Chernobyl nuclear reactor explosion

Cancer Risks The increased risk of thyroid cancer after thyroid irradiation in childhood has been recognized for nearly 50 years (Dolphin, 1968). Thus, a major concern of therapy relates to the risk of thyroid cancer. Detractors of therapy point to the increased rates of thyroid cancer and thyroid nodules observed in young children exposed to radiation from nuclear fallout at Hiroshima or after the Chernobyl nuclear reactor explosion. 

Cs is produced by reprocessing of nuclear fuel. Cs is generally present in the atmosphere as a result of nuclear weapons testing, though undoubtedly the Chernobyl nuclear reactor explosion has made a major contribution to environmental levels of Cs [5]. 

Epidemiological studies of populations in the FSU exposed to fallout from the 1986 nuclear reactor explosion at Chernobyl and releases from the Chelyabinsk-65 complex demonstrate the health effects associated with exposure to radioactive iodine, strontium, and caesium. A study of 2.81 X 10" individuals exposed along the Techa River, downstream from Chelyabinsk-65, revealed that a statistically significant increase in leukemia mortality arose between 5 yr and 20 yr after the initial exposure (37 observed deaths versus 14-23 expected deaths see Cochran et al. (1993) and cited references and comments). There has been a significant increase of thyroid cancers among children in the areas contaminated by fallout from the Chernobyl explosion (Harley, 2001 UNSCEAR, 2000). The initial external exposures from Chernobyl were due to and short-lived isotopes. Subsequently, external exposures to Cs and nd internal... 

The anthropogenic radionuclides of most concern are those produced as fission products from nuclear weapons and nuclear reactors. The most devastating release from the latter source to date resulted from the April 26, 1986, explosion, partial meltdown of the reactor core, and breach of confinement structures by a power reactor at Chernobyl in the Ukraine. This disaster released 5 x 107 Ci of radionuclides from the site, which contaminated large areas of Soviet Ukraine and Byelorussia, as well as areas of Scandinavia, Italy, France, Poland, Turkey, and Greece. Radioactive fission products that are the same or similar to elements involved in life processes can be particularly hazardous. One of these is radioactive iodine, which tends to accumulate in the thyroid gland, which may develop cancer or otherwise be damaged as a result. Radioactive cesium exists as the Cs+ ion and is similar to sodium and potassium in its physiological behavior. Radioactive strontium forms the Sr2+ ion and substitutes for Ca2+, especially in bone. 

On April 26, 1986, one of four nuclear reactors exploded more at the Chernobyl power station in Ukraine, a country that used to be a part of the old Soviet Union. The explosion burned for nine days, proving to be the worst nuclear accident in history. The disaster released at least 100 times more radiation than the atom bombs dropped in Nagasaki and Hiroshima. Much of the fallout fell close to Chernobyl,... 

The explosion of the nuclear reactor at Chernobyl (spelling changed recently to Chornobyl) in the Ukraine on April 26, 1986 sent radioactive material as far away as Sweden.90 The current death toll is 45. There has been a huge increase in childhood thyroid cancer, with cases as far as 500 km away 91 (U. S. bomb tests have also increased the incidence of thyroid cancers in the western United States.92) There is a 30-km exclusion zone around the plant where no one is allowed to live. This was created by the evacuation of 135,000 people 93 The accident is said to have happened because of combination of the physical characteristics of the reactor, the design of the control rods, human error and management shortcomings in the design, and implementation of the safety experiment. ... 

Certain chemical disasters have prominent places in medical history. In 1976, a chemical reactor explosion in Seveso, Italy, released 2,3,7,8-tetrachlorodibenzo-p-dioxin, which contaminated thousands of acres, killed 100,000 animals, and caused the evacuation of hundreds of people (Melius and Binder 1989). In 1984 in Bhopal, India, a carbamate pesticide plant released 30 tons of methyl isocyanate, causing more than 3,000 deaths and 50,000-300,000 injuries (Melius and Binder 1989). The Three Mile Island and Chernobyl nuclear accidents during the 1980s were the culmination of a string of eight nuclear accidents since 1952 (Melius and Binder 1989). Other chemical disasters severely affected local communities but did not generate widespread attention (De La Paz 1997 Withers 1988). 

On April 26, 1986, a low power engineering test was being conducted at one of the reactors of the Chernobyl nuclear power station in the Ukraine (then the USSR). The reactor became unstable, resulting in thermal explosions and fires that caused severe damage to the reactor and its building ( S. 10.2 and 20.1.2c). Radioactivity was released over the next ten days until the dres were extinguished and the reactor entombed in concrete. The radioactivity was released as gas and dust particles and initially blown by winds in a northerly direction. Outside Russia, the accident was first detected by increased... 

Nuclear fission provides about 20% of the electricity generated within the UK. Economic womies about the decommissioning of old nuclear stations, and major accidents in Windscale UK (1957), Three Mile Island USA (1979) and Chernobyl Ukraine (1986) have caused many people to question whether or not more nuclear plants should be built. This is a photograph of the fourth reactor at the Chernobyl nuclear power plant where an explosion resulted in the world s worst nuclear accident. 

Fission products were also used by Picciotto and Wilgain (1963) as a reference for measuring snow accumulations in Antarctica. Additional fission products were deposited in Antarctica after the accidental explosion of a nuclear reactor in Chernobyl, Ukraine, on April 26 of 1986 (Faure et al. 1997). 

The Chernobyl reactor explosion" on April 26, 1986, was a mnaway event for one type of reactor design. It involved a steam explosion. Heat from the reaction caused the explosion in the plant. It was not a nuclear explosion like that in a bomb. The major incident at Three Mile Island, PA, involved a mnaway reaction, but no explosion. ... 

The Chernobyl (former USSR now Ukraine) accident in 1986 was the result of a flawed reactor design that was operated by inadequately trained personnel and without proper attention to safety. The resulting steam explosion and fire released 5% of the radioactive material into the atmosphere. Such types of nuclear reactors were known to have unstable operating regions during shutdown. 

The artificial or human-made radioactive elements were discovered by I. Curie and F. Joliot in 1934 [1]. Since then, many of these elements have been produced by nuclear explosions and nuclear reactors. The primary sources of radionuclides produced by fission process and foimd in the environment are atmospheric testing of nuclear weapons and nuclear accidents, such as the well-known Chernobyl accident in April 1986 [2,3]. After the Chernobyl disaster, the initial widespread radioactivity that was most noticeable was due to however, its contribution became negligible after about two months because of its half-life of only 8 days. The remaining Cs and Cs were then the dominant radionuclides, with half-lives of 30 years and 2.1 years, respectively. Table 3.1 lists some of the cosmogenic, natural, and artificial radionuclides in the envirorunent. 

Meltdown of a nuclear reactor. This involves overheating and melting of the nuclear fuel rods with the subsequent, possible explosive release of radioactive material. It should be noted that the explosion in this case is not nuclear but related to the reactor cooling system. The reactor failures in Chernobyl in the Ukraine and at Fukushima in Japan are examples. Both produced the release of high concentrations of radioactive isotopes. 

Experience from the 1986 Chernobyl reactor accident in the Ukraine shows the potential magnitude and impact of a terrorist attack on a nuclear power plant. The accident involved an explosion in a reactor that releases very high levels of radiation for miles surrounding the reactor site. Low levels of radiation were spread by wind currents throughout Europe and the rest of the world. According to Caldicott 2002,... 

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