In the 1970s, Los Alamos National Laboratory explored a science-fiction approach to tunneling: using nuclear power to literally melt holes through rock and turn the melted rock into tunnel lining. by Steve Weintz Digging out deep underground complexes or undersea bases could be expedited the Atomic way, in an alternate universe where the wildest ideas of the 1950s, 60s and 70s came to pass. Although our own timeline relies on mega-engineering for transportation, energy and architectural infrastructure, for the past half-century we've mostly relied on conventional power sources and design principles.

Today's Tunnel Boring Machines (TBMs) rank among the wonders of modern machinery. As wide as a several-story building and as long as a football field, these giant metal worms chew their way through rock and earth to dig out the world's ever-expanding networks of subways, drain tunnels, mines and bunkers. Aft of a huge rotating cutting head, a series of powerful jacks press, push and release the TBM along the tunnel's walls, to drive the excavation forward.

From the tunnel head forward of the cutting head, the excavated material trundles through the bulk of the machine like food through a gut to waiting hopper cars, which carry the rock out of the tunnel to a dump area. The insides of the TBM form a mass of engines and moving parts as dense as a sub's interior, full of noise and motion.

But in the 1970s, Los Alamos National Laboratory explored a science-fiction approach to tunneling: using nuclear power to literally melt holes through rock and turn the melted rock into tunnel lining. One product of the lab's research was a patent for a nuclear subterrene—a machine which could theoretically move through rock the way a submarine moves through water.

"The Atomic Subterrene," writes Mark, the author of the superlative Atomic Skies blog, "is a very atompunkish name. It sounds like a gadget Tom Swift might invent, and which would then be stolen by vaguely Slavic communists." But it grew out of serious Cold War propulsion research and aimed to solve serious problems in civil engineering. In an alternate timeline, it might have transformed America.

During the pursuit of nuclear-powered flying machines in the 1950s, Los Alamos engineers built an electrically-powered mockup of a prototype reactor that heated propellant to 3000 degrees centigrade. When the reactor project was canceled, team members sought other applications for their work. After reading Edgar Rice Burroughs' At The Earth's Core, an engineer named Bob Potter decided to see if the tungsten heating elements developed for the reactor mockup could melt rock.

Potter's 1961 experiments showed that indeed, the technology could punch through rock by melting it into lava. But the lab turned to other matters and Potter's concept laid fallow until a curious incident at a coffee shop in 1970 revived the idea.

Lab workers were shooting the breeze after a meal and the subject of Potter's rock melter came up. Someone suggested driving the device with a nuclear reactor, and while the notion was being discussed a Congressman stopped by to greet the Los Alamos men. Mistaking their blue-sky talk for an actual program, the Congressman enthusiastically endorsed the idea and would raise it with his oversight committee. Upon learning of the Congressman's plan, Norris Bradbury, Los Alamos' director, approved of the idea and made the informal discussion a real thing.

A study group was assembled and a bold paper was produced. The nuclear subterrene when fully developed would be “capable of penetrating the earth to depths of tens of kilometers... To extend geological and geophysical exploration into the earth's mantle.”

A cutting head with no moving parts, which worked by melting rather than cutting, need not be circular and its tunnels need not be cylindrical but could be square or any other shape. With no moving parts, there would be almost no vibration, a key advantage where ground disturbance was an issue.

American life could be transformed. As Mark writes,

"Aside from mining, excavating underground roads and pipes was an obvious use. Chemicals and gasses could be stored in underground chambers. Electrical energy could be stored in the form of underground pressurized air ‘batteries,’ compressed in during periods of excess production and used to drive turbines when more energy was needed. The subterrene could dig storage cavities for toxic and nuclear waste, too deep for them to ever trouble the surface. The heat and pressure found deep underground could be exploited for chemical processing. Cities, even farms, could be extended underground."

In 1972 the National Science Foundation funded a full-scale study of the nuclear subterrene. Small-scale electrically-powered prototype drills were built and one was used by the National Park Service to drill drainage holes at Bandelier National Monument near Los Alamos. The rock penetrator's lack of vibration was essential to preserving the archaeological site while the holes were drilled.

The study's full-scale concepts, however, remain its most memorable results. Both subterrene designs channeled the tremendous heat of nuclear reactions into heating elements in the nose. Two cutting-head designs were looked into, one for common rock and one for hard rock. One combined a traditional rotary cutting head with the cylindrical rock-melters, while the other replaced the rotary head with dozens of nuclear-powered needle probes. The probes would unevenly heat the rock face causing it to crack and crumble. In both designs, most of the broken rock would be sent down the subterrene's core to waiting hoppers for disposal, just like modern TBMs.

Unique among excavation equipment, however, was how the subterrenes would handle tunnel reinforcement. Both designs used nuclear heat to melt some of the excavated rock into volcanic glass and extrude it as a lining on the inside of the growing tunnel. The subterrene would generate its own reinforced cladding out of the waste rock as it proceeded.

It's possible news of the subterrene project reached Gene Roddenberry, the creator of Star Trek. A RAND study about underground transport appeared in 1972 and in 1973 Roddenberry's pilot for a new sci-fi TV series premiered. In Genesis II (which failed to become a series) a system of underground transport tunnels, much like Elon Musk's Hyperloop, features as a key background feature. The "nuclear drilling device" is mentioned as key to the system's development.

But besides a bit part in a TV pilot, the nuclear subterrene didn't get much farther. In 1975, the project was transferred from the NSF to the new Department of Energy and quietly disappeared. The concept resurfaced in the 1980s as a way of digging tunnels for bases on the Moon and other worlds but remained a concept. Advances in conventional excavation equipment since the 1970s make modern TBMs perform as well or better than Los Alamos' conceptual nukes.

These days the only place you'll find the subterrene discussed is that wild and wooly backcountry populated by those obsessed with aliens, conspiracies, magic technology and general crankiness. But like other daring ideas from the twentieth century, time may one day bring the nuclear subterrene back for review. The human need for holes will only grow.

Steve Weintz, a frequent contributor to many publications such as WarIsBoring, is a writer, filmmaker, artist, animator.