Civilian Nuclear Accidents
A list of just some
- A fire in a cable duct after a short-circuit disabled the electrical power supply for all feedwater and emergency core cooling pumps. A power supply was improvised by the operating personnel after several hours.
- Operators neglected to remove moisture-absorbing materials from a fuel rod assembly before loading it into the KS 150 reactor at power plant A-1. The accident resulted in damaged fuel integrity, extensive corrosion damage of fuel cladding and release of radioactivity into the plant area. The affected reactor was decommissioned following this accident.
- 28 March 1979 – INES Level 5 - Middletown, Dauphin County, Pennsylvania, United States - Partial meltdown
- Equipment failures and worker mistakes contributed to a loss of coolant and a partial core meltdown at the Three Mile Island Nuclear Generating Station 15 km (9.3 mi) southeast of Harrisburg. While the reactor was extensively damaged, on-site radiation exposure was under 100 millirems (less than annual exposure due to natural sources). Area residents received a smaller exposure of 1 millirem (10 µSv), or about 1/3 the dose from eating a banana per day for one year. There were no fatalities. Follow-up radiological studies predict between zero and one long-term cancer fatality.
See also: Three Mile Island accident
- March 1981 — INES Level 2 - Tsuruga, Japan - Radioactive materials released into Sea of Japan + Overexposure of workers
- An operator error during a fuel plate reconfiguration in an experimental test reactor led to an excursion of 3×1017 fissions at the RA-2 facility. The operator absorbed 20 Gy of gamma and 17 Gy of neutron radiation which killed him two days later. Another 17 people outside of the reactor room absorbed doses ranging from 350 mGy to less than 10 mGy. pg103
- 26 April 1986 — INES Level 7 - Prypiat, Ukraine (then USSR) - Power excursion, explosion, complete meltdown
- An inadequate reactor safety system led to an uncontrolled power excursion, causing a severe steam explosion, meltdown and release of radioactive material at the Chernobyl nuclear power plant located approximately 100 kilometers north-northwest of Kiev. Approximately fifty fatalities (mostly cleanup personnel) resulted from the accident and the immediate aftermath. An additional nine fatal cases of thyroid cancer in children in the Chernobyl area have been attributed to the accident. The explosion and combustion of the graphite reactor core spread radioactive material over much of Europe. 100,000 people were evacuated from the areas immediately surrounding Chernobyl in addition to 300,000 from the areas of heavy fallout in Ukraine, Belarus and Russia. An "Exclusion Zone" was created surrounding the site encompassing approximately 3,000 km2 (1,200 sq mi) and deemed off-limits for human habitation for an indefinite period. Several studies by governments, U.N. agencies and environmental groups have estimated the consequences and eventual number of casualties. Their findings are subject to controversy.
See also: Chernobyl disaster
- 4 May 1986 – no INES Level - Hamm-Uentrop, Germany (then West Germany) - Fuel damaged
- Spherical fuel pebbles became lodged in the pipe used to deliver fuel elements to the reactor at an experimental 300-megawatt THTR-300 HTGR. Attempts by an operator to dislodge the fuel pebble damaged the pipe, releasing activated coolant gas which was detectable up to two kilometers from the reactor.
- A pressure buildup led to an explosive mechanical failure in a 34 m3 (1,200 cu ft) stainless steel reaction vessel buried in a concrete bunker under building 201 of the radiochemical works at the Tomsk-7 Siberian Chemical Enterprise plutonium reprocessing facility. The vessel contained a mixture of concentrated nitric acid, 8,757 kg (19,306 lb) uranium, 449 g (15.8 oz) plutonium along with a mixture of radioactive and organic waste from a prior extraction cycle. The explosion dislodged the concrete lid of the bunker and blew a large hole in the roof of the building, releasing approximately 6 GBq (160 mCi) of Pu 239 and 30 TBq (810 Ci) of other radionuclides into the environment. The contamination plume extended 28 km (17 mi) NE of building 201, 20 km (12 mi) beyond the facility property. The small village of Georgievka (pop. 200) was at the end of the fallout plume, but no fatalities, illnesses or injuries were reported. The accident exposed 160 on-site workers and almost two thousand cleanup workers to total doses of up to 50 mSv (the threshold limit for radiation workers is 20 mSv/yr).
- Operators attempting to insert one control rod during an inspection neglected procedure and instead withdrew three causing a 15 minute uncontrolled sustained reaction at the number 1 reactor of Shika Nuclear Power Plant. The Hokuriku Electric Power Company who owned the reactor did not report this incident and falsified records, covering it up until March, 2007.
- 30 September 1999 — INES Level 4 - Ibaraki Prefecture, Japan - Accidental criticality
- Inadequately trained part-time workers prepared a uranyl nitrate solution containing about 16.6 kg (37 lb) of uranium, which exceeded the critical mass, into a precipitation tank at a uranium reprocessing facility in Tokai-mura northeast of Tokyo, Japan. The tank was not designed to dissolve this type of solution and was not configured to prevent eventual criticality. Three workers were exposed to (neutron) radiation doses in excess of allowable limits. Two of these workers died. 116 other workers received lesser doses of 1 mSv or greater though not in excess of the allowable limit.
See also: Tokaimura nuclear accident
- Partially spent fuel rods undergoing cleaning in a tank of heavy water ruptured and spilled fuel pellets at Paks Nuclear Power Plant. It is suspected that inadequate cooling of the rods during the cleaning process combined with a sudden influx of cold water thermally shocked fuel rods causing them to split. Boric acid was added to the tank to prevent the loose fuel pellets from achieving criticality. Ammonia and hydrazine were also added to absorb 131I.
- 20 t (20 long tons; 22 short tons) of uranium and 160 kg (350 lb) of plutonium dissolved in 83 kl (2,900 cu ft) of nitric acid leaked over several months from a cracked pipe into a stainless steel sump chamber at the Thorp nuclear fuel reprocessing plant. The partially processed spent fuel was drained into holding tanks outside the plant.
- November 2005 — INES Level needed - Braidwood, Illinois, United States - Nuclear material leak
- 35 l (7.7 imp gal; 9.2 US gal) of a highly enriched uranium solution leaked during transfer into a lab at Nuclear Fuel Services Erwin Plant. The incident caused a seven-month shutdown. A required public hearing on the licensing of the plant was not held due to the absence of public notification.
- March 11–20, 2011 - INES Level 7 Fukushima Daiichi ("Fukushima I") Nuclear Power Plant, Japan - Partial meltdowns in multiple reactors
(The INES 7 rating is as of April 12, 2011. The previous INES rating had been 5, a final rating is expected after the situation has been completely resolved)
Main article: Fukushima Daiichi nuclear disaster
- After the 2011 Tōhoku earthquake and tsunami of March 11, the emergency power supply of the Fukushima-Daiichi nuclear power plant failed. This was followed by deliberate releases of radioactive gas from reactors 1 and 2 to relieve pressure.
- On March 12, triggered by falling water levels and exposed fuel rods, a hydrogen explosion occurred at reactor 1, resulting in the collapse of the concrete outer structure. Although the reactor containment itself was confirmed to be intact, the hourly radiation from the plant reached 1.015 Sv (101.5 rem) - an amount equivalent to that allowable for ordinary people in one year.
- Residents of the Fukushima area were advised to stay inside, close doors and windows, turn off air conditioning, and to cover their mouths with masks, towels or handkerchiefs as well as not to drink tap water. By the evening of March 12, the exclusion zone had been extended to 20 kilometres (12 mi) around the plant and 70,000 to 80,000 people had been evacuated from homes in northern Japan.
- On March 14, a second, hydrogen explosion (nearly identical to the first explosion in Unit 1) occurred in the reactor building for Unit 3, with similar effects.
- On March 15, a third explosion occurs in the “pressure suppression room” of Unit 2 and is initially said not to have breached the reactor’s inner steel containment vessel, but later reports indicated that the explosion damaged the steel containment structure of Unit 2 and much larger releases of radiation were expected than previously.
- On March 15, a fourth explosion damages the 4th floor area above the reactor and spent fuel pool of the Unit 4 reactor. Contrary to the TEPCO press release, aerial photos show that most of the outer building was actually destroyed. The fuel rods (both new and spent fuel) of reactor Unit 4, stored in the now exposed spent fuel pool, were reportedly exposed to air – this would have risked the melting of the nuclear fuel. However later research found the fuel rods been covered by water all the time.
- On 16 March TEPCO estimated that 70% of the fuel in Unit 1 had melted, and 33% in Unit 2, further suspecting that Unit 3's core might also be damaged. In November 2011 TEPCO released the report of the Modular Accident Analysis Program (MAAP). The report showed that the reactor pressure vessel (RPV) in Unit 1 (commonly known as the reactor core) had been damaged during the disaster, and that significant amounts of fuel had fallen into the bottom of the primary containment vessel (PCV) – the erosion of the concrete of the PCV by the molten fuel immediately after the disaster was estimated to have been stopped in approx. 0.7 metres (2 ft 4 in) depth, with the thickness of the containment being 7.6 metres (25 ft). Gas sampling done before the report detected no signs of an ongoing reaction of the fuel with the concrete of the PCV and all the fuel in Unit 1 was estimated to be "well cooled down, including the fuel dropped on the bottom of the reactor". MAAP further showed that fuel in Unit 2 and Unit 3 had melted, however less than Unit 1, and fuel was presumed to be still in the RPV, with no significant amounts of fuel fallen to the bottom of the PCV. The report further suggested that "there is a range in the evaluation results" from "most fuel in the RPV (some fuel in PCV)" in Unit 2 and Unit 3, to "all fuel in the RPV (none fuel fallen to the PCV)". For Unit 2 and Unit 3 it was estimated that the "fuel is cooled sufficiently". The larger damage in Unit 1 was according to the report due to long time that cooling water was no injected in Unit 1, letting much more decay heat accumulate – for about 1 day there was no water injection for Unit 1, while Unit 2 and Unit 3 had only a quarter of a day without water injection. As of December 2013, it was reported that TEPCO estimated for Unit 1 that "the decay heat must have decreased enough, the molten fuel can be assumed to remain in PCV (Primary container vessel)".
Military Nuclear Accidents
Here is a link toa bunch of criticality accident at USA "national labs"
And here is one a reader sent, sheesh, that was a good coverup!
Multiple accidents AT THE SAME SITE in Canada
Governments cover up, standard procedure
List of some Criticality Accidents
Here is more from the Johnston Archives of General Radiation Accidents
List of Civilian Accidents
Nuclear power plant accidents: listed and ranked since 1952
How many nuclear power plants have had accidents and incidents? Get the full list and find out how they're ranked
• Get the data
• Get the data
The explosions and nuclear fuel rods melting at Japan's Fukushima nuclear power plant, following the Sendai earthquake and tsunami last week, have caused fears of what will happen next. Today Japan's nuclear safety agency has raised the nuclear alert level for Japan from four to five - making it two levels lower than the Chernobyl disaster in 1986.
So far, the Japanese authorities have maintained that there is "no cause to fear a major nuclear accident".
We have identified 33 serious incidents and accidents at nuclear power stations since the first recorded one in 1952 at Chalk River in Ontario, Canada.
The information is partially from the International Atomic Energy Authority - which, astonishingly, fails to keep a complete historical database - and partially from reports. Of those we have identified, six happened in the US and five in Japan. The UK and Russia have had three apiece.
Using Google Fusion tables, we've put these on a map, so you can see how they're spread around the globe:
But how serious are they? The International Atomic Energy Authority ranks them using a special International Nuclear Events Scale (INES) - ranging from 'anomaly' to 'major accident', numbered from 1 to 7.
The events at Fukushima are level 5, so far and there has only been one 7 in history: Chernobyl in 1986. You can see the full ranking system below and on the attached spreadsheet
What can you do with the data?
|2011||Fukushima||5||Japan||Reactor shutdown after the 2011 Sendai earthquake and tsunami; failure of emergency cooling caused an explosion|
|2011||Onagawa||Japan||Reactor shutdown after the 2011 Sendai earthquake and tsunami caused a fire|
|2006||Fleurus||4||Belgium||Severe health effects for a worker at a commercial irradiation facility as a result of high doses of radiation|
|2006||Forsmark||2||Sweden||Degraded safety functions for common cause failure in the emergency power supply system at nuclear power plant|
|2006||Erwin||US||Thirty-five litres of a highly enriched uranium solution leaked during transfer|
|2005||Sellafield||3||UK||Release of large quantity of radioactive material, contained within the installation|
|2005||Atucha||2||Argentina||Overexposure of a worker at a power reactor exceeding the annual limit|
|2005||Braidwood||US||Nuclear material leak|
|2003||Paks||3||Hungary||Partially spent fuel rods undergoing cleaning in a tank of heavy water ruptured and spilled fuel pellets|
|1999||Tokaimura||4||Japan||Fatal overexposures of workers following a criticality event at a nuclear facility|
|1999||Yanangio||3||Peru||Incident with radiography source resulting in severe radiation burns|
|1999||Ikitelli||3||Turkey||Loss of a highly radioactive Co-60 source|
|1999||Ishikawa||2||Japan||Control rod malfunction|
|1993||Tomsk||4||Russia||Pressure buildup led to an explosive mechanical failure|
|1993||Cadarache||2||France||Spread of contamination to an area not expected by design|
|1989||Vandellos||3||Spain||Near accident caused by fire resulting in loss of safety systems at the nuclear power station|
|1989||Greifswald||Germany||Excessive heating which damaged ten fuel rods|
|1986||Chernobyl||7||Ukraine (USSR)||Widespread health and environmental effects. External release of a significant fraction of reactor core inventory|
|1986||Hamm-Uentrop||Germany||Spherical fuel pebble became lodged in the pipe used to deliver fuel elements to the reactor|
|1981||Tsuraga||2||Japan||More than 100 workers were exposed to doses of up to 155 millirem per day radiation|
|1980||Saint Laurent des Eaux||4||France||Melting of one channel of fuel in the reactor with no release outside the site|
|1979||Three Mile Island||5||US||Severe damage to the reactor core|
|1977||Jaslovské Bohunice||4||Czechoslovakia||Damaged fuel integrity, extensive corrosion damage of fuel cladding and release of radioactivity|
|1969||Lucens||Switzerland||Total loss of coolant led to a power excursion and explosion of experimental reactor|
|1967||Chapelcross||UK||Graphite debris partially blocked a fuel channel causing a fuel element to melt and catch fire|
|1966||Monroe||US||Sodium cooling system malfunction|
|1964||Charlestown||US||Error by a worker at a United Nuclear Corporation fuel facility led to an accidental criticality|
|1959||Santa Susana Field Laboratory||US||Partial core meltdown|
|1958||Chalk River||Canada||Due to inadequate cooling a damaged uranium fuel rod caught fire and was torn in two|
|1958||Vinča||Yugoslavia||During a subcritical counting experiment a power buildup went undetected - six scientists received high doses|
|1957||Kyshtym||6||Russia||Significant release of radioactive material to the environment from explosion of a high activity waste tank.|
|1957||Windscale Pile||5||UK||Release of radioactive material to the environment following a fire in a reactor core|
|1952||Chalk River||5||Canada||A reactor shutoff rod failure, combined with several operator errors, led to a major power excursion of more than double the reactor's rated output at AECL's NRX reactor|