Load following-up operation method

Purpose: To enable load following-up operation with neither increasing boron density excessively nor distorting axial power distribution at the full power operation. Method: Changes in the reactivity excepting that by the boron density is compensated by control rods. However, since control for the axial power distribution is made difficult if the control rod displaced greatly, the control rod position before the power-up is adjusted and power increase is effected stepwise up to the full power level, to thereby control the axial power distribution with no great distortion. After extraction of control rods and when axial offset approaches about to the stationary value (5 - 10%) at the full power level, boron content is diluted as required and control rod is maintained at that position. For the power-up, the control rods are entirely extracted to increase the power as far as possible, and maintain at that level for several hours, while the compensation for the reactivity due to decrease of xenon is compensated by the insertion of the control rods. (Moriyama, K.)