Magnetite Transport Characteristics in a CANDU reactor

For a CANDU reactor, one of the important aging phenomena is the flow accelerated corrosion (FAC), together with the pressure tube creep. The magnetite transport in the primary system, specifically the magnetite dissolution at the outlet feeder pipe and the magnetite deposition at the inlet feeder pipe, has an effect on a pressure drop in the primary system. Hence, the difference of the magnetite deposition on an inlet feeder pipe results to the difference of core pressure drop among 4 passages. Although CANDU 6 has the similarity characteristic between two passages and has the pressure equalizing system, the flow and thermal characteristics between 4 passages happen to be diverged as a plant operation due to an unexpected reason and it has a bad effect on the system stability in a normal operating condition. In this study, among many reasons which bring to the flow unbalance among 4 passages, the effect of the magnetite transport on the thermal-hydraulic characteristics of the system has been analyzed