Design Options for Ultra-compact Nuclear Driven Power Sources for Field Applications



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In the future, there will be demand for transportable power generation systems that can provide electricity and heating to remote, austere regions, for industrial, scientific, and military purposes. This thesis proposes that such a system should be compact, able to discharge its waste heat into the environment without a local water source, and have low logistical overhead. An air-cooled fast-spectrum nuclear reactor coupled to a direct Brayton cycle would be a viable and suitable design concept to fill this role. In order to support this claim, this thesis presents neutronics, thermal hydraulics, and thermodynamics of such a system.

As modeled in this thesis, a fast spectrum core 50 cm tall, with air as the working fluid, is able to drive a closed Brayton cycle core with a thermal efficiency of 37.5%, while the same core is unable to drive an open Brayton cycle with more than approximately 10% efficiency. This core could reach a burnup of 39 GWd/tHM, while remaining critical, controllable, and neutronically safe throughout the core lifetime.

Assuming heat is only removed via active cooling, this reactor would require 24 kW of pumping power in the first minutes of a Depressurization Loss of Coolant Accident scenario.

For both the open and closed Brayton cycle models, Argon-41 production is significant. However, in an open cycle mode, Argon-41 is unlikely to provide a harmful dose. In a closed cycle mode, Argon-41 may require some shielding of the primary coolant loop.