METHOD FOR CONTROLLING WATER QUALITY OF BOILING WATER REACTOR PLANT

PURPOSE: To reduce the occurrence of radioactivity emitted into a reactor water and at the same time reduce the adhesion of radioactivity onto a reactor outer pipe or an equipment by controlling Ni and Zn metal ion concentration in the reactor water to each specific range. CONSTITUTION: The metal ion concentration of Ni and Zn in a reactor water is controlled to 2-10 and 3-15ppb ranges, respectively. When the Ni ion concentration in the reactor water is equal to or less than 2ppb, the reactor water is supplied from a metal ion injection device 23 installed in a water supply system. On the other hand, when the Ni ion concentration is equal to or more than 10ppb, a flow adjustment valve 9 of a bypass line 10 of a hollow string film water-return filter 7 is opened, the ion exchange resin in the water return desalting device 8 is loaded with iron generated in the water return system, the Ni ion concentration of the reactor water is controlled to a specific concentration range by increasing the amount of leak iron. Zn is supplied from the metal ion injection device 23 installed in a water supply system. An automatic ion chromatography analyzer 25 installed in the reactor water system measures the metal ion concentration of Ni and Zn in the reactor water to see whether it is within a proper range or not.