EXPERIMENTS ON STEAM-GENERATOR WATER-LEVEL SWELL AND SHRINKAGE

Equipment that is one-tenth the size of the steam generators for the W estinghouse 900-MW(electric) nuclear power plants is used to study the swell and shrinkage of the water level. The cyclic aspect of level sw ell and shrinkage occurring during low-power operation of the nuclear power plants is realized by sequential steam dump valve control. Exper imental results show that a simple mathematical model based on the amo unt of steam generated during depressurization provides a good approxi mation for predicting level swell and shrinkage. Steam generation also causes water movement between the downcomer area and the inner part o f the vessel, the effect of which during the initial steam dump period is estimated and applied to adjust this model.