Two interesting pieces of history on display at the National Museum of Nuclear Science and History — the casings of two bombs involved in the 1966 Palomares incident:
“Broken Arrow” is U.S. Defense Dept. (DOD) terminology for an accidental event that involves nuclear weapons, warheads, or components but that does not create the risk of nuclear war. The DOD officially recognizes that 32 Broken Arrow incidents have occurred since the first use of nuclear weapons in 1945. The 1966 accident over the Spanish town of Palomares was one of the more blood-curdling of these.
From the placard:
On January 17, 1966, a B-52 collided with a KC-135 tanker during a routine refueling operation over Palomares, Spain on the Mediterranean sea coast. The B-52 was carrying four nuclear bombs, which fell over 28,000 feet. One bomb fell into the sea and the other three bombs landed on the ground. The bomb that fell into the sea was recovered at a depth of 2,500 feet after an extensive underwater search. The bomb was dented but intact, and there was no radiation leakage.
With two of the three other bombs, the high explosives detonated on impact and released some radioactive materials. Approximately 1,400 tons of contaminated soil and vegetation were removed to the U.S. for storage at the Savannah River Site. A small parachute deployed on the other bomb, and it remained relatively intact.
The casings from the two bombs that did not detonate during the Palomares incident are on display at the museum, and pictured above. The one on the left was the bomb subsequently retrieved from the Mediterranean, while the one on the right was the sole bomb to reach land under a working parachute. Note that these are casings of B28 thermonuclear bombs — once the mainstay of the U.S. Strategic Air Command during the cold war, and capable of a range of explosive yields between 70 kilotons and 1.45 megatons.
But this incident isn’t exactly something we can consign to the history books just yet. While 2.2 hectares (5.4 acres) of land was decontaminated by removing soil with high levels of radioactivity back in 1966, studies conducted in the past decade have found lingering contamination. As recently as 2012, Spain formally asked the U.S. to finish the site cleanup.