The Pentagon’s plan to buy small nuclear reactors that could be airlifted and quickly set up to provide 1–5 MW of battlefield power has been attacked on two flanks. A committee of the National Academies of Sciences, Engineering, and Medicine (NASEM) says in a new report that the proposed microreactors would neither be portable enough for use at the US Army’s forward operating bases nor match the army’s electric power requirements—the two main rationales for the program devoted to developing the reactors, Project Pele. Separately, a nuclear nonproliferation advocacy organization has warned that the reactors would be unsafe and economically unsound.
In March, the Department of Defense’s Strategic Capabilities Office awarded $28 million contracts to two companies, BWX Technologies and X-Energy, to complete their respective designs for battlefield reactors. A total of $133 million was appropriated to Project Pele during fiscal years 2020 and 2021, and the Biden administration has requested $60 million for the program in FY 2022. The department plans to select one of the high-temperature gas-cooled reactor designs next year and begin construction of a prototype at the Idaho National Laboratory. The reactor could begin operating in 2024.
Microreactors are supposed to meet the burgeoning need for electricity at forward operating bases and to reduce the threat of attacks on the frequent and vulnerable convoys that carry liquid fuels to the command outposts. In its report released on 9 June, the NASEM committee says that the size, weight, and time required to set up and power down the proposed reactors don’t comport with the army’s emerging concept of a highly mobile force that halts for only hours at a time to minimize its vulnerability. “With no base camps being established, it would be impractical to use a nuclear reactor (or any prime power source) in such a forward area,” it says. The panel recommends instead that diesel and aviation fuel continue to be the sole fuel for army forward operating bases at least through 2035.
“The Pele nuclear power plant program now under way may prove appropriate for domestic and permanent overseas bases,” the NASEM report states. “It will not, however, adequately meet the needs of expeditionary and defensive operations due to its limited power rating and mobility concerns.”
In defending Project Pele, Pentagon officials have repeatedly cited a nonpublic 2015 study by RAND that said 52% of all US casualties in the Afghanistan and Iraq conflicts from 2001 to 2010 happened during attacks on land transport missions, most of which were delivering fuel and water. But that threat, which was prevalent in the early stages of those conflicts, has diminished to near zero as the army has adapted its fuel delivery tactics, says an April report from the Nuclear Proliferation Prevention Project (NPPP) at the University of Texas at Austin.
The NPPP report also charges that the Pentagon has grossly underestimated the threat posed by an enemy missile strike on a reactor in the battlefield. A 2020 missile attack by Iran on a US base in Iraq showed that Iranian missiles were much more accurate than the DOD believed when Pele was conceived. Such an attack could breach a reactor and spew the radioactive fuel, thereby exposing thousands of US troops to contamination, the NPPP warns. And should a base be overrun by an adversary or quickly abandoned in an attack, the hostile force could use the hundreds of kilograms of irradiated fuel from the reactor to fashion radiological dirty bombs.
Eric Wesley, former deputy commanding general of Army Futures Command, told a second NASEM panel scrutinizing Project Pele that the threat posed by increasingly accurate Russian and Chinese missiles will create an “exponential” increase in demand for battlefield electricity. The additional power will be needed for directed energy weapons, such as lasers and rail guns, and for the electrified combat vehicles that are expected to be deployed in coming years, he said on 26 May. Wesley added that US troop withdrawals from Afghanistan, Iraq, South Korea, and Europe will lengthen supply lines and increase the threat of a fuel cutoff.
The NPPP report argues, however, that diesel power coupled with batteries could easily accommodate the demand from directed energy weapons, which draw large amounts of power only when fired. At an estimated cost of $1 to $10 worth of diesel fuel per firing, a high-energy laser weapon would have to be fired more than 20 million times to incur diesel fuel costs equal to the price of a microreactor, the report says. In practice, such a laser might be fired only hundreds of times during its lifetime, both in training and in combat.
The DOD regularly paid $50–$100 per gallon for diesel fuel delivered to bases in Iraq and Afghanistan, Project Pele program manager Jeff Waksman told the Advanced Nuclear Weapons Alliance Deterrence Center (ANWADC), an industry group, on 6 May. But NPPP coordinator Alan Kuperman notes cost estimates by the consulting group CNA of $12 per gallon for ground transport and $31 per gallon for air delivery to one base in Afghanistan. Diesel was airlifted only to tiny forward posts, when ground routes were surrounded by the enemy, Kuperman says. But such posts have never been proposed for microreactors because they use very little electricity.
The number of fuel convoys required to supply a forward operating base could be reduced by nearly one-third through feasible improvements to military vehicle fuel efficiencies, the NASEM committee says. The army could further lower its fuel supply needs by replacing the standard military jet propellant (JP-8) it uses in ground vehicles with diesel, which has 9% more energy content and is more readily available from local sources.
The Project Pele prototype reactor is required to be set up in no more than two days and trucked away within seven days of shutdown. It must also be able to operate continuously for three years at full power. To be carried aboard a C-17 transport, it must weigh no more than 40 tons and be accommodated in three or four standard shipping containers.
In the DOD’s concept, multiple microreactors would be deployed at forward bases to lessen the threat of a blackout from a missile strike, Wesley and Waksman told the NASEM committee. Each reactor would be staffed by six personnel, about the same number of soldiers that are assigned to operate and maintain the 750 kW diesel generator typically used at forward bases. The military’s plan to bury or cover the reactors to protect them from missile strikes could result in a cutoff of the airflow needed to prevent them from overheating, the NPPP warns.
No firm construction cost estimates for the prototype have been developed, Waksman told ANWADC. A 2016 report from the Defense Science Board, which recommended development of a battlefield reactor, estimated the prototype would cost several hundred million dollars. Waksman didn’t respond to interview requests.
Both reactor designs include the use of tri-structural isotropic (TRISO) particle fuel. Each of the millions of poppy-seed-size TRISO pellets in a reactor consists of a uranium-carbon-oxygen fuel kernel encapsulated by three layers of carbon- and ceramic-based materials, which are meant to prevent the release of highly radioactive fission products. In most tests, TRISO fuel has remained intact after being subjected to a temperature of 1800 °C for 300 hours. But in one 2019 test at Oak Ridge National Laboratory, TRISO fuel failed at 1500 °C and released a small amount of cesium-137.
The TRISO fuel will contain high-assay low-enriched uranium (HALEU), which is enriched to between 10% and 19.75% in the fissionable U-235 isotope. That’s just below the International Atomic Energy Agency’s (IAEA) lower boundary for potentially weapons-usable material. HALEU isn’t produced commercially; instead, the fuel is made by diluting surplus highly enriched uranium from the DOE stockpile at Oak Ridge, Tennessee. Centrus Energy, which once enriched uranium commercially, is developing gas centrifuges to produce small quantities of HALEU beginning next year under a cost-shared contract with the Department of Energy.
The Pentagon hasn’t adequately considered the nuclear regulatory burdens it would have to overcome to deploy microreactors in other nations, the NPPP says, nor has it taken into account permissions it would need to get to overfly countries on the delivery paths. Richard Meserve, the chair of one of the NASEM panels and former chair of the US Nuclear Regulatory Commission (NRC), noted that the IAEA Convention on Nuclear Safety provides regulatory authority to the country in which a reactor is located. Waksman said the DOD has held discussions on regulatory issues with some nations, which he declined to identify.
The nuclear industry is looking to Project Pele to demonstrate advanced reactor technologies that it hopes to commercialize for civilian power generation. In addition, small reactors are proposed to supplant diesel generation at tiny radar outposts on Pacific islands and remote Arctic villages and to provide an off-the-grid source of power to military bases in the US, Waksman and Wesley said.
Eight advanced reactor companies are being funded by a DOE demonstration program to develop conceptual designs for those small modular reactors, which are considerably larger than Project Pele’s. DOE has committed $3.2 billion in cost-shared funding over seven years to the construction of modular reactors built by X-Energy and TerraPower.
The energy agency is also providing $1.3 billion of the $6 billion estimated cost of NuScale Power’s 77 MW modular reactor. NuScale has received NRC approval for its design, and pending the NRC’s expected 2025 approval of a combined operating license, the company intends to build a yet-to-be-determined number of its modules at the Idaho National Laboratory for a consortium of small utilities.