Deformation Analysis of Horizontal Microreactor Control Drums Using Finite Element Methods

Abstract

With the diminishing availability of fossil fuel energy and the escalating impacts of climate change, nuclear energy is gaining recognition as a sustainable alternative. However, conventional large light-water nuclear reactors (LLWRs) in the United States pose a substantial financial hurdle due to their high upfront costs. To address this barrier, the development of nuclear microreactors, producing around 1 MWe instead of 1 GWe, is underway. HolosGen is actively designing a microreactor with a non-traditional geometry, deviating from the standard model employed since the 1950s. This project aims to assess the deformation of control components in the microreactor during operation and identify necessary refinements for improved fidelity in design. The reactor geometry proposed by HolosGen differs from a LLWR. In a LLWR, the reactor vessel is oriented vertically, and the control components (typically rods or blades) move in and out of the fuel region to control the reaction rate. In the Holosgen mircoreactor design, the reactor vessel is horizontal, and the control components are rotating cylinders (known as control drums) on the periphery of the vessel. This alteration in geometry introduces a different gravitational impact on the components. Additionally, the cylinder is comprised of two discrete materials. The different coefficients of thermal expansion are predicted to cause significant stress within the control element. This project explored the effects of gravity and thermal expansion of a control drum using ANSYS Discovery, a finite element method.