Water quality control method for reactor water

During operation of a BWR type nuclear reactor, chemical species such as chromium and molibdenum are supplied, in addition to hydrogen supplied so far, to reactor water for suppressing corrosion of materials, then the water quality is detected and a hydrogen concentration is controlled by a hydrogen supply rate. Both of the supply rate of the chemical species and the amount of chemical species captured to an ion exchange resin are varied to control the concentration of the chemical species. Thus, the amount of hydrogen injected required for the reduction of the progressing rate of cracks can be saved. Further, since these chemical species are converted into acids in reactor water to transfer pH to an acidic region, N-16 transferred radiation to a main steam system is reduced and the thickness of corrosive layers formed on materials is decreased. Then, since denser coating layers are formed, Co-60 radiation deposited on pipelines can be reduced. As a method for controlling the concentration of the reactor water, the amount of chemical species captured to the ion exchange resin in the reactor water cleanup system is previously controlled so as to balance with the concentration of the chemical species. (N.H.)