Numerical study on the effect of the PI-controller type on the quasi-steady reactor pressure in MAAP 5.04 code

Abstract

Abstract In this work, the boiling water reactor (BWR) was adopted as a physical model to study the influence of PI-controller type on the quasi-steady reactor pressure in MAAP 5.04 code. The designed reactor pressure can be simulated through the open area of a valve modified by PI controller. The proportional gain (k p) is equal to one in all cases. For the integral gain (k i) smaller than or equal to 100 (i.e., k i = 0.1, 1, 10 and 100), a scrammed reactor incurred by the high reactor water level (Level-8) that is due to the large reactor pressure drop does not occur in the simulation. Compared to k i = 1, 10 and 100, for k i = 0.1, the reactor pressure modified by the PI controller is more close to the designed reactor pressure; however, the time to meet the designed reactor pressure is longer. The reason is that k i = 1, 10 and 100 incur a larger overshoot in the modified reactor pressure through the feedback system; although the time to meet the designed reactor pressure can be shortened, the amplitude of the reactor pressure varying with time is obvious. To exactly simulate the reactor pressure of a nuclear power plant under the normal operation, our results can offer MAAP code users an important reference to design the PI controller.