Command and Control

Bob Peurifoy led a team at Sandia that was trying to create a “wooden bomb”—a nuclear weapon that wouldn’t require frequent maintenance or testing, that could sit on a shelf for years, completely inert, like a plank of wood, and then be pulled from storage, ready to go. Peurifoy had heard about a new kind of battery that didn’t need to be recharged. “Thermal batteries” had been invented by a Nazi rocket scientist, Georg Otto Erb, for use in the V-2 missiles that terrorized Great Britain during the Second World War. Erb revealed how the batteries worked during an interrogation by American intelligence officers after the war. Instead of employing liquid electrolytes, a thermal battery contained solid ones that didn’t generate any electricity until they reached a high internal temperature and melted. Peurifoy thought that thermal batteries would be an ideal power source for a nuclear weapon. They were small, rugged, and lightweight. They had a shelf life of at least twenty-five years, if not longer. And they could produce large amounts of current quickly, after being ignited by an electric pulse. The main drawback of a thermal battery, for most civilian applications, was that it couldn’t be reused or recharged. But Peurifoy didn’t consider that to be much of a problem, since the batteries in a nuclear weapon needed to work only once.

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.