This day in US nuclear accidents

[mhansen2]

13 December

1960 – Naval Ordnance Test Station, San Clemente Island, California

At approximately 7:45 PM PST, an explosion occurred in a storage bunker at the Naval Ordnance Test Station (NOTS) on San Clemente Island, approximately 40 miles west of San Diego, California. Two "development type" nuclear warheads were in the bunker at the time of the explosion; the warheads contained "toxic materials" but no high explosives. One of the warheads was damaged by flames. The explosion originated in a Jet-Assisted Take Off (JATO) rocket which was being prepared for mating to one of the developmental warheads in preparation for a test. The explosion resulted in one fatality and three additional casualties; all were NOTS personnel. No AEC news release was issued.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, pp.262-263.

For the source material, go here:

index.htm

 

[JGalt]

Gotta break a few eggs to make an omelet.

 

[mhansen2]

14-31 December

No reported incidents

 

[mhansen2]

Unknown date

1952 – B-50 / Alaska

Although checklists were followed and procedures approved by an on-board AEC representative, a nuclear weapon was unintentionally jettisoned from a B-50 when the release shackle became unlocked and the bomb fell through the bomb bay doors onto the
Alaskan tundra. (No other details currently available.)

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, p.239.

 

[mhansen2]

4 January

1958 – Railway Accident / Hamburg, New York

A derailment accident occurred on the Nickel Plate Road near Hamburg, New York approximately fifteen miles south of Buffalo at 4:50 AM EST. Thirty-two cars of a 78-car train were derailed behind the engine. No one was injured or killed; early assessment indicated that the accident was caused by a broken axle or defective junction box on the second car behind the engine. The AEC shipment was enroute from the manufacturing facility at Burlington, Iowa; it included assembled and loaded bomb casings, which were undamaged.

An early news release about the accident quoted a railroad employee as saying without official authorization that the shipment contained enough explosives to "blow up the western end of New York State." In order to counter this statement, the AEC issued a news release that stated: "The Commission has been advised of a wreck near Buffalo, New York of a freight train which carried a routine AEC classified shipment. The shipment included a quantity of non-nuclear conventional explosive. There was no danger of a nuclear detonation. The shipment was unharmed and will shortly be on its way again." The entire shipment left Buffalo at 10:00 AM on January 5, en route to its original destination. (Not a "Broken Arrow" accident.)

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, pp.245-246

 

[mhansen2]

5 - 8 January

No reported incidents.

 

[mhansen2]

9 January

1956 – B-36 / Kirtland AFB

A February 1991 Environmental Protection Agency (EPA) report lists an incident involving a B-36 carrying one or more nuclear weapons at Kirtland AFB on this date. No further details are currently available.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, p.240

 

[mhansen2]

11 January

1985 - PERSHING II MRBM / Heilbronn, West Germany

During the assembly of a PERSHING II missile, the motor caught fire, and exploded, killing three people.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, p.292.

 

[mhansen2]

12 January

No reported incidents.

 

[mhansen2]

13 January

1964 - B-52 / Near Cumberland, Maryland

A B-52D was enroute from Westover AFB, near Chicopee Falls, Massachusetts, to its home base at Turner AFB, near Albany, Georgia after having concluded an airborne CHROME DOME alert mission on January 12. The plane crashed at about 3:00 AM approximately 17 miles SW of Cumberland, Maryland in a remote, thickly wooded uninhabited area near Lonaconing, Maryland. The aircraft was carrying two unarmed war reserve weapons, both in tactical ferry configuration, with no mechanical or electrical connections made to the aircraft and safing switches in the "safe" position to preclude arming.

Before the crash, the pilot had requested a change in flight altitude because of severe air turbulence at 29,500 feet. The aircraft was cleared to climb to 33,000 feet; during the climb, the B-52 encountered violent air turbulence around 31,000 feet and the airframe structure failed (a two-day-long driving snowstorm was in progress and winds up to 145 knots at 30,000 feet had been reported in the vicinity of Washington, D.C.). The vertical fin separated from the bomber, striking the left horizontal stabilizer which broke off the aircraft and caused the tail section to tear loose. (By January 1964, at least four other B-52s had lost their tail sections in turbulence.) Of the five aircrewmen aboard the bomber, only the pilot and copilot survived after ejecting.

The tail gunner and navigator ejected successfully but died of exposure to sub-zero temperatures after reaching the ground alive. The radar navigator did not eject and died in the crash. The B-52 apparently disintegrated upon impact and cut a 100-foot wide by 100-yard long swath through a wooded area; only one engine remained recognizably intact. The crash site was an isolated mountainous and densely wooded area on the western side of Big Savage Mountain; 8 to 14 inches of new snow covered the aircraft wreckage which was scattered over an area of approximately 100 square yards. The aircraft's tail section was found 15 miles away.

Weather during recovery and cleanup operations included extreme cold (on the order of 0 to -10 F), nearly four feet of snow, and gusty winds. Two unarmed weapons remained aboard the aircraft until it crashed and were relatively intact, although heavily damaged, after impact near the center of the wreckage field; they were found approximately 20 to 25 yards apart in two feet of snow. There was no HE explosion nor was there any radiation hazard. The nearest inhabited residence was between one-half mile to one mile from the crash site.

The debris pattern indicated that the weapons, found near the center of the wreckage, remained secured to the aircraft until impact. The basic assembly of weapon number one cracked in three places, with one crack circumscribing three-quarters of the bomb casing circumference. The firing set, including detonator cables and two firing set cables, had been secured to the weapon by eight retaining bolts; the firing set was found about 15 feet from the basic assembly. The X-unit, the high-voltage source for the detonators, was sheared off the primary, but its thermal batteries did not fire. The rear case sections of both weapons had broken off and been consumed by the ensuing fuel fire after impact.

Weapon number two was less severely damaged: the thermal batteries did not fire, and there was no apparent damage to components within the basic assembly. Pullout wires to the fuzing system were broken, but the electrical system safing switch remained in the "safe" position.

The nuclear portions (basic assemblies) of both weapons were evacuated by air from Cumberland via an Air Force C-124 to Kelly AFB near San Antonio, Texas and were turned over to the AEC's Medina Modification Center where they were disassembled beginning on January 24, 1964. Postmortem examinations at Medina and later at Sandia verified that none of the weapon components were activated by the crash.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, pp.273-274.

 

[mhansen2]

14 - 15 January

No reported incidents

 

[mhansen2]

16 January

1961 – F-100D / United Kingdom airbase

At 9:50 AM local time, a USAF F-100D on quick reaction alert at an airbase in the United Kingdom, was involved in a fire. During engine run-up, the underwing fuel tanks were accidentally ejected and spilled fuel ignited. A nuclear weapon mounted on the aircraft's centerline pylon was scorched and blistered before the flames were extinguished by the flight line fire department. There were no personnel injuries, and the weapon was replaced.

This accident was very similar to that involving an F-100 at a Pacific base on January 18, 1959. As a result of these incidents, wing fuel tank ejection cartridges were removed before engine run-ups and fire trucks stood by in front of alert hangars in case of fire.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, p.263.

 

[mhansen2]

17 January

1966 - B-52 / Palomares, Spain

At 9:17 AM local time, a B-52G returning to Seymour Johnson AFB near Goldsboro North Carolina and a KC-135 tanker from an airbase at Moron, near Sevilla in southwestern Spain, collided during a routine high altitude air refueling operation in the "Saddle Rock" refueling area at about 31,000 feet as the planes flew westward over the Mediterranean Sea, just off the coast of Spain near Palomares, about 245 miles south of Madrid, when the B-52 overran the fueling boom on the KC-135.

The fueling boom penetrated the bomber's fuselage just aft of the wing trailing edge, in effect breaking the aircraft’s back, and causing the plane to pitch down and left and split apart. Both aircraft exploded and disintegrated and crashed, spreading about 250 tons of wreckage over a wide area. All four tanker crewmen died and four of seven B-52 crewmembers survived after ejecting and parachuting to safety. The B-52 radar navigator was burned by a fireball after he ejected; the navigator ejected at low altitude and was killed on impact with the ground. The B-52 gunner and electronic warfare officer did not eject and were killed in the crash.

The B-52 was on a standard SAC airborne alert mission and was carrying four unarmed MK 28FI nuclear weapons, each with a yield of 1.1 MT; the bombs were torn violently from the plane four to five seconds after the bomber began to disintegrate.

Guide and retardation parachutes deployed fully or partially on two of the bombs. Those without chutes continued on a ballistic trajectory onto the shore and a few miles inland. Bombs with deployed parachutes were blown by high 60 MPH winds to the northeast.

Bomb #1 landed relatively intact, and still attached to its release rack mechanism, in a steep bank of soft earth near the Almanzora riverbed onshore, having been slowed by a small 16-foot diameter ribbon chute, and was found eight hours after the crash when it was rendered safe. The weapon had a nine-inch gash in its nose and three of its four tail fins were missing.

Bomb #2, found the following morning, fell unretarded two miles farther inland and underwent a one-point detonation of its primary which ruptured the weapon and blew plutonium and plutonium oxide into the air and onto the ground. The explosion dug a crater about six feet deep and 20 feet in diameter; parts of the weapon were blown as far as 100 yards. The secondary was intact, as was the boost tritium gas reservoir found about 25 feet from the crater. The broken afterbody and parachute pack were found about 100 yards away.

Bomb #3 landed violently after being slowed slightly by a partially-deployed ribbon chute and also underwent a one-point explosion, dispersing uranium, plutonium and plutonium oxide; it was found near a retaining wall on a small farm midway between #1 and #2 on the outskirts of Palomares early in the morning after the crash. Parts of bomb #3, including its boost tritium gas reservoir, were blown 500 yards. Quantities of unburned HE were recovered. The secondary was found in a crater which measured about 10 feet in diameter and three feet deep. The afterbody was fairly intact with the main chute still inside.

Bomb #4, whose retardation parachutes deployed fully, was blown by high winds aloft for about eight miles until it fell into the Mediterranean Sea. After entering the water, the weapon, still suspended from its parachute, descended to a depth of 2,160 feet (355 fathoms), riding the prevailing currents. The bomb touched down on the rim of an underwater ridge and was apparently dragged over the edge by current forces on the chute, and subsequently slid into a deep submarine canyon.

From there it continued its descent to a depth of 2,550 feet (425 fathoms), leaving a smooth furrow (the furrow was discovered on March 1 and ultimately led to discovery of the weapon on the seafloor).

The bomb was salvaged intact on April 7 from a depth of 2,850 feet 12 miles off Palomares (the weapon had fallen into deeper water after being accidentally dropped during an earlier recovery attempt). The exterior of the bomb was in good shape, except for two gashes approximately 40 inches long at the bottom of the tail ballistic section and a severely dented nose section. Water had infiltrated all portions of the weapon, including the pressurized “physics package” warhead section, and mud was found inside the fuse and tail sections. All parachutes except the 30 inch stabilization chute had deployed. This weapon was displayed for the press to verify its recovery (this was the first time that a U.S. hydrogen weapon had been shown publicly). This weapon is now also on display at the National Atomic Museum.

None of the village's 1,540 inhabitants were immediately injured seriously by either the falling bombs or aircraft wreckage. A long narrow area slightly over one-half mile long and one-sixteenth of a mile wide was contaminated by plutonium; 20 clean-up workers were exposed to plutonium and U-235.

Approximately 1,400 tons of slightly contaminated soil and vegetation from a 558 acre area were removed to the continental U.S. and buried at the Savannah River AEC facility. Aircraft wreckage was either returned to the U.S. or dumped into deep, remote Atlantic Ocean waters. Representatives of the Spanish atomic energy commission monitored the cleanup operation. The accident resulted in the Spanish government withdrawing permission for overflights of its territory by nuclear-armed aircraft. The Air Force denied for three days after the accident that nuclear weapons were involved.

All uncontaminated aircraft wreckage was gathered and loaded aboard a barge and dumped into deep remote Atlantic Ocean waters by late February 1966.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, pp.278-283.

 

[mhansen2]

18 January

1959 – F-100 / Itazuke AB, Japan

At about 11:55 AM local time, the 8th Tactical Fighter Wing aircraft was parked on a revetted hardstand in ground alert configuration. The external load consisted of a MK 7 nuclear weapon on the left wing intermediate station, one 275 gallon drop tank on the right wing intermediate station, and one 200 gallon drop tank each on the left and right wing inboard stations. When the aircraft's engine starter button was depressed during a practice alert early in the morning, an explosion and fire occurred when the three external fuel tanks inadvertently jettisoned and the left wing 200 gallon tank ruptured and caught fire; the fire spread to the other two tanks.

The weapon was exposed to constant heat and intermittent flames from the burning fuel, resulting in the forward section of the bomb either melting or falling off, exposing fuzing components and the weapon’s nickel-cadmium batteries. The lower battery had shorted out. The upper battery was warped and its cables had burned through; however, the battery was still charged. Portions of the center section bottom were melted away, exposing detonators around the warhead sphere. Several of these detonators were cracked and scorched; insulation on several detonator lead cables was softened but intact. Pull-out wires were in place and the arm-safe switch was on “safe.”

Personnel in the aircraft's revetment and in adjacent revetments were evacuated as quickly as possible. Fire trucks at the scene put out the fire with foam and water in about seven minutes. The nuclear capsule for the bomb was not in the vicinity of the aircraft and was not involved in the accident. Desiccant bags in the aft end of the weapon caught fire and were burned; in addition, the radome at the front end of the bomb burned and a few detonator cables were scorched. The weapon’s HE appeared intact upon examination. There were no cleanup or nuclear contamination problems. The damaged weapon was returned to the U.S. for refit and further examination.

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

 

[mhansen2]

19 January

1961 – / B-52 / Monticello, Utah

A B-52B from Biggs AFB near El Paso, Texas carrying one or more nuclear weapons exploded in midair about 10 miles north of Monticello, Idaho at about 6:19 PM MST. The plane carried seven crewmen, of whom five were killed and two, the copilot and navigator, ejected and parachuted safely from the plane. The B-52 had left Biggs at about 5:15 PM for a routine "round-robin" training mission of eight hours duration. When near Monticello on its way to Bismarck, North Dakota, the aircraft was at an altitude of 36,000 feet and was estimated to have been about 23 miles east of its intended course (the autopilot had been disengaged earlier because of turbulence).

At about 6:18, the bomber began climbing from 36,000 to 40,000 feet; soon afterwards, the plane experienced a violent bump or lurch that was followed by a descending right roll of about 410 degrees, a short period of wings-level, nose-down flight, and then a violent spin. The aircraft descended rapidly, and broke into several pieces which landed within an area two miles wide by 11 1/2 miles long at an elevation of 7,000 feet. Observers on the ground saw a left-wing engine in flames; this was soon followed by a violent mid-air explosion. Parts of the aircraft were found as far as two miles from the main wreckage field.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, p.263.


1966 – TERRIER missile / Mayport Naval Station, Jacksonville, Florida

A W-45 warhead separated from a TERRIER surface-to-air missile while the rocket was being loaded aboard the U.S.S. LUCE (DLG-7) and fell eight feet. The warhead was dented but unbreached; there were no personnel casualties. (Not a "Broken Arrow" incident.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, p.284.

 

[mhansen2]

20 January

No reported incidents.

 

[mhansen2]

21 January

1968 - B-52 / Thule, Greenland

At 9:29 AM EST, a B-52G from Plattsburgh AFB, New York, departed for a 24-hour airborne alert mission. The aircraft crashed and burned at about 3:40 PM EST just over seven miles southwest of the runway at Thule AFB, Greenland. The B-52 was approaching the base for an emergency landing following the ignition of an on-board fire of undetermined origin in the lower crew compartment.

The aircraft commander declared an emergency about 42 miles from Thule AFB, and the plane passed over the base heading north; it made a 180 degree turn before crashing. All seven crewmen bailed out at altitudes between 8,000 and 9,000 feet about four miles from the base after smoke filled the cockpit and all aircraft power was lost. The pilot, copilot, radar navigator, electronic warfare officer, gunner, and navigator survived; two navigators were injured. A second pilot was killed while bailing out.

The B-52 plunged toward the ice below at an angle of about 15 degrees and began to disintegrate in midair and exploded on impact. The bomber carried four unarmed MK 28 nuclear weapons; the bombs were still inside the aircraft at impact and the HE in the primaries in all four detonated, blasting plutonium and uranium into the burning aircraft wreckage. The plane crashed at an estimated 560 MPH: the eight jet engines were found two to two-and-a-half miles from the point of impact. Most bomb fragments were subsequently destroyed by a fire fed by 35,000 gallons of jet fuel aboard the plane; this fire burned for at least 20 minutes, with a 2,200-foot long smoke plume reaching 2,400 feet, and covered an area 1,000 to 2,000 feet wide. A total of six kilograms (13.2 lbs.) of plutonium was involved in the crash.

Plutonium oxide particles were blasted into bomb and aircraft debris, entrained and carried forward in splashing jet fuel before it detonated, blown into the ice at the point of impact, and carried aloft and downwind for several hundred miles by the smoke from the burning fuel. Some radioactive contamination occurred in the area of the crash, which was on 30- to 48-inch thick snow-covered sea ice over North Star Bay on Bylot Sound atop 625 feet of water; the heat of the fire melted the ice which later froze, trapping bits of metal, carbon, unburned jet fuel, tritium, uranium-235, and plutonium in an area about a half mile long and 650 feet wide.

Most plutonium was recovered in an area about 110 yards wide by 760 yards long where it attached itself to surface ice and snow. Pieces of bombs and aircraft wreckage were found two to four miles beyond the leading edge of the blackened area. Search operations were hindered by adverse weather, continuous darkness, and -23 F ambient temperatures: two storms characterized by high winds dispersed plutonium over the ice and snow-covered land and seascapes. The largest portions of weapons recovered included five 64-foot and 16-foot diameter parachutes, four tritium reservoirs, and pieces of three primaries, secondaries, and weapon casings. Analysis by the AEC of secondary wreckage accounted for 85% of the uranium and 94%, by weight, of three secondaries; one secondary was recovered nearly intact and parts of at least one other were found two and-a-half miles from the crash site. (By February 23, the fourth weapon secondary was still missing; nonetheless, the Air Force announced publicly that "significant portions of all four weapons were recovered.") A small amount of aircraft wreckage, including possibly one complete MK 28 secondary assembly, apparently melted through the ice and settled on the sea floor. (No part of the plane’s tail had been found by February 2.) Crewmen aboard a small submersible named the STAR III identified but did not retrieve weapon pieces from the bottom of Bylot Sound in late August 1968.

Approximately 237,000 cubic feet (10,500 tons) of contaminated ice, snow, water, and crash debris mixed with borax to minimize potential criticality problems were removed from a three-square mile, 26-acre area to the continental U.S. and buried at the Savannah River AEC facility during the course of an eight-month long cleanup operation. Recovered aircraft debris was shipped to Oak Ridge for burial.

Although an unknown amount of contamination was dispersed by the crash, environmental sampling showed normal readings in the area after the cleanup was completed. Representatives of the Danish government monitored the cleanup operations. Following this accident, airborne alert flights by nuclear-armed SAC bombers, first started in 1958, were permanently halted.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, pp.285-287.

 

[mhansen2]

22 - 23 January

No reported incidents.

 

[mhansen2]

21 January addendum

50 years ago, a U.S. military jet crashed in Greenland – with 4 nuclear bombs on board

 

[mhansen2]

24 January

1961 – B-52 / Goldsboro, North Carolina

During a B-52G airborne alert mission 15 miles north of Seymour Johnson AFB, a fire began as a result of a major leak in a wing fuel cell which had caused the loss of 37,000 lbs. of fuel in two minutes. The fire and resultant explosion caused structural failure of the aircraft's right wing at an altitude of 8,000 feet after the crew had bailed out. This in turn resulted in two unarmed MK 39 weapons without nuclear capsules separating from the bomber during airframe breakup between 10,000 and 2,000 feet. The two bombs fell to earth near Goldsboro, North Carolina, about one mile from the crash site and 13 miles from Seymour Johnson. Five of the eight B-52 crew members survived. Wreckage of the aircraft was scattered over a wide area of approximately two square miles near Faro, North Carolina.

During the breakup of the airframe, three of four arming safety devices on one bomb were actuated, including arming wires pulled out, the pulse generator actuated, the explosive actuator fired, a timer run down, all contacts of the differential pressure switch closed, and the low and high voltage thermal batteries actuated. The arm-safe remained in a “safe” position and the rotary safing switch was not operated. The X-unit was not charged, nor was tritium injected into the pit.

These actions resulted in the bomb’s warhead going through nearly all of its arming sequence, including 100-foot diameter retardation parachute deployment, activation of internal timing mechanisms, development of high voltage in the firing system, etc. However, since the fourth arming device — the pilot’s arm/safe switch — was not activated, the warhead did not complete its arming sequence. This MK 39 descended by parachute and consequently suffered only minor damage when it impacted the ground, penetrating about 18 inches and deforming the frangible bomb casing nose assembly. The weapon remained in an upright position with its parachute hanging in a tree about a mile from the main aircraft wreckage field.

The second MK 39 bomb fell free and broke apart upon impact with the sandy clay earth about 500 yards from the main aircraft wreckage and three-quarters of a mile from the impact point of the first bomb. This weapon made a visible surface crater about eight feet in diameter and six feet deep. No explosion occurred, although this weapon was also partially armed upon release from the aircraft and further by closure of an arming switch upon impact. A high voltage switch was not closed, so this bomb also did not arm completely. This weapon’s fuzing and firing sequence underwent all of the actions of the first bomb, with the exception that the timer ran for only 12 to 15 seconds; only two contacts of the differential pressure switch closed; the high voltage thermal battery was not actuated; and the rotary safing switch was destroyed on impact. The nose crystals in both weapons, used for salvage fuzing, were crushed.

Upon impact, both the primary and secondary of the free-falling bomb smashed through the frangible nose of the weapon and penetrated farther into the waterlogged farmland. The tail of the bomb was located approximately 22 feet below ground surface.

Excavation began immediately after the crash, around 1:30 PM on January 24, but was hindered by freezing weather, water in the hole, and the presence of unexploded HE. During the remainder of January 24, manual and mechanical digging reached a depth of eight feet, where a portion of the main body section and pieces of the nose section were found.

The following day, at a depth of 12 feet, the top of the parachute pack was exposed. Adverse weather and a rising water table hindered recovery operations on January 26; however, digging reached 15 feet where the parachute pack, a section of the nose, and pieces of the primary and HE were recovered.

By January 28, digging had reached a depth of 18 feet and detonators, two arm/safe switches, trajectory arming device, more pieces of HE and the primary, and a tritium bottle were found. One of the arm/safe switches was found in the “armed” position.

The remainder of the primary and HE was recovered at a depth of 20 feet on January 29; the pit was found intact the following day. The crater was now 22 feet deep, 50 feet wide, and 70 feet long.

By February 7, digging had resulted in the excavation of a crater 42 feet deep and 200 feet in diameter. Recovery operations were canceled at this time because of cave-ins, freezing weather, equipment limitations, and rising water. The recovered bomb parts, including an undamaged tritium reservoir and the weapon’s afterbody, were taken to the AEC's Medina Base near San Antonio, Texas.

Uncontrollable flooding of the crater caused by a high local water table made further excavation impractical despite 14 pumps removing a combined total of 6,000 gallons of water per hour and further retrieval work was halted on May 25. Calculations based on the weight and configuration of the secondary, impact angle and velocity, and soil composition placed the missing bomb component at a depth of 180+10 feet. The probable minimum estimated cost of recovery was in the neighborhood of $500,000.

The Air Force subsequently purchased an easement to prevent digging in the vicinity of the point of impact. The missing weapon secondary was never located. (During a later accident, LASL told the Air Force that thermonuclear weapon secondaries were "virtually indestructible.") There was no detectable radiation in the area.

Chuck Hansen, “The Swords of Armageddon,” Vol. VII, pp.264-266.