Conceptual Structural Design of Core Components for a Horizontal, Compact HTGR

Abstract

This thesis investigates structural, thermomechanical, and fabrication-based challenges associated with a horizontally oriented High Temperature Gas Reactor (HTGR) concept and its core components. HTGRs hold significant potential in decarbonizing industrial process heat markets. Collaborators at MIT recently introduced the Horizontal, Compact HTGR (HC-HTGR), which expects to see a 20% reduction in overall cost with respect to vertical HTGRs. The horizontal re-orientation and modularization of the HC-HTGR and its accompanying structural challenges form the basis of this work.

First, a detailed thermal/irradiation expansion analysis is conducted to assess graphite interaction with reactor core spatial gaps. This also includes a study of the relative displacements that occur at horizontal control rod and/or control drum locations at various points along the core’s length, and addresses the resulting implications on potential support conditions for the control sleeve spans. Next, graphite element features and control element sleeves are analyzed for strength with consideration to varying material properties and reactor environment conditions. Finally, an assessment of perimeter graphite reflector elements for structural integrity and a design of metallic support components are performed. Through design and analysis, this thesis increases the feasibility of the HC-HTGR concept, provides cross-discipline implications from a structural perspective for reactor core components, and ultimately advances a potential carbon-free technology for high temperature process heat markets.