The evaluation of radioactive corrosion product at PWR as change of primary coolant chemistry for long-term fuel cycle

These days, nuclear power plant operation practice shifts to long-term fuel cycle such as from 12 month operating cycle to 18–24 month operating one. It is important to emphasize that the current trend to longer fuel cycle has complicated the dilemma of finding optimum pH range for the primary coolant chemistry. Although CRUD is not a high level waste, it is very important products because CRUD is the major source of ORE and its transport mechanism is not specified exactly yet. To analyze the generation mechanism of CRUD at the long-term fuel cycle, the COTRAN code used, which simulate the behavior of the CRUD based on double layer concept model and solubility difference. It turned out that the activities of CRUD decreases as the pH of the coolant increases, and for the same period of different fuel cycle, the generation of the CRUD increases as the operating fuel cycle duration increased. In this paper, enriched boric acid (40% enriched B10concentration) for the reactivity control is adopted for the simulation as the required chemical shim rather than natural boric acid.