A Brief History of Nuclear Accidents Worldwide - Re-Visited - 2013

Nuclear Power Industry

The UofCS reported in late 2013 in a generally overlooked article for reasons that will become obvious that serious nuclear accidents have been few and far between—but their stories will help prevent future catastrophes. Here is a brief review with comments where indicated:

Fukushima Daiichi Incident
Fukushima, Japan, March 2011

The earthquake and tsunami that struck eastern Japan on March 11, 2011, caused a serious accident at the Fukushima Dai-ichi nuclear power plant on the northeastern coast of Japan. 

How did it happen?
The earthquake cut off external power to the reactors [It was not the earthquake per se that cut the power, but the following tsunami], of which reached water levels more than twice as high as the plant was designed to withstand, [the flood] disabled backup diesel generators, crippling the reactor cooling systems. Battery power was quickly exhausted, and overheating fuel in the plant's operating reactor cores led [created hydrogen form the boiling water] to [which created] hydrogen explosions that severely damaged three of the reactor buildings. Fuel in three of the reactor cores melted, and radiation releases from the damaged reactors contaminated a wide area surrounding the plant and forced the evacuation of nearly half a million residents. [Note the radiation that was released was not widespread. The evaluation was called out of an abundance of caution, but no one died, and no one was irradiated as a result, although a few older people died of panic mostly created by the news media]

Media-created book: Fukushima: The Story of a Nuclear Disaster, A definitive, scientific retelling of exactly what happened at Fukushima—and an urgent reminder that U.S. nuclear power isn’t as safe as it could and should be [or so say the advertisements. The book contains many exaggerations, errors in fact, and was nothing more than pandering fear of radiation to the local population and around the world. No one died and no one was irradiated !]

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Chernobyl Disaster
Chernobyl, Ukraine (former Soviet Union), April 26, 1986

Chernobyl is considered the world’s worst nuclear disaster to date. It occurred on April 26, 1986, when a sudden surge in power during a reactor systems test resulted in an explosion and fire that destroyed Unit 4. Massive amounts of [detectable, but not dangerous] radiation escaped [detectable, but not dangerous] that spread across the western Soviet Union and Europe. As a result of the disaster, approximately 220,000 people had to be relocated from their homes. [About 30 people died becasue of radiation, and some 2,000 children contracted thyroid cancer as a result of drinking irradiated milk. 98% were cured, the a few died]

How did it happen?
Unit 4 was to be shut down for routine maintenance. A test was conducted to determine the plant equipment’s ability to provide sufficient electrical power to operate the reactor core cooling system and emergency equipment during the transition period between a loss of main station electrical power supply and the start-up of the emergency power supply. Workers did not implement adequate safety precautions or alert operators to the electrical test’s risks. This lack of awareness led the operators to engage in actions that diverged from safety procedures. Consequently, a sudden power surge resulted in explosions and nearly complete destruction of the reactor. The fires that broke out in the building contributed to the extensive radioactive releases. [Note: See subsequent investigations (here)]

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Three Mile Island Incident
Middletown, Pennsylvania, USA, March 28, 1979

The partial meltdown at Three Mile Island Unit 2 is considered the most serious nuclear accident in U.S. history, although it resulted in only small radioactive releases.

How did it happen?
The accident began with failures in the non-nuclear secondary system, followed by a human-operated relief valve in the primary system that stuck open, which allowed large amounts of nuclear reactor coolant to escape. Plant operators’ initial failure to correctly identify the problem compounded it. In particular, a hidden indicator light led to an operator manually overriding the automatic emergency cooling system because he mistakenly believed that too much coolant water in the reactor had caused the steam pressure release. Eventually the reactor was brought under control, although the full extent of the accident was not understood until later.[No one was killed or irradiated. The radiation released was onsite and very minor. The media generated an intense fear pandering series of announcements and programs, which were largely incorrect and unjustifiably damaging to the reputation nuclear power (more).]

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TBA ------

Enrico Fermi Unit 1 Incident
Frenchtown Charter Township, Michigan, USA, October 5, 1966

Coolant flow blockage in two fuel channels led to the partial meltdown of two fuel assemblies at Fermi Unit 1.

How did it happen?
Fermi Unit 1 was the nation’s first and only commercially operating liquid metal fast breeder reactor. Vibrations caused a component within the reactor vessel to loosen, which blocked coolant flow when hydrodynamic forces carried it up the fuel subassemblies’ inlet nozzle. Workers did not notice what had occurred until core temperature alarms sounded. Several fuel rod subassemblies reached temperatures of up to 700 degrees Fahrenheit, causing them to melt. After the reactor was shut down for repairs, it was returned to partial operation periodically until 1972, but it was never again fully operational. It was officially decommissioned in 1975. [Although this was a teaching event, it is worthwhile to note that no one died and no one was irradiated (more).]

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SL-1 Incident
Idaho Falls, Idaho, USA, January 3, 1961

The withdrawal of a single control rod caused a catastrophic power surge and steam explosion at the SL-1 boiling water reactor that killed all the workers on duty at the time.

How did it happen?
On January 3, 1961, workers were in the process of reattaching to their drive mechanisms control rods they had disconnected earlier that day to enable test equipment to be inserted in the reactor core. They lifted the central control rod 20 inches, instead of the four inches that was required.  This error caused the reactor to go critical and its power to surge 6,000 times higher than its normal level in less than a second. As a result, nuclear fuel vaporized and a steam bubble was created. The steam bubble expanded so quickly that it pushed water above it against the reactor vessel, which caused it to jump out of its support structure. It hit an overhead crane and then returned to the reactor vessel. In the process, all of the water and some of the fuel was released from the reactor vessel. All three workers on duty received lethal doses of radiation, in addition to trauma from the explosion. [Aside from being one of the first nuclear accident where workers were killed by radiation, there were rumors that the accident was caused by one of the workers over a marital dispute, both possibilities of which are covered in some detail (here)

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Sodium Reactor Experiment
Los Angeles, California, USA, July 1959

A partial meltdown occurred at the Sodium Reactor Experiment (SRE) due to cooling flow blockage that caused the reactor core to overheat.

How did it happen?
The Sodium Reactor Experiment experienced extensive fuel damage during a power run. Thirteen of forty-three fuel elements overheated when the cooling flow provided by the liquid sodium was blocked by tetralin, an oil-like fluid which had leaked into the primary sodium loop during prior power runs. This overheating caused the reactor core to fail. Fission products were released from the damaged fuel into the primary sodium loop. Some of the fission products leaked from the primary sodium loop into the high bay area, a region inside the building housing the reactor. Other fission products flowed with the helium cover gas over the liquid sodium in the reactor pool to gaseous storage tanks. Fission products from the high bay area and from the gaseous storage tanks were processed through the filters of a ventilation system and discharged to the atmosphere. [This is where the fear of radiation was first established in the U.S.. With the reports of the above incident came a flood of cancer claims in the neighborhood. After years in investigation, conflicting conclusions emerged. The final conclusions by those who should know is that none of the cancers reported were the result of the incident. (more). They concluded that the media coverage of medical conspiracies, pandered widely by the media drove the medical fears].

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Windscale
Cumberland (now Cumbria), UK, October 10, 1957

Windscale Unit 1’s core caught fire and melted, which led large amounts of radioactivity to be released to the surrounding area.

How did it happen?
Before the accident, Unit 1 was activated to release built-up energy in the graphite of the core. The fuel was cooler than the normal operating temperature and was warming more slowly than expected. A second release led to a higher temperature than workers expected. Eventually the temperature was more than 750 degrees Fahrenheit, so air was vented to cool it. The reactor caught fire, igniting an estimated 11 tons of uranium. Workers first used carbon dioxide to try to put out the fire, but that strategy failed. Next they used water, which eventually succeeded. It took workers a total of three days to put out the fire. In the meantime, radiation escaped through the chimney and contaminated much of the surrounding area and reached as far as mainland Europe. More than 200 cancer deaths are attributed to the disaster, which is considered to have been the worst to occur in the West. [Media accounts of this incident did not mention that any deaths occurred as the result of the fire in the reactor room. What was highly distributed by the new media was that there were nearly 200 reports of cancers in the surrounding area, including Europe. The milk was thought to be a contributor, but the news media blasted the fears around the world (more). No one died who was associated with the incident, which should have been an indicator that although radiation was released into the atmosphere, it was in diminishing concentrations].