The Airplane That Carried a Nuclear Reactor

Imagine a bomber that never has to land — that could circle the globe for days or weeks without refueling, because it carries a nuclear reactor in its belly. In the 1950s, the United States spent roughly a billion dollars and fifteen years trying to build exactly that. It even flew a real reactor through the skies over Texas. It just never managed to make the reactor fly the plane.

By the Curiosities Desk · 2026-07-10 · 5 min read · Filed under Engineering · Today’s round

Part of When Atoms Got Away From Us

What happened: The Airplane That Carried a Nuclear Reactor

The dream began in 1946 with a project called NEPA — Nuclear Energy for the Propulsion of Aircraft — which in 1951 grew into the Aircraft Nuclear Propulsion (ANP) program, run jointly by the Air Force and the Atomic Energy Commission. The logic was pure Cold War: a nuclear-powered bomber could stay airborne almost indefinitely, an ever-present deterrent against the Soviet Union that never needed to come down to refuel.

Engineers pursued two approaches to nuclear jet engines, one at General Electric and one at Pratt & Whitney, both aiming to use a reactor’s heat instead of burning jet fuel. To study the staggering problem of shielding a human crew from a reactor just feet away, the program modified a giant B-36 Peacemaker bomber into the NB-36H. Between 1955 and 1957 it flew 47 times over West Texas and southern New Mexico with a small, operational reactor on board. This was the only time the U.S. ever flew an aircraft with a working nuclear reactor inside it.

Here’s the catch: the reactor aboard the NB-36H never actually powered the plane. It ran while conventional engines did the flying, purely to test whether the crew’s shielding worked. A flight-worthy nuclear engine was never finished. In 1961, President Kennedy canceled the entire effort, noting that “15 years and about $1 billion have been devoted to the attempted development of a nuclear-powered aircraft; but the possibility of achieving a militarily useful aircraft in the foreseeable future is still very remote.”

Why it was strange: The Airplane That Carried a Nuclear Reactor

It’s the sheer audacity that lingers. Engineers seriously proposed flying tons of radioactive material over populated areas, and confronted nightmares that conventional aircraft never face: How do you shield a pilot from a reactor without making the plane too heavy to fly? What happens to the countryside if a nuclear bomber crashes? The crew of the NB-36H sat in a lead-and-rubber-lined cockpit weighing about 12 tons. The Soviets, not to be outdone, flew their own reactor-carrying testbed, the Tupolev Tu-95LAL.

It shares a shelf with The Plan to Set Off a Nuclear Bomb on the Moon So Everyone Could Watch, in When Atoms Got Away From Us.

What scientists learned: The Airplane That Carried a Nuclear Reactor

Beyond the hard limits of shielding and crash safety, the program ran headfirst into a strategic problem: by the time the technology might mature, it was obsolete. The first intercontinental ballistic missiles entered service in 1959, and a missile that can cross the world in half an hour made an always-airborne bomber far less necessary. The project is a clean lesson in how an engineering goal can be technically heroic and strategically pointless at the same time.

The same thread — Cold War — continues in The Flying Saucer the Air Force Built That Maxed Out at 35 MPH.

How it reaches us today: The Airplane That Carried a Nuclear Reactor

The nuclear airplane never happened, but the research wasn’t wasted. The Aircraft Reactor Experiment built for the program was the first molten salt reactor ever operated — and that work fed directly into later civilian molten-salt reactor research at Oak Ridge, a reactor concept that’s seeing renewed interest today for safer, more efficient nuclear power. Some of the program’s decommissioned test reactors are now on public display in a parking lot at Idaho National Laboratory.

Also in When Atoms Got Away From Us: The ‘Demon Core’: The Plutonium Sphere That Killed Two Scientists.

Fun fact: The Airplane That Carried a Nuclear Reactor

The same atomic-age enthusiasm spawned an even wilder cousin: Project Pluto, an effort to build a nuclear-powered ramjet missile designed to fly low and fast for weeks, spewing radiation in its wake. It, too, was abandoned — arguably for everyone’s benefit.

Sources: The Airplane That Carried a Nuclear Reactor

“Aircraft Nuclear Propulsion,” Wikipedia — https://en.wikipedia.org/wiki/Aircraft_Nuclear_Propulsion
“Convair NB-36H,” Wikipedia — https://en.wikipedia.org/wiki/Convair_NB-36H
“Review of Manned Aircraft Nuclear Propulsion Program,” Comptroller General of the United States, B-146759, Feb. 28, 1963 — https://fas.org/nuke/space/anp-gao1963.pdf