Transient Analysis of a Reactor Coolant Pump Rotor Seizure Nuclear Accident

Abstract

The reactor coolant pump (RCP) rotor seizure accident is defined as a short-time seizure of the RCP rotor. This event typically leads to an abrupt flow decrease in the corresponding loop and an ensuing reactor and turbine trip. The significant reduction of core coolant flow while the reactor is being operated at full load can have very negative consequences. This potentially dangerous event is typically characterized by a complex transient behavior in terms of flow conditions and energy transformation, which need to be analyzed and understood. This study constructed transient flow and rotational speed mathematical models under various degrees of rotor seizure using the test data collected from a dedicated transient rotor seizure test system. Then, bidirectional fluid-solid coupling simulations were conducted to investigate the flow evolution mechanism. It is found that the influence of the impeller structure size and transient braking acceleration on the unsteady head (H u ) is dominant in rotor seizure accident events. Moreover, the present results also show that the rotational acceleration additional head (H u1 ) is much higher than the instantaneous head (H u2 ).