Conventional and in-situ corrosion potential monitoring BWR

Hydrogen additions to the feedwater of boiling water reactors (BWR) are used to avoid stress corrosion cracking of stainless steel piping. The purpose of the addition is to suppress the corrosion potential of the steel below the critical potential for intergranular stress corrosion cracking (IGSCC). Recent measurements have shown that the corrosion potential can vary significantly depending on the location of the measurement and the measuring technique. By conventional corrosion potential monitoring in autoclaves connected to the reactor piping hydrogen demand is underestimated and the piping is not protected from IGSCC. By in-situ corrosion potential monitoring in the reactor piping the actual corrosion potential is determined. This paper describes in-situ corrosion potential monitoring in the Ringhals 1 BWR, and illustrates the differences in measured corrosion potentials which can occur between conventional and in-situ measuring technique. (author)