Improvement and Application of Water Chemistry Control Process during Shutdown of One 3^rd Generation PWR Unit

In order to effectively reduce the corrosion rate of reactor coolant system (RCP) materials of pressurized water reactor (PWR) units and effectively remove activated corrosion products, so as to reduce the exposure dose of workers to ensure the smooth progress of unit overhaul, a 3^rd Generation PWR unit uses enriched boric acid (EBA) for reactivity control, while taking advantage of its significant advantage of water chemistry control of RCP system coolant during power operation. At the same time, during the first overhaul of the unit, improvement measures are taken for the shutdown water chemistry control process (including the conversion from alkaline environment to acid environment, the conversion from reducing environment to oxidizing environment, the repeated addition of hydrogen peroxide to the primary loop during forced oxidation to maintain oxidizability, the maximum flow purification of the mixed bed of chemical and volumetric system, etc.), and the purpose of reducing the radiation dose of the unit and the radiation dose of workers is realized in the downward stage of unit shutdown.