In a move that has sent shockwaves through the global defense community, Russia successfully tested a nuclear-powered missile known as Skyfall (or Burevestnik in Russian) last October. This missile, which flew in loops over the Arctic Circle, represents a bold and perilous step in the evolution of military technology.
The missile’s unique propulsion system, powered by a small nuclear reactor, has sparked intense debate and concern among experts. Two researchers from the Massachusetts Institute of Technology (MIT)Jake Hecla and R. Scott Kemp have published an analysis that sheds light on how this nuclear-powered missile operates and the risks it poses.
The Dream of Nuclear Flight
The concept of nuclear-powered flight is not new. During the Cold War, both the United States and the Soviet Union explored the idea of nuclear-powered aircraft and missiles. The potential advantages were clear: nearly unlimited range and the ability to loiter near targets or attack from unpredictable directions.
The United States conducted experiments with a nuclear reactor inside a Convair B-36 bomber in 1955, and the Soviet Union followed suit with a modified Tupolev TU-95 bomber in 1961. However, safety concerns ultimately grounded these projects. The U.S. also worked on Project Pluto, a supersonic low-altitude cruise missile, but these efforts were eventually abandoned.
The Skyfall Missile: A New Kind of Reactor
When news of the Skyfall missile first emerged, many assumed it would be a variant of the Project Pluto engine. However, Hecla was skeptical. The shape of the Skyfall missile resembles a conventional subsonic cruise missile, making a nuclear ramjet design infeasible.
To understand how the Skyfall missile is powered, Hecla used videos posted by Russian media to determine its dimensions. He identified objects of known size in the factory where the videos were filmed and built a three-dimensional model of the missile. Based on his measurements, he concluded that the Skyfall missile is larger than other Russian cruise missiles but not enormous. Aerodynamic modeling showed it would need to travel around Mach 0.75 to stay airborne, similar to a commercial aircraft like the Airbus A320.
A Direct-Cycle Air-Breathing Nuclear Propulsion System
Hecla’s analysis suggests that the Skyfall missile uses a direct-cycle air-breathing nuclear propulsion system most likely driving a turbojet. This system pushes air from the atmosphere directly through the nuclear fuel. A compressor forces the air through tiny straw-like channels in the reactor core, where nuclear reactions cause the air to heat and expand out the back of the engine.
This design is radically different from most nuclear reactors, which use an indirect closed loop with water or another coolant to transfer heat out of the reactor while limiting radiation exposure. Hecla believes that the complexity and extra weight involved with building an indirect system make it unlikely that the Skyfall missile uses one.
The Risks of the Skyfall Missile
The direct-cycle system used in the Skyfall missile poses significant risks. As air passes through the engine, it becomes irradiated, and fission decay products from the nuclear fuel diffuse into the straw-like cavities and are shot out the back. Hecla’s calculations show that this system would produce large quantities of radioactive isotopes of argon, krypton, and carbon.
Additionally, heated, compressed atmospheric air is very good at eroding engine components. There’s no reason to think this new nuclear reactor would be different. The potential for radioactive contamination and the risks to anyone living or working near the test site are enormous.
While it offers potential advantages in terms of range and unpredictability, the risks associated with its nuclear propulsion system cannot be ignored. As the world watches Russia’s developments in this area, the need for international dialogue and cooperation on nuclear safety and arms control becomes ever more critical.
