Effects of Power Level Change on the Development of Damage in Boiling Water Reactors under Hydrogen Water Chemistry

Abstract The responses of the Dresden-2 boiling water reactor (BWR) to hydrogen water chemistry (HWC) at different power levels were simulated using a computer code, DAMAGE-PREDICTOR. HWC simulations were carried out for feedwater hydrogen concentration ranging from 0.0 ppm to 2.0 ppm and for power levels at 100%, 90%, 80%, and 70%. Variations in the oxygen, hydrogen peroxide, and hydrogen concentrations, electrochemical corrosion potential (ECP), and crack growth rate for six specific areas (the core support plate, the top guide, the side of the core shroud head, the base of the core shroud, the recirculation system outlet, and the bottom of the lower plenum) as a function of the feedwater hydrogen concentration and power level have been analyzed. It was found that lower power levels alleviate the amount of hydrogen injected into the feedwater that is required to protect the reactor components from intergranular stress corrosion cracking. HWC is particularly effective in protecting the core support plate, the base of the core shroud, and the recirculation system outlet, but is only moderately effective in protecting the bottom of the lower plenum. On the other hand, the ECP and the crack growth rate at the side of the top guide and the core shroud head seems to be indifferent to both the operating power level and the feedwater hydrogen concentration.