Effect of zinc addition on fuel crud deposition in simulated PWR primary coolant conditions

Abstract The purpose of this study is to investigate the effect of zinc addition to the simulated primary coolant of a PWR on fuel crud deposition behavior. Crud deposition tests were performed in recirculating hydrogenated water containing 2 ppm Li and 1000 ppm B at three different zinc concentrations (0, 20, and 100 ppb) at 325 °C and 120 bar. Crud deposited on the claddings was characterized as cubic nickel ferrites and the zinc contents incorporated in the crud were increased with the increase of the added zinc concentrations. The deposited crud mass at 100 ppb zinc was increased by about 55%, compared to that at 0 ppb zinc. The zeta potential differences between the magnetite nanoparticles and the cladding surfaces were significantly decreased at the 100 ppb zinc condition, resulting in an increase of crud.