January 17, 1966: The Palomares Incident

Today is the 41st anniversary of the Palomares Incident, a mid-air collision that dropped (but did not detonate) four hydrogen bombs near the small fishing village of Palomares, Spain. On January 17, 1966, a B-52 bomber from the U.S. Strategic Air Command (SAC) collided with a KC-135 aircraft tanker during a mid-air refueling over the Mediterranean Sea. Several B-52 fliers parachuted to safety, but all four crew members from the KC-135 died in mid-air. The B-52 Stratofortress carried four thermonuclear weapons, each with a fission-bomb trigger and containers of highly-combustible gas. In the event of nuclear war with the Soviet Union, the crew would arm the H-bombs manually while en route to their targets. Safety mechanisms protected internal components and ensured that accidentally dropping a hydrogen bomb from a high altitude would not cause a thermonuclear explosion. Witnesses near Palomares, however, described large blasts which were later determined to be caused by ruptured containers of tritium deuteride gas. The non-nuclear detonations spread radioactive material across the countryside and required both environmental remediation and a diplomatic offensive.

The three hydrogen bombs which landed near the village of Palomares required the excavation of 1,750 tons of material over a three-month period. While 1,600 members of the U.S. Air Force (USAF) cleaned up a 500-acre site, the U.S. government bought and destroyed farm products in the immediate area. On January 22, Reuters reported that "anxious peasants in southeast Spain" were wearing "miniature Geiger counters" given to them by U.S. officials. To counter Soviet claims that the Palomares incident had spread "lethal radioactivity", the U.S. government agreed to conduct continued medical surveillance and environmental monitoring. William D. Moss, a biochemist from Los Alamos National Laboratory (LANL), was dispatched to Madrid to help set up a bioassay lab. According to Moss, an initial examination of urine samples revealed "extremely high" concentrations of plutonium; however, the methodology was flawed. "You can't collect samples in the environment in which there's potential (plutonium) contamination," Moss later told a historian from the U.S. Department of Energy (DoE). When residents of Palomares were hospitalized in Madrid, Moss continued, "collection occurred under sterile conditions and the results were all zero".

The fourth hydrogen bomb which fell near Palomares landed in the Mediterranean Sea and sank to a depth of 2,500 feet. U.S. Navy (USN) submersibles struggled to pinpoint its location despite the eyewitness account of Francisco Simó Orts, a local fisherman. Using Bayesian theory, however, the USN was able to assign probabilities to individual squares on a map-like grid. On April 7, the Navy announced that the missing bomb had been found. U.S. ambassador Angier Biddle Duke, a media-savvy diplomat who had staged a swimming party off the coast of Palomares to prove the safety of its waters, hosted a public viewing of the H-bomb aboard the U.S.S. Albany. For his part, Francisco Simó Orts claimed salvage rights on the military's "broken arrow", but eventually settled out of court with the USAF.

Resources:

http://www.hss.energy.gov/healthsafety/ohre/roadmap/histories/0459/0459toc.html

http://airforcemedicine.afms.mil/latestnews/palomares.htm

http://www.mitpressjournals.org/doi/abs/10.1162/152039706775212067

http://en.wikipedia.org/wiki/Palomares

Editor's Note:

Like this story? See also February 5, 1958: The Tybee Bomb Incident.