An individual in France places radioactive graphite fuel plugs under the driver's seat of someone else's car. The victim sustains a 25- to 30-rad dose to his spinal bone marrow and 400-500 rads to his testes. The perpetrator is tried and convicted of poisoning by radiation, fined $1,000, and serves 9 months in prison.
Note: This date is uncertain, but is known to be prior to 1980.
During a power failure in Shanghai China, defective interlocks allow a worker to enter the irradiation chamber of a cobalt-60 source. The individual receives a 500-rad whole-body dose and also localized radiation injuries.
Fire destroys a transformer feeding electricity to La Hague reprocessing plant in France. The entire facility goes dark, but the critical loss is the pumps which must run constantly to cool the high-level wastes in storage tanks on-site. The liquid in the tanks begins to boil in three hours. All areas of the plant are contaminated. It takes several months to repair the electrical distribution system.
According to recently discovered documents, the AEC has dumped 12,000 barrels of radioactive waste at 10 previously undisclosed sites in the Pacific. To this date, the only known U.S dump site is south of the Farallon Islands off San Francisco, California. There, one-quarter of the 47,000 barrels have burst.
The USS Gurnard (SSN-662) spills 30 gallons of radioactive water in San Diego Bay. A Navy spokesman says a crewman of the Gurnard accidentally opened a valve, allowing the water to escape. The spokesman says a water sample taken in the area afterward shows normal levels of radioactivity.
Soviet Echo class nuclear-powered submarine K-66 has a reactor problem with radiation leakage 85 miles east of Okinawa. At least nine crew members are believed to have died from a fire in the propulsion compartment. A Soviet freighter arrives to evacuate the crew and a tugboat is readied to tow the stricken vessel to Vladivostok. Several warships stand by as escort.
The next day, the Japanese government advises ships to avoid the area, citing possible contamination. It refuses to allow the convoy to pass through Japanese territorial waters unless Moscow guarantees there are no nuclear weapons aboard and no danger of radiation leaks. The Soviets initially refuse, and their vessels enter Japanese waters. But on 24 August, to defuse the confrontation, Moscow issues the requested guarantee. Reportedly, Japanese forces later find evidence of radioactive contamination.
A BBC television programme alleges that plutonium was lost from an experimental reactor at Dounreay, Scotland in 1973 and 1977. The director of the facility, although unsure of the whereabouts of the fuel rods, remains adamant that they have not been stolen.
A B-52H carrying nuclear-armed AGM-69 short range attack missiles catches fire on the ground during an alert exercise at Grand Forks AFB, North Dakota. Fed by jet fuel from the number three main wing tank, the fire burns intensely for three hours and is only suppressed when the fuel flow stops. However, firefighters are aided by a strong favorable wind and prevent the flames from reaching the missiles.
An Air Force repairman doing routine maintenance in a Titan II ICMB silo near Damascus, Arkansas drops a wrench socket which rolls off a work platform and falls to the bottom of the silo. The socket strikes the missile on the way down, causing a leak of the volatile and toxic fuel in a pressurized tank. The launch complex and the surrounding area are evacuated. Roughly eight hours later, fuel vapors in the silo ignite, blowing off the two 670-ton silo doors and hurling the missile's 9-MT warhead 600 feet. The explosion kills an Air Force specialist and injures 21 other USAF personnel. The silo is filled in with gravel and operations are transferred to a similar installation at Rock, Arkansas.
Two canisters containing radioactive materials fall off a truck on New Jersey's Route 17, which traverses a number of suburban communities near New York City. The driver, en route from Pennsylvania to Toronto, Canada, does not notice the cargo loss until he reaches Albany, NY.
The Unit #2 reactor at Indian Point nuclear power plant, 30 miles up the Hudson from New York City, is shut down due to a series of mishaps that begins on 3 October. The accident results in 100,000 gallons of water spilling from the secondary coolant loop into the containment building. Indian Point officials do not report these events until several days after the shutdown.
The Royal Navy nuclear-powered attack submarine HMS Dreadnought suffers serious machinery damage—reportedly cracks in her secondary cooling system—which necessitate a complete reactor shutdown. This extensive damage and problems with scheduling a refit lead to the aging submarine being retired.
During a test, about 150 gallons of low-level radioactive water leak from a faulty valve on the USS Hawksbill (SSN-666). The ship is being overhauled at the Puget Sound Naval Shipyard. Five workers receive low-level contamination. A Navy spokesman says their doses are "less than that typically received by a chest X-ray."
An Auxiliary Unit Operator, working his first day on the job without proper training, inadvertently opens a valve and more than 110,000 U.S. gallons of radioactive coolant spray into the containment building of the Tennessee Valley Authority's Sequoyah 1 nuclear power plant in rural Tennessee. Eight workers are contaminated with radiation.
Failure to close a valve at the Tsuruga processing plant allows over 4,000 gallons of highly radioactive water to leak from a storage tank onto the floor of the waste reprocessing building. The water escapes the building through a manhole cover and a crack in the floor to wind up in Urazoko Bay, where high levels of cobalt-60 and manganese-54 are later found in the bay's edible seaweed. The leak is not noticed for three hours. During that time, 56 plant workers are exposed, receiving an average dose of 10 mRem.
The accident is not disclosed to the public until 18 April. Shortly afterward, six officials of Japan Atomic Power Corporation, including the Tsuruga plant's director, are replaced because of their roles in the cover-up. It is also found that serious incidents have occurred previously at the plant.
A technician in Saintes, France is changing the cobalt-60 source in a teletherapy machine. The source falls to the floor and the technician picks it up, holding it for 11 seconds. His hands receive a dose of over 10,000 rads, and both have to be amputated. Another worker also has to have both hands amputated, and a third loses three fingers. Eight other workers in the room receive doses of 1 to 100 rads.
The USS George Washington (SSBN-598) collides with the 2,350-ton Japanese freighter Nissho Maru in the East China Sea about 110 miles south-southwest of Sasebo, Japan. The freighter's hull is holed and it sinks in 15 minutes, killing two Japanese crewmen. Another 13 are rescued. The submarine suffers minor damage to its sail.
The incident, a month before a scheduled meeting between Prime Minister Zenko Suzuki and President Ronald Reagan, sparks a political furor in Japan. The United States is criticized because:
It took 24 hours to notify Japanese authorities;
Neither the submarine nor a P-3 Orion aircraft overhead made any attempt at rescue;
The submarine was operating so close to Japan, less than 20 miles outside its territorial waters.
The Navy initially says the George Washington surfaced but could not see any ship in distress becasue of fog and rain. President Reagan and other U.S. officials express regret over the accident, offer compensation and reassure the Japanese that there is no cause for worry about radioactive contamination. However, they do not explain what the submarine was doing so close to Japan or whether it carried nuclear weapons. (The George Washington is capable of carrying 16 ballistic missiles with 10 warheads each.)
Over the next several months, as the controversy continues, the Navy: accepts responsibility to preclude length litigation; is criticized for its preliminary report which says the submarine and Orion claimed not to have realized the freighter was sinking; relieves and reprimands the submarine's commander and officer of the deck. On 31 August the Navy releases a final report which concludes that the accident resulted from a highly coincidental set of circumstances, compounded by errors on the part of some members of the submarine's crew.
A hairline crack is discovered in the main cooling system of the Royal Navy nuclear-powered attack submarine HMS Valiant as it returns to Devonport after developing a fault in its cooling system while operating off the Cornish coast. The crack does not affect reactor operation and the vessel returns to port under its own power. The Royal Navy denies claims that contaminated water was discharged into Plymouth Sound, saying "A very small quantity of water leaked out [from the reactor] and this was drained off into a lead tank in a barge for treatment.
A Marine EA-6B Prowler aircraft crashes while landing on the USS Nimitz (CVN-68) operating 70 miles off Jacksonville, Florida, killing 14 and injuring 48. The Prowler reportedly applies power when landing and veers to the right, running into parked aircraft and causing ammunition to explode. The fires take an hour to extinguish. A total of $100 million in damage is done, with three F-14 Tomcats destroyed and 16 other aircraft damaged. The Nimitz returns to Norfolk, Virginia for several days of repairs. The crash sparks a five-month debate between the Navy and Rep. Joseph D. Addabo (D-NY), Chairman of the House Defense Appropriations Subcommittee, over whether drug use aboard the carrier may have been a contributing factor.
Douglas Crofut, an unemployed radiographer in Tulsa, Oklahoma, steals an industrial iridium-192 radiography source. The exposure he receives as a result proves fatal. The source suggests that this is intentional.
K-122 surfaces in the Philippine Sea after a fire disables its propulsion system. The Echo-I class nuclear-powered submarine must be towed back to port for repairs. Reports indicate as many as 15 crewmen die.
The USS Dallas (SSN-700) damages the lower portion of its rudder when it runs aground while approaching the Atlantic Underwater Test and Evaluation Center site at Andros Island in the Bahamas. After several hours, the submarine works itself free and returns on the surface to New London, CT for repairs.
"According to raw CIA intelligence reports", a Soviet nuclear submarine operating in the Baltic Sea undergoes "a series of strong and sudden physical shocks". Following these, the submarine lies dead in the water and is taken under tow, but only moved during the hours of darkness. It arrives at Kaliningrad after 36 hours. There, some sailors are removed from a sealed compartment and flown to Riga, Latvia, where they are hospitalized. The CIA reports that all of these sailors show signs of terminal radiation sickness.
Windscale reprocessing plant releases iodine-131 into local area at 300 times normal rate. The radioactive iodine contaminates milk supplies within a 2-mile radius of the plant in Cumbria, England. British Nuclear Fuels, Ltd. does not announce the leak until 8 October.
A Soviet Whiskey-class diesel-powered attack submarine runs aground 10 km from the Swedish naval base of Karlskrona, 300 km south of Stockholm. The Swedes impound the submarine and question her captain. He claims that bad weather and a faulty compass led to the inadvertent intrusion into Swedish waters. Swedish authorities contend that the vessel would not have made it so far without good navigation. They charge it was involved in illegal reconnaissance or mine-laying operations and demand an apology from the Soviet Union.
On 29 October, a Soviet tug is turned back by Swedish warships. Another submarine is detected in Swedish waters and is pursued by antisubmarine warfare helicopeters until it disappears. On 2 November the submarine is refloated by Swedish tugboats to prevent heavy seas from battering it against the rocks.
On 5 November, Sweden's Foreign Minister Ullsten announces that the intruding submarine probably carries nuclear weapons, and wonders publically what this says about the Soviets, who "have created the impression that they are more in favor than the United States" of arms control. Sweden releases the sub on 6 November and states that Soviet proposals in regard to the Baltic as a "sea of peace" are no longer credible. It is reported on 6 May 1982 that the USSR paid Sweden costs of $212,000 arising from the incident.
At Holy Loch, Scotland, a Poseidon ballistic missile is being moved aboard the submarine tender USS Holland (AS-32). An error by the crane operator drops the fully armed missile 13 to 17 feet; the fall is arrested by a safety device. Civilian observers warn that, had the missile struck the deck, a serious explosion with dispersal of radiation could have occurred. The Poseidon warhead uses an unstable conventional explosive known as LX-09. The U.S. Navy refuses to confirm or deny whether there were nuclear weapons on the missile and states "There was no damage done, no injuries occurred; there was no danger to personnel."
Pacific Gas and Electric (PG&E) reveals that blueprints for the Unit 1 reactor at Diablo Canyon have somehow been switched with those for Unit 2, now under construction. The mixup affects stress calculation for piping hangers in both reactors, and causes startup of Unit 1 to be postponed until further notice. The Nuclear Regulatory Commission is also investigating improper construction and the plant's ability to withstand an earthquake, since it was built on a previously unknown fault line.
While attempting to change tubes in an x-ray machine in La Plata, Argentina, the operator looks through the machine's window, not realizing it is powered up. He receives a whole-body dose of 12 rads and 580 rads to the lenses of his eyes, resulting in later development of cataracts.
A steam pipe breaks at Rochester Gas & Electric's Robert E. Ginna nuclear power plant in Ontario, New York, spilling 15,000 gallons of radioactive coolant water on the plant floor. Small amounts of radioactive steam escape into the air.
The USS Jacksonville (SSN-699) collides with the Turkish cargo ship General Z. Dogan while running on the surface 25 miles east of Cape Charles, Virginia. Damage to the Jacksonville is minor and characterized as "bumps and scrapes", while bow damage is reported on the General Z. Dogan.
The Soviet Project 705 Alfa-class submarine K-123 is on duty in the Barents Sea when a leak develops in her steam generator. This leads to a release of two tons of liquid metal coolant from the reactor. Presumably the sub is disabled and has to be towed home, and at least some of the crew is severely exposed. What is known is that it takes nine years to cool down and replace the irreparably damaged reactor, and to make other needed repairs.
In order to fix a jammed conveyer belt, an employee of the gamma-irradiation facility at the Institute for Energy and Technology in Kjeller, Norway enters the irradiation chamber when a 65.7-kCi cobalt-60 source is in unshielded position. The victim receives an estimated whole-body radiation dose of 2.5Sv (about 1,000 rem) and dies after 13 days.
The USS Sam Houston (SSN-609) spills less than 50 gallons of low-level radioactive water while it is in the Puget Sound Naval Shipyard at Bremerton, Washington for routine maintenance. The spill is stopped, the water is contained within the ship, and no radiation is released to the environment. Two individuals are in the area during the spill; one receives low-level exposure. The submarine's reactor is not operating at the time.
At the International Neutronics plant in Dover, New Jersey, radiation is used to treat gems for color, modify chemicals, and sterilize food and medical supplies. There is an accident involving a pump siphoning solution from the process baths to the plant's floor. The entire plant is contaminated, and contaminated water subsequently enters Dover's water system. Company executives conceal this event, and the Nuclear Regulatory Commission only learns of it from a whistleblower ten months later. The company and one of its top executives are convicted by a federal court in 1986 of conspiracy and fraud. Radiation remains in the vicinity of the plant, but the NRC says the levels are not hazardous.
The USS Thomas A. Edison (SSN-610) collides with the USS Leftwich (DD-984) 40 miles east of the U.S. naval base at Subic Bay, Philippines. The Edison is at periscope depth preparing to surface; it damages its sail and sail planes, but there is no flooding. Both ships remain operational after the accident.
The Department of Energy confirms that 1,200 tons of mercury have been released over the years from the Y-12 Nuclear Weapons Components Plant at Oak Ridge National Laboratory. In 1987, the DOE further reports that PCBs, heavy metals, and radioactive substances are in the groundwater beneath Y-12. It and the nearby K-25 and X-10 plants have contaminated the atmosphere, soils and streams in the area.
Kosmos 1402, a nuclear reactor-powered radar ocean reconnaisance satellite (or RORSAT), is launched by the Soviet Union on 30 August 1982. Like the other 31 RORSATs, its reactor core is designed to separate and boost itself to a higher orbit where it will remain for hundreds of years while the fission products decay to safe levels. However, the core fails to perform this maneuver. Ground operators manage to detach it from Kosmos 1402, making it more likely to disintegrate, but it remains in the same orbit. The satellite reenters in two pieces on 30 December 1982 and 23 January 1983. The reactor core follows on 7 February 1983. All three pieces either burn up completely or fall into the ocean. The core enters the Atlantic 1,600km east of Brazil; much of its 50kg of U-235 apparently burns up in the atmosphere. Aside from a temporary elevation of uranium in air samples taken in the area, no significant contamination from it has been detected.
There was a French claim that a large piece had been found, but that turned out to be a fragment of a disco ball that fell off a truck.
Note: Greenpeace dates this event as 27 Feb 1983. I accordingly moved it ahead by 1 slot.
During a problem at the Salem nuclear power plant in Salem, New Jersey, the Nuclear 1 reactor fails to shut down automatically. However, an operator spots the trouble and shuts it down manually 90 seconds before an "incident" can occur. The automatic shutdown had failed three days previously, and the plant released radioactive gas in March 1981 and September 1982.
British journalists claim they have evidence that Australian aborigines were exposed to fallout during Britain's atomic-bomb testing between 1953 and 1962. Some of the aborigines were reportedly burned, blinded, and even killed. Previously secret documents reportedly say that pellets containing cobalt-60 were left scattered around the test site. The Ministry of Defense admits that fallout from the "Totem 1" tests passed over aborigine encampments 160km northeast of the test site.
Soviet nuclear-powered cruise missile submarine K-429 (Charlie class) floods and sinks somewhere east of Sarannaya Bay off Petropavlosk naval base, near the southern tip of the Kamchatka Peninsula in the Pacific. Daring work by the captain and rescue divers rescues 104 of the 109 aboard, most of whom escape through torpedo tubes and make a free 150-foot ascent. The cause of the sinking is not known, but the absence of radioactive contamination in the area indicates that it probably is mechanical failure, not a reactor accident.
The Soviet navy salvages the vessel in early August 1983. She sinks again on 13 September while moored at home port; her captain is jailed for this accident. K-429 is again raised and leased to India, where she is renamed Chakra.
A private research group in the U.S., the Fund for Constitutional Government reports that U.S. Navy nuclear ships have leaked radiation at least 37 times. The leaks reportedly contaminated coastal and inshore waters of Japan, Britain and the U.S. on more than a dozen occasions. The FCG's report accuses the Navy of "suppressing information about a 30 year history of radiation accidents and safety problems."
Located in Buenos Aires, Argentina, the RA-2 Facility houses a low-power (the source says "essentially zero power") experimental reactor assembly. This can hold 19 fuel-element plates, but four of them are normally removed and two cadmium plates inserted for reaction-rate control. There is also a graphite reflector. The reactor vessel is filled with de-mineralized water for tests and is supposed to be drained during changes in fuel-plate configuration, or whenever people are in the room.
The reactor technician, a qualified operator with 14 years experience, is alone in the room making such a configuration change. The tank has not been drained. He inserts two new fuel-element plates while the cadmium plates are not installed. Criticality is apparently achieved during insertion of the second plate, since it is found partially inserted. The excursion yields approximately 4.5x1017 fissions. The operator's exposure, mostly on the upper right side of his body, is 2,000 rad from gamma rays and 1,700 from neutrons. He dies two days later. Two people in the control room receive doses of about 15 rad from neutrons and 20 from gamma rays. Six others receive smaller doses, down to 1 rad, and nine receive less than one rad.
El Señor Vicénte Soledo Alardín is a scrap dealer in Juarez, Mexico. Unfamiliar with the dangers of radioactive materials, he removes the source from a radiation therapy machine he has acquired. The source consists of 6,010 pellets of cobalt-60 encased in a tungsten shell. This shell is damaged during the dismantling process. When Sr. Alardín drives to the salvage yard Jonke Fénix to sell his prize, some of the pellets spill in the bed of his truck and onto the roads. Each of them reportedly contains 70 microcuries of isotope and can deliver a dose of 25 R/h at close range.
The junkyard operator is equally unfamiliar with radioisotopes. During processing, more pellets are scattered throughout the yard, contaminating 60 employees and most of the metal at the facility. Meanwhile, Sr. Alardín's truck is parked elsewhere for two months with a flat tire. It contaminates another 200 people who live and work nearby. Some of their exposures are the largest ever recorded in Mexico. The truck is later found to emit 50R/h at a distance of one meter.
Scrap from the junkyard is sold to a smelting facility, contaminating 5,000 tons of steel with an estimated 300 curies of activity. The steel is made into building materials and legs for kitchen tables. Some of it winds up in the U.S. and Canada. The situation is only discovered months later when a truck delivering building materials to Los Alamos National Laboratory takes a wrong turn and drives through a radiation monitor, setting off an alarm.
Using special airborne detection equipment loaned by the U.S. Department of Energy, the Mexican government locates hot spots along the roads used to transport the original source. In some cases the highways have to be torn up to recover pellets embedded in the road surface. Mexico also condemns 109 houses in the state of Sinaloa due to contaminated building materials. The incident prompts the U.S. Customs Service and the NRC to install radiation detection equipment at all major border crossings.
Note: If the rating and quantity for the pellets are correct, there's no way they can add up to 300 Curies. My guess is the rating for each pellet should be 7,000 µCuries. This allows for a loss of about one-quarter of the pellets on the way to Jonke Fénix.
Information published in the Austrian Daily Courier and said to be confirmed by Czech opposition parties reveals that 30 Soviet soldiers died in a nuclear explosion on 24 May 1983. The explosion is thought to be caused by a Soviet short-range nuclear missile.
The U.S. Navy's Nuclear Weapons Training Group Atlantic submits an "OPREP-3 Navy Blue Bent Spear" (reports a lost nuclear weapon) as a result of a failure in a W80 trainer warhead for the Tomahawk ship-launched cruise missile.
At a fossil-fuel power plant under construction in Mohammedia, Morocco, iridium-192 sources are being used to radiograph welds. One of these sources, containing approximately 30 curies of iridium-192, apparently becomes disconnected from its drive cable and is not properly returned to its shielded container. Subsequently, a passing laborer notices the tiny metal cylinder on the ground and takes it home. During May and June of 1984, a total of eight persons, including the laborer and his entire family and some relatives, die with the clinical diagnosis of "lung hemorrhages." Other individuals also receive significant doses of radiation that require medical attention. Three severely exposed individuals are hospitalized at the Curie Institute in Paris and later released in apparently satisfactory condition.
It is initially assumed that the deaths are the result of poisoning. Only after the last family member has died is it suspected that the deaths might be due to radiation. The source is recovered in June 1984. Although the source container is marked by the internationally recognized radiation caution symbol, the source itself bears no markings.
There is no information available on the precautionary radiation surveys that may have been performed at the time of the incident. However, it is apparent from the stated facts that radiation surveys of the type described in the NRC regulations, if performed, would have disclosed the problem and may have prevented the incident.
The USS Kitty Hawk (CV-63) is struck during night operations by a surfacing Soviet Victor-I class nuclear-powered attack submarine in the southern Sea of Japan, approximately 100 miles west of mainline Japan, while en route to the Yellow Sea. The Kitty Hawk sustains a minor hole below the water line in an aircraft fuel tank on her starboard side and continues normal operations. The Soviet vessel is observed dead in the water with a dent across its aft deck. It is aided by the Soviet Kara class cruiser Petropavlovsk and later towed by a Soviet salvage vessel to the naval base at Vladivostok. U.S. Navy officers say there is no evidence of leakage from the submarine.
The Kitty Hawk and her carrier group are taking part in joint U.S.-Korean "Team Spirit 84" exercises. The submarine, along with Soviet surface ships, has been follwoing these exercises for several days. Navy officials report that, after simulating its destruction 15 times, carrier group ships break contact with the submarine to enter a new phase of maneuvers in which the Kitty Hawk attempts to evade the trailing Soviet surface ships. The submarine apparently loses track of the Kitty Hawk during this phase and surfaces in order to locate her, causing the collision.
The Glasgow Herald reports that paint on the USS Sam Rayburn (SSN-635) is mildly radioactive when it returns from patrol in February 1984. The Navy says this radiation is so mild it cannot be detected by a Geiger counter. Rumors have been circulating that the submarine was involved in a collision in the fall of 1983. The Navy statement adds to the controversy.
A fire breaks out aboard the USS Guitarro (SSN-665) during a training exercise 65 miles northwest of San Diego, California, near San Clemente Island. A sailor making rounds discovers heat, steam and a glow coming from the battery well when he opens a well hatch. The submarine heads for port. By the time it gets there, the fire is under control but still burning.
While fishing in the Sea of Japan, the Japanese shrimping boat Sumiyoshi Maru catches a submarine in its net and is pulled backward until the 3-cm cable supporting the net is cut. On 20 September a Soviet Golf-II diesel-powered ballistic missile submarine is observed on the surface in the Sea of Japan, 380 miles west of Tokyo, with white smoke coming from its conning tower. Over the next two days it is attended by several Soviet ships. It proceeds toward Vladivostok under its own power on 23 September. Reports speculate that the problem was an electrical overload caused by its tussle with the Sumiyoshi Maru.
A Soviet Victor-I class nuclear-powered attack submarine is badly damaged when it collides with a Soviet tanker in the Strait of Gibraltar. The collision rips off the twin-hulled submarine's bow section, exposing the sonar and torpedo-tube compartments. It proceeds to the Soviet anchorage at Hammament, Tunisia for emergency repairs, and returns to its home port on the Kola Peninsula in early October.
Reports are that the submarine was travelling in the "noise shadow" of the tanker to avoid detection while exiting the Mediterranean Sea. Jane's Defense Weekly notes that the alternating layers of cold and warm water in the narrow Strait make it likely for a submarine "to encounter sudden thermal gradients which make her porpoise upwards," and this is thought to be the cause of the accident.
The USS Jacksonville (SSN-699) collides with a Navy barge off Norlolk, Virginia while travelling on the surface. The submarine strikes the barge amidships and reportedly sustains minor damage to her bows.
The Fernald Uranium Plant, a 1,050-acre uranium fuel production complex 20 miles northwest of Cincinnati, Ohio is temporarily shut down after the Department of Energy discovers that excessive amounts of radioactive materials have been released through ventilation systems. Subsequent reports document the following discharges into the valley of the Greater Miami River over the previous thirty years:
39 tons of uranium dust released into the atmosphere;
83 tons of uranium dust released into surface water;
230 tons of radioactive substances released into pits and swamps;
5,300 tons of hazardous chemicals released into pits and swamps.
Significant quantities of the radioactives and other hazardous materials in those pits and swamps find their way into local groundwater.
In addition, 337 tons of uranium hexafluoride are found to be unaccounted for, their whereabouts completely unknown. Residents of the valley sue in 1988 and are granted a $73 million settlement by the government. Plant operations are not shut down permanently until 1989.
A 61-year-old woman is undergoing therapy in Marietta, Georgia. The software controlling the Therac 25 radiation therapy accelerator has a defect allowing overexposure under certain conditions. The woman receives a dose of 15,000 to 20,000 rads and immediately reports pain. Clinic personnel do not recognize the accident until days later when the woman develops radiation burns. She loses one breast and suffers permament impairment.
Both main feedwater pumps in the cooling system at Davis-Besse nuclear power plant in Ohio shut down in succession. An operator makes mistakes in trying to start the emergency pumps, causing them to shut down as well. Had backup systems not functioned properly, a meltdown could have resulted. The NRC ultimately classifies the event as a "site area emergency."
The Royal Navy nuclear-powered ballistic missile submarine HMS Resolution is struck by the American yacht Proud Mary off Cape Canaveral, Florida in the early morning. The submarine suffers only minor damage, but the yacht has to be towed back to port. Fresh from a major refit at the naval shipyard in Rosyth, Scotland, the Resolution is en route to a position from which it can test-fire one of its Polaris missiles down the Atlantic Missile Range.
A defect in the computer program controlling the Therac 25 radiation therapy accelerator causes overexposure of a patient at the Ontario Cancer Foundation in Hamilton, Ontario, Canada. The 40-year-old woman, being treated for cancer, receives a localized dose of 13,000 to 17,000 rads and quickly reports pain. Operators do not recognize the problem until the woman returns to the clinic with radiation burns on 29 July. She dies of the original cancer on 3 November 1985.
The Project 671 Victor-I class submarine K-314 is at the Chazma Bay naval yard outside Vladivostok. During refueling operations, the reactor goes critical because control rods have been incorrectly withdrawn when the reactor lid is raised. The ensuing explosion releases large amounts of radioactivity, contaminating an area 6km in length on the Shotovo Peninsula and the sea outside the naval yard. Fortunately, the cloud does not reach Vladivostok. Ten people working on the vessel die in the accident. The damaged reactor compartment still contains its nuclear fuel.
A defect in the computer program controlling the Therac 25 radiation therapy accelerator causes overexposures to patients. A woman who receives several treatments from September 1985 until 6 January 1986 at Yakima Valley Memorial Hospital in Yakima, Washington suffers burns. Her injuries are not recognized as radiation burns until she suffers another injury in 1987.
The reactor of the nuclear-powered cruise missile submarine K-431 (Project 675 Echo-II class) overheats while the vessel is returning to base at Vladivostok. It is now laid up at the naval base in Pavlosk.
A container of highly toxic gas explodes at the Sequoyah Fuels Corporation uranium processing plant in Gore, OK. One worker dies when his lungs are destroyed; 130 others seek medical treatment. In response, the government fines the plant owner $310,000, citing poorly trained workers, poorly maintained equipment, and a disregard for safety and the environment.
Note: Sequoyah Fuels is owned at this time by Kerr-McGee. See also 13 Nov 1974 and 24 Nov 1992.
The USS Nathanael Greene (SSBN-636) runs aground in the Irish Sea, suffering damage to its ballast tanks and rudder. A Navy spokesman says "There was no effect on the propulsion, no injuries, and no damage to the Poseidon nuclear missiles." The submarine sails under its own power to Holy Loch, Scotland for emergency repairs. On 25 April it travels submerged to Charleston, SC. The extent of the damage leads to the vessel being decommissioned, partly in order to satisfy SALT II Treaty limitations on ballistic missiles.
At the East Texas Cancer Center in Tyler, Texas, one male patient is overexposed to radiation by a Therac 25 on 21 March, immediately feeling the pain of the estimated 16,500- to 25,000-rad localized dose. He receives various other radiation injuries over the next few weeks and dies five months after the initial exposure.
On 11 April, another male patient receives an overexposure to his face which produces immediate skin burns. He goes into a coma and dies on 1 May of radiation injury to the brain and brain stem.
A physicist on the staff of the ETCC delves into the problem and eventually identifies the software defect that is causing this rash of overexposures in clinics using the Therac 25.
I could be wrong, but what I remember is that an uninitialized variable in the program set up the machine for maximum exposure unless the operator manually entered a dose value at the start of every treatment.
A test of Unit 4 of the Chernobyl nuclear power plant near Kiev, USSR (now part of Ukraine) at excessively low power levels causes a runaway reaction. the core explosion and resulting fire in the graphite moderator kill 31 personnel, and several dozen more die from radiation exposure suffered during attempts to fight the fire. Dangerous levels of contamination cover the city of Pripyat, essentially a support community for the nuclear plant, and significant amounts are blown westward over much of Europe. An area of some 4,000 square miles becomes unusable for an indefinite period. The entire population of Pripyat is belatedly evacuated, as are 800,000 people from fallout areas of Ukraine, Russia and Belarus. The official death toll is still being tallied up.
The USS Atlanta (SSN-712) runs aground in the Strait of Gibraltar, damaging sonar gear and puncturing a ballast tank in the bow section. Navy officials stress that no radiation leaks from the nuclear reactor and no crew members are injured. With water entering through holes in the ballast tank, the vessel limps to Gibraltar for repairs.
An experimental THTR-300 PBMR located in Hamm-Uentrop, Germany is touted as the beginning of a "new generation" of accident-resistant reactor design. After the Chernobyl accident, the West German government discloses that its 300-MW reactor leaks radiation when one of its spherical fuel pellets lodges in the pipe used to deliver fuel elements to the core and attempts to dislodge it damage its cladding. Because the reactor has no containment building, contamination spreads as far as 2 km from the facility. This is initially blamed on the Chernobyl accident, but scientists in the Freiburg area announce that it is of a different character. This attempt to conceal the malfunction leads the government to shut down the reactor pending a review. Continuing technical problems result in its permanant shutdown for decommissioning in 1988.
A truck carrying low-level radioactive material swerves to avoid a farm implement on Route 84 in Idaho and falls off a bridge, dumping part of its cargo into the Snake River. Officials report finding measurable contamination.
The NRC revokes the license of a Radiation Technology, Inc. plant in New Jersey for worker safety violations. A safety interlock to prevent people entering the irradiation chamber during operation is bypassed, and a worker receives a near-lethal dose of radiation. Among the other 32 violations cited by the NRC is throwing radioactive garbage out with the regular trash.
Unit 2 at the La Salle County nuclear power plant in Seneca, Illinois fails to shut down properly in response to a mechanical malfunction. Comonwealth Edison does not alert the NRC or inform the local population for more than 12 hours.
The Soviet nuclear-powered ballistic missile submarine K-219 (Project 667A Yankee-I class), patrolling submerged 480 miles east of Bermuda, suffers an explosion and fire in one of its ballistic missile tubes. The explosion kills three crew members and causes a leak in the missile compartment. The submarine surfaces and the second reactor, which was offline at the time of the accident, is quickly started up. Despite the fact that water is entering the missile compartment, a fire breaks out there. The water apparently causes an electrical short circuit, triggering a scram of one of the two reactors. Another life reportedly is lost "in the struggle to lower the control rods." The submarine begins to lose buoyancy as water enters the ballast tanks. When the second reactor breaks down, the crew is transferred to a rescue vessel. The captain and nine crew members remain in the conning tower until the bow begins to sink; then the ship is abandoned.
North American television and newspapers carry pictures of the stricken submarine with steam and smoke issuing from one of its missile tubes. General Secretary Mikhail Gorbachev sends President Reagan a private communication regarding the accident in advance of the public announcement on 4 October, assuring him that there was no danger of nuclear explosion, radioactive contamination, or accidental launch of nuclear missiles. U.S. forces sample the air and water around the submarine and detect no radioactivity. Their conclusion is that the explosion resulted from the missile's nitrogen tetroxide propellant interacting with water in the tube. The submarine sinks under tow at 1103 hours on 6 October in 18,000 feet of water about 600 miles northeast of Bermuda. Her captain is charged with crimes against the state, but Gorbachev orders the charges dropped.
In late October, the USS Augusta (SSN-710) is damaged in an undersea collision while on a routine training patrol in the Atlantic. No crew members are injured and the vessel returns to Groton, CT for $2.7 mission of repairs. According to unnamed U.S. Defense Department sources, it is unclear whether the submarine struck the ocean floor or an underwater object, but there was no risk of the submarine sinking or danger to the nuclear reactor. A Defense Department spokesman refuses to comment on a CBS News report that the Augusta "very possibly" collided with a Soviet submarine.
At the Edwin I. Hatch nuclear power plant in Baxley, Georgia, approximately 141,000 gallons of radioactive water leak out of storage pools for spent fuel rods. An estimated 84,000 gallons pass through storm drains into wetlands on the plant property. Following the accident, Georgia Power issues a press statement claiming that only 5,000 gallons of water have leaked and assuring the public that there is no threat to health.
The U.S. government releases 19,000 pages of previously classified documents which reveal that the Hanford Engineer Works in Richland, Washington is responsible for the release of significant amounts of radioactive materials into the atmosphere and the adjacent Columbia River. Between 1948 and 1966, Hanford discharged billions of gallons of liquids and billions of cubic meters of gases containing plutonium and other radioactive substances into the Columbia Basin environment. Although deleterious effects were noticed as early as 1948, all reports critical of the facility remained classified.
By the summer of 1987, the cleanup cost was estimated to be $48.5 billion. In July 1990, the Technical Steering Panel of the government-sponsored Hanford Environmental Dose Reconstruction Project released the following statistics: Of the 270,000 people living in the affected area, most received low doses of radiation from iodine, but about 13,500 received a total dose some 1,300 times the annual amount of airborne radiation considered safe for civilians by the Department of Energy. Approximately 1,200 children received doses in excess of this number, and many more received additional doses from contaminants other than iodine.
Note: Hanford is a bad deal that may fairly be called the American Mayak. But this report is not a clear explanation of the problem. See also May 1997 and July 2000.
An individual accidentally enters the irradiation room at a facility in Zhengzhou, China. He is exposed to the cobalt-60 source for 10 to 15 seconds, getting a whole-body dose of 135 rads. Four hours later he suffers anorexia and nausea and subsequently develops radiation sickness from which he recovers slowly.
A defect in the computer program controlling the Therac 25 radiation therapy accelerator causes overexposure of patients. A male patient at Yakima Valley Memorial Hospital in Yakima, Washington reports pain immediately after receiving an estimated 8,000 to 10,000-rad dose. The patient has terminal cancer but dies in April 1987, earlier than projected, of complications related to the radiation overdose.
France's Superphenix experimental breeder reactor develops a sodium leak of 500kg per day from the main fuel transfer tank to the secondary shell. The accident puts the entire fuel loading and unloading device out of operation. A new device has to be designed.
A foreign company dumps chemical wastes at the port of Koko in Nigeria. Some of the wastes contain radioactive materials. Examination of 26 workers who handled the wastes shows chemical injuries along with minor effects of exposure to radiation.
The Royal Navy nuclear-powered attack submarine HMS Conqueror suffers a fire while at Devonport for a four-month overhaul, damaging its engine room. The British Navy stresses that the fire was far from the submarine's nuclear reactors.
Scavengers raid an abandoned cancer clinic in Goiania, Brazil. They dismantle a radiation therapy machine and remove its 1,400-Curie cesium-137 source, which they sell to a junkyard. Five days later, a junkyard worker breaks open the lead canister to find a blue-glowing powder. Pinches of this material are sold as curiosities and good-luck charms; some people rub it on their bodies. The crisis is not discovered until 28 September, when a worker at the Goiania public clinic correctly diagnoses a case of radiation poisoning. Contamination is found on 244 people; 54 require immediate hospitalization, and the 20 most severely exposed receive doses of 100 to 800 rad. Many are internally contaminated as well. It is no doubt due to prompt, effective medical intervention that only four die.
The Royal Navy nuclear-powered ballistic missile submarine HMS Renown suffers a leak of reactor coolant during tests in the reactor compartment while at the Rosyth naval base, Scotland for a refit. The Navy says it was a minor incident "without any radiation hazard".
The Nuclear Regulatory Commission shuts down the Oyster Creek nuclear power plant in Forked River, New Jersey when it finds plant operators have disabled key safety valves during a test and attempted to cover up the violation by destroying records.
Staff of the Canadian Atomic Energy Control Board discover contaminated dirt and asphalt in a parking lot in northeast Calgary, Alberta. A spokesman says the contamination poses no health hazard "because it is in a parking lot."
The Idaho Falls Post Register reports that plutonium has been found in sediments hundreds of feet below the Idaho National Engineering Laboratory, an experimental reactor testing station and nuclear waste storage site located near Idaho Falls.
The National Research Council panel releases a report listing 30 "significant unreported incidents" at the Savannah River production plants over the previous 30 years. As with their report on Hanford Engineer Works in 1986, the panel noted significant groundwater contamination due to pushing production of radioactive materials past prudent limits at this weapons complex. In January 1989, scientists discovered a fault running under the entire site through which contaminants reached the underground aquifer, a major source of drinking water for the southeast U.S. Turtles in nearby ponds were found to contain strontium-90 at up to 1,000 times normal background levels.
At an irradiation facility in Zhao Xian, China, an individual accidentally enters the source room, becoming exposed to a cobalt-60 source for about 40 seconds. He gets a whole-body dose of about 520 rads, suffers acute radiation sickness, recovers, and remains alive three years later.
The Royal Navy nuclear-powered ballistic missile submarine HMS Resolution suffers an electrical malfunction while docked at Faslane, Scotland. The Observer claims that the malfunction shuts down the primary coolant pumps, almost leading to a core meltdown. The Ministry of Defense denies this.
Radiation Sterilizers, Inc. reports that a leak of cesium-137 has occurred at their Decatur, Georgia facility. Seventy thousand medical supply containers and milk cartons are recalled for exposure to radiation. Ten employees also receive significant exposures; three of them have "enough on them that they [contaminate] other surfaces," according to Jim Setser of the Georgia Department of Natural Resources.
In the nuclear trigger assembly facility at the Rocky Flats plant in Colorado, two employees and a Department of Energy inspector inhale radioactive particles. The plant is closed as a result. Several safety violations are cited, including radiation monitors out of calibration, inadequate fire equipment, and groundwater contaminated with radioactivity.
In November, according to a Soviet press account, the Soviet nuclear-powered icebreaker Rossiya narrowly avoids a reactor meltdown when coolant is accidentally released. Emergency procedures prevent the core from overheating. The ship is docked in Murmansk at the time.
A 20-mm cannon on an A-7 Corsair aircraft accidentally fires during maintenance. Six other aircraft on board the USS Nimitz (CVN-68) are set ablaze, and one sailor is killed. The Nimitz continues operations in the Arabian Sea.
In Beijing, China, two individuals are accidentally exposed to a cobalt-60 source for about 4 minutes. They receive whole-body doses of 87 and 61 rads and suffer mild haemopoietic radiation sickness from which they both recover.
Running on the surface, the USS Norfolk (SSN-714) collides with the USS San Diego (AFS-6) as both ships are heading out to sea near the Chesapeake Bay Bridge-Tunnel. No injuries are reported, and the ships incur only minor damage.
The Delmed Company operates a medical sterilizer firm in El Salvador's capital city of San Salvador. Sterilization is done by cobalt-60 sources on a remotely-controlled rack which slides in and out of its shield. When the source rack becomes stuck in the unshielded position and one source falls to the floor, the operator disables the alarms and enters the room with two other employees to fix it. All three receive estimated whole-body exposures of 400 to 600 rads; they are treated in San Salvador and later go to Mexico City for more specialized treatment. One dies 6.5 months later from lung damage complicated by injury sustained during treatment; the other two survive but lose their legs. Other employees may have been exposed as well. Since the radiation monitors have been disabled, workers entering the room unknowingly put themselves at risk.
The Soviet nuclear-powered attack submarine Komsomolets, K-278 (Project 685 Mike class), is running submerged at a depth of 160m about 180 miles south of Bear Island on her way to Zapadnaya Litsa, her home port. At 1103 hours an alarm sounds due to a fire in the seventh compartment. The vessel surfaces eleven minutes later. By this time the fire has shorted out the electrical system, tripping the reactor offline, and burned a hole in the compressed air system. The crew is unable to extinguish the fire, which is fanned by the compressed air leak. By 1700, the compressed air runs out and the Komsomolets loses buoyancy and stability. The crew begins to evacuate into life rafts, but there are not enough rafts and some have drifted too far away for crew members to reach. The submarine sinks at 1708 hours with a loss of 41 lives including her commander. Five officers try to enter an escape capsule, but three are felled by fumes. Then the release mechanism is jammed. The capsule does not separate until K-278 strikes the bottom 1685 meters down; then it shoots to the surface. One of the two occupants dies from air embolisms when the hatch is opened, due to the great pressure differential. The Aleksandr Khlobystsov arrives 81 minutes later and takes aboard 25 survivors and 5 fatalities. The exact cause of the fire is unknown.
The Russian Echo-II class nuclear-powered cruise missile submarine K-192 surfaces in the Norwegian Sea, about 60 nautical miles north-west of Senja in Troms, Norway, after a leak develops in the primary cooling system for one of its two reactors. The reactor is not immediately shut down, and the contaminated coolant is pumped into the sea. The crew supplies additional cooling water from the submarine's fresh water tanks. When this runs out, the newly arrived Soviet Northern Fleet service ship Amur takes over the task of cooling the reactor. Its core temperature starts to come down. The Amur also takes the waste water on board, pumping it into tanks designed for that purpose.
At this point the crew of K-192 try to seal the leaking pipe. Coolant flow from Amur is shut off in order to permit this. For reasons that are in dispute, the support ship is late in restoring the flow; when it is restored, the cold liquid fractures overheated fuel elements. Amur cannot handle the now heavily contaminated water, and again it is pumped into the sea.
Eventually the reactor is brought under control. K-192 returns to the Kola Peninsula under diesel power, arriving on 28 June. The submarine is laid up at the Ara Bay facility until 1994; then it is towed to Navy yard No. 10 at Skval. There it remains, still containing its damaged reactor and fuel elements.
Crew members working on repairs have received significant doses of radiation; they are later treated, but details are not available. Releases of radioactive iodine are detected in the areas immediately surrounding the accident location, and sometime later at a monitoring post at Vardø in northern Norway.
A Soviet Echo-II class nuclear-powered cruise missile submarine is spotted on the surface in the Barents Sea off the coast of Norway. Smoke billows from her observation tower. According to the Soviets, the ship is on a training mission and has just shifted its power load to a battery when one of the cells short-circuits. The smoke is said to be exhaust from the submarine's diesel engine. This suggests a reactor problem, but is not conclusive.
Fire breaks out in an electric motor on the Royal Navy nuclear-powered submarine HMS Valiant at the Faslane submarine base on the River Clyde in southwest Scotland. There are no reported injuries and a Defense Ministry spokesperson says the fire posed no danger to the submarine's reactor.
A bubble of argon gas forms in the core of the "Phoenix" fast breeder reactor at Marcoule, France, causing the reactor to scram automatically three times. Engineers at the site reportedly do not realize the danger posed by the bubble, which might have led to a meltdown if it formed in another location.
A report by the U.S. General Accounting Office documents excessive radioactive contamination at civilian sites which have been declared decommissioned. The sites are:
Westinghouse Fuel Fabrication plant in Chester, Pennsylvania
The Combination Engineering site in Hematite, Missouri
The Texas Instrument plant south of Boston, Massachusetts
The Gulf United Nuclear Corporation fabrication plant near Pawling, New York
The Kerr-McGee facility in Cushing, Oklahoma
The Kerr-McGee Cimarron Uranium Enrichment Facility in Crescent, Oklahoma
The Nuclear Fuel Services site in Erwin, Tennessee
All of these sites have groundwater contamination higher than federal standards allow. Kerr-McGee's Cimarron Facility has levels 400 times higher than standards, and the Nuclear Fuels Services site exceeds those standards by 730 times.
A report by the Washington-based Nuclear Information and Resource Service shows that, of the 112 commercial nuclear power plants operating in the United States, 59 have not completed safety modifications required by the NRC in the wake of the Three Mile Island accident in 1979.
In addition, Congress is investigating allegations of bribery in the nuclear power industry. John Delcore, a worker who exposed poor safety practices at North East Utilities, was reportedly offered $15,000 for his silence. This may relate to the Millstone nuclear power plant in Waterford, CT. The Texas Utility Electric Company is also under investigation for bribes connected to problems at the Comanche Peak nuclear power plant.
An accident at Canada's Pickering nuclear power plant exposes a mechanic to six times the legal yearly radiation limit. Another worker standing nearby receives a lesser exposure. The men are removing a control rod from the reactor when a radiation monitor worn by one of them goes off-scale. The protective gear they are using is intended for training and does not contain the proper lead shielding.
The USS Narwhal (SSN-671) sustains minor damage when it is torn from its moorings by Hurricane Hugo. The ship is submerged at the Charleston Naval Base in South Carolina, and tied with two 3-inch ship's lines and nine double wires. Despite this, the captain discovers during the eye of the storm that the vessel has drifted to the center of the Cooper River. Tugboats and the submarine's crew try to return her to the dock, but fail. The captain then submerges the submarine where it is and it rides out the rest of the storm there.
A device used in the Caithness nuclear plant at Dounreay, Scotland to test radiation alarms is reported missing. Investigators discover it has not been seen for a month before that. Investigators suspect that the device, consisting of a steel tube and a glass bead of radioactive caesium-137, may have been stolen or sent to a local waste dump.
In response to a request from the Sunday Herald, Dounreay releases a copy of its internal report on the investigation into the loss in March 2005. This previously secret report describes an extensive search conducted of plant facilities. Personnel and vehicles entering and leaving the site were also examined, but there were gaps attributed to dead batteries in portable radiation monitors and to the lack of police resources. The United Kingdom Atomic Energy Agency informed the public in 1989 of the disappearance of the source, distributed photographs, and publicly appealed for information.
Addressing the possibility that the source had inadvertently been discarded with plant garbage, the report described a search of an industrial waste skip at Dounreay and of Langlands Quarry, a landfill site near Thurso that was formerly used by the UKAEA. These searches, however, found no trace of the missing source. The conclusion was that the source never went into the trash stream or is buried too deep in the landfill to be detected.
The report is very critical of safety procedures in effect at the time. It notes that although the lead pot in which the source was kept was checked as present every working day, its contents were not. This was "not untypical", the report says. In general, it describes inadequate controls, records and guidance and broken radiation monitoring equipment.
Sources at Dounreay confirmed that information about the source has never turned up in the intervening years. According to Dr Michael Clark, a scientist from the government's National Radiological Protection Board, the lost source could still cause radiation burns in close contact with the skin.
Lorraine Mann, from Scotland Against Nuclear Dumping, expressed concern over these facts and criticized current safety standards at the Caithness plant. UKAEA spokesman Colin Punler disagreed, saying "Our records show that new procedures were introduced to improve the control of sources."
As the Sunday Herald predicted two years ago, Dounreay is now facing prosecution for leaking hundreds of thousands of radioactive particles into the sea and onto beaches. But it is unlikely to end up in court for losing the radiation source because that occurred while the plant was still protected by Crown immunity.
A wave sweeps 3 sailors and 38 non-nuclear missiles from USS Dwight D. Eisenhower (CVN-69) during night-time cargo loading about 90 miles south of Cape Hatteras, North Carolina. One sailor is drowned and two are rescued.
In order to test the emergency shutdown system in a new reactor at Greifswald nuclear power plant in East Germany, three of the six cooling water pumps are shut off. When a fourth pump breaks down, the reactor overheats and some local fuel element damage occurs. Apparently the relay that is supposed to trigger shutdown on failure of this pump is sticking.
Note: This facility had serious accidents in 1974, 1976, and 1981. Worse, normal conditions at the plant include sinking foundations, miswired cables, missing equipment, drunken workers... a veritable textbook case of how not to build and run a nuclear plant. The Atom City description is not fully coherent; I'm looking for a better one.
Investigators from Scientec, Inc., an engineering management company specializing in nuclear safety issues, discover several kilograms of plutonium-239 in an exhaust duct for a plutonium processing building at Rocky Flats. In addition to being a serious lapse of inventory control, this amount of lost plutonium could potentially go critical under the right conditions, exposing workers to radiation and contaminating the environment. Rocky Flats management has been warned about previous losses of material and other problems, but apparently has not corrected its defective safety culture.