Peurifoy had recently heard about an explosive called 1,3,5-triamino-2,4, 6-trinitrobenzene (TATB). It had been invented in 1888 but had been rarely used since then — because TATB was so hard to detonate. Under federal law, it wasn’t even classified as an explosive; it was considered a flammable solid. With the right detonators, however, it could produce a shock wave almost as strong as the high explosives that surrounded the core of a nuclear weapon. TATB soon became known as an “insensitive high explosive.” You could drop it, hammer it, set it on fire, smash it into the ground at a speed of 1,500 feet per second, and it still wouldn’t detonate. The explosives being used in America’s nuclear weapons would go off from an impact one tenth as strong. Harold Agnew was now the director of Los Alamos, and he thought using TATB in hydrogen bombs made a lot more sense — as a means of preventing plutonium dispersal during an accident — than adding two or three thousand extra pounds of steel and padding.
All the necessary elements for nuclear weapon safety were now available: a unique signal, weak link/strong link technology, insensitive high explosives. The only thing missing was the willingness to fight a bureaucratic war on their behalf — and Bob Peurifoy had that quality in abundance. He was no longer a low-level employee, toiling away on the electrical system of a bomb, without a sense of the bigger picture. As the head of weapon development, he now had some authority to make policy at Sandia. And he planned to take advantage of it. Three months into the new job, Peurifoy told his superior, Glenn Fowler, a vice president at the lab, that all the nuclear weapons carried by aircraft had to be retrofitted with new safety devices. Peurifoy didn’t claim that the weapons were unsafe; he said their safety could no longer be presumed. Fowler listened carefully to his arguments and agreed. A briefing for Sandia’s upper management was scheduled for February 1974.
The briefing did not go well. The other vice presidents at Sandia were indifferent, unconvinced, or actively hostile to Peurifoy’s recommendations. The strongest opponents of a retrofit argued that it would harm the lab’s reputation — it would imply that Sandia had been wrong about nuclear weapon safety for years. They said new weapons with improved safety features could eventually replace the old ones. And they made clear that the lab’s research-and-development money would not be spent on bombs already in the stockpile. Sandia couldn’t force the armed services to alter their weapons, and the Department of Defense had the ultimate responsibility for nuclear weapon safety. The lab’s upper management said, essentially, that this was someone else’s problem.
In April 1974, Peurifoy and Fowler went to Washington and met with Major General Ernest Graves, Jr., a top official at the Atomic Energy Commission, whose responsibilities included weapon safety. Sandia reported to the AEC, and Peurifoy was aiming higher on the bureaucratic ladder. Graves listened to the presentation and then did nothing about it. Five months later, unwilling to let the issue drop and ready to escalate the battle, Peurifoy and Fowler put their concerns on the record. A letter to General Graves was drafted — and Glenn Fowler placed his career at risk by signing and sending it. The “Fowler Letter,” as it was soon called, caused a top secret uproar in the nuclear weapon community. It ensured that high-level officials at the weapons labs, the AEC, and the Pentagon couldn’t hide behind claims of plausible deniability, if a serious accident happened. The letter was proof that they had been warned.
“Most of the aircraft delivered weapons now in stockpile were designed to requirements which envisioned… operations consisting mostly of long periods of igloo storage and some brief exposure to transportation environments,” the Fowler letter began. But these weapons were now being used in ways that could subject them to abnormal environments. And none of the weapons had adequate safety mechanisms. Fowler described the “possibility of these safing devices being electrically bypassed through charred organic plastics or melted solder” and warned of their “premature operation from stray voltages and currents.” He listed the weapons that should immediately be retrofitted or retired, including the Genie, the Hound Dog, the 9-megaton Mark 53 bomb — and the weapons that needed to be replaced, notably the Mark 28, SAC’s most widely deployed bomb. He said that the secretary of defense should be told about the risks of using these weapons during ground alerts. And Fowler recommended, due to “the urgency associated with the safety question,” that nuclear weapons should be loaded onto aircraft only for missions “absolutely required for national security reasons.”
