To evaluate the thermal insulation performance of the canned motor for the nuclear main pump during the coolant hot-start process

a comprehensive coupled heat transfer numerical model was established based on the computational fluid dynamics and fluid-solid coupling heat transfer theories. In the model the motor's solid components

internal flow ducts

externally wound helical tube heat exchanger

and the coolant pump casing were integrated. Using this model

the temperature field of the nuclear main pump canned motor was simulated for the entire process in which the coolant temperature increases from 50 ℃ to 303 ℃. The evolution patterns of temperature and temperature rise rate for key components

such as the stator winding insulation

stator shielding sleeve

and casing

as well as the primary water

were clarified. The results indicate that the insulation structure can effectively suppress the heat transfer from the coolant to the main solid components of the motor

with the peak temperature of the stator winding insulation increasing by only 3.4%. The temperature and the temperature rise rate of the primary water between the flywheel and the coolant are significantly higher than those inside the motor

identifying this region as a critical focus for thermal management in the canned motor of the nuclear main pump. This study provides a quantitative basis for the thermal stress analysis and insulation design of the nuclear main pump canned motor.