Structural integrity verification of a primary circuit pump flywheel for the OPAL Research Reactor

Abstract

The flywheels on nuclear reactor coolant pump motors provide inertia to ensure a slow decrease in coolant flow in the event of loss of power; thus preventing fuel damage due to the reduced coolant flow. During operation at normal speed, a flywheel has sufficient kinetic energy to produce high-energy missiles and excessive vibration of the coolant pump assembly if the flywheel should fail. The structural integrity of a large steel flywheel to be used in the primary cooling circuit of the OPAL research reactor at Lucas Heights was evaluated according to the requirements of the US Nuclear Regulatory Commission guide RG 1.14. This guide was developed for nuclear power plants where significant over-speeds in pumps are possible. In the OPAL reactor at ANSTO such pump over-speeds are not possible, however, the code was used to demonstrate the incredibility of failure of the flywheel and consequently a guillotine failure of the primary cooling system pipework.