Nuclear is getting smaller, literally, and it’s opening opportunities for the industry. Much has been published about SMRs (Small Modular Reactors) but less so of micro-reactors. Micro-reactors will be small enough to be transported by truck, rail, or air and could help solve energy challenges in many areas, ranging from remote commercial or residential locations to military bases.
Micro-reactor designs vary. They are not defined by the type of fuel they use or their coolant and they produce 1 to 20 megawatts of thermal energy that could be used directly as heat or converted to electric power. They can be used to generate clean and reliable electricity for commercial use or for non-electric applications such as district heating, water desalination, and hydrogen fuel production.
Most designs will require HALEU fuel – High Assay Low Enriched Uranium (concentration of uranium-235 between 5% and 20%), although some may benefit from use of high temperature moderating materials that would reduce fuel enrichment requirements while maintaining the small system size.
The U.S. Department of Energy (DOE) supports a variety of advanced reactor designs, including gas, liquid metal, molten salt, and heat pipe-cooled concepts.
Three microreactor designs were recently awarded DOE funding for test bed experiments at the INL (Idaho National Laboratory) – Radiant, Ultra Safe Nuclear Corporation, and Westinghouse.
Radiant’s design, called Kaleidos, is a high-temperature gas-cooled (HGTR) microreactor. This El Segundo, California-based company was set up in 2020 by former SpaceX engineers Doug Bernauer and Bob Urberger. Kaleidos will be capable of generating up to 1.2MWe or 1.9 MWt for facility heating, water desalination, or as a replacement for diesel generators.
Ultra Safe’s design, called PYLON, is also a high-temperature gas-cooled (HGTR) microreactor. The Seattle, Washington-based company designed this microreactor to be easily transportable for off-grid locations on Earth and in space. The nuclear heat supply system module and the balance-of-plant module are located inside a 20-foot (6 meter) container, capable of producing 1.5 – 5 MWe.
Westinghouse’s design, called eVinci, is a heat pipe microreactor This Pittsburg, Pennsylvania-based company designed this microreactor to produce up to 5 MWe or 12 MWt. It could be used to produce high temperature heat for industrial applications or as a battery, providing power for a variety of applications such as remote communities, universities, mining operations, industrial centers, data centers, universities, defense facilities, and even on the surface of the Moon.