Analysis of the continuous operational characteristics of the control rod eddy current retarder

• The torque performance of the control rod eddy current retarder during continuous operation. • The eddy current retarder with the compensation cladding has a torque rebound phenomenon during continuous operation. • Using compensation claddings can effectively mitigate the impact of thermal fade and improve the torque stability. The control rod eddy current retarder (CRECR) serves as the primary damping device during the control rod dropping process in the high temperature gas-cooled reactor, converting the gravitational potential energy into eddy current losses inside the conductor disk of CRECR. In order to analyze the torque performance of CRECR during continuous operation, a multi-node coupling method for electromagnetic and thermal simulation was proposed, and an electromagnetic-thermal coupling simulation model was established. Subsequently, the model was experimentally verified and the influence of speed, operating time and compensation claddings were analyzed. The torque deviation remains consistently below 7 % within 300 s. Additionally, continuous operation at speeds exceeding 300 rpm resulted in non-ignorable changes in component temperature and torque, necessitating careful consideration in engineering tests. Furthermore, a torque rebound phenomenon was observed during continuous operation, indicating that using compensation claddings can effectively mitigate the impact of thermal fade and improve the torque stability.