NUCLEAR-POWERED CONVAIR NB-36H "PEACEMAKER": Depicted here is a view of the Convair NB-36H Peacemaker experimental aircraft and a Boeing B-50 Superfortress chase plane during research and development taking place at the Convair plant at Forth Worth, Tex. The NB-36H was modified to carry a three-megawatt, air-cooled nuclear reactor in its bomb bay. This was the only known airborne reactor experiment undertaken by the U.S. with an operational nuclear reactor on board.
Image courtesy of U.S. Defenseimagery.mil photo no. DF-SC-83-09332

More than 50 years ago, aerospace engineers spent over $1 billion—in 1950s money—designing atomic-powered airplanes in the hope that such superfast jets could remain aloft for 15,000 miles (21,150 kilometers) at a time. They expected one pound (half a kilogram) of nuclear material would eliminate the need for refueling stops. An intriguing concept, but nuclear aircraft were grounded before the end of the Cold War due to, among other things, concerns about passenger and crew exposure to radiation. As airlines grapple with the high cost of petroleum and the growing demand for a cleaner form of fuel, might it be time to take another look at nuclear?

Between 1946 and 1961 the U.S. Air Force and the now-defunct Atomic Energy Commission (whose regulatory duties were taken over by the Nuclear Regulatory Commission, or NRC in 1975) oversaw the Aircraft Nuclear Propulsion (ANP) program. But ANP engineers and management were mired in debate over reactor technologies, how best to transfer nuclear power to a conventional engine, and the best material to shield the crew from radiation. Ultimately, they retrofitted the Convair B-36, a hybrid prop/jet-engine bomber weighing more than 400,000 pounds* (181,435 kilograms) and with a wingspan of 230 feet (70 meters), to house an air-cooled reactor in the aft bomb bay. Up front, the plane was outfitted with a 12-ton lead-and-rubber-shielded crew compartment. The atomic version of Convair's plane, called "Peacemaker," made 47 test flights over Texas and New Mexico between July 1955 and March 1957.

But by the end of the decade, advances in conventional aircraft and engine design outmoded the atom-powered B-36 and the public became concerned about the dangers of a nuclear reactor flying overhead. The program also failed to yield a commercial aircraft due to its steep cost (hundreds of millions in today's dollars, says Stephen Schwartz, editor of The Non Proliferation Review, published by California's Monterey Institute of International Studies), prompting Pres. John F. Kennedy to cancel the ANP in 1961. The U.S. government promptly redirected much of the project's resources toward space exploration and the race with the Soviet Union to reach the moon.

Recently, however, the search for cleaner fuels has once again raised the specter of such airships. Ian Poll, professor of aerospace engineering at the Cranfield University in England, in a recent lecture covered by the Times of London called for a "big research program to help the aviation industry convert from fossil fuels to nuclear energy." Poll, head of technology for the British government–funded Omega Project, a division of Manchester Metropolitan University that partners with industry to study the environmental impact of aviation and offer possible solutions, pointed out the need for nonkerosene-powered aircraft

"I think nuclear-powered airplanes are the answer beyond 2050," he said, concluding, "If we want to continue to enjoy the benefits of air travel without hindrance from environmental concerns, we need to explore nuclear power. If aviation remains wedded to fossil fuels, it will run into serious trouble."