The US White House on 12 January released the text of an executive order, which seeks promote the development of small modular reactors (SMRs) for space and defence applications.

This comes less than a month after issuing a policy directive on space nuclear power. The 16 December publication of Space Policy Directive (SPD) 6, outlined a roadmap for both space nuclear reactors and nuclear propulsion systems, prioritising development of surface nuclear power systems over nuclear thermal propulsion.

The executive order, Promoting Small Modular Reactors for National Defense and Space Exploration, which was signed by President Donald Trump on 5 January, says nuclear energy is critical to US national security. “That is why I have taken a series of actions to promote its development and facilitate its use, he notes, adding that “the purpose of this order is to take an important additional step to revitalize the United States nuclear energy sector, reinvigorate America’s space exploration programme, and develop diverse energy options for national defence needs”.

According to the order, the US government “will coordinate its nuclear activities to apply the benefits of nuclear energy most effectively toward American technology supremacy, including the use of small modular reactors for national defence and space exploration”.  Trump adds that this “is critical to advancing my Administration’s priorities for the United States to lead in research, technology, invention, innovation, and advanced technology development; its mission to promote and protect the United States national security innovation base; its drive to secure energy dominance; and its commitment to achieving all of these goals in a manner consistent with the highest nuclear non-proliferation standards”.

The order says the ability to use SMRs “will help maintain and advance United States dominance and strategic leadership across the space and terrestrial domains”.

US policy aims to promote advanced reactor technologies, including SMRs, to support defence installation energy flexibility and energy security, and for use in space exploration, guided by the following principles:

  • A healthy and robust nuclear energy industry is critical to the national security, energy security, and US economic prosperity;
  • The USA “should maintain technology supremacy for nuclear research and development, manufacturing proficiency, and security and safety”;
  • The US government should bolster national defence and space exploration capabilities and enable private-sector innovation of advanced reactor technologies.

Micro-reactors for military installations

Section 3 of the order concerns the demonstration of commercial reactors to enhance energy flexibility at a defence installation. As micro-reactors have the potential to enhance energy flexibility and energy security at domestic military installations in remote locations, the Secretary of Defense must within 180 days “establish and implement a plan to demonstrate the energy flexibility capability and cost effectiveness of a Nuclear Regulatory Commission-licensed micro‑reactor at a domestic military installation”.

If the demonstration is successful, the Secretary of Defence will identify opportunities at domestic military installations where this capability could enhance or supplement the fulfilment of energy requirements, taking into account:

  • the ability to provide resilient, independent energy delivery to installations in the event that connections to an electrical grid are compromised;
  • the ability to operate for an extended period of time without refuelling;
  • system resistance to disruption from an electro‑magnetic pulse event; and
  • system cybersecurity requirements.

Section 4 looks at defence needs noting that fuel demands for the military have dramatically grown since World War II and are anticipated to continue to increase. “In this context, nuclear power could significantly enhance national defence power capabilities.” The Secretary of Defence if instructed to consult with the Secretary of State, the Secretary of Commerce, the Secretary of Energy, and the NASA Administrator to:

  • determine whether advanced nuclear reactors can be made to benefit DOD future space power needs;
  • pilot a transportable micro-reactor prototype;
  • direct an analysis of alternatives for personnel, regulatory, and technical requirements to inform future decisions with respect to nuclear power usage; and
  • direct an analysis of US military uses for space nuclear power and propulsion technologies and an analysis of foreign adversaries’ space power and propulsion programmes.

Nuclear power sources for space exploration

Section 5 focuses on space exploration, noting that “nuclear power sources that use uranium fuel or plutonium heat sources are essential to deep space exploration and in areas where solar power is not practical”.  Nuclear power sources in the kilowatt range may be needed “for demonstrating In-situ Resource Utilisation (ISRU) and robotic exploration of permanently shadowed craters on the Moon that contain frozen water”.  Nuclear reactors up to 100 kilowatts may be needed to support human habitats, ISRU, other facilities, and rovers on both the Moon and Mars.  Power sources in the megawatt range would be necessary for efficient, long‑duration deep space propulsion. Affordable, lightweight nuclear power sources in space would enable new opportunities for scientific discovery. The sustainable exploration of the Moon, Mars, and other locations “will be enhanced if small modular reactors can be deployed and operated remotely from Earth”.

Within 180 days NASA in consultation with heads of other executive departments and agencies (agencies) are to define requirements for NASA utilisation of nuclear energy systems for human and robotic exploration missions to 2040 and analyse the costs and benefits of such requirements.  NASA must take into account:

  • transportability of a reactor before and after deployment;
  • thermal management in a reducedor zero-gravity environment in a vacuum or near-vacuum;
  • fluid transfer within reactor systems in a reduced or zero-gravity environment;
  • reactor size and mass for launching from Earth and assembly in space;
  • cooling of nuclear reactors in space;
  • electric power requirements;
  • space safety rating to enable operations as part of human space exploration missions;
  • period of time for which a reactor can operate without refuelling; and
  • conditioning of reactor components for use in space.

Establishing US-origin HALEU supply

Section 6 looks at domestic fuel supply, noting that a thriving and secure domestic nuclear fuel supply chain is critical to US national interests.  A viable domestic nuclear fuel supply chain supports defence and national security activities, and enables the success of the commercial nuclear industry. However, many advanced reactor concepts require high-assay, low-enriched uranium (HALEU), “for which no domestic commercial enrichment capability currently exists”. The USA must take steps to ensure a viable US-origin HALEU supply.

DOE must complete its ongoing three-year, $115 million demonstration of a US-origin enrichment technology capable of producing HALEU for use in defence-related advanced reactor applications. The Secretary of Energy should develop a plan to promote successful transition of this technology to the private sector for commercial adoption.

Goal for a common technology roadmap

Section 7 exhorts the Secretary of State, Defence Secretary, Commerce, Energy Secretary and NASA to develop a common technology roadmap to 2030 “that describes potential development programmes and that coordinates, to the extent practicable, terrestrial-based advanced nuclear reactor and space-based nuclear power and propulsion efforts”. The roadmap must include:

  • assessments of foreign nations’ space nuclear power and propulsion technological capabilities;
  • pathways for transitioning technologies developed through Federally supported programmes to private-sector activities; and
  • other applications supporting the goals of the order.