Energy is a critical enabling component of military operations and demand for it will continue to increase over time. In particular, energy usage during contingency operations will likely increase significantly over the next few decades. The modern operational space has amplified the need for alternative energy sources to enable mobility in forward land based and maritime military operations. In 2008, during the height of combat in Iraq, the Government Accountability Office estimated that more than 900,000 gallons of fuel went to bases for basic power needs like lighting and refrigeration (on top of the 6.7 million gallons the military burned that year in jets and ground vehicles.)
Storms, blown transformers or sabotage can disable power grids, which is of concern to military installations connected to them. In isolated areas or military installations, the loss of power to site infrastructure can result in significant financial loss or loss of life. The U.S. Department of Defense envisions a kind of portable nuclear reactor that could move with units and provide all the power needs for a remote military base, eliminating the need to transport lots of fuel and maintain long supply lines to keep a base fueled up. Portable nuclear reactors are also useful for conflicts such as Iraq or Afghanistan, where convoys laden with diesel fuel are at risk of ambush. These SMRs have also potential to power modern Laser and High power Microwave Directed Energy Weapons which require large amount of power.
The 2010 NDAA directed the department to study the feasibility of nuclear power for military installations, but a study concluded that the reactors available at the time were simply too big. In August, 2016, the Defense Science Board identified key gaps in its report: Energy Systems for Forward Remote Operating Bases and concluded, “There is an opportunity for exploration of the use of nuclear energy applications at forward and remote operating bases and expeditionary forces.” The board concluded that the best approach for these super small reactors was radioisotope thermoelectric generators. They work simply: as the reactor fuel — either plutonium-238 or strontium-90 — decays, it slowly but surely releasing lots of heat, which is converted by thermocouples into electricity.
Small modular reactors (SMRs) defined as nuclear reactors generally 300MWe equivalent or less. SMRs have generated global interest, and potential future applications are a subject of international research directives. Their are around 50 different SMR designs worldwide according to the IAEA. Project proposals include use of SMRs for desalination, process heat generation, biofuel conversion and military base installations.
U.S. Department of Defense (DOD) is increasingly interested in the potential of SMRs mainly from two critical vulnerabilities it has identified in its infrastructure and operations: the dependence of U.S. military bases on the fragile civilian electrical grid, and the challenge of safely and reliably supplying energy to troops in forward operating locations. SMR safety systems reduce threats to public health; decrease the global stockpile of weapons-grade material and radioactive waste; and provide critical infrastructure support on military installations worldwide.
The Army’s small nuclear reactors generated power for remote installations in Greenland, Antarctica, Alaska, and other locations. This program ended in 1979 due to a number of factors, including the accident at Three Mile Island, cheap fossil fuel prices, and an overall waning of national interest in nuclear power. As Suid writes, the Army concluded “that the development of complex, compact nuclear plants of advanced design was expensive and time consuming…that the costs of developing and producing such plants are in fact so high that they can be justified only if the reactor has a unique capability and fills a clearly defined objective backed by the Department of Defense…[and that] the Army and the Pentagon had to be prepared to furnish financial support commensurate with the AEC’s [U.S. Atomic Energy Commission’s] development effort on the nuclear side.”
However, new developments in the commercial sector are opening up more options. American companies Westinghouse (0.2-5 MWe), NuScale (1-10 MWe), and UltraSafe Nuclear (5 MWe) are all developing reactors with less than 10 MWe output, while Sweden’s LeadCold (3-10 MW3) and a U.K. consortium led by Urenco (4 MWe) are also working on developing similar systems.
SMRs provide a number of benefits compared to the commercialized light water reactors, or LWRs, some of which are of particular interest to the Department of Defense. SMR designs for military base applications, such as the FliBe Energy’s Liquid Fluoride Thorium Reactor, provide a mobile and reliable avenue for on-site electrical power generation and desalination.
The U.S. Army’s own study declared that small, mobile nuclear reactors present “a classic example of disruptive innovation,” the study said, “The return of nuclear power to the Army and DOD will have a significant impact on the Army, our allies, the international community, commercial power industry, and the nation. U.S. nuclear industry growth affects the nation economically and geopolitically. With nuclear industry growth, there is significant potential for generating thousands of jobs… while provid[ing] a deployable, reliable, and sustainable option for reducing petroleum demand and focusing fuel forward to support Combatant Commander (CCDR) priorities and maneuver in multi-domain operations.”
The Pentagon announced Project Dilithium, its effort to develop a portable nuclear reactor, in January 2019. According to its plan, the reactor “should be less than 40 tons total weight; small enough to be transported by truck, ship, and aircraft; able to run for at least three years without refueling; and capable of semi-autonomous operation.”
Employing SMR technology on military bases will also allow for access to clean water, which is a largely unavailable resource across the globe. The U.S. Navy nuclear-powered aircraft carriers desalinate an estimated 400,000 gallons per day. SMRs use technology that establishes dynamic safety; enhances nuclear waste management protocols that benefit nonproliferation; and generates on-site electricity and potable water on military installations.
Small mobile nuclear reactors can make the DOD’s domestic infrastructure resilient to an electrical grid attack and fundamentally change the logistics of forward operating bases, both by making more energy available and by drastically simplifying the complex fuel logistical lines which currently support existing power generators operating mostly on diesel fuel. Additionally, a small mobile nuclear reactor would enable a more rapid response during Humanitarian Assistance and Disaster Relief (HADR) operations. Small mobile nuclear reactors have the potential to be an across-the-board strategic game changer for the DOD by saving lives, saving money, and giving soldiers in the field a prime power source with increased flexibility and functionality.
According to Dr. Jonathan Cobb, a spokesman for the World Nuclear Association, small nuclear reactors come in three flavors. The first, small modular reactors, sit in the 20-300 MWe range and are approaching the point they will appear on market. The second category sits from 10-100 megawatts, and have been used in transports such as icebreakers. According to Cobb, a pair of 32 MWe reactors, based on icebreaker technology, are being used aboard the Akademik Lomonosov, a Russian “floating power plant.” The third category, covering what the Pentagon appears most interested in, is a category known as microreactors. The challenge, Cobb said, is that this group is the furthest behind technologically, with demonstrations of commercial systems targeted for “the second half of the 2020s,” putting them in the “ballpark” of what DoD is looking for with its A&S effort.
The World Nuclear Association lists the features of an SMR, including:
- Small power and compact architecture and usually (at least for nuclear steam supply system and associated safety systems) employment of passive concepts. Therefore there is less reliance on active safety systems and additional pumps, as well as AC power for accident mitigation.
- The compact architecture enables modularity of fabrication (in-factory), which can also facilitate implementation of higher quality standards.
- Lower power leading to reduction of the source term as well as smaller radioactive inventory in a reactor (smaller reactors).
- Potential for sub-grade (underground or underwater) location of the reactor unit providing more protection from natural (e.g. seismic or tsunami according to the location) or man-made (e.g. aircraft impact) hazards.
- The modular design and small size lends itself to having multiple units on the same site.
- Lower requirement for access to cooling water – therefore suitable for remote regions and for specic applications such as mining or desalination.
- Ability to remove reactor module or in-situ decommissioning at the end of the lifetime.
The major disadvantage of nuclear power compared with other types of electricity generation is that nuclear power is expensive. According to a 2014 report by the Wall Street advisory firm Lazard, the cost of generating a megawatt-hour of electricity from a new nuclear reactor (without considering government subsidies, including those for liability for severe accidents) is between US $92 and $132. Compare that with $61 to $87 for a natural-gas combined-cycle plant, $37 to $81 for wind turbines, and $72 to $86 for utility-scale solar. Nuclear’s high costs result directly from the very high costs of building a reactor—estimated by Lazard at $5.4 million to $8.3 million for each.
However, Edwin Lyman, director of the Nuclear Safety Project at the Union of Concerned Scientists, has concerns about the availability of fuel to power a proliferation of small nuclear reactors. He noted, “there are no clear plans for manufacturing the quantity of high-assay low enriched uranium, much less the production of high-quality TRISO [TRi-structural ISOtropic particle] fuel, that would be able to meet timelines this decade.”
Pentagon awards contracts to design mobile nuclear reactor
The Pentagon in March 2020 issued three contracts to start design work on mobile, small nuclear reactors, as part of a two-step plan towards achieving nuclear power for American forces at home and abroad. The department awarded contracts to BWX Technologies, Inc. of Virginia, for $13.5 million; Westinghouse Government Services of Washington, D.C. for $11.9 million; and X-energy, LLC of Maryland, for $14.3 million, to begin a two-year engineering design competition for a small nuclear microreactor designed to potentially be forward deployed with forces outside the continental United States.
The combined $39.7 million in contracts are from “Project Pele,” a project run through the Strategic Capabilities Office (SCO), located within the department’s research and engineering side. The prototype is looking at a 1-5 megawatt (MWe) power range. The Department of Energy has been supporting the project at its Idaho National Laboratory. Pele “involves the development of a safe, mobile and advanced nuclear microreactor to support a variety of Department of Defense missions such as generating power for remote operating bases,” said Lt. Col. Robert Carver, a department spokesman. “After a two-year design-maturation period, one of the companies funded to begin design work may be selected to build and demonstrate a prototype.”
“The Pele Program’s uniqueness lies in the reactor’s mobility and safety,” said Jeff Waksman, Project Pele program manager, in a department statement. “We will leverage our industry partners to develop a system that can be safely and rapidly moved by road, rail, sea or air and for quick set up and shut down, with a design which is inherently safe.”
A second effort is being run through the office of the undersecretary of acquisition and sustainment. That effort, ordered in the 2019 National Defense Authorization Act, involves a pilot program aiming to demonstrate the efficacy of a small nuclear reactor, in the 2-10 MWe range, with initial testing at a Department of Energy site in roughly the 2023 timeframe.
If the testing goes well, a commercially developed, Nuclear Regulatory Commission licensed reactor will be demonstrated on a “permanent domestic military installation by 2027,” according to DoD spokesman Lt. Col. Mike Andrews. “If the full demonstration proves to be a cost effective energy resilience alternative, NRC-licensed [reactors] will provide an additional option for generating power provided to DoD through power purchase agreements.”
The best way to differentiate between the programs may be to think of the A&S effort as the domestic program, built off commercial technology, as part of an effort to get off of local power grids that are seen as weak targets, either via physical or cyber espionage. Pele is focused on the prototyping a new design, with forward operations in mind — and may never actually produce a reactor, if the prototype work proves too difficult.
US Navy eyes small modular reactors for its Bases
Navy had better success with developing nuclear power for its aircraft carriers and submarines. But these have quite different requirements from today’s SMR proposals. A submarine reactor is designed to operate under stressful conditions—to provide a burst of power when the vessel is accelerating, for example. And unlike civilian power plants, naval nuclear reactors don’t have to compete economically with other sources of power production. Their overwhelming advantage is that they enable a submarine to remain at sea for long periods of time without refueling.
Navy secretary Ray Mabus says there’s another alternative his department’s hasn’t explored yet: nuclear, and its time may have come. While nearly a fifth of the Navy’s ships run on nuclear power, the only land-based nuclear reactors the service operates are for training purposes. But Mabus said he wants to explore the concept of installing small, modular nuclear reactors on bases to continue their push toward independence from off-base energy. Rather than the large, utility-scale nuclear plants currently in use by civilian power companies, Mabus said he envisions a system of small, “distributed” nuclear generators networked together via a microgrid on a given base.
“With some of the new technology that’s coming along, it’s much safer, it produces far less residue and nuclear waste, and it is an option that I think we should explore,” he said at the Council on Foreign Relations in New York. “They are safer than traditional nuclear plants because of automated safety features and containment systems that are entirely underground, and cheaper because they can be fabricated in factories and quickly assembled at the sites where they’ll be used.”
SMR Military Requirements
The Pentagon wants a reactor capable of making 1 to 10 megawatts of electricity, and is clear that the reactor needs to be safe, incapable of melting down and contaminating nearby troops with harmful radioactivity. The military emphasizes safety and trouble-free operation, but also acknowledges that such a reactor is “not expected to survive a direct kinetic attack.” But a prominent nuclear organization just weighed in, arguing that such a plan is a colossal mistake. The Bulletin of the Atomic Scientists—the people known for their “two minutes to midnight” Doomsday Clock—argues that while such a reactor probably is feasible from a technical standpoint, it would never be safe enough to deploy on the battlefield. The risk of meltdown and radiation release would be too great ever to justify deploying the reactor into the field, the scientists say.
According to the NEI study, the reduced size and increased simplicity of microreactors mean a procurement and manufacturing cycle could take “between 3 and 5 years from the order of long lead materials to the delivery of the largest component, with a nominal target of 4 years. Most of the components will need to arrive on-site at least 6 months prior to startup in order to support the achievement of construction milestones.” “How they then would be developed to commercial applications may depend not only on industry developments, but also on establishing an effective regulatory environment. Most likely though we would be looking at microreactors coming into a commercial basis in the 2030s,” Cobb explained.
OUSD(R&E), SCO is interested in responding to these needs by developing a small mobile nuclear reactor design that can address electrical power needs in rapid response scenarios. At a time when military operations are more energy-intensive than ever before, it is crucial that the Department of Defense (DOD) seek out game-changing technologies such as nuclear energy, which is a safe, reliable, and nearly unlimited resource.
SCO is interested in small mobile nuclear reactor concept designs that produce electricity and which satisfy, at minimum, the following requirements:
- Threshold Power: 1-10 MWe of electric power generation
- Size/Transportability: < 40 tons total weight, sized for transportability by truck, ship, and C-17 aircraft
- Inherently safe design, ensuring that a meltdown is physically impossible in various complete failure scenarios such as loss of power/cooling.
- Ultimate heat sink: Ambient Air, capable of passive cooling
- Time to Install and reach Point of Adding Heat (POAH): Threshold: <72 hrs
- Life: Able to generate threshold power (1-10 MWe of electric power generation) for >3 years without refueling.
- Time for planned shutdown, cool down, disconnect and removal for transport:
- Threshold: < 7 days
- Operation: Semiautonomous – Not requiring manned control by operators to ensure safe operation. Minimal manning to monitor overall reactor and power plant system health.
- Safe Shutdown: Series of both automatic shutdowns as well as failsafe shutdowns with passive cooling upon loss of power.
- Health & Safety: No net increase in risk to public safety by either direct radiation from operation or contamination with breach of primary core. Minimized consequences to nearby personnel in case of adversary attack.
- Proliferation: Technology, engineering, and operations must demonstrate minimization of added proliferation risk.
- Fuel: Core design must use high-assay low enriched uranium (HALEU) advance gas reactor (AGR) tristructural isotropic (TRISO) fuel.Objectives
For purposes of this RFI, OUSD(R&E), SCO is interested in small mobile nuclear reactor concept designs that produce electricity and which satisfy, at minimum, the following requirements:
• Threshold Power: 1-10 MWe of electric power generation
• Size/Transportability: < 40 tons total weight, sized for transportability by truck, ship, and C-17 aircraft
• Inherently safe design, ensuring that a meltdown is physically impossible in various complete failure scenarios such as loss of power/cooling.
• Ultimate heat sink: Ambient Air, capable of passive cooling
• Time to Install and reach Point of Adding Heat (POAH): Threshold: <72 hrs
• Life: Able to generate threshold power (1-10 MWe of electric power generation) for >3 years without refueling.
• Time for planned shutdown, cool down, disconnect and removal for transport:
o Threshold: < 7 days
• Operation: Semiautonomous – Not requiring manned control by operators to ensure safe operation. Minimal manning to monitor overall reactor and power plant system health.
• Safe Shutdown: Series of both automatic shutdowns as well as failsafe shutdowns with passive cooling upon loss of power.
• Health & Safety: No net increase in risk to public safety by either direct radiation from operation or contamination with breach of primary core. Minimized consequences to nearby personnel in case of adversary attack.
• Proliferation: Technology, engineering, and operations must demonstrate minimization of added proliferation risk.
• Fuel: Core design must use high-assay low enriched uranium (HALEU) advance gas reactor (AGR) tristructural isotropic (TRISO) fuel.
Safety, Security and Regulatory issues
One major advantage of SMRs is their implementation of advanced safety features. SMRs employ passive safety systems that allow natural coolant circulation pathways to control reactor conditions. Passive safety requires that indefinite self-cooling and safe shutdown is possible without operator input, electrical power and additional coolant input.
SMRs are also significantly more compact than commercial LWRs. This reduces overall complexity and reduces potential modes of reactor control system failure. The Toshiba Super-Safe, Small and Simple and the Lawrence Livermore National Laboratory Small Secure Transportable Autonomous Reactor utilize a tamper-proof system that includes remote shutdown, sealed reactor core and autonomous operation. These safety features minimize on-site personnel and allow for global SMR usage because they assist in securing the reactor core against violent non-state actors and terrorist groups seeking to gain access to nuclear material.
The Bulletin of Atomic Scientists says a hassle-free, low-maintenance reactor is unlikely at this point of technological development. The reactor could possibly run on highly enriched uranium (HEU), which can also serve as fuel for nuclear weapons. In addition, war bring a variety of inescapable problems; a reactor on a battlefield could be buried by debris or damaged to the point that it can no longer cool itself. If the reactor is unable to prevent its temperature from spiking, its military outpost could have a big problem on its hands in the form of a meltdown.
Lyman believes that the department’s past efforts have “consistently underestimated”the “spectrum of mission risks posed by these microreactors,” mostly around the technical challenges of keeping the radioactive fuel safe and operational in battlefield conditions. “Fielding these reactors without commanders fully understanding the radiological consequences and developing robust response plans to cope with the aftermath could prove to be a disastrous miscalculation,” warned Lyman.
Security would remain a major factor as well, with the risk of nuclear material from a reactor falling into the hands of terrorist groups needing to be accounted for. While the nuclear material likely to be used in these reactors is “highly impractical” for a pure nuclear weapon, Lyman warned that an enemy could still seek the material and use it in some form of dirty bomb scenario which could deny American forces access to a specific area; additionally, security protocols would need to be put in place to deal with the transfer of the reactors.
However, Marc Nichol, NEI’s Senior Director of New Reactors, believes the refueling process should be fairly simple, with the non-mobile reactors sought by A&S likely having a 10 year lifespan in between refueling needs and the mobile reactors brought back whole to the U.S. when they need a refresher. “The idea is these would be refueled back in the United States at a centralized facility designed and equipped to do this work. No one is envisioning that these would be refueled in the field,” Nichol said. “Because they would be in a specialized facility here in the United States, there would be safety and security protocols in place for that. We have a lot of experience handling used fuel for our commercial reactors.”
Finally, there may be political challenges involved in deploying such systems. Some partner nations may balk at the idea of hosting a nuclear reactor, no matter how small. For instance, it is easy to picture the U.S. seeking to put a system for potential deployment, or as a power backup on a local base, in Japan, a key location for America’s force posture to counter China; such a move would likely be met with strong hostility, if not from politicians than from local protesters.
“I think most of these issues — including who would have regulatory authority and where liability would reside — have yet to be resolved,” said Lyman.” And even if the legal pathway were clear, there could be significant public opposition in certain host countries to deployment of these reactors if solely under U.S. authority.”
Nonproliferation and Waste Management
The generation of radioactive waste, such as Uranium-238 and Plutonium-239, occurs over the course of a commercial LWR fuel cycle. The production and storage of these materials is a threat to public health and inhibits nuclear armistice. Pu-239 is the most common material used in nuclear weaponry. The reduction of Pu-239 stockpiles aids the movement for nonproliferation of the global nuclear arsenal by decreasing the amount of material available for weapons production.
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