosion, whereas the minimum oxidation was observed on the Pd-plated specimens. The water loop tests showed consistent results with the static corrosion testing. The adhesion forces after a four-month corrosion test were similar to those before. The overall performance tests indicated that electroless Pd plating on the inner surfaces of venturis could be a viable solution for mitigating fouling in pressurized water reactors.