Nuclear Bomb Dropped in Georgia
No Nuclear Capsule Inserted, Documents Show |
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Several news papers have carried stories about a nuclear weapon that was
dropped by a U.S. Air Force B-47 strategic bomber near Savanna River in Georgia
on February 5, 1958. The weapon has never been recovered and some papers have
stated that the weapon could explode with a nuclear yield or that radioactive
materials may have leaked from the weapon.
Documents released by the Air Force and obtained under FOIA
help alleviate some of the rumors about the accident.
For years the Air Force has been less than forthcoming with
information about the accident, but in April 2001 the Air Force released a
Search and Recover Assessment of the accident the gave new information about
the weapon. This report disclosed that the weapon was a Mk-15 Mod 0 and that the
nuclear capsule was not inserted at the time of the accident (download Air Force
document in the right-hand bar).
In addition, the Temporary Custodian Receipt used to transfer
the weapon from the Atomic Energy Commission (AEC) to the Air Force in 1958 has
been released under FOIA. It confirms that the weapon was the Mk-15 Mod 0, and
that AEC did not "allow any active capsule to be inserted into it at any time."
(download Air Force document in the right-hand bar).
Mk-15 thermonuclear bomb similar to the one dropped
near Savannah River in 1958. Source: U.S. Air Force.
Another FOIA document, the History of Strategic Air Command
(SAC) for January-June 1958, provides important background information to
understand the management of nuclear weapons custody at the time. The document
also provides information about weapons design and the risk of accidental
nuclear explosion in accidents like that at Savanna River (download Air Force
document in the right-hand bar).
Shortly after the Savannah River accident, the design of the Mk-15 was
changed from insertable component to sealed-pit (designated Mk-15 Mod 2).
This was completed
in May 1958. But the first sealed-pit weapons were not delivered to the Air Force
until June 1958, four months after the Savanna River accident.
Had the capsule been inserted in the weapon jettisoned at
Savannah River, the SAC history shows, the probability of a nuclear explosion
would have been significant: a 15 percent probability of up to 40.000 pounds of
nuclear yield in the event of one point detonation. The design of pit weapons
improved safety considerably, but a significant risk of accidental nuclear
explosion remained:
"...there was no significant degradation of safety when
flying [a sealed-pit weapon] with safety pins installed and the U-2 rack
locked. There was, however, a significant degradation of safety if the
weapon was involved in an aircraft crash or was jettisoned with the safety
pins removed. The estimated probability of a nuclear detonation of the
weapon in a crash with pins removed was one in ten thousand. The estimated
probability of a nuclear detonation if the weapon was jettisoned or an
inadvertent release occurred with pins removed was one in five hundred."
Source: Memo, Col Roland A. Campbell, Ch. Ops
Div, D/Ops, to General Terrill, "USAF Safety Review of Sealed Pit Weapons,"
January 14, 1958.
The accident at Savannah River, however, is not
included in the SAC history. The document includes descriptions of three B-47
crashes during the first half of 1958, but does not mention the mid-air
collision between the B-47 and a F-86 near Savannah, Georgia.
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