The U.S. military is developing a land-based, portable micro-reactor designed to provide reliable energy for remote military bases. This small modular reactor features high mobility and rapid deployment capabilities, enabling stable operation in extreme environments. The design of the land-based portable micro-reactor emphasizes safety and maintainability to minimize reliance on external support. Its development indicates the U.S. military's efforts to enhance energy self-sufficiency for global strategic deployment and reduce dependence on traditional fuels. The advancement of this technology will have profound implications for global military energy strategies. This article analyzes the development trends and impacts of the U.S. military's land-based portable micro-reactor.

The land-based microreactor is essentially a miniature, mobile nuclear power plant that generates electricity using the heat produced by a nuclear reactor. It mainly consists of a nuclear reactor, an energy conversion system, a control system, and auxiliary systems. The U.S. military's land-based microreactors typically have an electrical power output in the megawatt range and can be transported by trucks, ships, or aircraft to supply power to military bases in remote areas such as the polar regions. They are characterized by long refueling cycles and high inherent safety. Land-based microreactors are an optimal choice for meeting the diverse energy supply needs and rapid response requirements of future battlefield operations.

1. The Development Process and Latest Trends in the United States

In the year, the "Army Reactor Program" was initiated, with the United States targeting the power supply needs of military bases in remote areas such as the polar regions, to develop land-based micro nuclear power sources that could be quickly disassembled and transported. Over the years, the U.S. Army gradually developed and constructed several land-based small nuclear reactors with a power output of megawatts, including models -, -, -, -, and - (some of which were mobile reactors). Due to technical and cost issues, all of these reactors were operational and subsequently decommissioned by the 1980s.

Since the beginning of the century, the U.S. Department of Defense (DoD) has once again placed significant emphasis on land-based mobile microreactors. This renewed interest stems from the increasing demand for energy density and mobility at forward and remote military bases, the growing vulnerability of diesel fuel supply logistics, and the maturing technology of a new generation of microreactors. In 2019, the DoD's Strategic Capabilities Office launched the "Project Pele" initiative, deciding to construct and demonstrate a mobile microreactor with a power output of 1-5 megawatts, capable of operating at full power for at least three years. In March 2020, the DoD awarded contracts to three companies—BWX Technologies, X-energy, and Westinghouse—to commence the design of land-based microreactors. By March 2021, the DoD announced its selection of the high-temperature gas-cooled reactor technology proposed by BWX Technologies and X-energy to proceed with further design work. In June 2022, the DoD released an environmental assessment report for land-based microreactors, evaluating the environmental impacts of fuel and reactor manufacturing, transportation, and operation. In May 2023, the DoD issued a statement announcing plans to construct and demonstrate a prototype reactor at Idaho National Laboratory, with the goal of conducting an operational demonstration at a domestic military base by 2025.

2. Key Technologies and Major Challenges

The key technologies involved in the proposed land-based micro-reactor technology scheme under the U.S. "Bailey" project mainly include reactor type selection, inherent safety design, and reactor fuel loading design, featuring the following characteristics: First, high power density and long operational cycles. The reactor has an electrical power output in the megawatt range, with a maximum of only kilograms of nuclear fuel in the core, allowing it to operate for over a year on a single fuel loading, significantly reducing the number of diesel generators and diesel consumption for power supply at military bases. Second, it boasts excellent mobility and extremely simple operation. The reactor weighs no more than a few tons and, with its modular design, can be placed in a standard shipping container and transported via trucks, ships, and C-130 transport aircraft, among other methods. Third, it features rapid deployment and withdrawal capabilities. After the reactor module components arrive at the destination, they can be assembled and started within hours, and after shutdown, the core can be cooled and dismantled for withdrawal within days. Fourth, it has excellent safety features. In the event of an accident, the reactor can automatically shut down and cool, and the nuclear fuel used in the reactor is heat-resistant and structurally extremely robust, greatly reducing the release of radioactive materials in the event of external damage to the reactor.

The U.S. military's land-based micro-reactor design employs a high-temperature gas-cooled reactor. This design is the most likely to meet the requirements for size, weight, and mobile deployment at a power generation level of several megawatts. High-temperature gas-cooled reactors use helium, carbon dioxide, and nitrogen as coolants, eliminating the need for liquid cooling. This significantly reduces the demand for water cooling resources such as lakes, rivers, and oceans, offering greater flexibility in site selection.

The U.S. military's land-based microreactor incorporates multiple safety designs. The reactor uses "isotropic triple-coated" fuel, with the reactor core encapsulated in carbon-based and ceramic-based material layers that can withstand high temperatures up to ℃. In the event of an accident caused by an attack, it does not require large-scale evacuation like traditional nuclear power plants. The reactor also features passive cooling capabilities, allowing it to safely shut down without intervention in the event of an attack or accident, thereby preventing harm to nearby personnel and public health.

The U.S. military's land-based micro-reactors utilize high-assay low-enriched uranium (HALEU) that enhances uranium loading capacity and proliferation resistance. The uranium enrichment level does not exceed a certain percentage, meeting the international definition standards for low-enriched uranium and fulfilling international non-proliferation requirements. The enrichment level is also significantly higher than the current levels of no more than a certain percentage in existing nuclear power plants, which can greatly increase the loading of fissile materials within the reactor. This is beneficial for the miniaturization of the reactor and the extension of its operational lifespan, meeting the target of full-power operation for over a certain number of years.

The U.S. military's land-based microreactors are still in the design and experimental phase, and there is a distance to go before actual deployment and application. The main challenges include: in terms of regulation, the lack of a regulatory system for microreactors, requiring consideration of the applicability of international nuclear technology control treaties and rules of engagement; technically, issues such as the lack of commercial supply of reactor fuel and the design of efficient energy conversion systems need to be addressed; in application, the physical security during operation and transportation must be considered to prevent the reactors from being attacked.

3. Impact Analysis

According to statistics from the U.S. Department of Defense, the U.S. military consumes approximately hundreds of millions of kilowatt-hours of electricity annually and over tens of thousands of liters of fuel daily. The large-scale overseas operations and forward military bases of the U.S. face numerous challenges in logistics supply, including high costs of fuel transportation, limitations imposed by terrain and extreme weather conditions, and vulnerability to attacks during transportation. Land-based microreactors are considered the ideal military energy source for the future.

A powerful trump card in shaping the strategic landscape.

Currently, the United States is accelerating the militarization of its forward bases in the Indo-Pacific region, intensifying the development of advanced military equipment to ensure its global leadership and strategic advantage. Land-based micro mobile reactors, with their enduring, stable, and abundant energy supply capabilities, can significantly enhance the self-sustainability of these bases, ensuring that U.S. forces can sustain high-intensity operations in the Indo-Pacific region. These reactors effectively mitigate numerous challenges associated with conventional energy acquisition for military bases, reduce the consumption of conventional fuels for daily power supply, decrease the frequency, cost, and casualties of logistical energy resupply, and require minimal on-site operation and maintenance personnel. They streamline the number of diesel generators and maintenance staff within the bases, reduce the footprint of fuel storage facilities, and lower the risk of personnel casualties and potential attacks. In summary, land-based micro mobile reactors offer irreplaceable and prominent advantages in battlefield situational awareness and strategic offensive and defensive weapons, with their application benefits becoming even more pronounced in higher, deeper, and more extreme battlefield environments.

(2) A Powerful Guarantee for Enhancing Equipment Effectiveness

New concept weapons such as lasers, microwaves, and electromagnetic railguns have seen an exponential increase in energy and power demands. For instance, a megawatt-class ballistic missile defense high-energy laser system requires a matching megawatt-level main power supply; high-power microwave weapons, which can destroy targets hundreds of kilometers away, need at least multi-megawatt power supplies, which are difficult to sustain with diesel engines and energy storage systems for continuous combat operations. Additionally, as the informatization and intelligence of weaponry continue to advance, the power demands of forward-deployed troops have significantly increased. For example, the missile defense system radars deployed by the U.S. military in remote bases such as Guam and Alaska have enormous power requirements. The new operational concepts proposed by the U.S. military, such as "reconnaissance deterrence," require a large number of drones to perform long-term continuous surveillance missions, further increasing energy demands. Ground-based micro-mobile reactors, with their significant feature of high-power density continuous power supply, combined with energy storage devices, can support high-power new quality weaponry and multi-domain high-power combat applications, comprehensively enhancing the operational effectiveness of the equipment system.

(3) A Strong Backbone for Enhancing Energy Security Capabilities

Land-based micro-mobile reactors will significantly enhance the comprehensive support capabilities of U.S. military bases. On one hand, they effectively alleviate challenges such as difficulties in logistical energy supply faced by military bases in obtaining conventional energy sources. On the other hand, they meet diverse battlefield needs through flexible deployment, rapid assembly, and plug-and-play functionality. Additionally, they support the living needs of base personnel by providing electricity, heating, and seawater desalination, thereby boosting the energy support capabilities of military bases and ensuring comprehensive energy application requirements on the battlefield.

(4) Propelling a Powerful Engine for Leading-edge Technology Advancement

Leveraging breakthroughs in land-based micro-reactor technology will drive the development of a range of cutting-edge technological innovations. Key advancements in high-assay low-enriched uranium, particle technology, compact reactor design, and advanced high-temperature structural materials in land-based portable micro-reactors will propel the development of common technologies across multiple domains including sea, land, air, and space. This will provide a powerful engine for the systematic development of new materials, designs, and processes, thereby advancing small nuclear power technology in more operational domains.

IV. Conclusion

In recent years, the United States has regarded land-based microreactors as a "game-changing" disruptive technology, accelerating their development and deployment. This initiative is set to revolutionize the future mode of military energy supply in the U.S., significantly enhancing the expeditionary combat capabilities of the U.S. military, and thus warrants high attention.