Eric Schlosser - Command and Control

At about the same time that thermal batteries were being added to America’s atomic and hydrogen bombs, another important design change was being developed at Los Alamos. A weapon “boosted” by tritium and deuterium gas would use much less fissile material to produce a large explosion. Right before the moment of detonation, these hydrogen gases would be released into the weapon’s core. When the core imploded, the gases would fuse, release neutrons, multiply the number of fissions, and greatly increase the yield. And because the fissile core would be hollow and thin, a lesser amount of explosives would be needed to implode it. As a result, boosted weapons could be light and small. The first widely deployed hydrogen bomb, the Mark 17, was about twenty-five feet long and weighed roughly forty thousand pounds. The Mark 17 was so big and heavy that the Air Force’s largest bomber could carry only one of them. The Strategic Air Command hoped to replace it eventually with the Mark 28, a boosted weapon. The Mark 28 was eight to twelve feet long, depending on its configuration, and weighed just two thousand pounds. It was small enough and light enough to be delivered by a fighter plane — and a single B-52 could carry at least four of them.

The military advantages of boosted weapons were obvious. But the revolutionary new design raised a number of safety concerns. The nuclear core of a boosted weapon wouldn’t be stored separately. It would be sealed inside the weapon, like the pit within a plum. Boosted, “sealed-pit” weapons would be stored fully assembled, their cores already surrounded by high explosives, their thermal batteries ready to ignite. In many respects, they’d be wooden bombs. And that is what could make them, potentially, so dangerous during an accident.

The first sealed-pit weapon scheduled to enter the stockpile was the Genie, a rocket designed for air defense. Conventional antiaircraft weapons seemed inadequate for destroying hundreds of Soviet bombers during a thermonuclear attack. Failing to shoot down a single plane could mean losing an American city. The Air Force believed that detonating atomic warheads in the skies above the United States and Canada would offer the best hope of success — and that view was endorsed in March 1955 by James R. Killian, the president of MIT, who headed a top secret panel on the threat of surprise attack. At the height of American fears about a bomber gap, atomic antiaircraft weapons promised to counter the Soviet Union’s numerical advantage in long-range bombers, much the same way tactical nuclear weapons were supposed to compensate for the Red Army’s greater troop strength in Europe. The Genie would be carried by Air Force fighter-interceptors. It had a small, 1.5-kiloton warhead and a solid-fueled rocket engine. Unlike conventional air defense weapons, it didn’t need a direct hit to eliminate a target. And it could prove equally useful against a single Soviet bomber or a large formation of them.

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.

The risks of plutonium exposure were becoming more apparent in the mid-1950s. Although the alpha particles emitted by plutonium are too weak to penetrate human skin, they can destroy lung tissue when plutonium dust is inhaled. Anyone within a few hundred feet of a weapon accident spreading plutonium can inhale a swiftly lethal dose. Cancers of the lung, liver, lymph nodes, and bone can be caused by the inhalation of minute amounts. And the fallout from such an accident may contaminate a large area for a long time. Plutonium has a half-life of about twenty-four thousand years. It remains hazardous throughout that period, and plutonium dust is hard to clean up. “The problem of decontaminating the site of [an] accident may be insurmountable,” a classified Los Alamos report noted a month after the Genie’s one-point safety test, “and it may have to be ‘written off’ permanently.”