Page 27 - Curriculum Visions Dynamic Book

fallout: radioactive particles that reach the ground from radioactive materials in the atmosphere.
half-life: the time it takes for the radiation coming from a sample of a radioactive element to decrease by half.
Strontium
Strontium is a soft, silvery metal
that behaves very much like calcium. Strontium-90 has a half-life of 28 years.
Strontium was discovered nearly two centuries ago, but its radioactive forms were only discovered much more recently.
Strontium-90 is one of the products of nuclear explosions, and as a result of them, levels of strontium in the atmosphere increased during periods of atmospheric nuclear tests.
Because it becomes absorbed by the bones and can irradiate marrow cells and cause leukaemia, strontium is thought to be the most dangerous form of radioactive fallout from nuclear explosions.
Cobalt
Cobalt (symbol Co) is a hard, silver metal. It gets its name from the German Kobold (a mythological underground demon). The ores in which cobalt are found also contain arsenic, and the first people to work the ore died from arsenic poisoning. Ironically, cobalt is a vital trace element and important for health. Zaïre has two- thirds of the world’s reserves of cobalt.
Cobalt-60 is an artificially produced isotope (form) of cobalt. It is made
by bombarding naturally occurring cobalt-59 with neutrons inside an atomic reactor. Cobalt-60 has healing properties when used as part of radiation therapy. It is used as a source of gamma radiation, which is similar
to X-rays.
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