Aaron Horwood, Andrew Thueme and Travis Knight | 11.23.22
Liquid fuel logistics is both the lifeblood modern military operations and its tether. Without it, strategy is mere fantasy, as it enables everything a military force does. If a command of logistics is what separates professionals from amateurs, then liquid fuel logistics is where the battlefield most ruthlessly enforces this axiom. Alumina Dimple Tiles
But what if the US military can break free of that tether? The Strategic Capabilities Office’s Project Pele is an innovative, small, mobile nuclear reactor designed to provide assured energy to DoD’s most critical assets. The actual value of Project Pele is not just this single output, however. The project is a pathfinder for future larger mobile reactors and a catalyst enabling the development of synthetic liquid fuel production technology. Together these capabilities could free DoD from its traditional supply chains, fundamentally changing how it does logistics.
Unfortunately, specious claims in a report by the Nuclear Proliferation Prevention Project (NPPP) out of the University of Texas at Austin by the career antinuclear activist Dr. Alan Kuperman (and during an accompanying press conference with Dr. Edwin Lyman), an article in War on the Rocks by Jake Hecla, and a report from the RAND Corporation by a 1st Lt. Kyle Haak have badly misinformed the public risk analysis debate on Pele. There is ample room for debate about the best way ahead for DoD in its quest to solve a range of energy problems. Indeed, such debate is crucial. But it must be grounded in demonstrable facts.
According to the NPPP report and press conference, Pele meets no valid military need while it puts troops at unnecessary risk. Kuperman implies that the Army G-4 intentionally distorted Pele’s technical data, misrepresented casualty statistics, and mischaracterized the risk of shipping petroleum along lines of communication. Other inaccurate claims are that the Army will deploy Pele to forward “war bases” and intends to break federal laws in transporting Pele domestically. These critics further state that Pele will be vulnerable to terrorists and is a cash grab by defense contractors. Hecla argues that the technical risks have not been sufficiently examined. He questions tri-structural isotropic (TRISO) fuel safety, specifically the risks expelled fuel fragments pose. Hecla further argues that Pele could be used as an area-denial weapon if captured. His final claim is that there will be difficulty in gaining public support. The core contention of Haak’s RAND report is that nuclear power offers no unique capability or cost savings compared to alternative energy sources. Many of these claims’ technical, policy, and historical aspects are deeply misleading. However, the fundamental flaw throughout all of these criticisms is that they remove Pele’s cost-benefit analysis from its military context. This is epitomized by Kuperman’s claim that DoD’s forward energy problems have already been fixed by including thermostats and insulation in temporary military structures.
This mistake comes from a cultural risk aversion. New energy solutions must be technically valid and historically grounded to overcome this culture. Military and scientific communities must compare all energy system alternatives across the tactical, operational, and strategic levels of a future conflict. The stakes are high: in a near-peer conflict, energy can start, define, and end a war.
Capacity factor is an energy-sector term related to the reliability or availability of a power source. The NPPP report claims that DoD’s projected initial 75 percent capacity factor is unrealistic; instead of operating eighteen-hour days for forty years, the report argues, it will likely operate for nine-hour days for ten years (a 38 percent capacity factor). In the report’s estimation, this increases Pele’s cost sixteen-fold and makes it seven times more expensive than average diesel generator costs.
But Pele has a planned three-year lifecycle, not forty. It will be operated at isolated or critical locations where fuel costs are commonly several times the average price and have to potential to be orders of magnitude greater. Some prototype reactors from the 1960s had capacity factors around 38 percent but modern nuclear reactors operate twenty-four hours a day, seven days a week and have a capacity factor of 92–94 percent, shutting down only to refuel every few years. As Pele will not be refueled, DoD’s initial goal of a 75 percent capacity factor is conservative. Further, nuclear power excels compared to potential alternative energy sources, to the point that it requires two to three equally sized systems to match the long term output of a nuclear system.
The critiques of Pele are concerned that an attack could entomb the reactor and result in a meltdown. The NPPP report raises a further dubious concern that infiltrators could surreptitiously cover the reactor with insulating blankets. In such an event, however, Pele will fail to a safe state. Once the reactor shuts down, decaying heat and radiation will drop exponentially to a small amount. This heat will transfer to the surrounding environment without reaching the 1,800 degrees Celsius required for TRISO’s hermetically sealed containment to fail.
Hecla also takes issue with the ability of the silicon carbide layer of TRISO to survive military attacks. Any such data would be likely be classified but DoD will assuredly do extensive testing. However, some initial conclusions can be drawn from the fact that the Army’s helmets and body armor are made from silicon carbide. Also, when TRISO fuel is reprocessed, the silicon carbide layer requires an intense mechanical cracking process to be broken.
Another claim Hecla makes is that the dose from a pea-size TRISO fuel fragment at fifty centimeters would “impart a near-fatal dose in under an hour.” While eye-catching, this statement is both irrelevant and a flawed exaggeration. TRISO fuel fragments would be dangerous. But Hecla’s scenario would first require a successful attack in a rear area; then for personnel to be present in the exclusion zone explicitly designed to stop such an exposure. Additionally, the report he cites at best gives a rough approximation of this situation as its looks at other types of fuel at one hundred centimeters. In the worst-case first hour, using this method, the dose rate would be about 8 percent of a lethal dose at fifty centimeters and approximately 2 percent at one hundred centimeters. These values would continue to drop off exponentially as time goes by or the distance from the fragment increases.
Critiques of Project Pele also get some of the fundamental facts with respect to policy wrong. Both the NPPP report and Hecla’s article claim, for instance, that current Pele designs do not include adequate military protection; this criticism is premature as Pele is only at the prototype development stage. Most protective measures for Pele will be external to the system itself. Moreover, the NPPP report claims that the drop in US casualties associated with moving fuel between 2005 and 2013 shows Pele is unnecessary. This drop in casualties did happen, but the problem of force protection for fuel convoys was only “solved” years into the wars in Iraq and Afghanistan by offloading the risk to local national contractors. This solution does not work in large-scale ground combat. Additionally, Kuperman claims Pele will deploy to forward to “war bases,” but DoD has made no claim that it would be deployed to forward areas; on the contrary, the department intends for Pele to provide assured power to critical rear areas.
The NPPP report repeatedly implies, without presenting evidence, that DoD plans to violate the law by transporting Pele by air. DoD will work with Congress and within our nation’s laws and agreements with foreign countries to transport Pele whether by land, sea, or air. The diplomatic concerns expressed by Hecla have merit, and of course should be accounted for. But they are also not unique to Pele or nuclear power. Changes to a nation’s security situation can rapidly overcome such diplomatic hurdles. For example, Germany’s security policy—even its strategic culture—underwent a seismic shift when Russia’s attack on Ukraine eroded the European security environment. Its rapid shift from blocking overflights of US weapon shipments to Ukraine in January to supplying Ukraine with heavy weapons is indicative of a remarkable strategic sea change. A similar change could, of course, see Pele moved by air, with the acquiescence of allied parties. If not, the claim that DoD would violate agreements with foreign countries—not to mention US law—simply has no backing.
Both the NPPP report and Hecla’s article claim that Pele is at risk of being seized and used in a radiological terrorist attack, destroyed by long-range precision fires, or used as an area-denial weapon. Each of those contentions has problems. Long-range precision fires could destroy a Pele reactor, but this cannot physically result in a nuclear explosion. Employing sufficiently effective long-range fires or seizing and holding a US military installation long enough to weaponize TRISO fuel requires substantial capabilities. Any highly capable state actor already has access to conventional area-denial weapons and radiological materials. At the same time, nonstate actors would find such an attack and fuel processing impractical and unwarranted, especially with more suitable radiological material commonly used in civilian settings, which are much easier targets.
While debris from a Pele reactor targeted in an attack would be dangerous, it should have little significant short-term environmental or human impacts as the debris would be contained within the reactor’s exclusion zone and by the TRISO particles. In the long term continued isolation and cleanup efforts would be relatively simple compared to traditional nuclear power plants.
Critics seem eager to characterize the dangers faced by Pele and any potential successors as unique; they are, however, no different from the risks faced by the Navy’s nuclear power program. More broadly, this risk of attack is not even unique to nuclear energy, as every fuel farm and ammo depot already represents a high-value target. Moreover, the explosive dangers of these targets can be orders of magnitude larger than those of a Pele reactor, they are often difficult to conceal or protect, they require substantial personnel to defend, their destruction can also have long-term environmental impacts, and it can be a struggle to establish effective exclusion zones in the event of an attack (or accident). Some examples of such incidents include the 1916 Black Tom attack, the 1917 Halifax Explosion, the 1943 SS El Estero incident, the 1947 destruction of Texas City’s port, and the 1989 Exxon Valdez and 2013 Deep Water Horizon oil spills.
The risks of each energy option outside of armed conflict must also be considered in any effective risk analysis. The average life-cycle risk of diesel generators results in between 470 and 613 more premature deaths than nuclear power on an MWe-to-MWe basis (megawatts electric). Even in terms of radioactivity, coal power plants release one hundred times the amount of radioactive material as a similar-sized nuclear plant. There are no perfect energy solutions for DoD, only trade-offs that must be rigorously analyzed, risks that must be mitigated, and informed decisions that must be made.
The Haak report claims that Pele offers no unique advantage to DoD. Economically this is wrong as he uses a price point of double the US average cost of fuel, which is well below the cost of fuel in remote locations currently incurred and orders of magnitude below what could be faced in a contingency operation. The more fatal flaw in this claim is that Haak ignores that Pele carries a three-year internal fuel supply, which is its primary advantage over conventional generators. Pele very real advantage can be seen when it is compared to the nearest historic analog—the Vietnam era T2 power tanker program. This program saw the conversion of eleven World War II–era T2 oil tankers into mobile power generators that were deployed across Vietnam to produce power in the same 1-5 MWe range as Pele. Each of these ships carried a two-year internal fuel supply consisting of 5,880,000 gallons of fuel and had a length of 524 feet and a beam of 68 feet. Pele, in contrast, is a system that fits within four standard twenty-foot shipping containers.
The Context of Military Risk
On the morning of October 24, 1944, near the island of Samar, the destroyers USS Johnston, USS Samuel B. Roberts, and USS Hoel counterattacked a Japanese force of four battleships, eight cruisers, and eleven destroyers. The Japanese ships sunk all three US ships with significant loss of life within their crews. Devoid of context, the actions of US Navy Task Unit 77.4.3, whose call sign was Taffy 3, are a senseless tragedy. When properly contextualized, this decision was a heroic act of self-sacrifice in the highest traditions of the US Navy.
At the tactical level, the three US vessels turned to interpose themselves between Taffy 3’s six escort carriers and the enemy, buying time for four of the escort carriers to escape. At the operational level, the fleet they fought and forced to withdraw was the main Japanese effort for the Battle of Leyte Gulf. The Japanese Imperial Navy intended to attack the otherwise undefended US Army amphibious assault forces on nearby Leyte Island. At the strategic level, the successful Army landings were a turning point in the Pacific War; the invasion cut Imperial Japan off from its primary oil fields. While every reasonable effort should be made to protect individuals, the story of Taffy 3 clearly shows the intrinsic necessity for appropriately high individual risk tolerance in the military.
In 1941 the Japanese faced an oil embargo that resulted in a rapid depletion of their oil reserves. This situation came to a head on December 7 when the Japanese attacked Pearl Harbor to buy the time and space necessary to seize oil fields across the pacific. Ironically the Japanese failed to destroy Pearl Harbor’s fuel storage sites and fleet oilers. Loss of the fuel storage sites would have forced the Pacific Fleet to withdraw to the West Coast, while the loss of the oilers would have tethered the Navy to its ships’ four to five days of internal fuel supply. Admiral Chester Nimitz stated, “Had the Japanese destroyed the oil, it would have prolonged the war another two years.”
In 1942 fuel continued to dominate the war as the Pacific Fleet had only eleven of seventy-two required oilers and faced fuel shortages. The fuel shortages were so dire that the Navy was forced to siphon fuel from the sunken battleships in Pearl Harbor at the end of the year. This problem was compounded as Nazi U-boats sank a quarter of the US oiler and tanker fleet in 1942. Fortunately, losses in the Pacific were minimal, as the Japanese did not prioritize commerce raiding. The Battle of Guadalcanal demonstrates the practical impact of all these problems. When the supporting aircraft carriers were forced to withdraw two days into the battle to refuel, it denied US ground forces the critical advantage of air support. By late 1943 the dynamic had flipped as US production rose and successful commerce raiding and seizure of oil fields began to starve the Japanese military.
With peer enemies investing deeply into antiaccess / area-denial capabilities, the ability to project liquid fuel globally is at risk. The difficulty Russia is having delivering fuel just a few dozen kilometers beyond its borders into Ukraine stands as a stark example of this new dynamic. In this environment, an expeditionary force may easily see its average fuel costs exceed the shockingly high costs of fuel in the Iraq and Afghanistan conflicts. As the Army transitions to an all-electric force by 2050, a matching electrical generating capacity must be grown. A modern division’s planning factor of around half a million gallons per day translates to a generating capacity of about 214 MWe. This requirement is far more than what is currently available within DoD. The federal government put only 122 MWe into Puerto Rico in the forty-two days following Hurricane Maria. This 122 MWe was the bulk of the government’s portable generation capability, the majority provided by DoD. Other green energy technologies cannot meet this scale and remain mobile: a division would require, at a minimum, about 1.9 million solar panels or 353 giant windmills. Nuclear is the only energy option that is small enough to deploy rapidly, meet the scale of demand, and dramatically cut internal lines of communication.
The Navy asked and answered this same energy problem sixty years ago and today nuclear power gives the US Navy a decisive advantage. Its submarines and aircraft carriers can operate for decades between refuelings and have a stellar operational and safety record. Energy logistics will be vital in deterring or winning the next war with a peer competitor and this capability is not something that DoD can plan to build or acquire quickly once a conflict starts.
The debate on each option’s relative merits and costs must be informed and occur across DoD, Congress, and the public sphere. The consistently poor framing and substantial technical and policy errors of too much of the analysis surrounding Project Pele highlight clear biases, which only distract and detract from this complicated but critical conversation.
In future large-scale ground combat, whether DoD can meet its energy needs will be a decisive factor, and Pele offers a way to give assured power to our most critical capabilities. It may also open the door for the development of follow-on reactors to provide a large-scale assured power supply and synthetic fuel to our expeditionary forces. While there are substantial risks with military nuclear power to its operators, there are similar or greater risks with every alternative energy source. These tactical risks pale in comparison to the broader operational and strategic risks that DoD and the United States would face if energy supply lines were cut in a future war. In this context, the one risk DoD cannot afford is forgoing the decisive military advantage Pele and follow-on systems could provide.
Aaron Horwood is a nuclear engineering PhD candidate at the University of South Carolina who previously served as an active duty engineer officer in the US Army. His areas of study include military use of small modular reactors for military and disaster relief, small modular reactor survivability, TRISO fuel, radiological survey and modeling, logistics, maintenance, combat engineering, and program of instruction management.
Andrew Thueme is a civilian assistant professor at the US Army Command and General Staff College and retired US Army officer. He has extensive experience as an engineer officer from the platoon to the theater level, as well as extensive instructional experience at the National Training Center and the Command and General Staff College.
Dr. Travis Knight is the chair of the University of South Carolina Mechanical Engineering Department and the director of its nuclear engineering program. His area of expertise includes advanced nuclear fuels and materials, used fuel disposition, reactor design, space nuclear power and propulsion, and nuclear safeguards.
The views expressed are those of the authors and do not reflect the official position of the United States Military Academy, Department of the Army, or Department of Defense.
Image: Full-scale mockup of the Army’s ML-1 nuclear power plant in the early 1960s. (Credit: Office of History, HQ, US Army Corps of Engineers)
US Navy submarines and aircraft carriers use nuclear power. The other ships all burn gas.
Considering that every cruiser, destroyer, amphibious ship, and supply ship could fit one of your small reactors aboard, why don't they?
Naval nuclear power is the best real-world case to compare to, but there's no analysis of the decision-making history or logic.
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