Nuclear power is any nuclear technology designed to extract usable energy from atomic nuclei via controlled nuclear reactions. The only method in use today is through nuclear fission, though other methods might one day include nuclear fusion and radioactive decay (see below). All utility-scale reactors^[1] heat water to produce steam, which is then converted into mechanical work for the purpose of generating electricity or propulsion. In 2007, 14% of the world's electricity came from nuclear power. Also, more than 150 nuclear-powered naval vessels have been built, and a few radioisotope rockets have been produced. Nuclear power is a low carbon power source.

Spent fuel is highly radioactive and needs to be handled with great care and forethought.^{[citation needed]} However, spent nuclear fuel becomes less radioactive over the course of thousands of years of time. After about 5 percent of the rod has reacted the rod is no longer able to be used. Today scientists are experimenting on how to recycle these rods to reduce waste. In the meantime, after 40 years, the radiation flux is 99.9% lower than it was the moment the spent fuel was removed, although still dangerously radioactive.^[57]

Spent fuel rods are stored in shielded basins of water (spent fuel pools), usually located on-site. The water provides both cooling for the still-decaying fission products, and shielding from the continuing radioactivity. After a few decades some on-site storage involves moving the now cooler, less radioactive fuel to a dry-storage facility or dry cask storage, where the fuel is stored in steel and concrete containers until its radioactivity decreases naturally ("decays") to levels safe enough for other processing. This interim stage spans years or decades or millenia, depending on the type of fuel. Most U.S. waste is currently stored in temporary storage sites requiring oversight, while suitable permanent disposal methods are discussed.

As of 2007, the United States had accumulated more than 50,000 metric tons of spent nuclear fuel from nuclear reactors.^[68] Underground storage at Yucca Mountain in U.S. has been proposed as permanent storage. After 10,000 years of radioactive decay, according to United States Environmental Protection Agency standards, the spent nuclear fuel will no longer pose a threat to public health and safety.^{[citation needed]}

The amount of waste can be reduced in several ways, particularly reprocessing. Even so, the remaining waste will be substantially radioactive for at least 300 years even if the actinides are removed, and for up to thousands of years if the actinides are left in.^[^{citation
needed}^] Even with separation of all actinides, and using fast breeder reactors to destroy by transmutation some of the longer-lived non-actinides as well, the waste must be segregated from the environment for one to a few hundred years, and therefore this is properly categorized as a long-term problem. Subcritical reactors or fusion reactors could also reduce the time the waste has to be stored.^[69] It has been argued^[who?] that the best solution for the nuclear waste is above ground temporary storage since technology is rapidly changing. There is hope that current waste may well become a valuable resource in the future.

According to a 2007 story broadcast on 60 Minutes, nuclear power gives France the cleanest air of any industrialized country, and the cheapest electricity in all of Europe.^[70] France reprocesses its nuclear waste to reduce its mass and make more energy.^[71] However, the article continues, "Today we stock containers of waste because currently scientists don't know how to reduce or eliminate the toxicity, but maybe in 100 years perhaps scientists will ... Nuclear waste is an enormously difficult political problem which to date no country has solved. It is, in a sense, the Achilles heel of the nuclear industry

Uranium enrichment produces many tons of depleted uranium (DU) which consists of U-238 with most of the easily fissile U-235 isotope removed. U-238 is a tough metal with several commercial uses — for example, aircraft production, radiation shielding, and armor — as it has a higher density than lead. Depleted uranium is also useful in munitions as DU penetrators (bullets or APFSDS tips) 'self sharpen', due to uranium's tendency to fracture along adiabatic shear bands.^[79]^[80]

There are concerns that U-238 may lead to health problems in groups exposed to this material excessively, like tank crews and civilians living in areas where large quantities of DU ammunition have been used in shielding, bombs, missile warheads, and bullets. In January 2003 the World Health Organization released a report finding that contamination from DU munitions were localized to a few tens of meters from the impact sites and contamination of local vegetation and water was 'extremely low'. The report also states that approximately 70% of ingested DU will leave the body after twenty four hours and 90% after a few days

The anti-nuclear movement is a loosely-linked international social movement opposed to the use of nuclear technologies. The chief focus of the movement is opposition to nuclear power (see Nuclear debate), but also includes other issues such as:

Pursuing nuclear disarmament

Opposing the use of depleted uranium in warfare

Opposing the use of food irradiation

Opposing the widespread use of radiation

Historically, this opposition has come from both political organisations and grassroots movements. Common political targets are new nuclear plants (see EPR image to right), waste repository sites, transport of waste, nuclear reprocessing, uranium mining, or any other nuclear-connected technology, because of perceived and real environmental consequences of these activities

http://en.wikipedia.org/wiki/Anti-nuclear_movement

Radioactive waste is a waste product containing radioactive material. It is usually the product of a nuclear process such as nuclear fission. However, industries not directly connected to the nuclear industry may produce quantities of radioactive waste. The majority of radioactive waste is "low-level waste", meaning it contains low levels of radioactivity per mass or volume. This type of waste often consists of used protective clothing, which is only lightly contaminated but still dangerous in case of radioactive contamination of a human body through ingestion, inhalation, absorption, or injection.

The issue of disposal methods for nuclear waste was one of the most pressing current problems the international nuclear industry faced when trying to establish a long term energy production plan, yet there was hope it could be safely solved. A report giving the Nuclear Industry's perspective on this problem is presented in a document from the IAEA (The International Atomic Energy Agency) published in October 2007. It summarizes the current state of scientific knowledge on whether waste could find its way from a deep burial facility back to soil and drinking water and threaten the health of human beings and other forms of life. In the United States, DOE acknowledges progress in addressing the waste problems of the industry, and successful remediation of some contaminated sites, yet some uncertainty and complications in handling the issue properly, cost effectively, and in the projected time frame.^[1] In other countries with lower ability or will to maintain environmental integrity the issue would be even more problematic.

In the United States alone, the Department of Energy states there are "millions of gallons of radioactive waste" as well as "thousands of tons of spent nuclear fuel and material" and also "huge quantities of contaminated soil and water."^[1] Despite copious quantities of waste, the DOE has stated a goal of cleaning all presently contaminated sites successfully by 2025.^[1] The Fernald, Ohio site for example had "31 million pounds of uranium product", "2.5 billion pounds of waste", "2.75 million cubic yards of contaminated soil and debris", and a "223 acre portion of the underlying Great Miami Aquifer had uranium levels above drinking standards."^[1] The United States has at least 108 sites designated as areas that are contaminated and unusable, sometimes many thousands of acres.^[1]^[2] DOE wishes to clean or mitigate many or all by 2025, however the task can be difficult and it acknowledges that some may never be completely remediated. In just one of these 108 larger designations, Oak Ridge National Laboratory, there were for example at least "167 known contaminant release sites" in one of the three subdivisions of the 37,000-acre (150 km²) site.^[1] Some of the U.S. sites were smaller in nature, however, cleanup issues were simpler to address, and DOE has successfully completed cleanup, or at least closure, of several sites.^[1]

Claims exist that the problems of nuclear waste do not come anywhere close to approaching the problems of fossil fuel waste.^[3]^[4] A 2004 article from the BBC states: "The World Health Organization (WHO) says 3 million people are killed worldwide by outdoor air pollution annually from vehicles and industrial emissions, and 1.6 million indoors through using solid fuel."^[5] In the U.S. alone, fossil fuel waste kills 20,000 people each year.^[6] A coal power plant releases 100 times as much radiation as a nuclear power plant of the same wattage.^[7] It is estimated that during 1982, US coal burning released 155 times as much radioactivity into the atmosphere as the Three Mile Island accident.^[8]

The World Nuclear Association provides a comparison of deaths due to accidents among different forms of energy production. In their comparison, deaths per TW-yr of electricity produced from 1970 to 1992 are quoted as 885 for hydropower, 342 for coal, 85 for natural gas, and 8 for nuclear.^[

Radioactive waste typically comprises a number of radioisotopes: unstable configurations of elements that decay, emitting ionizing radiation which can be harmful to human health and to the environment. Those isotopes emit different types and levels of radiation, which last for different periods of time..

Physics

The radioactivity of all nuclear waste diminishes with time. All radioisotopes contained in the waste have a half-life - the time it takes for any radionuclide to lose half of its radioactivity and eventually all radioactive waste decays into non-radioactive elements. Certain radioactive elements (such as plutonium-239) in “spent” fuel will remain hazardous to humans and other living beings for hundreds of thousands of years. Other radioisotopes remain hazardous for millions of years. Thus, these wastes must be shielded for centuries and isolated from the living environment for millennia.^[10] Some elements, such as Iodine-131, have a short half-life (around 8 days in this case) and thus they will cease to be a problem much more quickly than other, longer-lived, decay products but their activity is much greater initially. The two tables show some of the major radioisotopes, their half-lives, and their radiation yield as a proportion of the yield of fission of Uranium-235.

The faster a radioisotope decays, the more radioactive it will be. The energy and the type of the ionizing radiation emitted by a pure radioactive substance are important factors in deciding how dangerous it will be. The chemical properties of the radioactive element will determine how mobile the substance is and how likely it is to spread into the environment and contaminate human bodies. This is further complicated by the fact that many radioisotopes do not decay immediately to a stable state but rather to a radioactive decay product leading to decay chains

Pharmacokinetics

Exposure to high levels of radioactive waste may cause serious harm or death. Treatment of an adult animal with radiation or some other mutation-causing effect, such as a cytotoxic anti-cancer drug, may cause cancer in the animal. In humans it has been calculated that a 5 sievert dose is usually fatal, and the lifetime risk of dying from radiation induced cancer from a single dose of 0.1 sieverts is 0.8%, increasing by the same amount for each additional 0.1 sievert increment of dosage.^[11] Ionizing radiation causes deletions in chromosomes.^[12] If a developing organism such as an unborn child is irradiated, it is possible a birth defect may be induced, but it is unlikely this defect will be in a gamete or a gamete forming cell. The incidence of radiation-induced mutations in humans is undetermined, due to flaws in studies done to date. ^[13]

Depending on the decay mode and the pharmacokinetics of an element (how the body processes it and how quickly), the threat due to exposure to a given activity of a radioisotope will differ. For instance Iodine-131 is a short-lived beta and gamma emitter but because it concentrates in the thyroid gland, it is more able to cause injury than cesium-137 which, being water soluble, is rapidly excreted in urine. In a similar way, the alpha emitting actinides and radium are considered very harmful as they tend to have long biological half-lives and their radiation has a high linear energy transfer value. Because of such differences, the rules determining biological injury differ widely according to the radioisotope, and sometimes also the nature of the chemical compound which contains the radioisotope

Waste from the front end of the nuclear fuel cycle is usually alpha emitting waste from the extraction of uranium. It often contains radium and its decay products.

Uranium dioxide (UO₂) concentrate from mining is not very radioactive - only a thousand or so times as radioactive as the granite used in buildings. It is refined from yellowcake (U₃O₈), then converted to uranium hexafluoride gas (UF₆). As a gas, it undergoes enrichment to increase the U-235 content from 0.7% to about 4.4% (LEU). It is then turned into a hard ceramic oxide (UO₂) for assembly as reactor fuel elements.

The main by-product of enrichment is depleted uranium (DU), principally the U-238 isotope, with a U-235 content of ~0.3%. It is stored, either as UF₆ or as U₃O₈. Some is used in applications where its extremely high density makes it valuable, such as the keels of yachts, and anti-tank shells.^[14] It is also used (with recycled plutonium) for making mixed oxide fuel (MOX) and to dilute highly enriched uranium from weapons stockpiles which is now being redirected to become reactor fuel. This dilution, also called downblending, means that any nation or group that acquired the finished fuel would have to repeat the (very expensive and complex) enrichment process before assembling a weapon.

A number of incidents have occurred when radioactive material was disposed of improperly, shielding during transport was defective, or when it was simply abandoned or even stolen from a waste store.^[56] In the Soviet Union, waste stored in Lake Karachay was blown over the area during a dust storm after the lake had partly dried out.^[57] At Maxey Flat, a low-level radioactive waste facility located in Kentucky, containment trenches covered with dirt, instead of steel or cement, collapsed under heavy rainfall into the trenches and filled with water. The water that invaded the trenches became radioactive and had to be disposed of at the Maxey Flat facility itself. In other cases of radioactive waste accidents, lakes or ponds with radioactive waste accidentally overflowed into the rivers during exceptional storms.^[^{citation
needed}^] In Italy, several radioactive waste deposits let material flow into river water, thus contaminating water fit for domestic use.^[58] In France, in the summer of 2008 numerous incidents happened;^[59] in one, at the Areva plant in Tricastin, it was reported that during a draining operation liquid containing untreated uranium overflowed out of a faulty tank and about 75 kg of the radioactive material seeped into the ground and, from there, into two rivers nearby;^[60]; in another case, over 100 staff were contaminated with low doses of radiation.^[61]

Scavenging of abandoned radioactive material has been the cause of several other cases of radiation exposure, mostly in developing nations, which may have less regulation of dangerous substances (and sometimes less general education about radioactivity and its hazards) and a market for scavenged goods and scrap metal. The scavengers and those who buy the material are almost always unaware that the material is radioactive and it is selected for its aesthetics or scrap value.^[62] Irresponsibility on the part of the radioactive material's owners, usually a hospital, university or military, and the absence of regulation concerning radioactive waste, or a lack of enforcement of such regulations, have been significant factors in radiation exposures. For an example of an accident involving radioactive scrap originating from a hospital see the Goiânia accident.^[62]

Transportation accidents involving spent nuclear fuel from power plants are unlikely to have serious consequences due to the strength of the spent nuclear fuel shipping casks.

This article covers notable accidents involving nuclear devices and radioactive materials. These accidents can hurt or kill almost anything that is around it while the accident is happening. In some cases, a release of radioactive contamination occurs, but in many cases the accident involves a sealed source or the release of radioactivity is small while the direct irradiation is large. Due to government and business secrecy, it is not always possible to determine with certainty the frequency or the extent of some events in the early days of the radiation industries. Modern misadventures, accidents, and incidents, which result in injury, death, or serious environmental contamination, tend to be well documented by the International Atomic Energy Agency

Because of the different nature of the events it is best to divide the list into nuclear and radiation accidents. An example of nuclear accident might be one in which a reactor core is damaged such as in the Chernobyl Nuclear Power Plant Accident, while an example of a radiation accident might be some event such as a radiography accident where a worker drops the source into a river. These radiation accidents such as those involving the radiography sources often have as much or even greater ability to cause serious harm to both workers and the public than the well known nuclear accidents.

Radiation accidents are more common than nuclear accidents, and are often limited in scale. For instance at Soreq, a worker suffered a dose which was similar to one of the highest doses suffered by a worker on site at Chernobyl on day one. However, because the gamma source was never able to leave the 2-metre thick concrete enclosure, it was not able to harm many others.

The web page at the International Atomic Energy Agency, which deals with recent accidents is [2]. The safety significance of nuclear accidents can be assessed and conveyed using the International Atomic Energy Agency International Nuclear Event Scale.

Nuclear Regulatory CommissionHeadquarters and Regional staff members typically participate in four full-scale and emergency response exercises each year, selected from among the list of full-scale Federal Emergency Management Agency (FEMA)-graded exercises required of nuclear facilities. Regional staff members and selected Headquarters staff also participate in post-plume, ingestion phase response exercises. On-scene participants include the NRC licensee, and State, county, and local emergency response agencies.(http://www.nrc.gov/about-nrc/emerg-preparedness/exercise-schedules/nrc-ex-schedule.html) This allows for Federal Interagency participation that will provide increased preparedness during the potential for an event at an operating nuclear reactor.

The US Nuclear Regulatory Commission (NRC) collects reports of incidents occurring at regulated facilities. The agency currently (2006) uses a 4 level taxonomy to classify reported incidents:

Notification of Unusual Event

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Chernobyl disaster

The nuclear reactor after the disaster. Reactor 4 (image center). Turbine building (image lower left). Reactor 3 (center right)
Date	26 April 1986 (1986-04-26)
Time	01:23:45 a.m. (UTC+3
Location	Pripyat, Ukraine
Casualties
56 direct deaths
600,000 (est) suffered radiation exposure, which may result in as many as 4,000 cancer deaths over the lifetime of those exposed, in addition to the approximately 100 000 fatal cancers to be expected due to all other causes in this population.^[1]

· The Chernobyl disaster was a nuclear reactor accident at the Chernobyl Nuclear Power Plant in Ukraine, then part of the Soviet Union. It is considered to be the worst nuclear power plant disaster in history and the only level 7 instance on the International Nuclear Event Scale. It resulted in a severe release of radioactivity following a massive power excursion which destroyed the reactor. Two people died in the initial steam explosion, but most deaths from the accident were attributed to radiation.

· On 26 April 1986 01:23:45 a.m. (UTC+3) reactor number four at the Chernobyl plant, near Pripyat in the Ukrainian Soviet Socialist Republic, exploded. Further explosions and the resulting fire sent a plume of highly radioactive fallout into the atmosphere and over an extensive geographical area. Four hundred times more fallout was released than had been by the atomic bombing of Hiroshima.^[2]

· The plume drifted over extensive parts of the western Soviet Union, Eastern Europe, Western Europe, Northern Europe, and eastern North America, with light nuclear rain falling as far as Ireland. Large areas in Ukraine, Belarus, and Russia were badly contaminated, resulting in the evacuation and resettlement of over 336,000 people. According to official post-Soviet data,^[3] about 60% of the radioactive fallout landed in Belarus.

· The accident raised concerns about the safety of the Soviet nuclear power industry, slowing its expansion for a number of years, while forcing the Soviet government to become less secretive. The countries of Russia, Ukraine, and Belarus have been burdened with the continuing and substantial decontamination and health care costs of the Chernobyl accident. It is difficult to accurately quantify the number of deaths caused by the events at Chernobyl, as the Soviet-era cover-up made it difficult to track down victims. Lists were incomplete, and Soviet authorities later forbade doctors to cite "radiation" on death certificates.^[4]

· The overall cost of the disaster is estimated at US$200 billion, taking inflation into account. This places the Chernobyl disaster as the most costly disaster in modern history.^[5]^[^{unreliable source?}^]

· The 2005 report prepared by the Chernobyl Forum, led by the International Atomic Energy Agency (IAEA) and World Health Organization (WHO), attributed 56 direct deaths (47 accident workers, and nine children with thyroid cancer), and estimated that there may be 4,000 extra cancer deaths among the approximately 600,000 most highly exposed people.^[1] Although the Chernobyl Exclusion Zone and certain limited areas remain off limits, the majority of affected areas are now considered safe for settlement and economic activity.^[6]

***************

The nuclear meltdown produced a radioactive cloud that floated not only over the modern states of Russia, Belarus, Ukraine and Moldova, but also Turkish Thrace, the Southern coast of the Black Sea, Macedonia, Serbia, Croatia, Bosnia-Herzegovina, Bulgaria, Greece, Romania, Lithuania, Estonia, Latvia, Finland, Denmark, Norway, Sweden, Austria, Hungary, the Czech Republic and the Slovak Republic, The Netherlands, Belgium, Slovenia, Poland, Switzerland, Germany, Luxembourg, Italy, Ireland, France (including Corsica ^[50]) the United Kingdom and the Isle of Man.^[51]^[52]

The initial evidence that a major exhaust of radioactive material was affecting other countries came not from Soviet sources, but from Sweden, where on 27 April workers at the Forsmark Nuclear Power Plant (approximately 1,100 km (680 mi) from the Chernobyl site) were found to have radioactive particles on their clothes.^[53] It was Sweden's search for the source of radioactivity, after they had determined there was no leak at the Swedish plant, which led to the first hint of a serious nuclear problem in the western Soviet Union and, incidentally, triggered evacuation of Pripyat over 36 hours after the initial explosions. The rise of radiation levels had at that time already been measured in Finland, but a civil service strike delayed the response and publication.^[54]

Contamination from the Chernobyl accident was scattered irregularly depending on weather conditions. Reports from Soviet and Western scientists indicate that Belarus received about 60% of the contamination that fell on the former Soviet Union. However, the 2006 TORCH report stated that half of the volatile particles had landed outside Ukraine, Belarus and Russia. A large area in Russia south of Bryansk was also contaminated, as were parts of northwestern Ukraine. Studies in countries around the area say that over one million people could have been affected by radiation.^[55]

Recently published data of a long-term monitoring programme (The Korma-Report^[56]) show a decrease of internal radiation exposure of the inhabitants of a region in Belarus close to Gomel. Resettlement may even be possible in prohibited areas provided that people comply with appropriate dietary rules.

In Western Europe, measures were taken including seemingly arbitrary regulations pertaining to the legality of importation of certain foods but not others. In France some officials stated that the Chernobyl accident had no adverse effects.

Like many other releases of radioactivity into the environment, the Chernobyl release was controlled by the physical and chemical properties of the radioactive elements in its core. While plutonium is often perceived as particularly dangerous nuclear fuel by the general population, its effects are almost eclipsed by those of its fission products. Particularly dangerous are highly radioactive compounds that accumulate in the food chain, such as some isotopes of iodine and strontium.

The external gamma dose for a person in the open near the Chernobyl site.

The contributions by the various isotopes to the dose (in air) in the contaminated area soon after the accident.

Two reports on the release of radioisotopes from the site were made available, one by the OSTI, and a more detailed report by OECD, both in 1998.^[57]^[58] At different times after the accident, different isotopes were responsible for the majority of the external dose. The dose that was calculated is that received from external gamma irradiation for a person standing in the open. The dose to a person in a shelter or the internal dose is harder to estimate.

The release of the radioisotopes from the nuclear fuel was largely controlled by their boiling points, and the majority of the radioactivity present in the core was retained in the reactor.

All of the noble gases, including krypton and xenon, contained within the reactor were released immediately into the atmosphere by the first steam explosion.

About 55% of the radioactive iodine in the reactor was released, as a mixture of vapor, solid particles and as organic iodine compounds.

Caesium and tellurium were released in aerosol form.

Two sizes of particles were released: small particles of 0.3 to 1.5 micrometers (aerodynamic diameter) and large particles of 10 micrometers. The large particles contained about 80% to 90% of the released nonvolatile radioisotopes zirconium-95, niobium-95, lanthanum-140, cerium-144 and the transuranic elements, including neptunium, plutonium and the minor actinides, embedded in a uranium oxide matrix.

In the aftermath of the accident, 237 people suffered from acute radiation sickness, of whom 31 died within the first three months.^[59]^[60] Most of these were fire and rescue workers trying to bring the accident under control, who were not fully aware of how dangerous the radiation exposure (from the smoke) was (for a discussion of the more important isotopes in fallout, see fission product). 135,000 people were evacuated from the area, including 50,000 from Pripyat.^{[citation needed]}

Residual radioactivity in the environment

Rivers, lakes and reservoirs

The Chernobyl nuclear power plant lies next to the Pripyat River which feeds into the Dnieper River reservoir system, one of the largest surface water systems in Europe. The radioactive contamination of aquatic systems therefore became a major issue in the immediate aftermath of the accident.^[61] In the most affected areas of Ukraine, levels of radioactivity (particularly radioiodine: I-131, radiocaesium: Cs-137 and radiostrontium: Sr-90) in drinking water caused concern during the weeks and months after the accident. After this initial period however, radioactivity in rivers and reservoirs was generally below guideline limits for safe drinking water.^[61]

Bio-accumulation of radioactivity in fish^[62] resulted in concentrations (both in western Europe and in the former Soviet Union) that in many cases were significantly above guideline maximum levels for consumption.^[61] Guideline maximum levels for radiocaesium in fish vary from country to country but are approximately 1,000 Bq/kg in the European Union.^[63] In the Kiev Reservoir in Ukraine, activity concentrations in fish were several thousand Bq/kg during the years after the accident.^[62] In small "closed" lakes in Belarus and the Bryansk region of Russia, activity concentrations in a number of fish species varied from 0.1 to 60 kBq/kg during the period 1990–92.^[64] The contamination of fish caused concern in the short term (months) for parts of the UK and Germany and in the long term (years-decades) in the Chernobyl affected areas of Ukraine, Belarus and Russia as well as in parts of Scandinavia.^[61]

Groundwater

Map of radiation levels in 1996 around Chernobyl.

Groundwater was not badly affected by the Chernobyl accident since radionuclides with short half-lives decayed away a long time before they could affect groundwater supplies, and longer-lived radionuclides such as radiocaesium and radiostrontium were adsorbed to surface soils before they could transfer to groundwaters.^[65] Significant transfers of radionuclides to groundwaters have occurred from waste disposal sites in the 30 km (19 mi) exclusion zone around Chernobyl. Although there is a potential for off-site (i.e. out of the 30 km (19 mi) exclusion zone) transfer of radionuclides from these disposal sites, the IAEA Chernobyl Report^[65] argues that this is not significant in comparison to current levels of washout of surface-deposited radioactivity.

Flora and fauna

After the disaster, four square kilometres of pine forest in the immediate vicinity of the reactor turned ginger brown and died, earning the name of the "Red Forest".^[66] Some animals in the worst-hit areas also died or stopped reproducing. Most domestic animals were evacuated from the exclusion zone, but horses left on an island in the Pripyat River 6 km (4 mi) from the power plant died when their thyroid glands were destroyed by radiation doses of 150–200 Sv.^[67] Some cattle on the same island died and those that survived were stunted because of thyroid damage. The next generation appeared to be normal.^[67]

A robot sent into the reactor itself has returned with samples of black, melanin-rich fungi that are growing on the reactor's walls.^[68]

Chernobyl after the disaster

The Prypiat Ferris wheel as seen from inside the town's Palace of Culture.

Following the accident, questions arose about the future of the plant and its eventual fate. All work on the unfinished reactors 5 and 6 was halted three years later. However, the trouble at the Chernobyl plant did not end with the disaster in reactor 4. The damaged reactor was sealed off and 200 metres (660 ft) of concrete was placed between the disaster site and the operational buildings. The Ukrainian government continued to let the three remaining reactors operate because of an energy shortage in the country. A fire broke out in the turbine building of reactor 2 in 1991;^[69] the authorities subsequently declared the reactor damaged beyond repair and had it taken offline. Reactor 1 was decommissioned in November 1996 as part of a deal between the Ukrainian government and international organizations such as the IAEA to end operations at the plant. On 15 December 2000, then-President Leonid Kuchma personally turned off Reactor 3 in an official ceremony, effectively shutting down the entire plant^[70] transforming the Chernobyl plant from energy producer to energy consumer.

Chernobyl's Exclusion Zone

In his book, Disasters: Wasted Lives, Valuable Lessons, Economist and Crisis Consultant Randall Bell writes after his research at Chernobyl, "There is a 17-mile Exclusion Zone around Chernobyl where officially nobody is allowed to live, but people do. These "resettlers" are elderly people who lived in the region prior to the disaster. Today there are approximately 10,000 people between the ages of 60 and 90 living within the Zone around Chernobyl. Younger families are allowed to visit, but only for brief periods of time.

"Eventually the land could be utilized for some sort of industrial purpose that would involve concrete sites," Randall Bell continues. "But estimates range from 60 – 200 years before this would be allowed. Farming or any other type of agricultural industry would be dangerous and completely inappropriate for at least 200 years. It will be at least two centuries before there is any chance the situation can change within the 1.5-mile Exclusion Zone. As for the #4 reactor where the meltdown occurred, we estimate it will be 20,000 years before the real estate will be fully safe." ^[71]

Controversy over "Wildlife Haven" claim

The Exclusion Zone around the Chernobyl nuclear power station is reportedly a haven for wildlife.^[72] As humans were evacuated from the area about 25 years ago, animals moved in. Existing populations multiplied and species not seen for decades, such as the lynx and eagle owl, began to return.^[72] Birds even nest inside the cracked concrete sarcophagus shielding the shattered remains of the reactor.^[73]

The Exclusion Zone is so flush with wildlife and greenery that the Ukrainian government designated it a wildlife sanctuary in 2000.^[74]

Wildlife has returned despite radiation levels that have been reported to be 10 to 100 times higher than background levels - according to a 2005 U.N. report - though they have fallen significantly since the accident, due to radioactive decay.^[73]

Some researchers claim that by halting the destruction of habitat, the Chernobyl disaster helped wildlife flourish. Biologist Robert J. Baker of Texas Tech University was one of the first to report that Chernobyl had become a wildlife haven and that many rodents he has studied at Chernobyl since the early 1990s have shown remarkable tolerance for elevated radiation levels.^[73]

However a paper published in the Journal of Animal Ecology shows that reproductive and annual survival rates are much lower in wildlife inhabiting the Chernobyl exclusion zone. ^[75] One study demonstrated that less than 15% of barn swallows inhabiting Chernobyl return each year, while in the researchers native country of Italy the survival rate is around 40%. ^[75] Some species "such as the barn swallow, are particularly vulnerable to radioactive contaminants, because they arrive in the area exhausted and with depleted reserves of protective antioxidants due to their arduous journey. ^[75] The scientists are also concerned that the mutated birds will pass on their abnormal genes to the global population. ^[75] "In the worst case scenario these genetic mutations will spread out, and the species as a whole may experience enhanced levels of mutation." ^[75] Some scientists have suggested that soy plants in the area have also mutated to adapt to the high radiation levels and toxic metals present.^[76] More research is needed into the long-term health effects on Chernobyl's wildlife species.^[73]

The Chernobyl reactor is now enclosed in a large concrete sarcophagus which was built quickly to allow continuing operation of the other reactors at the plant.^[77] However, the structure is not strong or durable. Some major work on the sarcophagus was carried out in 1998 and 1999. Some 200 tons of highly radioactive material remains deep within it, and this poses an environmental hazard until it is better contained.

A New Safe Confinement structure will be built by the end of 2011, and then will be put into place on rails. It is to be a metal arch 105 meters high and spanning 257 metres, to cover both unit 4 and the hastily built 1986 structure. The Chernobyl Shelter Fund, set up in 1997, has received €810 million from international donors and projects to cover this project and previous work. It and the Nuclear Safety Account, also applied to Chernobyl decommissioning, are managed by the European Bank for Reconstruction and Development (EBRD).^{[citation needed]}

As of 2006, some fuel at units 1 to 3 remained in the reactors, most of which is in each unit's cooling pond, as well as some material in a small interim spent fuel storage facility pond (ISF-1).

In 1999 a contract was signed for construction of a radioactive waste management facility to store 25,000 used fuel assemblies from units 1–3 and other operational wastes, as well as material from decommissioning units 1–3 (which will be the first RBMK units decommissioned anywhere). The contract included a processing facility, able to cut the RBMK fuel assemblies and to put the material in canisters, which were to be filled with inert gas and welded shut. The canisters were to be transported to dry storage vaults, where the fuel containers would be enclosed for up to 100 years. This facility, treating 2500 fuel assemblies per year, would be the first of its kind for RBMK fuel. However, after a significant part of the storage structures had been built, technical deficiencies in the concept emerged, and the contract was terminated in 2007. The interim spent fuel storage facility (ISF-2) will now be completed by others by mid 2013.^{[citation needed]}

Another contract has been let for a Liquid radioactive Waste Treatment Plant, to handle some 35,000 cubic meters of low- and intermediate-level liquid wastes at the site. This will need to be solidified and eventually buried along with solid wastes on site.^{[citation needed]}

In January 2008 Ukrainian government announced a 4-stage decommissioning plan which incorporates the above waste activities and progresses towards a cleared site.^[55]

[edit] Lava-like Fuel Containing Materials (FCMs)

The radioactivity levels of different isotopes in the FCM, as back-calculated by Russian workers to April 1986

According to official estimates, about 95% of the fuel (about 180 tonnes) in the reactor at the time of the accident remains inside the shelter, with a total radioactivity of nearly 18 million curies (670 PBq). The radioactive material consists of core fragments, dust, and lava-like "fuel-containing materials" (FCM) that flowed through the wrecked reactor building before hardening into a ceramic form.

Three different lavas are present in the basement of the reactor building; black, brown and a porous ceramic. They are silicate glasses with inclusions of other materials present within them. The porous lava is brown lava which had dropped into water thus being cooled rapidly.

[edit] Degradation of the lava

It is unclear how long the ceramic form will retard the release of radioactivity. From 1997 to 2002 a series of papers were published which suggested that the self irradiation of the lava would convert all 1,200 tons into a submicrometre and mobile powder within a few weeks.^[78] But it has been reported that it is likely that the degradation of the lava is to be a slow and gradual process rather than a sudden rapid process.^[79] The same paper states that the loss of uranium from the wrecked reactor is only 10 kg (22 lb) per year. This low rate of uranium leaching suggests that the lava is resisting its environment. The paper also states that when the shelter is improved, the leaching rate of the lava will decrease.

Some of the surfaces of the lava flows have started to show new uranium minerals such as Na₄(UO₂)(CO₃)₃ and uranyl carbonate. However the level of radioactivity is such that during one hundred years the self irradiation of the lava (2 × 10¹⁶ α decays per gram and 2 to 5 × 10⁵ Gy of β or γ) will fall short of the level of self irradiation which is required to greatly change the properties of glass (10¹⁸ α decays per gram and 10⁸ to 10⁹ Gy of β or γ). Also the rate of dissolution of the lava in water is very low (10^–7 g-cm^–2 day^–1) suggesting that the lava is unlikely to dissolve in water.^[79]

Possible consequences of further collapse of the Sarcophagus

The Sarcophagus, the concrete block surrounding reactor #4

The protective box which was placed over the wrecked reactor was named object "Shelter" by the Soviet government, but the media and the public know it as the sarcophagus.

The present shelter is constructed atop the ruins of the reactor building. The two "Mammoth Beams" that support the roof of the shelter are resting partly upon the structurally unsound west wall of the reactor building that was damaged by the accident.^[^{citation
needed}^] The western end of the shelter roof was supported by a wall (at a point designated axis 50). This wall is reinforced concrete, which was cracked by the accident. In December 2006 the Designed Stabilisation Steel Structure (DSSS) was extended until 50% of the roof load (circa 400 tons) was transferred from the axis-50 wall to the DSSS.^[^{citation
needed}^] The DSSS is a yellow steel object which has been placed next to the wrecked reactor; it is 63 metres (207 ft) tall and has a series of cantilevers which extend through the western buttress wall and is intended to stabilise the sarcophagus.^[80] This was done because if the wall of the reactor building or the roof of the shelter were to collapse, then large amounts of radioactive dust and particles would be released directly into the atmosphere, resulting in a large new release of radioactivity into the environment.

A further threat to the shelter is the concrete slab that formed the "Upper Biological Shield" (UBS), situated above the reactor prior to the accident.^[^{citation
needed}^] This concrete slab was thrown upwards by the explosion in the reactor core and now rests at approximately 15° from vertical. The position of the upper bioshield is considered inherently unsafe, as only debris supports it in its nearly upright position. A collapse of the bioshield would further exacerbate the dust conditions in the shelter, possibly spreading some quantity of radioactive materials out of the shelter, and could damage the shelter itself.

Grass and forest fires

It is known that fires can make the radioactivity mobile again.^[81]^[82]^[83]^[84] In particular V.I. Yoschenko et al. reported on the possibility of increased mobility of caesium, strontium, and plutonium due to grass and forest fires.^[85] As an experiment, fires were set and the levels of the radioactivity in the air down wind of these fires was measured.

Grass and forest fires have happened inside the contaminated zone, releasing radioactive fallout into the atmosphere. In 1986 a series of fires destroyed 23.36 km² (5,772 acres) of forest, and several other fires have since burned within the 30 km (19 mi) zone. In early May 1992 a serious fire occurred which affected 5 km² (1,240 acres) of land including 2.7 km² (670 acres) of forest. This resulted in a great increase in the levels of caesium in airborne dust.^[81]^[86]^[87]^[88]

Recovery process

The Chernobyl Shelter Fund was established in 1997 at the Denver G7 summit to finance the Shelter Implementation Plan (SIP). The plan calls for transforming the site into an ecologically safe condition through stabilization of the sarcophagus, followed by construction of a New Safe Confinement (NSC). While original cost estimate for the SIP was US$768 million, the 2006 estimate is $1.2 billion. The SIP is being managed by a consortium of Bechtel, Battelle, and Electricité de France, and conceptual design for the NSC consists of a movable arch, constructed away from the shelter to avoid high radiation, to be slid over the sarcophagus. The NSC is expected to be completed in 2012, and will be the largest movable structure ever built.

Dimensions:

Span: 270 m (886 ft)

Height: 100 m (330 ft)

Length: 150 m (492 ft)

The United Nations Development Programme has launched in 2003 a specific project called the Chernobyl Recovery and Development Programme (CRDP) for the recovery of the affected areas.^[89] The programme launched its activities based on the Human Consequences of the Chernobyl Nuclear Accident report recommendations and has been initiated in February 2002. The main goal of the CRDP’s activities is supporting the Government of Ukraine to mitigate long-term social, economic and ecological consequences of the Chernobyl catastrophe, among others. CRDP works in the four most Chernobyl-affected areas in Ukraine: Kyivska, Zhytomyrska, Chernihivska and Rivnenska.

The International Project on the Health Effects of the Chernobyl Accident (IPEHCA) was created and received $20 million US, mainly from Japan, in hopes of discovering the main cause of health problems due to I¹³¹ radiation. These funds that were given to IPEHCA were divided between Ukraine, Belarus, and Russia, the three main affected countries, for further investigation of health effects. As corruption played an important role of the former Soviet countries, most of the foreign aid was given to Russia, and no positive outcome from this money was ever shown.

Assessing the disaster's effects on human health

Main article: Chernobyl disaster effects

An international assessment of the health effects of the Chernobyl accident is contained in a series of reports by the United Nations Scientific Committee of the Effects of Atomic Radiation (UNSCEAR).^[90] UNSCEAR was set up as a collaboration between various UN bodies, including the World Health Organisation, after the atomic bomb attacks on Hiroshima and Nagasaki, to assess the long-term effects of radiation on human health.

UNSCEAR has conducted 20 years of detailed scientific and epidemiological research on the effects of the Chernobyl accident. Apart from the 57 direct deaths in the accident itself, UNSCEAR originally predicted up to 4,000 additional cancer cases due to the accident,^[1] however the latest UNSCEAR reports insinuate that these estimates were overstated.^[91] In addition, the IAEA states that there has been no increase in the rate of birth defects or abnormalities, or solid cancers (such as lung cancer) corroborating UNSCEAR's assessments.^[92]

Precisely, UNSCEAR states:

"Among the residents of Belaruss 09, the Russian Federation and Ukraine there had been, up to 2002, about 4,000 cases of thyroid cancer reported in children and adolescents who were exposed at the time of the accident, and more cases are to be expected during the next decades. Notwithstanding problems associated with screening, many of those cancers were most likely caused by radiation exposures shortly after the accident. Apart from this increase, there is no evidence of a major public health impact attributable to radiation exposure 20 years after the accident. There is no scientific evidence of increases in overall cancer incidence or mortality rates or in rates of non-malignant disorders that could be related to radiation exposure. The risk of leukaemia in the general population, one of the main concerns owing to its short latency time, does not appear to be elevated. Although those most highly exposed individuals are at an increased risk of radiation-associated effects, the great majority of the population is not likely to experience serious health consequences as a result of radiation from the Chernobyl accident. Many other health problems have been noted in the populations that are not related to radiation exposure."^[91]

Thyroid cancer is generally treatable.^[93] The five year survival rate of thyroid cancer is 96%, and 92% after 30 years, with proper treatment.^[94]

The Chernobyl Forum is a regular meeting of IAEA, other United Nations organizations (FAO, UN-OCHA, UNDP, UNEP, UNSCEAR, WHO and The World Bank) and the governments of Belarus, Russia, and Ukraine, which issues regular scientific assessments of the evidence for health effects of the Chernobyl accident.^[95] The Chernobyl Forum concluded that twenty-eight emergency workers died from acute radiation syndrome, 15 patients died from thyroid cancer, and it roughly estimated that cancers deaths caused by Chernobyl may reach a total of about 4000 among the 600 000 people having received the greatest exposures. It also concluded that a greater risk than the long-term effects of radiation exposure, is the risk to mental health of exaggerated fears about the effects of radiation:^[96]

" ... The designation of the affected population as “victims” rather than “survivors” has led them to perceive themselves as helpless, weak and lacking control over their future. This, in turn, has led either to over cautious behavior and exaggerated health concerns, or to reckless conduct, such as consumption of mushrooms, berries and game from areas still designated as highly contaminated, overuse of alcohol and tobacco, and unprotected promiscuous sexual activity."^[97]

While it was commented by Fred Mettler that 20 years later:^[98]

The population remains largely unsure of what the effects of radiation actually are and retain a sense of foreboding. A number of adolescents and young adults who have been exposed to modest or small amounts of radiation feel that they are somehow fatally flawed and there is no downside to using illicit drugs or having unprotected sex. To reverse such attitudes and behaviors will likely take years although some youth groups have begun programs that have promise.

In addition, disadvantaged children around Chernobyl suffer from health problems which are not only to do with the Chernobyl accident, but also with the desperately poor state of post-Soviet health systems.^[95]

Another study critical of the Chernobyl Forum report was commissioned by Greenpeace, which is well known for its anti-nuclear positions. In its report, Greenpeace alleges that "the most recently published figures indicate that in Belarus, Russia and Ukraine alone the accident could have resulted in an estimated 200,000 additional deaths in the period between 1990 and 2004." However, the Greenpeace report failed to discriminate between the general increase in cancer rates that followed the dissolution of the USSR's health system and any separate effects of the Chernobyl accident.^[99]

Lastly, in its report Health Effects of Chernobyl, the German affiliate of the International Physicians for the Prevention of Nuclear War (IPPNW) argued that more than 10,000 people are today affected by thyroid cancer and 50,000 cases are expected in the future.^[100] According to some commentators, both the Greenpeace and IPPNW reports suffer from a lack of any genuine or original research and failure to understand epidemiologic data.^[91] This said, it is important to bear in mind that many of the conclusions from reports such as UNSCEAR remain disputed by other commentators and scientists in the field.^[101]

In the popular consciousness

Main article: Chernobyl in the popular consciousness

See also: Nuclear debate

The Chernobyl accident attracted a great deal of interest. Because of the distrust that many people had in the Soviet authorities (people both within and outside the USSR) a great deal of debate about the situation at the site occurred in the first world during the early days of the event. Due to defective intelligence based upon photographs taken from space, it was thought that unit number three had also suffered a dire accident.

A few authors claim that the official reports underestimate the scale of the Chernobyl tragedy, counting only 30 victims;^[102] some estimate the Chernobyl radioactive fallout as hundreds of times that of the atomic bomb dropped on Hiroshima, Japan,^[103]^[104] counting millions of exposed.

In general the public knew little about radioactivity and radiation and as a result their degree of fear was increased. It was the case that many professionals (such as the spokesman from the UK NRPB) were mistrusted by journalists, who in turn encouraged the public to mistrust them.^[105]

It was noted^[106] that different governments tried to set contamination level limits which were stricter than the next country.

In Italy, the fear of nuclear accidents was dramatically increased by the Chernobyl accident: this was reflected in the outcome of the 1987 referendum about the construction of new nuclear plants in Italy. As a result of that referendum, Italy began phasing out its nuclear power plants in 1988.

Commemoration of the disaster

The Front Veranda (1986), a lithograph by Susan Dorothea White in the National Gallery of Australia shows awareness of the event worldwide. Heavy Water: A film for Chernobyl was released by Seventh Art in 2006 to commemorate the disaster through poetry and first-hand accounts [2]. The film secured the Cinequest Award as well as the Rhode Island 'best score' award [3] along with a screening at Tate Modern [4].

Chernobyl 20

This exhibit presents the stories of 20 people who have each been affected by the disaster, and each person's account is written on a panel. The 20 individuals whose stories are related in the exhibition are from Belarus, France, Latvia, Russia, Sweden, Ukraine, and the United Kingdom.

Developed by Danish photo-journalist Mads Eskesen, the exhibition is prepared in multiple languages including in German, English, Danish, Dutch, Russian and Ukrainian.

In Kiev, Ukraine, the exhibition was launched at the "Chernobyl 20 Remembrance for the Future" conference on 23 April 2006. It was then exhibited during 2006 in Australia, Denmark, the Netherlands, Switzerland, Ukraine, the United Kingdom, and the United States.

Dimensions:

Span: 270 m (886 ft)

Height: 100 m (330 ft)

Length: 150 m (492 ft)

Precisely, UNSCEAR states:

Thyroid cancer is generally treatable.^[93] The five year survival rate of thyroid cancer is 96%, and 92% after 30 years, with proper treatment.^[94]

While it was commented by Fred Mettler that 20 years later:^[98]

[edit] In the popular consciousness

Main article: Chernobyl in the popular consciousness

See also: Nuclear debate

It was noted^[106] that different governments tried to set contamination level limits which were stricter than the next country.

Tokaimura nuclear accident

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Japan's worst nuclear radiation accident took place at a uranium reprocessing facility in Tokai-mura, Ibaraki prefecture, northeast of Tokyo, Japan, on 30 September 1999. The accident occurred in a very small fuel preparation plant operated by JCO (formerly Japan Nuclear Fuel Conversion Co.), a subsidiary of Sumitomo Metal Mining Co.^[1]

The direct cause of the criticality accident was workers putting uranyl nitrate solution containing about 16.6 kg of uranium, which exceeded the critical mass, into a precipitation tank. 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, and two of these workers died; a further 119 received lesser doses of 1 mSv or greater.^[1]

Dozens of emergency workers and nearby residents were hospitalised and hundreds of thousands of others were forced to remain indoors for 24 hours

June 23, 1942 – Leipzig, Germany (then Third Reich) – 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]

A sketch of Louis Slotin’s criticality accident used to determine exposure of those in the room at the time.

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.^[2]

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.^[3] Both men, Daghlian and Slotin, were working with the same bomb core which was known as the “demon core”.

1950s

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

· An American B-36 bomber #44-92075 was flying a simulated combat mission from Eielson Air Force Base, near Fairbanks, Alaska, to Carswell Air Force Base in Fort Worth, Texas carrying one weapon containing a dummy warhead. The warhead contained uranium instead of plutonium. After six hours of flight, the bomber experienced mechanical problems and was forced to shut down three of its engines at an altitude of 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.^[4]

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 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.^[4]

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

· B-50 aircraft on a training mission from Biggs Air Force Base with a nuclear weapon flew into the ground. High explosive detonation, but no nuclear explosion.^[5]

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

1950s

December 12, 1952 — INES Level 5 - Chalk River, Ontario, Canada - Reactor core damaged

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. The operators purged the reactor's heavy water moderator, and the reaction stopped in under 30 seconds. A cover gas system failure led to hydrogen explosions, which severely damaged the reactor core. The fission products from approximately 30 kg of uranium were released through the reactor stack. Irradiated light-water coolant leaked from the damaged coolant circuit into the reactor building; some 4,000 cubic meters were pumped via pipeline to a disposal area to avoid contamination of the Ottawa River. Subsequent monitoring of surrounding water sources revealed no contamination. No immediate fatalities or injuries resulted from the incident; a 1982 followup study of exposed workers showed no long-term health effects. Future U.S. President Jimmy Carter, then a nuclear engineer in the US Navy, was among the cleanup crew.^[1]^[2]

May 24, 1958 — INES Level needed - Chalk River, Ontario, Canada - Fuel damaged

Due to inadequate cooling a damaged uranium fuel rod caught fire and was torn in two as it was being removed from the core at the NRU reactor. The fire was extinguished, but not before radioactive combustion products contaminated the interior of the reactor building and to a lesser degree, an area surrounding the laboratory site. Over 600 people were employed in the clean-up.^[3]^[4]

October 25, 1958 - INES Level needed - Vinča, Yugoslavia - Criticality excursion, irradiation of personnel

During a subcritical counting experiment a power buildup went undetected at the Boris Kidrich Institute's zero-power natural uranium heavy water moderated research reactor ^[5]. Saturation of radiation detection chambers gave the researchers false readings and the level of moderator in the reactor tank was raised triggering a criticality excursion which a researcher detected from the smell of ozone ^[6]. Six scientists received radiation doses between 200 to 400 rems ^[7] (p.96). An experimental bone marrow transplant treatment was performed on all of them in France and five survived, despite the ultimate rejection of the marrow in all cases. A single woman among them later had a child without apparent complications. This was one of the first nuclear incidents investigated by then newly-formed IAEA. ^[8]

July 26, 1959 — INES Level needed - Santa Susana Field Laboratory, California, United States - Partial meltdown

A partial core meltdown took place when the Sodium Reactor Experiment (SRE) experienced a power excursion that caused severe overheating of the reactor core, resulting in the melting of one-third of the nuclear fuel and significant releases of radioactive gases. ^[9]

1960s

A nuclear meltdown is a term for a severe nuclear reactor accident. This can occur when a nuclear power plant system or component failure causes the reactor core to cease being properly controlled and cooled to the extent that the sealed nuclear fuel assemblies – which contain the uranium or plutonium and highly radioactive fission products – begin to overheat and melt. A meltdown is considered very serious because of the possibility that the reactor containment will be defeated, thus releasing the core's highly radioactive and toxic elements into the atmosphere and environment. From an engineering perspective, a meltdown is likely to cause serious damage to the reactor, and possibly total destruction.

Several nuclear meltdowns of differing severity have occurred, from localized core damage to complete destruction of the reactor core. In some cases this has required extensive repairs or decommissioning of a nuclear reactor. In the most extreme cases, such as the Chernobyl disaster, deaths have resulted and the near-permanent civilian evacuation of a large area was required.

A nuclear explosion does not result from a nuclear meltdown because, by design, the geometry and composition of the reactor core do not permit the special conditions necessary for a nuclear explosion. However, the conditions that cause a meltdown may cause a non-nuclear explosion. For example, several power excursion accidents have caused coolant to rapidly over-pressurize, resulting in a steam explosion

The Three Mile Island accident of 1979 was a partial core meltdown in Unit 2 (a pressurized water reactor manufactured by Babcock & Wilcox) of the Three Mile Island Nuclear Generating Station in Dauphin County, Pennsylvania near Harrisburg. It was the most significant accident in the history of the American commercial nuclear power generating industry, resulting in the release of up to 481000 TBq (13 million curies) of radioactive noble gases, but less than 740 GBq (20 curies) of the particularly hazardous iodine-131 ^[1]

The accident began at 4:00 A.M. on Wednesday, March 28, 1979, with failures in the non-nuclear secondary system, followed by a stuck-open pilot-operated relief valve (PORV) in the primary system, which allowed large amounts of reactor coolant to escape. The mechanical failures were compounded by the initial failure of plant operators to recognize the situation as a loss of coolant accident due to inadequate training and ambiguous control room indicators. The scope and complexity of the accident became clear over the course of five days, as employees of Metropolitan Edison (Met Ed, the utility operating the plant), Pennsylvania state officials, and members of the U.S. Nuclear Regulatory Commission (NRC) tried to understand the problem, communicate the situation to the press and local community, decide whether the accident required an emergency evacuation, and ultimately end the crisis.

The health effects of the 1979 Three Mile Island nuclear accident are widely, but not universally, agreed to be very low level. According to the official radiation release figures, average local radiation exposure was equivalent to a chest X-ray, and maximum local exposure equivalent to less than a year's background radiation. Local activism based on anecdotal reports of negative health effects led to scientific studies being commissioned. A variety of studies have been unable to conclude that the accident had substantial health effects, but a debate remains about some key data (such as the amount of radiation released, and where it went) and gaps in the literature.

WASH-740

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WASH-740, "Theoretical Possibilities and Consequences of Major Accidents in Large Nuclear Power Plants" (also known as "The Brookhaven Report") estimated maximum possible damage from a meltdown with no containment building at a large nuclear reactor. The report was published by the U.S. Atomic Energy Commission (USAEC) in 1957.

The conclusions of this study estimated the possible effects of a "maximum credible accident" for nuclear reactors then envisioned as being 3400 deaths, 43,000 injuries and property damage of $7 billion. The estimate of probability was one in a hundred thousand to one in a billion per reactor-year. When WASH-740 was revised in 1964-65 to account for the larger reactors then being designed, the new figures indicated that there could be as many as 45,000 deaths, 100,000 injuries, and $17 billion in property damage.

However, the assumptions underlying the results were unrealistic (including the worst meteorological conditions, no containment building, and that half the reactor core is released into the atmosphere as micrometre-sized pellets without any examination of how this might occur). These were due to conservatism (estimating the maximum possible damage) and the need to use atomic bomb fallout data, which had been collected from tests (computers in 1955 being greatly insufficient to do the calculations).

As knowledge, models and computers improved the conclusions of this report were replaced by those of first WASH-1400 (1975, The Rasmussen Report), then CRAC-II (1982), and most recently NUREG-1150 (1991). Now all of these studies are considered obsolete (see the disclaimer to NUREG-1150), and are being replaced by the State-of-the-Art Reactor Consequence Analyses study.

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TMI 25 Years Later: The Three Mile Island Nuclear Power Plant Accident and Its Impact is a 2004 book^[1] which reviews the Three Mile Island accident and its causes, and the subsequent cleanup process which lasted more than a decade. A section with photographs tells the visual story of the tremendous tasks facing engineers and technicians after the nuclear accident occurred.^[2]

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Canada has an active anti-nuclear movement, which includes major campaigning organisations like Greenpeace and the Sierra Club. Over 300 public interest groups across Canada have endorsed the mandate of the Campaign for Nuclear Phaseout (CNP). Some environmental organisations such as Energy Probe, the Pembina Institute and the Canadian Coalition for Nuclear Responsibility (CCNR) are reported to have developed considerable expertise on nuclear power and energy issues. There is also a long-standing tradition of indigenous opposition to uranium mining.^[1]^[2]

Criteria

In dividing up accidents to create the list nuclear accidents, the following criteria^{[citation needed]} have been followed:

There must be well-attested and substantial health damage, property damage or contamination for an event to be listed.

To qualify as "civilian", the nuclear operation/material must be principally for non-military purposes, "military" accidents include all other accidents. (Main article: List of military nuclear accidents)

For a "nuclear" accident the event should involve fissile material, fission or a reactor, all other accidents are considered radiation accidents as they involve radioactive not nuclear materials (accidents with non-radioactive X-ray and electron beam generators are also included in this class). (Main article: List of civilian radiation accidents)

The damage must be related directly to radioactive/nuclear material, not merely (for example) at a nuclear power plant. Hypothetical examples of nonradiation/nonnuclear accidents occurring at nuclear/radiation facilities would be:

A nuclear worker crashing his private car in the car park of a nuclear power plant into a lamp post or even a truck carrying a spent fuel cask, property damage has occurred but no release of radiation or contamination will have occurred so it is a simple road traffic accident.

A veterinarian, while preparing a frightened dog for radiography, is bitten by the animal. While the bite is an injury which occurred while a radiation worker was at work (and was performing a task related to radiation work), the accident did not involve exposure of a human (or canine) to radiation so it is a simple dog bite.

Serious accidents

Main articles: List of civilian nuclear accidents, List of civilian radiation accidents, List of military nuclear accidents, and List of crimes involving radioactive substances

The worst nuclear accident in history is the Chernobyl disaster. Other serious nuclear and radiation accidents include the Mayak disaster, Soviet submarine K-431 accident, Soviet submarine K-19 accident, Three Mile Island accident, Costa Rica radiotherapy accident, Zaragoza radiotherapy accident, Goiania accident, Windscale fire, Church Rock Uranium Mill Spill and the SL-1 accident.

Accident types

Loss of coolant accident

Main article: Loss of coolant

See also: Nuclear meltdown

See also: Design Basis Accident

Criticality accidents

A criticality accident (also sometimes referred to as an "excursion" or "power excursion") occurs when a nuclear chain reaction is accidentally allowed to occur in fissile material, such as enriched uranium or plutonium. The Chernobyl accident is an example of a criticality accident. This accident destroyed the plant and left a large geographic area uninhabitable. In a smaller scale accident at Sarov a technician working with highly enriched uranium was irradiated while preparing an experiment involving a sphere of fissile material. The Sarov accident is interesting because the system remained critical for many days before it could be stopped, though safely located in a shielded experimental hall [3]. This is an example of a limited scope accident where only a few people can be harmed, while no release of radioactivity into the environment occurred. A criticality accident with limited off site release of both radiation (gamma and neutron) and a very small release of radioactivity occurred at Tokaimura in 1999 during the production of enriched uranium fuel [4]. Two workers died, a third was permantly injured, and 350 citizens were exposed to radiation

Decay heat

Decay heat accidents are where the heat generated by the radioactive decay causes harm. In a large nuclear reactor, a loss of coolant accident can damage the core: for example, at Three Mile Island a recently shutdown (SCRAMed) PWR reactor was left for a length of time without cooling water. As a result the nuclear fuel was damaged, and the core partly melted. The removal of the decay heat is a significant reactor safety concern, especially shortly after shutdown. Failure to remove decay heat may cause the reactor core temperature to rise to dangerous levels and has caused nuclear accidents. The heat removal is usually achieved through several redundant and diverse systems, and the heat is often dissipated to an 'ultimate heat sink' which has a large capacity and requires no active power, though this method is typically used after decay heat has reduced to a very small value. However, the main cause of release of radioactivity in the Three Mile Island accident was a Power Operated Relief Valve on the primary loop which stuck in the open position. This caused the overflow tank into which it drained to rupture and release large amounts of radioactive cooling water into the Containment Building.

Transport

Transport accidents can cause a release of radioactivity resulting in contamination or shielding to be damaged resulting in direct irradiation. In Cochabamba a defective gamma radiography set was transported in a passenger bus as cargo. The gamma source was outside the shielding, and it irradiated some bus passengers.

In the United Kingdom, it was revealed in a recent court case that a radiotherapy source was transported from Leeds to Sellafield with defective shielding. The shielding had a gap on the underside. It is thought that no human has been seriously harmed by the escaping radiation.^[1]

TAZKIRAH INSANi

Monday 24 September 2012

psikoloji Testing

Thursday 20 September 2012

nikah mut'ah telah dilarang sejak fathul makkah

Wednesday 19 September 2012

fakta about nuclear

Pharmacokinetics

Residual radioactivity in the environment

Rivers, lakes and reservoirs

Groundwater

Flora and fauna

Chernobyl after the disaster

Chernobyl's Exclusion Zone

Controversy over "Wildlife Haven" claim

[edit] Lava-like Fuel Containing Materials (FCMs)

[edit] Degradation of the lava

Possible consequences of further collapse of the Sarcophagus

Grass and forest fires

Recovery process

Assessing the disaster's effects on human health

In the popular consciousness

Commemoration of the disaster

Chernobyl 20

[edit] In the popular consciousness

Tokaimura nuclear accident

From Wikipedia, the free encyclopedia

1950s

1950s

1960s

WASH-740

From Wikipedia, the free encyclopedia

Criteria

Accident types

Loss of coolant accident