SCC Mitigation in Boiling Water Reactors: Platinum Deposition and Durability on Structural Materials
Noble metal injection is widely used to mitigate stress corrosion cracking (SCC) of reactor components. Despite its wide use, there are still open questions regarding the parameters affecting the application process and possible improvements to it. Laboratory experiments in a high-temperature water loop at PSI were complemented by exposure of specimens in the mitigation monitoring system (MMS) at KKL. The influence of parameters such as flow conditions, structural material composition, surface roughness and geometry on the deposition behavior of the platinum (Pt) nanoparticles was investigated. Furthermore, the long-term stability of the coverage of surfaces by Pt particles was analyzed. The composition of the underlying alloy was found to have an effect on the deposition behavior, whereas surface roughness has no measurable impact. Pt showed a limited durability on steel surfaces and, after the end of the application, the remobilized Pt seems to re-deposit only minimally on nearby surfaces.
KeywordsSCC mitigation BWR Noble metal Platinum Nanoparticles NobleChemTM
The financial support by the Swiss Federal Nuclear Safety Inspectorate (ENSI) is gratefully acknowledged. We are also indebted to the Swiss nuclear power plants KKL and KKM for their precious in-kind contributions to the project. Beat Baumgartner and Pia Reichel (both PSI) are thanked for their experimental contribution.
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