Investigative Research on Design Parameters and Criticality Models for Microreactors

With increased energy demand and the desire to reduce reliance on fossil fuels, nuclear power will need to play a prominent role in achieving carbon-free energy independence. Large nuclear reactors are necessary to meet this objective. However, they are expensive and take a long time to build. For remote locations (e.g., military bases) and smaller communities, large nuclear reactors would not be feasible or cost effective. Small reactors (microreactors) can fill this necessary gap. These reactors would be factory-built, delivered quickly, and operated with high intrinsic levels of safety. With microreactors still in conceptual and testing states, there is a large need to study how these reactors produce consistent energy in a much smaller package. The objective of this research is to develop design parameters and criticality models for a reactor core that can be used in a microreactor, which would self-regulate based on automatic control functions. This research investigates parameters and constraints for the reactor design, including a reactor core fueled with TRISO fuel, different cooling methods, and graphite moderators. Sensitivity studies are conducted on temperature, fuel depletion, and criticality control methods, and an enrichment of 20% U-235 will be used as the primary source of heat. A core achieving a critical state with temperatures ranging from room temperature to 1200K is considered. Feedback mechanisms are also investigated, including inherently safe fuel design and control rod manipulation.