Pentagon’s microreactor program faces safety and nonproliferation concerns

The Pentagon is on track to produce a working version of a transportable nuclear reactor, one that would become the first of the many proposed advanced reactors in the US to produce electricity. But whether the reactor ever gets deployed in the field hinges on resolving thorny domestic and international policy issues.

The high-temperature, gas-cooled microreactor being built for Project Pele, as the program is known, will need approvals from nuclear regulators, foreign governments, and the public before versions can be installed at military bases in the US and in strategic locations in other countries.

The first Pele reactor is scheduled for commissioning at the Idaho National Laboratory in late 2025. A team headed by BWX Technologies was selected last year to design and build the 1–5 MWe reactor. The company will also produce the fuel by downblending highly enriched uranium from the Department of Energy stockpile to less than 20% uranium-235 and fabricating it into millions of 1-mm-diameter coated pebbles known as tri-structural isotropic fuel.

Named for the Hawaiian goddess of fire, Project Pele is the US military’s first attempt since 1977 to develop a mobile power reactor (see the box below to learn about previous efforts). It is intended to address the military’s desire for uninterruptible power at bases that operate drones or that host crucial computers, satellite downlinks, and other critical operational centers, according to Jeff Waksman, the program manager in the Office of the Secretary of Defense. Pele reactors also are designed to be transportable by plane, train, or truck to foreign US military operating locations. The Pentagon has long desired to reduce both operational reliance on diesel and aviation fuel and the concomitant vulnerability to attacks on supply lines. Remote Pacific islands hosting radar systems or satellite links are another potential application, Waksman said. He spoke at a 2 August webinar hosted by the American Nuclear Society.

The goal is to enable military personnel to shut off and break down a Pele reactor within seven days, for transportation and restart in a new location. The reactor is to be capable of operating for a minimum of three years without refueling. Although operations would be mainly autonomous, two trained operators would mind the reactor at all times, Waksman said at the webinar.

The Pentagon has backed off its earlier proposal to install Pele reactors at forward operating bases near battlefields, Waksman indicated. “I don’t think it would be allowed on a battlefield in a place like Ukraine,” he said. “We are looking at putting them many hundreds if not thousands of miles from where shooting is happening.” Yet even such locations could be vulnerable to missile or terrorist attack, he acknowledged.

Safety of troops

Alan Kuperman, coordinator of the Nuclear Proliferation Prevention Project at the University of Texas at Austin, authored a 2021 report in which he condemned Project Pele as unsafe and economically unsound. He says a missile attack on the reactor could scatter fuel and expose soldiers to radiation from the decay of fission products and transuranic elements. That would happen regardless of whether the fuel pellets themselves were ruptured.

Waksman admitted that “you can imagine a scenario where you would break the thing and release radioactivity, but we’re trying to minimize that as much as we can.”

Because the Pele prototype will be built on land owned by DOE, the agency will regulate its design, construction, and operation. But the Nuclear Regulatory Commission, which oversees all commercial nuclear reactors, will certify the design and regulate Pele’s over-the-road transport when moved from one location to another within the US, Waksman said.

“Almost no one in this program anticipated how complicated it is to get regulatory approval on a new reactor, even through DOE, which has an easier process than NRC,” Waksman said. “You have to consider ‘What if this goes wrong, and there’s an earthquake, and there’s a fire, and all [our] computers go out?’ ”

The reactor could see commercial use eventually, although the Department of Defense has no current plans in that direction, Waksman said.

Apart from safety, other sociopolitical factors could delay deployment plans. “This is a technology that is sitting at the cusp of military and civil applications. It’s a big gray area,” says Kenneth Luongo, president of the Partnership for Global Security. “It’s a very significant change for the military because all its other reactors are in naval vessels.”

Deployment overseas will require the consent of hosting governments. That could be accomplished through “status of forces agreements,” similar to those negotiated with nations that allow US nuclear warships to enter their ports, according to Waksman. But Luongo says that Germany, a major US strategic ally, might well reject a Pele reactor on its soil because it has fully renounced nuclear power.

International safeguards

Yet to be resolved is the nuclear safeguards regime that will guard against nefarious use of the Pele nuclear fuel and technology. The International Atomic Energy Agency (IAEA), which monitors and inspects commercial nuclear facilities worldwide, has no authority over military nuclear operations. “What about a reactor on a domestic military installation that is there to provide resilient power for a weapons system but is also tied to the grid? Is that commercial or military power?” Waksman said, noting that much of his time is spent working with the State Department, the National Nuclear Security Administration, and the White House to resolve that question.

“We want to be sure we’re not doing something that will encourage other countries to evade IAEA safeguards,” Waksman said.

Luongo doubts that the Pentagon will permit IAEA inspections. Yet it’s important that the US set an example for the international community in the transparent management of the technology, he says. “How are you going to manage things if other countries deploy these kinds of reactors?”

Also left unsettled is whether Pele reactors could be moved by aircraft from one site within the US to another, given the existing ban on air transport of plutonium, Waksman said. Once they are put into operation, all reactors produce some plutonium as a byproduct. Project officials also have been trying to figure out how much radiation will remain in soils once a Pele reactor is removed.