Corrosion product characterization in a BWR primary system

To assess the radiation buildup in the primary system of a 336 MW(e) BWR, the water chemistry and the crud deposited in a recirculation loop bypass line were anlaysed. Before and during a feedwater oxygen dose experiment, samples of suspended material were collected for particle size distribution analysis. The corrosion film of the bypass line, assessed by various instrumental analysis methods, is in principle comparable to other such films described in various BWR literature. It consists of a (Fe,Ni)(Fe,Cr)O4 spinel layer of about 10 μm in depth. No loose haematite surface layer was detected. With start of the oxygen dose experiment, the suspended load in the feedwater and reactor water could be lowered. In parallel, the suspended material activity per volume of water was significantly reduced. The smallest suspended particle fraction analysed in feedwater and reactor water samples was increased with enhanced feedwater oxygen concentration. (author)