Command and Control

Once the enemy was spotted, the fire-control system of the American fighter plane would calculate the distance to the attacker and set the timer of the Genie’s warhead. The fighter pilot would launch the Genie, its rocket motor would burn for about two seconds, and the weapon would shoot toward the target at about three times the speed of sound. The Genie’s nuclear warhead would detonate when the timer ran out. The ensuing fireball would destroy any aircraft within about one hundred yards, and the blast wave would cause severe damage at an even greater distance. But the burst of radiation released by the explosion would pose the most deadly threat to Soviet aircrews. The Genie could miss its target badly and still prove effective. It had a “lethal envelope” with a radius of about a mile, and the “probability of kill” (PK) within that envelope was likely to be 92 percent. The Soviet aircrew’s death from radiation might take as long as five minutes — a delay that made it even more important to fire the Genie as far as possible from urban areas. Detonated at a high altitude, the weapon produced little fallout and didn’t lift any debris from the ground to form a mushroom cloud. After the bright white flash, a circular cloud drifted from the point of detonation, forming an immense smoke ring in the sky.

The Air Force wanted the Genie to be deployed by January 1, 1957. But first the Atomic Energy Commission had to determine whether the weapon was safe. Thousands of Genies would be stored at American airfields. Moreover, thousands of Nike missiles, as well as hundreds of BOMARCS, armed with small nuclear warheads, would soon be deployed in and around dozens of American cities. All of these weapons had been designed to explode in the skies above North America; their detonation on the ground would be catastrophic. “The Department of Defense has a most urgent need for information pertaining to the safety of nuclear weapons,” an AEC official wrote in a top secret memo, as the Genie’s deployment date approached. In the decade or so since the first atomic bomb was dropped, the subject of nuclear weapon safety had received little attention. The bombs had always been stored and transported without their nuclear cores. What would a fuel fire, a high-speed collision, or shrapnel from a nearby explosion do to a sealed-pit weapon? The AEC hurriedly began a series of tests to find out.

Project 56 was the code name for an AEC safety investigation of sealed-pit weapons secretly conducted in a remote valley at the Nevada Test Site. Computers still lacked the processing power to simulate the behavior of a nuclear weapon during an accident, and so actual devices had to be used. Under normal conditions, a sealed-pit weapon would fully detonate when all the explosive lenses surrounding its core went off at once, causing a symmetrical implosion. The AEC’s greatest concern was that an imperfect, asymmetrical implosion — caused, for example, by a bullet setting off some of the high explosives — could produce a nuclear yield.

The Project 56 tests focused on what would happen if one of the explosive lenses were set off at a single point. It was thought almost impossible for more than one bullet or more than one piece of shrapnel to strike a weapon at different points, simultaneously, during an accident. The velocity of these high explosives was so fast that a lens would go off within microseconds of being struck, allowing no time for something else to hit. If the weapon’s high explosives went off at a single point, the nuclear core might simply blow to pieces, without producing any yield. That’s what the scientists of Project 56 hoped to observe: weapons that were “one-point safe.” But the core might also implode just enough to cause a nuclear detonation.

Between November 1955 and January 1956, the nuclear components of four weapon designs underwent safety tests in the Nevada desert. Each device was placed inside a small wooden building — and then a single detonator was set off. Three of the designs passed the test; a one-point detonation didn’t produce any yield. The fourth design failed the test, surprising everyone with a substantial detonation. The Genie’s warhead was among those pronounced one-point safe. But Project 56 revealed that a nuclear detonation wasn’t the only danger that a weapon accident might pose. The core of the Genie contained plutonium — and when it blew apart, plutonium dust spread through the air.