A declassified document shows that thousands of people could have died instantly due to an explosion at a US military base and a nuclear warhead flying 25 meters away.
Residents of Rapid City (South Dakota, USA) did not know for decades how close they were to death. It wasn’t until 58 years later that this report became available thanks to a freedom of information request filed last year by former journalist Harrison Kremer.
The report detailed how a 1.2 megaton nuclear warhead fell 25 meters to the ground as a result of an explosion in a missile silo.
It also described how the US Air Force tried to solve the problem on its own without seeking help from warhead designers.
The report, compiled by nuclear research organization Sandia Corporation, criticized the military for acting alone, potentially risking an explosion.
The incident took place on December 5, 1964. At Ellsworth Air Force Base, a repeater attached to a Minuteman missile accidentally fired in the missile silo.
The explosion knocked the warhead out of the rocket head and it fell to the ground. The warhead flew 25 meters to the side and fell. Fortunately, the impact did not detonate the warhead and no nuclear material leaked. The Mark 56 nuclear warhead had a yield of 1.2 megatons.
Despite the panic, the potentially wrong actions of the military were not made public until today.
The report stated that Explosive Ordnance Disposal (EOD) crews within the Air Force were not necessarily qualified to operate a nuclear warhead.
The Mark 56 warhead was fairly new at the time of the incident, but the type remained in service until 1993.
“The incident was not reported to the press,” the 1965 report says. “The whole operation was carried out in such a way that the people living nearby did not know about it and did not show even the slightest interest in the operation.
The warhead yield was 1.2 megatons, which puts it on par with the largest bomb in the current US arsenal. Since then, all Mark 56s have been dismantled.
If the warhead had exploded during the fall, there would have been an explosion capable of killing thousands of people. A 1.2 megaton blast would have destroyed much of Rapid City.
Experts estimate that a 1.2 megaton explosion at Ellsworth Air Force Base would have created a radiant heat radius of 11.6 kilometers.
The blast would have left residents of eastern Rapid City severely injured or disabled from third-degree burns. Most of the inhabitants of the satellite city of Box Elder died from a nuclear fireball with a diameter of 1.35 kilometers. Those who survived would receive a potentially lethal dose of radiation.
At the time of the incident, Rapid City had a population of approximately 42,000.