Fallout, Chernobyl iodine

Half-lives span a very wide range (Table 17.5). Consider strontium-90, for which the half-life is 28 a. This nuclide is present in nuclear fallout, the fine dust that settles from clouds of airborne particles after the explosion of a nuclear bomb, and may also be present in the accidental release of radioactive materials into the air. Because it is chemically very similar to calcium, strontium may accompany that element through the environment and become incorporated into bones once there, it continues to emit radiation for many years. About 10 half-lives (for strontium-90, 280 a) must pass before the activity of a sample has fallen to 1/1000 of its initial value. Iodine-131, which was released in the accidental fire at the Chernobyl nuclear power plant, has a half-life of only 8.05 d, but it accumulates in the thyroid gland. Several cases of thyroid cancer have been linked to iodine-131 exposure from the accident. Plutonium-239 has a half-life of 24 ka (24000 years). Consequently, very long term storage facilities are required for plutonium waste, and land contaminated with plutonium cannot be inhabited again for thousands of years without expensive remediation efforts. 

Irwin Goodwin. Fallout of Atmospheric Nuclear Tests in 1950s and 1960s Exposed More People to Iodine-131 than Chernobyl Accident. Physics Today. 50 (Sept. 1997) 54-55. 

Public interest in radioactive aerosols began in the mid-1950s, when world-wide fallout of fission products from bomb tests was first observed. The H-bomb test at Bikini Atoll in 1954 had tragic consequences for the Japanese fisherman, and the inhabitants of the Ronge-lap Atoll, who were in the path of the fallout. In 1957, radio-iodine and other fission products, released in the accident to the Windscale reactor, were tracked over much of Europe, and these events were repeated on a much larger scale after the Chernobyl accident. 

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... 

Increased radioactive fallout was first observed by the control system of a nuclear power plant on the east coast of Sweden after the Chernobyl accident. Nonetheless, no increase has later been observed in thyroid cancer incidence among children in that special region, emphasizing the importance of iodine sufficiency. 

Problem 10.56. One of the products of radiation fallout from atmospheric bomb testing or nuclear accidents as at Chernobyl is iodine-131. People living in a region where iodine-131 was known to have been deposited were encouraged to use salt enriched with nonradioactive iodine-127. What was the basis of this treatment ... 

Radioactive iodine gained notoriety through the nuclear disaster at the Chernobyl power plant in 1986, which resulted in an increase of thyroid carcinomas among small children by a factor of around 10-30. It is now presumed that many of these cancer cases might have been prevented by prophylactic administration of iodide. The longer term consequences of the nuclear fallout from the Fukushima Daiichi accident in 2011, where also a number of different radionuclides were released, are still being evaluated. 

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