Investigation of bond graphs for nuclear reactor simulations

Abstract

This work proposes a simple and effective approach to modeling multiphysics nuclear reactor problems using bond graphs. The conventional method of modeling the coupled multiphysics transients in nuclear reactors is operator splitting, which treats the single physics individually and exchanges the information at every time step. This approach has limited accuracy, and so there is interest in the development of methods for fully coupled physics simulation. The bond graph formalism was first introduced to solve the multiphysics problem in electromechanical systems. Over the years, it has been used in many fields including nuclear engineering, but with limited scope due to its perceived impracticality in large systems. In this work, the bond graph formalism is for the first time applied to neutron transport, and coupled to heat transfer in a nuclear reactor. Fully coupled 1D diffusion reaction model is derived using bond graphs, and the transient solution obtained using a proof-of-concept bond graph processing code. The bond graph-based approach to coupled nuclear reactor simulation was shown to be accurate and stable. Suggestions are made for the expansion of the approach to larger problems and higher fidelity simulations.