Improvement of feedwater control system of supercritical water cooled fast reactor

The supercritical water cooled fast reactor (super fast reactor) adopts once-through direct cycle. The whole coolant from the feedwater pump is driven to the turbine. The main steam temperature sensitively changes with the power-to-flow ratio. In this study, the feedwater control system of the super fast reactor is improved for suppressing the variation of the main steam temperature through the different feedback terms. Three improvement projects are studied. In the first, it is to keep the ratio of power to feedwater flow rate constant; in the second, the core power must vary to the setpoint in operation, and in the third, the feedwater flow rate increases with increase of core power. Then, the control parameters are optimized by test calculations. At last, the best improvement project is identified by the comparison in power variation operation. (authors)