Abstract: A method for recognizing the step movement sequence of a control rod drive mechanism of a nuclear reactor, which withdraws and inserts a control rod of a nuclear reactor, includes the steps of: measuring current and voltage flowing through an electromagnetic coil used in the control rod drive mechanism of the nuclear reactor; calculating inductance of the coil by using the measured current and voltage; calculating a distance between a rotor and a stator of the control rod drive mechanism on the basis of the calculated inductance; and recognizing the step movement sequence of the control rod drive mechanism on the basis of the calculated distance. This method ensures good reliability in determining the step movement sequence, allows easy implementation using a digital signal processor, and is hardly affected by external factors such as noise.

Abstract: In a method for detecting a fault of a power module for a control system of a control rod drive mechanism of a nuclear reactor, a fault of the power module is separately detected in a “go” mode, a “hold” mode and a “double hold” mode of a control rod. In the “go” mode, fault is detected by comparing voltage ripples of a movable gripper coil, a stationary gripper coil and a lifting coil of the control rod drive mechanism. In the “hold” mode, fault is detected by means of power spectrum analysis at a predetermined frequency using a Discrete Fourier Transform (DFT) for a stationary gripper coil, and by means of a Root Means Square (RMS) calculation of coil voltage for a movable gripper coil. In the “double hold” mode, fault is detected using power spectrum analysis at a predetermined frequency using a DFT for both stationary and movable gripper coils.

Abstract: A method for recognizing the step movement sequence of a control rod drive mechanism of a nuclear reactor, which withdraws and inserts a control rod of a nuclear reactor, includes the steps of: measuring current and voltage flowing through an electromagnetic coil used in the control rod drive mechanism of the nuclear reactor; calculating inductance of the coil by using the measured current and voltage; calculating a distance between a rotor and a stator of the control rod drive mechanism on the basis of the calculated inductance; and recognizing the step movement sequence of the control rod drive mechanism on the basis of the calculated distance. This method ensures good reliability in determining the step movement sequence, allows easy implementation using a digital signal processor, and is hardly affected by external factors such as noise.