The flywheels on reactor coolant pump motors provide inertia to ensure a slow decrease in coolant flow in order to prevent fuel damage as a result of a loss of power to the pump motors. During operation at normal speed, a flywheel has sufficient kinetic energy to produce high-energy missiles and excessive vibration of the reactor coolant pump assembly if the flywheel failed. Overspeed of the pump rotor assembly during a transient increases both the potential for failure and the kinetic energy of the flywheel. The safety consequences could be significant because of possible damage to the reactor coolant system, the containment, or other equipment or systems important to safety.
Usually, the design of connection between flywheel and pump rotor has two types, one is keyway, and the other is rotor shrink fitting. This paper has done the research on the analysis of the integrity of flywheel in design rules and guidelines, such as NUREG, RG and NB, which have given the allowable stress limits but not given the potential for failures types and the stress verification type. So the stress verification of the flywheel is different in different technicals and structures. Some papers also have different analysis methods in China.
This paper considers the failures mode of flywheel, using the analytical method in THEORY OF ELASTICITY and Tresca criteria to give the method of the stress analysis of flywheel. Next, this paper pays attention on the analysis of the flywheel integrity about two connection types, and gives the other requirements of integrity. Such as stress analysis, fatigue analysis, ductile failure analysis, non-ductile failure analysis, crack propagation analysis etc.
Seismic stress analysis of feeder lines to LOFT primary coolant pump motors