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.
4. To qualify as "accident", the damage should not be intentional, unlike in nuclear warfare.

• June 23, 1942 – Leipzig, Germany (then Nazi Germany) – Steam explosion and reactor fire

• 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.^[1][2]

• August 21, 1945 – Los Alamos National Laboratory, Los Alamos, New Mexico, USA – Accidental criticality

• 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.^[3]

• May 21, 1946 – Los Alamos National Laboratory, Los Alamos, New Mexico, USA – Accidental criticality

• 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, yet three died within a few decades from conditions believed to be radiation-related.^[4]

In the above incidents, both Daghlian (August 21, 1945 case) and Slotin (May 21, 1946 case), were working with the same bomb core which became known as the "demon core".

• February 13, 1950 – British Columbia, Canada – Non-nuclear detonation of a simulated atomic bomb

• A USAF B-36 bomber, AF Ser. No. 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 six engines at an altitude of 12,000 feet (3,700 m). Fearing that severe weather and icing would jeopardize a safe emergency landing, the weapon was jettisoned over the Pacific Ocean from a height of 8,000 ft (2,400 m). 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.^[5]

• April 11, 1950 – Albuquerque, New Mexico, USA – Loss and recovery of nuclear materials

• Three minutes after departure from Kirtland Air Force Base in Albuquerque a USAF 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 15 miles (24 km). 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.^[5]

• July 13, 1950 – Lebanon, Ohio, USA – Non-nuclear detonation of an atomic bomb

• USAF B-50 aircraft on a training mission from Biggs Air Force Base with a nuclear weapon flew into the ground resulting in a high explosive detonation, but no nuclear explosion.^[6]

• November 10, 1950 – Rivière du Loup, Québec, Canada – Non-nuclear detonation of an atomic bomb

• Returning one of several U.S. Mark 4 nuclear bombs secretly deployed in Canada, a USAF B-50 had engine trouble and jettisoned the weapon at 10,500 feet (3,200 m). The crew set the bomb to self-destruct at 2,500 ft (760 m) and dropped over the St. Lawrence River. The explosion shook area residents and scattered nearly 100 pounds (45 kg) of depleted uranium used in the weapon's tamper. The plutonium core ("pit") was not in the bomb at the time.^[7]

• March 1, 1954 – Bikini Atoll, Republic of the Marshall Islands (then Trust Territory of the Pacific Islands) – Nuclear test accident

• 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 15 megatons of TNT (63 PJ). Of the total yield, 10 Mt (42 PJ) 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 not evacuated before the explosion due to the financial cost involved, but many of the Marshall Islands natives have since suffered from radiation burns and radioactive dusting and also similar fates as the Japanese fishermen and their children and grandchildren have suffered from birth defects and have received little if any compensation from the federal government^{[citation needed]}. A Japanese fishing boat, Daigo Fukuryu Maru/Lucky Dragon, 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. Personal accounts of the Rongelap people can be seen in the documentary Children of Armageddon.

• November 29, 1955 – Idaho, USA – Partial meltdown

• 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 significant repair.^[8][9]

• March 10, 1956 – Over the Mediterranean Sea – Nuclear weapons lost

• A USAF B-47 Stratojet, AF Ser. No. 52-534, on a non-stop mission from MacDill Air Force Base to an overseas base descended into a cloud formation at 14,000 feet over the Mediterranean in preparation for an in-air refuelling and vanished while carrying two nuclear weapon cores. The plane was lost while flying through dense clouds, and the cores and other wreckage were never located.^[10][11][12]

• July 27, 1956 – Lakenheath in Suffolk, UK – Nuclear weapons damaged

• A USAF 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.^[13]

• May 22, 1957 – Kirtland AFB in New Mexico, USA – Non-nuclear detonation of an atomic weapon

• A B-36 ferrying a nuclear weapon from Biggs AFB to Kirtland AFB dropped a nuclear weapon on approach to Kirtland AFB. The weapon impacted the ground 4.5 miles south of the Kirtland control tower and 0.3 miles west of the Sandia Base reservation. The weapon was completely destroyed by the detonation of its high explosive material, creating a crater 12 feet deep and 25 feet in diameter. Radioactive contamination at the crater lip amounted to 0.5 milliroentgen.^[12]

• July 28, 1957 – Atlantic Ocean – Two weapons jettisoned and not recovered

• A USAF C-124 aircraft from Dover Air Force Base, Delaware was carrying three nuclear bombs over the Atlantic Ocean when it experienced a loss of power. The crew jettisoned two nuclear bombs to protect their safety, which were never recovered.^[6]

• September 11, 1957 – Rocky Flats Plant, Golden, 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 27 kilometres (17 mi) 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.^{[14][15][16][17]}

• 29 September 1957 – Kyshtym, Chelyabinsk Oblast, Russia (then USSR) – Explosion, release of nuclear materials
  • See Kyshtym disaster. 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.^[18]
• October 8–12, 1957 – Sellafield, Cumbria, UK – Reactor core fire

• See Windscale 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 led 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 200-square-mile (520 km²) 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.^[19][20][21]

• October 11, 1957 – Homestead Air Force Base, Florida – Nuclear bomb burned after B-47 aircraft accident^[22]

• B-47 aircraft crashed during take-off after a wheel exploded; one nuclear bomb burned in the resulting fire.

• January 31, 1958 – Morocco – Nuclear bomb damaged in crash^[22]

• During a simulated takeoff a wheel casting 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.^[23][24]

• February 5, 1958 – Savannah, Georgia, USA – Nuclear bomb lost

• See Tybee Bomb. A USAF B-47 bomber jettisoned a Mark 15 Mod 0 nuclear bomb over the Atlantic Ocean after a midair collision with a USAF F-86 Sabre during a simulated combat mission from Homestead Air Force Base, Florida. The F-86's pilot ejected and parachuted to safety. The USAF claimed the B-47 tried landing at Hunter Air Force Base, Georgia three times before the bomb was jettisoned at 7,200 ft (2,200 m) near Tybee Island, Georgia. The B-47 pilot successfully landed in one attempt only after he first jettisoned the bomb. A 3-square-mile (7.8 km²) 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 group of investigators in 2004 claim to have found an underwater object which they think is the bomb.^[25]

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

• A USAF B-47 bomber flying from Hunter Air Force Base in Savannah, Georgia accidentally released a atomic bomb.^[26] A home was destroyed and several people injured but the bomb's plutonium core did not explode.^[27]

• June 16, 1958 – Oak Ridge, Tennessee, USA – Accidental criticality

• 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 ${\displaystyle 1.3*10^{18))$ 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.^[28]

• December 30, 1958 – Los Alamos, New Mexico, USA – Accidental criticality

• During chemical purification a critical mass of a plutonium solution was accidentally assembled at Los Alamos National Laboratory. A chemical operator named Cecil Kelley 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.^[28]

• July, 1959 – Simi Valley, California, USA – Explosion

• The Sodium Reactor Experiment was a pioneering nuclear power plant built by Atomics International at the Santa Susana Field Laboratory, nearby Simi Valley, California. The reactor operated from 1957 to 1964. In July 1959, the reactor suffered a serious incident in which the reactor core was damaged causing the controlled release of radioactive gas to the atmosphere.^[29]

• November 20, 1959 – Oak Ridge, Tennessee, USA – Explosion

• 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 15 grams (0.53 oz) of ²³⁹Pu.

• June 7, 1960 – New Egypt, New Jersey, USA – Nuclear warhead damaged by fire

• A helium tank exploded and ruptured the fuel tanks of a USAF BOMARC-A surface-to-air missile at McGuire Air Force Base, New Jersey. The fire destroyed the missile, and contaminated the area directly below and adjacent to the missile.^[24][30]

• October 13, 1960 – Barents Sea, Arctic Ocean – Release of nuclear materials

• 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).^[31]

• January 3, 1961 – National Reactor Testing Station, Idaho, USA – Accidental criticality, steam explosion, 3 fatalities, release of fission products

• During a maintenance shutdown, the SL-1 experimental nuclear reactor underwent a prompt critical reaction causing core materials to explosively vaporize. Water hammer estimated at 10,000 pounds per square inch (69,000 kPa) struck the top of the reactor vessel propelling the entire reactor vessel upwards over 9 feet (2.7 m) in the air. One operator who had been standing on top of the vessel was killed when a shield plug impaled him and lodged in the ceiling. Two other military personnel were also killed from the trauma of the explosion, once of which had removed the central control rod too far. The plant had to be dismantled and the contamination was buried permanently nearby. Most of the release of radioactive materials was concentrated within the reactor building.

Further information: SL-1

• January 24, 1961 – Goldsboro B-52 crash – Physical destruction of a nuclear bomb, loss of nuclear materials
  • A USAF B-52 bomber caught fire and exploded in midair due to a major leak in a wing fuel cell 12 miles (19 km) north of Seymour Johnson Air Force Base, North Carolina. 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 100-foot (30 m) 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 700 mph (300 m/s) and disintegrated. Its tail was discovered about 20 feet (6 m) 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 55 feet (17 m) 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.^[32]

• March 14, 1961 – 1961 Yuba City B-52 crash
  • USAF B-52 bomber experienced a decompression event that required it to fly below 10,000 feet. Resulting increased fuel consumption led to fuel exhaustion; the aircraft crashed with two nuclear bombs, which did not trigger a nuclear explosion.

• 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 800 °C (1,500 °F), 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.

• May 1, 1962 – Sahara desert, French Algeria – Accidental venting of underground nuclear test
  • The second French underground nuclear test, codenamed Béryl, took place in a shaft under mount Taourirt, near In Ecker, 150 km (100 mi) north of Tamanrasset, Algerian Sahara. Due to improper sealing of the shaft, a spectacular flame burst through the concrete cap and radioactive gases and dust were vented into the atmosphere. The plume climbed up to 2600 m (8500 ft) high and radiation was detected hundreds of km away. About a hundred soldiers and officials, including two ministers, were irradiated. The number of contaminated Algerians is unknown.

• April 10, 1963 – Loss of nuclear reactor
  • Submarine USS Thresher sinks about 190 nmi (220 mi; 350 km) east of Cape Cod, Massachusetts due to improper welds allowing in seawater which forced a shutdown of the reactor. Poor design of its emergency ballast system prevented the ship from surfacing and the disabled ship ultimately descended to crush depth and imploded.

• January 13, 1964 – Salisbury, Pennsylvania and Frostburg, Maryland, USA – Accidental loss and recovery of thermonuclear bombs
  • A USAF B-52 on airborne alert duty encountered a severe winter storm and extreme turbulence, ultimately disintegrating in mid-air over South Central Pennsylvania.^[33] 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 150,000 feet (46 km) above the Indian Ocean.^[34] The satellite's SNAP-9a generator contained 17 kCi (630 TBq)^[35] of ²³⁸Pu (2.1 pounds), which at least partially burned upon reentry.^{[36][37][38][39]} Increased levels of ²³⁸Pu were first documented in the stratosphere four months later. Indeed NASA (in the 1995 Cassini FEIS)^[35] indicated that the SNAP-9a plutonium release was nearly double the 9000Ci added by all the atmospheric weapons tests to that date.^[40][41] The United States Atomic Energy Commission reported a resulting threefold increase in global ²³⁸Pu fallout.^[42][43] All subsequent Transit satellites were fitted with solar panels; RTG's were designed to remain contained during re-entry.

• 8 December 1964 – Bunker Hill Air Force Base, USA – Fire, radioactive contamination

• USAF B-58 aircraft carrying a nuclear weapon caught fire while taxiing. Nuclear weapon burned, causing contamination of the crash area.^[6]

• 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.^[44]

• 11 October 1965 – Rocky Flats Plant, Golden, Colorado, USA – 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
  • A U.S. Navy A-4E Skyhawk aircraft with one B43 nuclear bomb on board fell off the aircraft carrier Ticonderoga into 16,200 feet (4,900 m) of water while the ship was underway from Vietnam to Yokosuka, Japan. The plane, pilot and weapon were never recovered. There is dispute over exactly where the incident took place—the U.S. Defense Department originally stated it took place 500 miles (800 km) off the coast of Japan, but Navy documents later show it happened about 80 miles (130 km) from the Ryukyu Islands and 200 miles (320 km) from Okinawa.^[45]

• January 17, 1966 – Palomares incident – Accidental destruction, loss and recovery of nuclear bombs
  • A USAF 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 12 miles (19 km) 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, 1,500 tonnes (1,700 short tons) 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. 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.^[46]

• January 21, 1968 – 1968 Thule Air Base B-52 crash, Greenland – Loss and partial recovery of nuclear bombs
  • A fire broke out in the navigator's compartment of a USAF B-52 near Thule Air Base, Greenland. The bomber crashed 7 miles (11 km) from the air base, rupturing its nuclear payload of four hydrogen bombs. The recovery and decontamination 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.

• May 22, 1968 – 740 km (400 nmi) southwest of the Azores – Loss of nuclear reactor and two W34 nuclear warheads
  • The USS Scorpion (SSN-589) sank while enroute from Rota, Spain, to Naval Base Norfolk. The cause of sinking remains unknown; all 99 officers and men on board were killed. The wreckage of the ship, its S5W reactor, and its two Mark 45 torpedoes with W34 nuclear warheads, remain on the sea floor in more than 3,000 m (9,800 ft) of water.

• 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, 1968 – Severodvinsk, 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, 1969 – Rocky Flats Plant, Golden, Colorado, USA – Plutonium fire, contamination
  • An accident in which 5 kilograms of plutonium burnt inside a glovebox at Rocky Flats. Cleanup took two years and was the costliest industrial accident ever to occur in the United States at that time.^[47][48][49]

• April 12, 1970 – Bay of Biscay – Loss of a nuclear submarine
  • The Soviet November-class attack submarine K-8 sank during salvage with 52 sailors onboard after suffering fires in two compartments simultaneously. Both reactors were shut down. The crew attempted to hook a tow line to an Eastern Bloc merchant vessel, but ultimately failed.^[50]

• December 18, 1970 – Nevada 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.^[51] A plume of hot gases and radioactive dust was released three and a half minutes after ignition,^[52] 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.^[53] 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.^[54] The three diverging jet stream layers conducted radionuclides across the US to Canada, the Gulf of Mexico and the Atlantic Ocean. Some 86 workers at the site were exposed to radioactivity, but according to the Department of Energy none received a dose exceeding site guidelines and, similarly, radiation drifting offsite was not considered to pose a hazard by the DOE. ^[55] In March 2009, TIME magazine identified the Baneberry Test as one of the world's worst nuclear disasters.^[56]
• December 12, 1971 – New London, Connecticut, USA – Spill of irradiated water
  • During the transfer of radioactive coolant water from the submarine USS Dace to the submarine tender USS Fulton 500 US gallons (1,900 L; 420 imp gal) were spilled into the Thames River (USA).
• 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 1975 – Apra Harbor, Guam – Spill of irradiated water
  • While disabled, the submarine tender USS Proteus discharged radioactive coolant water. A Geiger counter at two of the harbor's public beaches showed 100 millirems/hour, fifty times the allowable dose. ^{[citation needed]}

• August 1976 – Benton County, Washington, USA – Explosion, contamination of worker
  • An explosion at the Hanford site Plutonium Finishing Plant blew out a quarter-inch-thick lead glass window. Harold McCluskey, a worker, was showered with nitric acid and radioactive glass. He inhaled the largest dose of ²⁴¹Am ever recorded, about 500 times the U.S. government occupational standards. 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. He died of natural causes in 1987 at age 75.^[57]

• 1977 – coast of Kamchatka – Loss and recovery of a nuclear warhead
  • The Soviet submarine K-171 accidentally released a nuclear warhead. The warhead was recovered after a search involving dozens of ships and aircraft.^[58]

• January 24, 1978 – North West Territories, Canada – Spill of nuclear fuel
  • Cosmos 954, a Soviet Radar Ocean Reconnaissance Satellite with an onboard nuclear reactor, failed to separate from its booster and broke up on reentry over Canada. The fuel was spread over a wide area and some radioactive pieces were recovered. The Soviet Union eventually paid the Canadian Government $3 million CAD for expenses relating to the crash.

• May 22, 1978 – near Puget Sound, Washington, USA – Spill of irradiated water
  • A valve was mistakenly opened aboard the submarine USS Puffer releasing up to 500 US gallons (1,900 L; 420 imp gal) of radioactive water.

• September 18, 1980 – At about 6:30 p.m., an airman conducting maintenance on a USAF Titan-II missile at Little Rock Air Force Base's Launch Complex 374-7 in Southside (Van Buren County), just north of Damascus, Arkansas, dropped a socket from a socket wrench, which fell about 80 feet (24 m) before hitting and piercing the skin on the rocket's first-stage fuel tank, causing it to leak. The area was evacuated. At about 3:00 a.m., on September 19, 1980, the hypergolic fuel exploded. The W53 warhead landed about 100 feet (30 m) 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 launch complex was destroyed.^[59]
• 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 35 miles (56 km) from Vladivostok in Chazhma Bay, Soviet submarine K-431, a Soviet Echo-class submarine had a reactor explosion, producing fatally high levels of radiation. Ten men were killed, but the deadly cloud of radioactivity did not reach Vladivostok.^[60]
• 1986 – The U.S. government declassifies 19,000 pages of documents indicating that between 1946 and 1986, the Hanford Site near Richland, Washington, released thousands of US gallons of radioactive liquids. Many of the people living in the affected area received low doses of radiation from ¹³¹I.
• October 3, 1986 – 480 miles (770 km) 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 Gorbachev 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 18,000 feet (5,500 m) of water.^[61]
• October 1988 – At the nuclear trigger assembly facility at Rocky Flats in Colorado, two employees and a D.O.E. inspector inhaled radioactive particles, causing closure of the plant. Several safety violations were cited, including uncalibrated monitors, inadequate fire equipment, and groundwater contaminated with radioactivity.

• 1997 – Georgian soldiers suffer radiation poisoning and burns. They are eventually traced back to training sources abandoned, forgotten, and unlabeled after the dissolution 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.^[62]

• August 2000: The Russian Oscar II class submarine Kursk sank in the Barents Sea after an explosion. The investigation showed that a leak of hydrogen peroxide in a torpedo led to an explosion of its fuel, causing the submarine to hit the bottom which in turn triggered the detonation of further torpedo warheads about two minutes later. The Kursk's two nuclear reactors, encased in 13 centimetres (5.1 in) of steel and resiliently mounted to absorb shocks in excess of 50g withstood the explosion, allowing the two reactors to shut down automatically; preventing nuclear meltdown or contamination. All 118 sailors and officers aboard Kursk died.

• 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 Y-12 (now B&W Y-12), a partnership of Babcock & Wilcox and Bechtel, was fined $82,500 for the accident.^[63]

• International Nuclear Event Scale
• List of accidents and incidents involving military aircraft
• List of civilian nuclear accidents
• List of disasters
• List of nuclear reactors – a comprehensive annotated list of the world's nuclear reactors
• Lists of nuclear disasters and radioactive incidents
• Nuclear weapons
• Radiation
• United States military nuclear incident terminology

• ProgettoHumus: From Trinity Test to... List of nuclear explosions in the world
• ProgettoHumus List of all nuclear accidents in the history (updated)
• Bibliography of military nuclear accidents from the Alsos Digital Library for Nuclear Issues
• Official List of accidents involving nuclear weapons from the UK Ministry of Defence
• Schema-root.org: Nuclear Power Accidents 2 topics, both with a current news feed
• US Nuclear Regulatory Commission (NRC) website with search function and electronic public reading room
• International Atomic Energy Agency website with extensive online library
• Concerned Citizens for Nuclear Safety Detailed articles on nuclear watchdog activities in the US
• World Nuclear Association: Radiation Doses Background on ionizing radiation and doses
• Canadian Centre for Occupational Health & Safety More information on radiation units and doses.
• Radiological Incidents Database Extensive, well-referenced list of radiological incidents.
• [2] Bellona's listing of accidents of Soviet / Russian submarines, a fair number of which are nuclear powered. Currently not many are included in the list above.
• 20 Mishaps That Might Have Started Accidental Nuclear War A handy (if somewhat chilling) list of close calls.
• US Nuclear Weapons Accidents list published by the Center for Defense Information (CDI)
• Trinity Atomic Bomb by U.S. National Atomic Museum

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