Motion Equation of Temperature Induced Plane Transversal Vibrations of a Rod: Numerical–Analytical Solution

Abstract—

In the process of designing the new NEPTUN pulsed reactor, the phenomenon of dynamic bending was discovered; it is a feature of the dynamics of pulsed reactors that does not appear in reactors of other types; however, it plays a significant role in evaluating the stability of reactor operation. Movements of fuel elements (fuel rods) under the influence of periodically changing temperature can lead to significant changes in the reactivity and fluctuations of the reactor power. To accurately simulate the operation of the reactor, it is necessary to know the shape of the fuel element at the time of the next power pulse. Since numerical methods for solving this dynamic problem of thermoelasticity require a computation time that is too large, an analytical method was applied. In this study, the first results of the numerical–analytical solution of the equation of induced oscillations of a fuel rod, as well as the prospects for using the method in studying the dynamics of the NEPTUN reactor, are presented.