The Day We Lost the H-Bomb: Cold War, Hot Nukes, and the Worst Nuclear Weapons Disaster in History

They learned, much to their surprise, that the greatest danger came from the immediate plutonium cloud and that the concentration of plutonium decreased rapidly with time. In Palomares, Langham said, the major plutonium hazard had vanished before anyone knew what had happened.

At the time of the accident, Langham also knew how much plutonium a human could ingest without danger. (He had used himself as a guinea pig, placing a bit of plutonium on his skin to measure absorption and also drinking a tiny amount in a glass of water.) At the time, the “maximum permissible body burden,” the total amount of plutonium that a person can carry safely in his or her body, was judged to be six tenths of one millionth of a gram, about the weight of a dust particle. (Current limits, based on annual uptake, are more restrictive.) The maximum permissible air concentration was.00003 millionth of a gram per cubic meter of air, an amount akin to a grain of salt in four cubic yards of soil.

Plutonium-239, the material used in the Mark 28 weapon, has a half-life of 24,360 years. So if the Americans left any traces in Palomares, the villagers would have to live with it for a long, long time.

Operation Roller Coaster was designed to study the long-term effects of plutonium ingestion, as well as the problem of resuspension — what happens when the heavy plutonium settles in the soil but then wind, weather, or people send it back into the air. But the tests had been conducted only four years before. Despite Langham's confidence, nobody in 1966 knew what the effects of such an accident would be in twenty or thirty years. But Langham, together with a team of Spanish and American scientists, plus military and government officials, had to invent a decontamination plan for Palomares now.

Studying Bud White's maps of the contaminated land, Langham calculated how much soil and vegetation the Air Force would have to remove in order to clean up the plutonium. Then, to be absolutely safe, he applied the standard “factor of ten,” setting the safe levels ten times below his calculations, and created a proposal for cleanup. The Spanish officials looked at his numbers and shook their heads. They wanted more assurance that the area would be safe — that tourists would keep coming to Spain's sunny coasts, that real estate values would keep climbing, and that the farmers of Palomares could sell their next tomato crop. The Spanish drew up a counterproposal and gave it to Langham's team. They wanted the Americans to remove topsoil from more than one hundred acres of land, replacing it with uncontaminated dirt.

The Air Force considered this excessive. If the accident had happened on American soil, it would never agree to this level of decontamination. Eventually the two sides reached a compromise. The Air Force would remove any topsoil reading above 400 micrograms of plutonium per square meter.

Areas with less contamination would be watered and/or plowed under to a depth of ten inches, diluting the plutonium to a safe level. This meant that Bud White's team would have to remove topsoil from only 5.5 acres of land. They would have to plow or water more than five hundred acres more.

The area around the site of bomb number two posed its own set of problems. The ground there was too steep and rocky to plow, but it was also the most contaminated. The Air Force agreed to turn the area by hand, with picks and shovels, until the radiation count dropped below the level of detection.

They also agreed to work with the Spanish government to create a long-term monitoring program of Palomares and its people.

The Strategic Air Command had actually been through similar situations before. According to the U.S. Departments of Defense and Energy, there had been at least twenty-eight nuclear accidents before the one in Spain. Here are a few examples, paraphrased from official DOD/DOE records:

March 11, 1958: A B-47 left Hunter Air Force Base, Georgia, en route to an overseas base. After leveling off at 15,000 feet, the plane accidentally jettisoned an unarmed nuclear weapon, which landed in a sparsely populated area 6½ miles east of Florence, South Carolina. The bomb's high explosive detonated on impact, causing property damage and several injuries on the ground.

October 15, 1959: A B-52 bomber and a KC-135 tanker were refueling in the air, 32,000 feet over Hardinsburg, Kentucky. Shortly after the B-52 began refueling, the two planes collided. Four members of the B-52 crew ejected from the plane, but four did not. All four men aboard the KC-135 tanker were killed. The B-52's two unarmed nuclear weapons were recovered intact. One had been partially burned but did not disperse any nuclear material.