The susceptibility of Ontario Hydro’s steam generators to the denting corrosion phenomenon is investigated as one aspect of an ongoing research program designed with the objective to specify limiting steam generator water contaminant concentrations for reliable unit operation. Isothermal test capsules and static autoclave experiments with cylindrical shrouds and heated crevice assemblies were used to assess the influence of sludge and heat flux on the concentration of solutes in crevice or low flow regions with lake waters as the test environments at 288°C. Rapid corrosion of carbon steel was observed. Sludge packed crevices enhance the concentration phenomenon, which is also very dependent on heat flux.