Integrity Analysis For Fall-Off Flywheel Of Nuclear Reactor Coolant Pump

Nuclear main pump is short for nuclear reactor coolant pump, located in the nuclear primary circuit in the system, is the only rotating equipment in the primary circuit system, is an important part of the circuit system, called the heart of the nuclear power plant, belonging to the nuclear grade I safety pump. Flywheel of nuclear main pump is one of the important functional components in the main pump,its main effect is when nuclear power accident occurred, the main pump unit by running down inertia flywheel speed down slowly, the heat in the reactor coolant slowly away, and to avoid the reactor fuel burned.Because of the special role of nuclear main pump flywheel, there are few public literature on the flywheel in foreign, and domestic research is mostly concentrated in the diesel engine flywheel and other industries of the flywheel.At present, the finite element method to calculate the combined stress of the flywheel is relatively mature, but there are few studies on the local plastic yielding and the plastic yield of the flywheel. At the same time, the study on the fracture analysis of the flywheel is mostly focused on the calculation of stress intensity factor or the experimental means to observe the fracture surface to speculate the reasons for fracture.In this paper, the analysis method of the integrity of the flywheel are combined analytic method with the finite element method, and the results of two methods are verified by each other. In analytical method, based on elastic mechanics theory, the analytical formula of the combined stress is derived, and the analytical solution of the rotational speed of the flywheel plastic failure is derived based on this formula; Based on the linear elastic fracture mechanics theory, the analytical solution of the combined stress intensity factor is derived, and the crack growth length is calculated by using this analytical solution and the Paris formula. In the finite element method, using nonlinear contact algorithm to calculate the combined stress and plastic failure speed, and using the finite element software of professional fracture analysis to calculate stress intensity factor and crack growth process of three dimensional flywheel model. The work of this paper has perfected the analytical method of combined stress analysis and plastic failure analysis of flywheel, and filled up the blank of the analytical calculation of stress intensity factor and finite element analysis of fracture propagation.Finally,this paper takes the study of the integrity of the third generation nuclear main pump fall-off flywheel, the results provide a basis for the evaluation of integrity of the nuclear main pump fall-off flywheel.