Definitions

# List of military nuclear accidents

This article lists notable military accidents involving nuclear material. Civilian accidents are listed at List of civilian nuclear accidents. For a general discussion of both civilian and military accidents, see nuclear and radiation accidents.

In listing military nuclear accidents, the following criteria have been adopted:

1. There must be well-attested and substantial health damage, property damage or contamination.
2. The damage must be related directly to radioactive material, not merely (for example) at a nuclear power plant.
3. To qualify as “military”, the nuclear operation/material must be principally for military purposes.

## 1940s

*Shortly after the Leipzig L-IV atomic pile — worked on by Werner Heisenberg and Robert Doepel — demonstrated Germany’s first signs of neutron propagation, the device was checked for a possible heavy water leak. During the inspection air leaked in igniting the uranium powder inside. The burning uranium boiled the water jacket, generating enough steam pressure to blow the reactor apart. Burning uranium powder scattered throughout the lab causing a larger fire at the facility.

*Harry K. Daghlian, Jr. dropped a tungsten carbide brick onto a plutonium core, inadvertently creating a critical mass at the Los Alamos Omega site. He quickly removed the brick, but was fatally irradiated, dying September 15.

*While demonstrating his technique to visiting scientists at Los Alamos, Canadian physicist Louis Slotin manually assembled a critical mass of plutonium. A momentary slip of a screwdriver caused a prompt critical reaction. Slotin died on May 30 from massive radiation poisoning, with an estimated dose of 1,000 rads (rad), or 10 grays (Gy). Seven observers, who received doses as high as 166 rads, survived. Both men, Daghlian and Slotin, were working with the same bomb core which was known as the “demon core”.

## 1950s

*An American B-36 bomber #44-92075 was flying a simulated combat mission from Eielson Air Force Base, near Fairbanks, Alaska, to Carswell Air Force Base in Fort Worth, Texas carrying one weapon containing a dummy warhead. The warhead contained uranium instead of plutonium. After six hours of flight, the bomber experienced mechanical problems and was forced to shut down three of its engines at an altitude of . Fearing that severe weather and icing would jeopardize a safe emergency landing, the weapon was jettisoned over the Pacific Ocean from a height of . The weapon’s high explosives detonated upon impact. All of the sixteen crew members and one passenger were able to parachute from the plane and twelve were subsequently rescued from Princess Royal Island. The Pentagon’s summary report does not mention if the weapon was later recovered.

*Three minutes after departure from Kirtland Air Force Base in Albuquerque a B-29 bomber carrying a nuclear weapon, four spare detonators, and a crew of thirteen crashed into a mountain near Manzano Base. The crash resulted in a fire which the New York Times reported as being visible from The bomb’s casing was completely demolished and its high explosives ignited upon contact with the plane’s burning fuel. However, according to the Department of Defense, the four spare detonators and all nuclear components were recovered. A nuclear detonation was not possible because, while on board, the weapon’s core was not in the weapon for safety reasons. All thirteen crew members died.

*Returning one of several U.S. Mark 4 nuclear bombs secretly deployed in Canada a B-50 had engine trouble and jettisoned the weapon at . The crew set the bomb to self-destruct at and dropped over the St. Lawrence River. The explosion shook area residents and scattered nearly of depleted uranium used in the weapon's tamper. The plutonium core (“pit”) was not in the bomb at the time.

*During the Castle Bravo test of the first deployable hydrogen bomb, a miscalculation resulted in the explosion being over twice as large as predicted, with a total explosive force of . Of the total yield, were from fission of the natural uranium tamper, but those fission reactions were quite dirty, producing a large amount of fallout. Combined with the much-larger-than-expected yield and an unanticipated wind shift radioactive fallout was spread eastward onto the inhabited Rongelap and Rongerik Atolls. These islands were evacuated, but many of the Marshall Islands natives have since suffered from birth defects and have received some compensation from the federal government. A Japanese fishing boat, Daigo Fukuryu Maru, also came into contact with the fallout, which caused many of the crew to take ill with one fatality. The test resulted in an international uproar and reignited Japanese concerns about radiation, especially with regard to the possible contamination of fish.

*Operator error led to a partial core meltdown in the experimental EBR-I breeder reactor, resulting in temporarily elevated radioactivity levels in the reactor building and necessitating a significant repair.

* A B-47 crashed into a storage igloo spreading burning fuel over three Mark 6 nuclear bombs at RAF Lakenheath. A bomb disposal expert stated it was a miracle exposed detonators on one bomb did not fire, which presumably would have released nuclear material into the environment.

• September 11, 1957Denver, Colorado, USA – Fire, release of nuclear materials
• :A fire began in a materials handling glove box and spread through the ventilation system into the stack filters at the Rocky Flats weapons mill from Denver, Colorado. Plutonium and other contaminants were released, but the exact amount of which contaminants is unknown; estimates range from 25 mg to 250 kg.
• September 29, 1957Kyshtym, Chelyabinsk Oblast, Russia (then USSR) – Explosion, release of nuclear materials
• A cooling system failure at the Mayak nuclear processing plant resulted in a major explosion and release of radioactive materials. Hundreds of people died and hundreds of thousands were evacuated.
• October 8–12, 1957 – Sellafield, Cumbria, UK – Reactor core fire
• :. Technicians mistakenly overheated Windscale Pile No. 1 during an annealing process to release Wigner energy from graphite portions of the reactor. Poorly placed temperature sensors indicated the reactor was cooling rather than heating. The excess heat lead to the failure of a nuclear cartridge, which in turn allowed uranium and irradiated graphite to react with air. The resulting fire burned for days, damaging a significant portion of the reactor core. About 150 burning fuel cells could not be lifted from the core, but operators succeeded in creating a firebreak by removing nearby fuel cells. An effort to cool the graphite core with water eventually quenched the fire. The reactor had released radioactive gases into the surrounding countryside, primarily in the form of iodine-131 (131I). Milk distribution was banned in a area around the reactor for several weeks. A 1987 report by the National Radiological Protection Board predicted the accident would cause as many as 33 long-term cancer deaths, although the Medical Research Council Committee concluded that “it is in the highest degree unlikely that any harm has been done to the health of anybody, whether a worker in the Windscale plant or a member of the general public.” The reactor that burned was one of two air-cooled graphite-moderated natural uranium reactors at the site used for production of plutonium.
• January 31, 1958Morocco – Nuclear bomb damaged in crash

*During a simulated takeoff a wheel failure caused the tail of a USAF B-47 carrying an armed nuclear weapon to hit the runway, rupturing a fuel tank and sparking a fire. Some contamination was detected immediately following the accident.

*see Tybee Bomb. A B-47 bomber jettisoned a Mark 15 Mod 0 nuclear bomb over the Atlantic Ocean after a midair collision with an F-86 Sabre during a simulated combat mission from Homestead Air Force Base in Florida. The F-86’s pilot ejected and parachuted to safety. The USAF claimed the B-47 tried landing at Hunter Air Force Base three times before the bomb was jettisoned at near Tybee Island, Georgia. The B-47 pilot maintains he successfully landed in one attempt only after he first jettisoned the bomb. A area near Wassaw Sound was searched for 9 weeks before the search was called off. The bomb was searched for in 2001 and not found. A new group in 2004 claims to have found an underwater object which it thinks is the bomb.

• March 11, 1958 – Florence, South Carolina, USA – Non-nuclear detonation of a nuclear bomb

*A B-47 bomber flying from Savannah, Georgia accidentally released a nuclear bomb after the bomb lock failed. The chemical explosives detonated on impact in the suburban neighborhood of Florence, South Carolina. Radioactive substances were flung across the area. Several minor injuries resulted and the house on which the bomb fell was destroyed. No radiation sickness occurred.

*A supercritical portion of highly enriched uranyl nitrate was allowed to collect in the drum causing a prompt neutron criticality in the C-1 wing of building 9212 at the Oak Ridge National Laboratory Y-12 complex. It is estimated that the reaction produced $1.3 * 10^\left\{18\right\}$ fissions. Eight employees were in close proximity to the drum during the accident, receiving neutron doses ranging from 30 to 477 rems. No fatalities were reported.

*During chemical purification a critical mass of a plutonium solution was accidentally assembled at Los Alamos National Laboratory. The crane operator died of acute radiation sickness. The March, 1961 Journal of Occupational Medicine printed a special supplement medically analyzing this accident. Hand-manipulations of critical assemblies were abandoned as a matter of policy in U.S. federal facilities after this accident.

*A chemical explosion occurred during decontamination of processing machinery in the radiochemical processing plant at Oak Ridge National Laboratory in Tennessee . (Report ORNL-2989, Oak Ridge National Laboratory). The accident resulted in the release of about of 239Pu.

## 1960s

*A helium tank exploded and ruptured the fuel tanks of a BOMARC-A surface-to-air missile at McGuire Air Force Base. The fire destroyed the missile, and contaminated the area directly below and adjacent to the missile.

*A leak developed in the steam generators and in a pipe leading to the compensator reception on the ill-fated K-8 while the Soviet Northern Fleet November-class submarine was on exercise. While the crew rigged an improvised cooling system, radioactive gases leaked into the vessel and three of the crew suffered visible radiation injuries according to radiological experts in Moscow. Some crew members had been exposed to doses of up to 1.8 - 2 Sv (180 - 200 rem).

*During maintenance procedures the SL-1 experimental nuclear reactor underwent a prompt critical reaction causing the water surrounding the core to explosively vaporize. A pressure wave struck the top of the reactor vessel propelling the control rods and entire reactor vessel upwards. One operator who had been standing on top of the vessel was killed when flying control rods pinned him to the ceiling. Two other military personnel supervising the maintenance operations were also killed. See SL-1.

• January 24, 1961Goldsboro, North Carolina – Physical destruction of a nuclear bomb, loss of nuclear materials
• A B-52 bomber caught fire and exploded in midair due to a major leak in a wing fuel cell north of Seymour Johnson Air Force Base. Five crewmen parachuted to safety, but three died—two in the aircraft and one on landing. The incident released the bomber’s two Mark 39 hydrogen bombs. Three of the four arming devices on one of the bombs activated, causing it to carry out many of the steps needed to arm itself, such as the charging of the firing capacitors and, critically, the deployment of a diameter retardation parachute. The parachute allowed the bomb to hit the ground with little damage. The fourth arming device — the pilot’s safe/arm switch — was not activated preventing detonation. The second bomb plunged into a muddy field at around and disintegrated. Its tail was discovered about down and much of the bomb recovered, including the tritium bottle and the plutonium. However, excavation was abandoned due to uncontrollable ground water flooding. Most of the thermonuclear stage, containing uranium, was left in situ. It is estimated to lie around below ground. The Air Force purchased the land and fenced it off to prevent its disturbance, and it is tested regularly for contamination, although none has so far been found.
• July 4, 1961 – coast of Norway – Near meltdown
• The Soviet Hotel-class submarine K-19 suffered a failure in its cooling system. Reactor core temperatures reached , nearly enough to melt the fuel rods, although the crew was able to regain temperature control by using emergency procedures. The incident contaminated parts of the ship, some of the onboard ballistic missiles and the crew, resulting in several fatalities. The movie K-19: The Widowmaker, starring Harrison Ford and Liam Neeson, offers a controversially fictionalized story of these events.
• January 13 1964Salisbury, Pennsylvania and Frostburg, Maryland, USA – Accidental loss and recovery of thermonuclear bombs
• A B-52 on airborne alert duty encountered a severe winter storm and extreme turbulence, ultimately disintegrating mid-air over South Central Pennsylvania. Only the two pilots survived. One crew member failed to bail out and the rest succumbed to injuries or exposure to the harsh winter weather. A search for the missing weapons was initiated, and recovery was effected from portions of the wreckage at a farm northwest of Frostburg, MD.
• April 21 1964 – Indian Ocean – Launch failure of a RTG powered satellite
• A U.S. Transit-5BN-3 nuclear-powered navigational satellite failed to reach orbital velocity and began falling back down at above the Indian Ocean. The satellite’s SNAP generator contained 16 kCi (590 TBq) of 238Pu, which at least partially burned upon reentry. Increased levels of 238Pu were first documented in the stratosphere four months later. The EPA estimated the abortive launch resulted in little 238Pu contamination to human lungs (0.06 mrem or 0.6 µSv) compared to fallout from weapons tests in the 1950s (0.35 mrem or 3.5 µSv) or the EPA’s Clean Air Act airborne exposure limit of 10 mrem (100 µSv). All subsequent Transit satellites were fitted with solar panels.
• January 1965 – Livermore, California, USA – Release of nuclear materials
• An accident at Lawrence Livermore National Laboratory released 300 kCi (11 PBq) of tritium gas. Subsequent study found this release was not likely to produce adverse health effects in the surrounding communities.
• October, 1965Denver, Colorado – Fire, exposure of workers
• A fire at Rocky Flats exposed a crew of 25 to up to 17 times the legal limit for radiation.
• December 5, 1965 – coast of Japan – Loss of a nuclear bomb
• January 17, 1966 – Palomares, Spain – Accidental destruction, loss and recovery of nuclear bombs
• A B-52 carrying four hydrogen bombs collided with a USAF KC-135 jet tanker during over-ocean in-flight refueling. Four of the B-52's seven crew members parachuted to safety while the remaining three were killed along with all four of the KC-135’s crew. The conventional explosives in two of the bombs detonated upon impact with the ground, dispersing plutonium over nearby farms. A third bomb landed intact near Palomares while the fourth fell off the coast into the Mediterranean sea. The US Navy conducted a three month search involving 12,000 men and successfully recovered the fourth bomb. The U.S. Navy employed the use of the deep-diving research submarine DSV Alvin to aid in the recovery efforts. During the ensuing cleanup, of radioactive soil and tomato plants were shipped to a nuclear dump in Aiken, South Carolina. The U.S. settled claims by 522 Palomares residents for \$600,000. The town also received a \$200,000 desalinization plant. This accident would later be called the Palomares hydrogen bombs incident. The motion picture Men of Honor (2000), starring Cuba Gooding, Jr. as USN Diver Carl Brashear, and Robert De Niro as USN Diver Billy Sunday, contained an account of the fourth bomb’s recovery.
• January 22, 1968Thule Air Base, Greenland – Loss and recovery of nuclear bombs
• A fire broke out in the navigator’s compartment of a B-52 south of Thule Air Base, Greenland. The bomber crashed, scattering three hydrogen bombs on land and dropping one into the sea. The recovery effort was complicated by Greenland's harsh weather. Contaminated ice and debris were buried in the United States. Bomb fragments were recycled by Pantex, in Amarillo, Texas. The incident caused outrage and protests in Denmark, as Greenland is a Danish possession and Denmark forbade nuclear weapons on its territory. One warhead was recovered by Navy SEALs and Seabees (U.S. naval engineers) in 1979. An August 2000 report suggests that the other bomb remains at the bottom of Baffin Bay.
• May 24, 1968 – location unknown – loss of cooling, radioactive contamination, nuclear fuel damaged
• During sea trials the Soviet nuclear submarine K-27 (Project 645) suffered severe problems with its reactor cooling systems. After spending some time at reduced power, reactor output inexplicably dropped and sensors detected an increase of gamma radiation in the reactor compartment to 150 rad/h. The safety buffer tank released radioactive gases further contaminating the submarine. The crew shut the reactor down and subsequent investigation found that approximately 20% of the fuel assemblies were damaged. The entire submarine was scuttled in the Kara Sea in 1981.
• August 27, 1968Severodvinsk, Russia (then USSR) – Reactor power excursion, contamination
• While in the naval yards at Severodvinsk for repairs Soviet Yankee-class nuclear submarine K-140 suffered an uncontrolled increase of the reactor’s power output. One of the reactors activated automatically when workers raised control rods to a higher position and power increased to 18 times normal, while pressure and temperature levels in the reactor increased to four times normal. The accident also increased radiation levels aboard the vessel. The problem was traced to the incorrect installation of control rod electrical cables.
• May 11, 1969Denver, Colorado, USA – Plutonium fire, contamination
• An accident in which 5 kilograms of plutonium burnt inside a glove box at Rocky Flats. Cleanup took two years and was the costliest industrial accident ever to occur in the United States at that time.

## 1970s

• December 18 1970Nevada Test Site – Accidental venting of nuclear explosion
• In Area 8 on Yucca Flat, the 10 kiloton "Baneberry" weapons test of Operation Emery detonated as planned at the bottom of a sealed vertical shaft 900 feet below the earth's surface but the device's energy cracked the soil in unexpected ways, causing a fissure near ground zero and the failure of the shaft stemming and cap. A plume of hot gases and radioactive dust was released three and a half minutes after ignition, and continuing for many hours, raining fallout on workers within NTS. Six percent of the explosion's radioactive products were vented. The plume released 6.7 MCi of radioactive material, including 80 kCi of Iodine-131 and a high ratio of noble gases. After dropping a portion of its load in the area, the hot cloud's lighter particles were carried to three altitudes and conveyed by winter storms and the jet stream to be deposited heavily as radionuclide-laden snow in Lassen and Sierra counties in northeast California, and to lesser degrees in northern Nevada, southern Idaho and some eastern sections of Oregon and Washington states. The three diverging jet stream layers conducted radionuclides across the US to Canada, the Gulf of Mexico and the Atlantic Ocean.
• December 12, 1971New London, Connecticut, USA – Spill of irradiated water
• December 1972 – Pawling, New York, USA – Contamination
• A major fire and two explosions contaminated the plant and grounds of a plutonium fabrication facility resulting in a permanent shutdown.
• 1975 – location unknown – Contamination
• Radioactive resin contaminates the American Sturgeon-class submarine USS Guardfish after wind unexpectedly blows the powder back towards the ship. The resin is used to remove dissolved radioactive minerals and particles from the primary coolant loops of submarines. This type of accident was fairly common; however, U.S. Navy nuclear vessels no longer discharge resin at sea.
• October–November 1975 – While disabled, the submarine tender USS Proteus discharged radioactive coolant water into Apra Harbor, Guam. A Geiger counter at two of the harbor's public beaches showed 100 millirems/hour, fifty times the allowable dose.
• August 1976 – An explosion at the Hanford site Plutonium Finishing Plant contaminated several workers. The plant converted plutonium nitrate solutions into metallic form for nuclear weapons production facilities. The explosion blew out a quarter-inch-thick lead glass window that shielded workers from radioactive materials. One 64-year-old worker, Harold McCluskey, was showered with nitric acid and radioactive pieces of glass. The worker inhaled the largest dose of 241Am ever recorded. He inhaled about 500 times the U.S. government occupational standards for the element. The worker was placed in isolation for five months and given an experimental drug to flush the isotope from his body. By 1977, his body’s radiation count had fallen by about 80 percent. When the worker returned home, friends and church members avoided him. His minister finally had to tell people it was safe to be around him. He died of natural causes in 1987 at age 75.
• 1977 – The Soviet submarine K-171 accidentally released a nuclear warhead while off the coast of Kamchatka. After a frantic search involving dozens of ships and aircraft, the warhead was recovered.
• January 24, 1978Cosmos 954, a Soviet Radar Ocean Reconnaissance Satellite with an onboard nuclear reactor, broke up on reentry over Canada; some radioactive pieces were recovered.
• May 22, 1978 – Aboard the submarine USS Puffer near Puget Sound, Washington, a valve was mistakenly opened, releasing up to of radioactive water.

## 1980s

• September 18, 1980 – At about 6:30 p.m., an airman conducting maintenance on the Titan-II missile at Launch Complex 374-7 in Southside (Van Buren County), just north of Damascus, Arkansas, dropped a socket wrench, which fell about eighty feet before hitting and piercing the skin on the rocket’s first-stage fuel tank, causing it to leak. At about 3:00 a.m., on September 19, 1980, the missile exploded. The W53 warhead landed about from the launch complex’s entry gate; its safety features operated correctly and prevented any loss of radioactive material. An Air Force airman was killed, and the complex was destroyed.
• August 8, 1982 – While on duty in the Barents Sea, there was a release of liquid metal coolant from the reactor of the Soviet Project 705 Alfa-class submarine K-123. The accident was caused by a leak in the steam generator. Approximately two tons of metal alloy leaked into the reactor compartment, irreparably damaging the reactor such that it had to be replaced. It took nine years to repair the submarine.
• January 3, 1983 – The Soviet nuclear-powered spy satellite Kosmos 1402 burns up over the South Atlantic.
• August 10, 1985 – About from Vladivostok in Chazhma Bay, a Soviet Echo-class submarine had a reactor explosion, producing fatally high levels of radiation. Ten officers are killed, but the deadly cloud of radioactivity does not reach Vladivostok.
• 1986 – The U.S. government declassifies 19,000 pages of documents indicating that between 1946 and 1986, the Hanford Site in Richland, Washington, released thousands of US gallons (several ) of radioactive liquids. Of 270,000 people living in the affected area, most received low doses of radiation from 131I.
• October 3, 1986 – east of Bermuda, K-219, a Soviet Yankee I-class submarine experienced an explosion in one of its nuclear missile tubes and at least three crew members were killed. Sixteen nuclear missiles and two reactors were on board. Soviet leader Mikhail Gorbachyov privately communicated news of the disaster to U.S. President Ronald Reagan before publicly acknowledging the incident on October 4. Two days later, on October 6, the submarine sank in the Atlantic Ocean while under tow in of water.
• October 1988 – At the nuclear trigger assembly facility at Rocky Flats in Colorado, two employees and a D.O.E. inspector inhale radioactive particles, causing closure of the plant. Several safety violations were cited, including uncalibrated monitors, inadequate fire equipment, and groundwater contaminated with radioactivity.

## 1990s

• 1997 – Georgian soldiers suffer radiation poisoning and burns. They are eventually traced back to training sources abandoned, forgotten, and unlabeled after the collapse of the Soviet Union. One was a 137Cs pellet in a pocket of a shared jacket which put out about 130,000 times the level of background radiation at 1 meter distance.

## 2000s

• February 2003: Oak Ridge, Tennessee Y-12 facility. During the final testing of a new saltless uranium processing method, there was a small explosion followed by a fire. The explosion occurred in an unvented vessel containing unreacted calcium, water and depleted uranium. An exothermic reaction among these articles generated enough steam to burst the container. This small explosion breached its glovebox, allowing air to enter and ignite some loose uranium powder. Three employees were contaminated. BWXT, a partnership of BWX Technologies and Bechtel National, was fined \$82,500 for the accident.