Towards the reliability prediction of mechanical components for nuclear safety cases

Abstract

The thesis presents a modelling method to increase accuracy in reliability predictions of mechanical components. Such predictions are used in nuclear safety case documentation that is required for a nuclear site license to be granted. The methodology proposed is the use of front-end Finite Element fatigue analysis using the ANSYS software to effectively evaluate the mechanical reliability of nuclear safety systems/mechanisms, to evaluate the Mean Cycles To Failure of any steel three dimensional component. No inference is attempted with reference to the validity of the reliability values calculated, though they are shown to be reasonable when a simplistic constant hazard rate reliability model is employed. Some rudimentary evidence is provided showing that reductions of the fatigue safety factor by just less than a quarter may increase the design life of the component four-fold, ergo significantly reducing the on-site expected failure rates. The methodologies explored herein therefore effectively show that the ANSYS-Workbench software can be used to predict the life, ergo the reliability of mechanical components in-situ.