| Summary: | BackgroundThe corrosion products deposited on the surface of pressurized water reactor (PWR) zirconium alloy will form chalk rivers unidentified deposit (CRUD), which will reduce the heat transfer capacity of fuel cladding and affect the primary radioactivity level. The main component of CRUD is ferronickel spinel whilst the zinc, as a more active metal than ferronickel, may change the composition of CRUD through displacement reaction, or precipitate in a higher heat flux environment and form a new metal complex with ferronickel. Hence zinc injection, as a hydrochemical regulating method, is being more and more widely used in nuclear power plants.PurposeThis study aims to investigate the effect of zinc injection on CRUD of zirconium allay surface.MethodsExperiments were conducted in artificial CRUD facility under similar PWR operation environment. Scanning electric microscope (SEM) and X-ray photoelectric spectroscopy (XPS) were employed to analyze the morphology, element and oxidized particles porosity of CRUD before and after zinc injection.ResultsThe experimental results show that zinc mainly precipitates inside CRUD in heating region; after zinc injection, the nickel-iron ration of CRUD elevates from 0.58 to 0.65, while oxidized particles porosity of CRUD decreases from 30.15% to 10.08%. Compared with the non-zinc environment, the cracking of CRUD becomes more obvious, and the micro size of CRUD changes from loose porous shape to dense shape.ConclusionsThese results provide a reference for evaluating the influence of zinc injection on fuel performance of in-service PWRs.
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