The problem is energy. No matter the size or complexity of a project, the availability of energy can sustain it over time or lead to its cancellation before it leaves the drawing board. We need abundant energy that is easy to generate, and in many cases, mobile. The U.S. Army experimented with portable nuclear reactors in the 1960s, and although they caused more problems than they solved, the possibility of their return with new technology is already being explored...
The U.S. research base known as Camp Century operated between 1959 and 1967. Located 240 kilometers east of Thule Air Base in Greenland, its real goal was to serve as prototype or pilot test for the Project Iceworm program, which sought to develop a network of nuclear launch sites capable of withstanding a 'first strike' situation and reaching special targets in the Soviet Union. Publicly, Camp Century was just a demo for exploring ice construction techniques and detecting potential drawbacks of nuclear energy. That's right: Camp Century had a reactor.
Uranium in the Ice
The reactor, named PM-2A, was built by the American Locomotive Company for the U.S. Army. Many sources cite the PM-2A as the world's first portable nuclear reactor ... as long as we ignore its 330 tons. In reality, the PM-2A achieved portability through modular components that allowed it to be transported in a Hercules C-130. The army team took 77 days to assemble the reactor (its total construction took 18 months), inserting just 44 pounds (less than 20 kilograms) of uranium-235 into its core.
Once it achieved criticality, experts immediately confirmed that PM-2A was going to be problematic. The neutron leak forced the reactor to be shut down, and additional shielding based on lead shields and walls made of 200-liter barrels filled with ice and sawdust had to be built to protect the operators. Still, that was far from an adequate solution.
Neutrons for Everyone
PM-2A operated for two years. The defenders' argument was not that weak: 20 kilograms of uranium replaced almost four million liters of diesel that had to be transported and consumed at the base. However, in 1964 it was ordered to be dismantled. The neutron leak contaminated everything, from sodium traces in the snow to the metal pipes. The officer in charge of the process, Joseph Franklin, was exposed for two minutes to a field estimated at 2,000 rads per hour. In 2002, Franklin lost his prostate and one of his kidneys. In 2015, cancer had reached his bones and lungs. He died in March 2017.
PM-2A was the third reactor in a group of eight portable units built for the Army. PM-3A ended up at McMurdo (Antarctica), and with 438 failures in 10 years, it caused a disaster that its managers had to clean up from start to finish. SL-1 exploded and killed three men. ML-1 had multiple design problems, never exceeded 50 percent of the calculated power, and only accumulated hundreds of hours in testing.
Project Pele
The United States and Denmark still have to resolve tensions and negotiate responsibilities for the existing contamination at Camp Century, but despite a relatively poor record, the concept of portable nuclear reactors is seeking to return under the so-called Project Pele of the Department of Defense. Three companies received contracts totaling $40 million, and one of them is expected to be selected in 2022 to build the first prototype.
However, doubts multiply. On one hand, the liquid fuel consumption of the U.S. armed forces equals that of a country like Portugal. Reducing fuel supply missions with reactors installed at remote bases sounds tempting to the Pentagon. On the other hand, how reasonable is it to expose nuclear reactors to enemy fire? Even worse: what would happen if one of those portable reactors fell into the hands of terrorists...?
Sources: Atlas Obscura, Physics Today
