Project Plowshare imagined using nuclear weapons as infrastructure-building tools

At 10 a.m. local time on July 6, 1962, a quiet stretch of Nevada desert near Las Vegas erupted in violence. The ground shook and bulged skyward almost 300 feet, then exploded in a blast that kicked up more than 12 million tons of soil. The resulting dust cloud rose 12,000 feet. The latest underground atomic test, codenamed Sedan, was taking place 65 miles north of Sin City at the 1,400-square mile Nevada Test Site, pockmarked with craters from dozens of nuclear and conventional weapons tests dating to 1951. 

However, Sedan was special. 

At 104 kilotons, Sedan was the largest underground nuclear test on record. Nearly seven times more powerful than the bomb dropped on Hiroshima, Japan, in August 1945, Sedan left history’s largest manmade crater, 330 feet deep and 1,280 feet across. No nuclear test conducted in the United States produced more fallout; radioactive detritus from Sedan showered several states.

People stand at the edge of a gigantic crater created by the Project Sedan nuclear test explosion. (Corbis via Getty Images)

Sedan was an exercise meant to advance Project Plowshare, a Cold War-era effort to employ nuclear weapons for infrastructure projects. The idea of harnessing the atom for civilian use dated to the end of World War II. Scientists, some of whom had worked on the Manhattan Project to develop the atomic bomb, saw nuclear energy as a tool for more than merely leveling cities. These advocates believed the technology had potential utility in medicine, the study of elements, and power generation. They also wanted to take things a step further by using targeted nuclear explosions to reshape America’s waterways, carve roads out of mountains, and mine for oil and natural gas.  

Congress established the civilian-run Atomic Energy Commission on August 1, 1946, to oversee all aspects of nuclear science to improve the public welfare, promote peace, and strengthen free enterprise. AEC scientists relished their role as the public faces of peaceful nuclear know-how. Frederick Reines, a physicist at the Los Alamos National Laboratory, speculated in Bulletin of the Atomic Scientists in 1950 about using atomic bombs “in such activities as mining, where the fission products would be confined to relatively small regions,” or to “divert a river by blasting a large volume of solid rock.” Mathematician John von Neumann and colleagues at the University of California Radiation Laboratory near San Francisco, now known as Lawrence Livermore National Laboratory, expressed similar ideas. 

Atomic bombs could alter in seconds landscapes that men using machines needed months, even years, to reshape. Of course, there was the risk that fallout could poison those landscapes for millennia, severely limiting a project’s scope and locations. Nuclear fusion changed that. 

Atomic explosions employ fission, the splitting of atoms to unleash energy. Fission-based weapons were expensive,  time-consuming to manufacture, had limited explosive potential, and produced heavy fallout. A fusion reaction, however, fuses nuclear material to create a more powerful explosion with much less fallout. Such thermonuclear, or hydrogen, bombs also cost less to make.

The first hydrogen bomb, codenamed Mike, was tested on November 1, 1952, at Enewetak, a Pacific atoll known at the time as “Eniwetok.” Mike’s 10.4-megaton blast obliterated an island called Elugelab, leaving nothing but a crater more than a mile wide and 164 feet deep. 

Dr. Edward Teller, the physicist primarily responsible for the hydrogen bom, championed using nukes to dig a new Panama Canal. (Photo by Nat Farbman/The LIFE Picture Collection via Getty Images)

Mike’s accidental remaking of the atoll intrigued the AEC. “We needn’t take a coastline as it happens to be,” said physicist Edward Teller, veteran of the Manhattan Project and the man primarily responsible for the hydrogen bomb. “We can make a harbor, a water-level canal, even across the American isthmus.” The October 1956 Suez Canal crisis, triggered when Egypt nationalized the man-made passage linking the Mediterranean and the Red Sea, further inspired talk of what Teller liked to call “geographical engineering.” Egypt’s refusal to allow Israel access to the canal led Harold Brown at Lawrence Livermore to suggest excavating a second sea-level canal for Israeli shipping by detonating thermonuclear devices. 

Detonation of the H-bomb code named Mike in 1952 inspired Atomic Energy Commission dreams of using nuclear power to reorder the Earth’s surface. (Bettmann/Getty Images)

In February 1957, AEC scientists gathered at the Livermore lab for the First Plowshare Symposium. Taking its name from a biblical verse in Isaiah 2:4—“They shall beat their swords into plowshares”—the conference explored uses of nuclear technology to produce power, create new atomic elements for research and medicine, and undertake major public works. In June, the AEC established Project Plowshare amid growing public and political opposition to nuclear programs. Nuclear tests routinely produced unacceptably high levels of fallout, and the subsequent appearance in drinking water, milk, meat, and produce of strontium-90, cesium-137, and other cancer-causing radioactive elements had generated a movement demanding a worldwide ban on airborne nuclear tests.

Scientists opted to move nuclear testing underground. Doing so eliminated worry about atmospheric conditions or radioactivity, which would be trapped in molten rock after a blast. On September 19, 1957, the first underground test, codenamed Rainier, was detonated. 

Other developments during this time boosted government support for Plowshare. The Soviet Union’s successful August 1957 test of an intercontinental ballistic missile  and the USSR’s epochal  launch of its Sputnik satellite that October infused Plowshare with urgency. Nuclear paranoia was running rampant in America at the thought of the Soviets deploying nuclear weapons at will. The media obsessed over the risk of nuclear war. Films, television programs, and books portrayed a dim future with a sinister radioactive glow. 

Desperate to counter doomsday thinking, AEC scientists struggled to offer practical examples that would persuade the public of the wisdom of continuing nuclear research. Plowshare advocates saw thermonuclear excavation as a selling point. Massive nuclear-driven public works would showcase American ingenuity and nukes’ civic utility, they believed. One possibility was creating a major new waterway.  

The Panama Canal, in operation since 1914, was becoming less functional as a route connecting the Atlantic and Pacific Oceans. Expanded international shipping and construction of ever larger classes of transport vessel were diminishing the Big Ditch’s utility. In addition, the Suez Crisis, Cold War tensions, and political unrest in Panama all suggested that the Panama Canal was a highly vulnerable military target. A September 1958 Panama Canal Company report outlined alternate routes through Panama, Nicaragua, Costa Rica, and Colombia. Seizing on Teller’s offhand comment about creating a sea-level canal, Plowshare scientists and engineers proposed using nuclear bombs to excavate a navigable channel across Central America. Each proposal called for multiple devices with total yields of hundreds of megatons.

The Atomic Energy Commission proposed several routes for a new, nuclear-excavated Panama Canal. (Department of Energy)

To sell Americans on pursuing such a project abroad, the AEC first needed a domestic dress rehearsal. AEC Chairman Lewis Strauss approved a plan to use nuclear weapons to create an American harbor in a way that would protect people and wildlife, meet data collection requirements, and deliver long-term practical value. 

The decision was made to test-market Plowshare with 2.4 megatons of nuclear firepower at Cape Thompson, on Alaska’s northwest shore. Project Chariot would use four 100-kiloton bombs to blast a channel 6,000 feet long and 1,200 feet wide. The resulting waterway would allow vessels access to a basin 6,000 feet long and 3,000 feet wide created by two one-megaton bombs. Technicians would bury the devices 300 to 400 feet underground, a step AEC officials believed would trap about 95 percent of the resulting radioactivity. That stray five percent did not worry them. The AEC believed the region to be an uninhabited Arctic wasteland.

Teller traveled to the newly enfranchised state to sell the harbor, telling reporters and politicians Plowshare could do anything, even “dig a harbor in the shape of a polar bear,” and declaring “Anything new that is big needs big people in order to get going and big people are found in big states.” 

In the July 24, 1960, Fairbanks News-Miner editor George Sundberg wrote, “We think the holding of a huge nuclear blast in Alaska would be a fitting overture to the new era which is opening for our state.” Local politicians were likewise enthused. 

Environmental scientists, as well as many Alaskan locals, were not sold. They doubted AEC estimates that a bomb crater harbor would be handling $176 million in annual exports within 25 years. Cape Thompson adjoined large deposits of coal and oil, but it also was iced in nine months out of every 12. 

And the cape was only 30 miles south of Point Hope, an Inuit village whose residents subsisted on the region’s abundant wildlife. Irked by critics, Teller vented to economist George Rogers, “We are not interested in preserving the Eskimo as a hunter. We are interested in giving him the opportunity of becoming a coal miner.” 

Project Chariot became mired in environmental studies and public debates, forcing repeated downscalings and reschedulings. By summer 1962 recalcitrant Alaskans and their scientific allies had killed the venture. Deprived of that showcase, the AEC began conducting underground tests intended to prove Plowshare’s viability and justify the agency’s ever larger budget requests. Project Gnome, the first underground test run for Plowshare—specifically to test heat and isotope generation for power and scientific research—took place on December 10, 1961. The blast occurred 1,200 feet down in salt beds near Carlsbad, New Mexico. The Gnome explosion had a yield of slightly more than 3 kilotons. 

Gnome flopped, venting radioactive material—small amounts, the AEC hastened to note—into the atmosphere while failing to create the promised underground heat reservoir for generating power. Seven months later, Sedan’s massive fallout led politicians to ask if Plowshare was worth the environmental cost. Unless the AEC could come up with a winning nuclear hand, the dream of a sea level canal across Central America was dead.

Gasbuggy, a 1967 attempt to set off an explosion to tap a huge underground reserve of natural gas in New Mexico, seemed to work, until radioactive byproducts were detected. (Department of Energy)

Hope rode in by rail. The Atchison, Topeka, and Santa Fe Railway approached the AEC in December 1962 about using hydrogen bombs to cut a passage through Southern California’s Bristol Mountains to level out that railroad’s route and shorten the trip across Southern California. The California Department of Public Works got on board because highway builders could use the same cut to straighten a winding stretch of Interstate 40 and shorten the drive from Las Vegas to Los Angeles. 

A feasibility study codenamed Carryall concluded that opening the new pass would take 22 nuclear devices totaling 1.7 megatons to move 68 million cubic yards of earth and cut a path 11,000 feet long and 600 to 1,300 feet wide. The cost of nuclear excavation would beat that of conventional digging by more than a third. The railroad and the state were adamant to have highway and train traffic using the pass by 1969, but the AEC wanted to perform more tests, including row-charge explosions of nuclear devices in Nevada. 

Carryall’s design made it a perfect dress rehearsal for a sea-level canal—until the plan collided with the Limited Test Ban Treaty. As of October 10, 1963, that international agreement forbade nuclear detonations in the air, ocean, and space. Underground tests could take place, but only if the nation involved could guarantee no fallout would enter another nation’s air space. AEC Chairman and Nobel Prize-winning physicist Glenn Seaborg told Congress’s Joint Committee on Atomic Energy that to accommodate large projects like Carryall the treaty would have to be rewritten. Teller believed radiation generated from Plowshare projects would be well below harmful levels, but federal officials read the treaty to mean that its language barred explosions generating any fallout at all. Frustrated, the State of California and the Atchison, Topeka, and Santa Fe walked away from Carryall in September 1966.

Plowshare kept running underground tests but notions of a Central American sea-level canal and other nuclear excavations withered and died. The AEC had to shift gears. Perhaps a more universal goal than a harbor or a mountain railway would broaden public support.

America needed energy. People were making more money that they were spending on more vehicles and more electric and gas appliances. Most estimates had the nation’s energy use rising sharply the next three decades. Domestic natural gas production was barely keeping pace with demand, and the United States was buying more foreign oil. Inability to meet the nation’s energy demands was not only an economic risk but a national security risk as well. Plowshare might be able to help by reaching deep-set oil and natural gas. 

El Paso Natural Gas agreed to work with the AEC on Project Gasbuggy, an attempt to tap roughly 64 trillion cubic feet of natural gas under company-owned land in northwest New Mexico. On December 10, 1967, a 29-kiloton device was detonated more than 4,000 feet underground. The point was to fracture rock and create a cavity into which freed gas would flow, to be accessed by El Paso Natural Gas drilling rigs. 

Gasbuggy seemed to work. Monitors detected no leakage of radioactivity, and El Paso reported increased natural gas capacity at wells in the area. Du Pont, Gulf General Atomics, and other energy companies pitched the AEC on similar projects. The agency scheduled more gas and oil stimulation projects. Plowshare finally appeared to have found its calling.

However, follow-up tests at the Gasbuggy site showed that the nuclear blast had altered the composition of the affected natural gas. Natural gas consists mainly of burnable hydrocarbons with trace amounts of carbon dioxide. Gasbuggy-produced gas was only 41 percent hydrocarbon—less than half as potent as ordinary natural gas—plus carbon dioxide and large amounts of radioactive tritium, a byproduct of nuclear fusion. The tritium could be burned off through a process called flaring, but flaring wasted natural gas and released fallout. 

Despite Gasbuggy’s drawbacks, the AEC planned Project Rulison, mostly underwritten by Austral Oil Company and CER Geonuclear Corporation. On September 10, 1969, technicians detonated a 50-kiloton device buried 8,400 feet underground at the Nevada test site. Trying to avoid Gasbuggy’s tritium troubles, scientists used a fission bomb, believing that the depth at which the blast occurred would minimize radioactivity.

A month after Rulison, the site had produced more gas than conventional methods had delivered in six years. Tritium levels were significantly lower than with Gasbuggy, but still detectable. Environmentalists sued Austral to prevent the flaring of contaminated gas. The company prevailed, but at the expense of being branded as selling a radioactive product. 

Environmental groups organized protests and sued the AEC. Representative Teno Roncalio (D-Wyoming), convinced the AEC was wasting natural gas and uranium, emerged as an anti- Plowshare crusader bent on killing the project. Uranium could be put to better use in nuclear reactors, Roncalio said, adding that hydraulic fracturing, or fracking, was a better and cheaper way to get at underground gas deposits.

Government spending on Plowshare evaporated, forcing the AEC to rely more heavily on private-sector money. CER Geonuclear agreed to pick up most of the tab for Project Rio Blanco, a gas stimulation test near Rifle, Colorado. Rio Blanco planned to use three 33-kiloton devices placed vertically at depths of 5,838 feet, 6,230 feet, and 6,689 feet and exploded in sequence. In theory, staggered blasts would fracture more rock and avoid the shockwaves released by a single 99-kiloton blast. 

By 1973, when deadly cesium-137 and strontium-90 were detected after the Rio Blanco blast, environmental protests and opposition led by Rep. Teno Roncallo, D-Wyoming, had Project Plowshare on its last legs. ( Denver Post/Getty Images)

Rio Blanco was set off on May 17, 1973. However, the staggered charges left not one large chimney that held extractable gas but three  underground cavities nearly impossible to reach. The gas that could be collected did not contain tritium, but it was loaded with the far deadlier compounds cesium-137 and strontium-90.

The AEC’s relationship with industry foundered amid complaints by energy companies that the agency frequently botched its budgets, leading to higher than anticipated costs. The agency also dragged contractors through bureaucratic hoops, with as many as 300 regulatory bodies weighing in on any given project. Environmental opposition, besides generating costly lawsuits, made energy companies involved with Plowshare look like monsters. 

After Rio Blanco, the project’s final detonation, Plowshare starved to death for lack of corporate interest and federal funding. The last AEC annual report to Congress mentioning Project Plowshare came in 1974, and by 1978 the program, after 27 tests involving 35 individual nuclear detonations, had been completely defunded. Despite all the data collected during that time, the AEC never quite grasped the most important lesson to be learned from Project Plowshare. Mankind’s desire to absolutely control the power of the atom outweighed his ability to do so. 

This story appeared in the October 2020 issue of American History.