This day in US nuclear accidents

10 November

1950 – B-50 / St. Lawrence River, Quebec, Canada

A B-50 with a crew of 12 aboard was on a weapons ferry flight from Goose Bay, Labrador to its home base at Davis-Monthan AFB in Tucson, Arizona, when it lost power in two of its four engines. In order to maintain altitude, an unarmed MK 4 weapon without its nuclear capsule was jettisoned from an altitude of 10,500 feet just before 4:00 PM over the St. Lawrence River near the town of St. Alexandre-de-Kamouraska, about 90 miles northeast of Quebec, Canada.

The HE in the weapon was seen to detonate on impact near the middle of the 12-mile wide river. The shock from the blast rattled windows 25 miles away; a cloud of pale yellow smoke rose to an altitude of 3,000 feet. The official Air Force explanation at the time of the incident was that a B-50 had jettisoned three 500 lb. conventional HE bombs.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, p.238
 
12 November

1958 – AEC storage site

Two MK 49Y1 Mod 0 warheads loaded aboard a trailer for movement to a storage structure fell to the paved hardstand when the trailer tilted. The weapon casings were dented as a result of the impact; however, damage was slight and there was no leakage of tritium or radiological contamination. The units were shipped to the AEC's Burlington and Rocky Flats plants and the Sandia Corporation for inspection and possible repair and return to stockpile.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, p.252.
 
13 November

1963 - AEC Storage Igloo / Medina Base, near San Antonio, Texas

At about 10:24 AM, while workmen were placing pits from dismantled atomic bombs into a storage magazine, a fire and ensuing explosion involving 120 lbs. of HE components of nuclear weapons caused minor injuries to three AEC employees while they were dismantling a weapon primary. The HE in the primary ignited with a force of about 60 tons of TNT and set off a larger amount of explosives nearby, completely destroying the storage magazine, and making a 20 foot deep crater. There was little contamination from nuclear components of disassembled obsolete weapons stored elsewhere in the building. The three men nearby were able to take cover before the blast and suffered only cuts, bruises, and sprains.

An AEC press release dated November 22, 1963 stated that "the accident occurred while three men were placing subassemblies containing natural and depleted uranium, aluminum, and chemical high explosives into an igloo for storage, preparatory to complete disassembly for reclamation of the metals and destruction of the chemical high explosives by burning." The AEC theorized that there may have been a mechanical contact between two subassemblies as they were being placed in the igloo; this led to a spark-induced fire and subsequent high-order explosion of other subassemblies. (The Medina Works was closed in 1966.)

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, pp.272-273.
 
20 November

1957 – Aircraft / Unknown

AEC document 907/4 dated November 20, 1957 refers to an "aircraft incident" on this date. No other details currently available.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, p.245.
 
26 November

1958 - B-47 / Chennault AFB, near Lake Charles, Louisiana

A B-47 loaded with a sealed-pit weapon containing no plutonium and some tritium caught fire on the ground after the accidental discharge of assisted take-off (ATO) bottles during the pilot's acceptance check. Discharge of the JATO units propelled the aircraft off the runway, where it collided with a towing vehicle and caught fire. The nuclear weapon case and all other components, with the exception of a few small pieces of high explosives, were destroyed by the fire; however, even in spite of one minor explosion, the secondary remained intact and the tritium reservoir was recovered. Contamination was limited to the immediate vicinity of the weapon residue within the aircraft wreckage.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, p.252.
 
28 November

1977 – CH-47 helicopter / West Germany

An Army CH-47 carrying nuclear warheads on a logistical movement crashed shortly after takeoff when it lost power in its no. 1 engine after the engine caught fire. The fire was extinguished by an internal extinguisher. The aircraft dropped rapidly, hit a row of trees and came to rest in a planted field approximately 200 to 300 meters from the point of takeoff. The aircraft bounced once and slid about 15 meters. The weapons were removed from the helicopter and taken to a storage site. There were no personnel injuries. The accident was categorized as a "Dull Sword" incident.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, p.290.
 
Unknown date in December

1958 – An MB-1T missile (Genie) separated from an aircraft pylon upon landing. The aircraft had been on range operations and returned carrying one rocket which had failed to fire. The impact of a normal landing caused the rocket to separate from the pylon when the aircraft’s brakes were applied. The missile skidded 135 feet down the runway.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, p.253.

1960 - C-124 / Kelly AFB, San Antonio, Texas

A MK 39Y1 Mod 2 bomb was being hoisted aboard a C-124 aircraft when one of the hoisting cables broke. The weapon, secured to its transportation dolly, dropped to the ramp and overturned. Damage to the weapon consisted of a scratch on the curved nose section and a damaged tail fin. Inspection of the arm/safe switch, dessicant compartments, parachute, thermal battery, safing switch, timers, and pull-out rods revealed that none of these devices had functioned.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, p.262.

1960 - W-25 Warhead / Kingsley Field, Klamath Falls, Oregon

When a service electrical check of a W-25 warhead in an MB-1 GENIE rocket was made, an abnormality occurred, indicating a possible short circuit in the high-voltage power supply. After a one-hour evacuation of the testing area, the test was conducted again
without abnormal results.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, p.262.

1 December

1961 – JUPITER missiles / Italy

Two JUPITER missiles armed with W-49 warheads were struck by lightning, resulting in radar fuse thermal battery activation in both warheads. One missile was returned to operational status after 76 days, the other after 59 days.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, p.269.
 
3 December

1962 – Railroad train / Marietta, Georgia

Two railroad cars and a locomotive of a Louisville & Nashville train were derailed at 5:00 AM EST about five miles north of Marietta while carrying uranium weapons components. The material was not damaged, but three couriers were injured. Neither of the boxcars overturned.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, p.271.
 
5 December

1964 – MINUTEMAN / Ellsworth AFB, near Rapid City, South Dakota

An LGM-30B MINUTEMAN ICBM was on strategic alert at Launch Facility (LF) L-02 near Vale, South Dakota, about 75 miles northwest of Rapid City, when two airmen were dispatched to the LF to repair the inner zone security system. In the midst of their checkout of the system, stray electrical voltage caused one retrorocket below the re-entry vehicle (RV) to fire, and the RV fell about 75 feet to the bottom of the silo and bounced off the interior silo wall and grazed the missile's second stage. Windscreen and heat shield material on the RV were detached and the warhead punctured.
When the RV struck the floor of the silo, the arming and fuzing altitude control subsystem containing batteries was torn loose, thus removing all sources of power from the RV. The RV structure received considerable damage. All safety devices functioned properly in that they did not sense the proper sequence of events to allow warhead arming. There was no detonation or radioactive contamination. A postmortem inspection at the AEC's Medina Base revealed that the primary assembly and HE within the RV were undamaged. Nonetheless, the warhead was deemed “no longer useable.”

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, p.275.

1965 – A-4 / Near Ryukyu Islands, Pacific Ocean

During a nuclear weapons loading exercise, an A-4E armed with a MK 43 weapon rolled off an elevator on the U.S.S. TICONDEROGA (CVA-14) and fell into the sea. The pilot, aircraft, and weapon were lost in 16,000 feet of water. The incident occurred 80 miles from one of the Ryukyu Islands near Okinawa. Water pressure broke the weapon apart and its fissile components were dispersed.
No public announcement of the accident was made at the time, nor was any ever intended: the subject was considered sensitive because of the potential impact upon visits of the TICONDEROGA and other U.S. naval warships carrying nuclear weapons to foreign ports. Many foreign countries allowed warships to visit only if they were certified by their governments not to be bearing nuclear weapons; oftentimes, both countries involved knew that the warships were carrying weapons anyway.
In July 1989, after the incident was made public in greater detail, Japanese scientists collected water samples at various depths at eight locations near where the bomb went into the sea; no radioactivity (above normal background levels) was found.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, p.278.
 
8 December

1964 - B-58 / Bunker Hill (now Grissom) AFB, near Peru, Indiana

At about 11:59 local time, SAC aircraft were taxiing during an Operational Readiness Alert inspection exercise in bad weather. As one B-58 carrying a BA-53 warhead in a BLU-2/B pod and four other nuclear weapons reached a position directly behind the aircraft on the runway ahead of it, the leading aircraft throttled up. As a result of the combination of the jet blast from the leading aircraft, icy runway surface, and power applied to the trailing B-58 while attempting to turn onto the runway, control was lost and the B-58 slid off the left side of the taxiway into mud. There was approximately 4" of snow on the ground.

The left main landing gear passed over a flush-mounted taxiway light fixture and 10 feet farther along in its travel, grazed the left edge of a concrete light base. Ten feet farther, the left main landing gear struck a concrete electrical manhole box and collapsed; the left wing engine nacelles were torn off and the aircraft fuselage struck the ground and began burning (a frequent occurrence following B-58 landing gear failure).

When the aircraft came to rest, all three crew members abandoned the B-58. The aircraft commander and defensive systems operator escaped with superficial burns. The navigator ejected in his escape capsule, which landed heavily 548 feet from the burning aircraft (the parachute did not deploy). He did not survive. The high explosives in all five weapons detonated. Portions of three of the five nuclear weapons aboard the plane burned; tritium contamination from one weapon was limited to the immediate area of the crash and was subsequently cleaned up. There was no plutonium contamination. The aircraft and weapons wreckage burned for two hours. There were 14,000 gallons of JP-4 aboard the B-58.

The pod surrounding the BA-53 and the warhead were badly damaged by fire, which essentially destroyed the HE and pit. The left-forward MK 43 was extensively damaged, including a ruptured tritium reservoir. The right-forward bomb had fire damage; the basic assemblies of the two aft MK 43s were intact, and their interiors were relatively undamaged and the HE in excellent condition. During recovery operations on December 9, the secondary of the left forward MK 43 burst into flame, and the fire burned itself out. The next day, when this secondary was moved, it ignited again and was extinguished with sand.

In November 2000, parts of the B-58 and radioactive soil were dug up and replaced by clean dirt, as part of the post-deactivation of the airbase after the Air Force moved out in 1991. Unsalvageable parts of the plane had been buried several hundred yards from the crash site. Wreckage of the burned weapons had been sent to Oak Ridge after the crash in 1964. Four B-58s crashed at Grissom between 1964 and 1969.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, pp.275-277.
 

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