Abstract: A method for controlling vessel chemistry in a boiling water reactor (BWR) includes a targeted injection of hydrazine (N2H4) to overcome intergranular stress corrosion cracking (IGSCC) and provide other advantages. The method does not require the injection of hydrogen as a reducing species nor the costly equipment needed to store and control the injection of hydrogen, but it is optional. The method involves: 1) adding a carefully selected amount of N2H4 at a carefully selected location such that reaction with hydrogen peroxide (H2O2) is targeted for reduction prior to treated vessel water (feed water combined with steam dryer/separator liquid effluent) entering the reactor core and 2) providing sufficient residence time to keep all but a tolerable amount of the N2H4 from entering the reactor core.