The magnetic jack type control rod drive mechanism (CRDM) is the key actuator in the nuclear power plant reactor. The latch assembly of the CRDM acts as the execution component to lift, insert, and release the control rod assembly to accomplish the reactor startup, power regulation, and shutdown, etc. The accuracy and the timeliness of CRDM latch assembly action will directly determine the safety operation of the reactor. Considering the time variation of the structural strength deterioration in the latch assembly, the time‐dependent reliability of CRDM's lift action is evaluated based on the Gamma degradation process. P‐S‐N curve is introduced to model the shape function and the scale parameter of the Gamma process. The stress subjected to the key structure of the latch assembly is calculated by a multi‐physics field coupling simulation scheme with utilization of MATLAB to transfer simulated results between the ANSYS and ADAMS software. Finally, the time‐dependent reliability is calculated based on the Monte Carlo simulation method. In this paper, the lift pole thread of the assembly is presented to demonstrate the effectiveness of the proposed method.
The motion simulation analysis of the control rod drive mechanism is a typical multi-disciplinary cross-coupling problem covering electromagnetic field, flow field, and dynamic field. Ensuring effective simulation accuracy is an important advance for accurately predicting the reliability of nuclear reactors. In this paper, a multi-disciplinary co-simulation method is proposed based on time unit differentiation, which solves the coupling problem of parameters by micro-element thought. It can avoid affecting the accuracy of simulation results due to the inequality of multi-disciplinary parameters in the co-simulation process. This paper takes the nuclear reactor control rod drive mechanism as the verification object. The multi-disciplinary co-simulation platform in Isight is built based on the co-simulation method. By differentiating the overall process of multidisciplinary co-simulation according to time unit and using the same simulation time interval for each discipline, the Newmark method is used to determine the minimum simulation time integration step of each discipline. The multi-field co-simulation is carried out including electromagnetic field, flow field, gravitational field, and motion field of the driving mechanism in the working process. Through comparison with the actual measurement results, the simulation results have an error within 5%, which is better than existing motion simulation results of driving mechanism.
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