Exploration of Emerging Microreactors, and Investigation into the Size Options of Light Water Nuclear Reactors for Prospective Microreactor Designs
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In response to the economic realities of the American nuclear market, numerous corporations have formed with the goal of bringing new types of nuclear reactor designs to market. A survey was undertaken of these emerging small modular reactor and microreactor designs, with the NuScale Power Module (NPM) identified as a technological forerunner. A neutronics model of this reactor was developed and used to characterize and explore miniaturization alternatives for the development of a light water microreactor based on the proposed reduced size NPM. This model was characterized and the design iterated to arrive at a potential candidate light water micro reactor. Available literature on proposed nuclear reactor designs was reviewed. Government documentation, NRC applications, and company released technical details were collected to present an overview of design alternatives. Of these designs the NuScale reactor alternative was found to have the greatest technological readiness and availability of engineering detail. Using these details, a monte carlo N-particle (MCNP) neutronics model was developed and used to explore options by which this core could be miniaturized. Using a reduced number of assemblies with graphite reflectors, a reactor model was developed that offered the same performance of the proposed reduced size NPM. This design has a two and three quarter year lifespan producing 10 MWe using existing Pressurized Water Reactor (PWR) 17x17 fuel assemblies. Power coefficients were calculated for this proposed design to establish that, for normal operation, the core would be safely operable. Critical heat flux(CHF) was found and a departure from nucleate boiling ratio (DNBR) calculated for hot channels to ensure that the system operated inside safe thermal hydraulic bounds. This reactor bears out existing small reactor designs that incorporate graphite reflectors as a miniaturization technique. It offers a near term inexpensive microreactor using existing, well validated technology with proven fabrication techniques and supply lines. Future work would incorporate computation fluid dynamics (CFD) models being developed to complement the neutronics model for this core, and the exploration of design variations in the choice of fuel assembly and type.
Brownfield, Ryan David (2020). Exploration of Emerging Microreactors, and Investigation into the Size Options of Light Water Nuclear Reactors for Prospective Microreactor Designs. Master's thesis, Texas A&M University. Available electronically from