Strontium-90

Strontium-90

Infobox isotope
alternate_names =
symbol =Sr
mass_number =90
mass =
num_neutrons =52
num_protons =38
abundance =
halflife =28.8 years
error_halflife =
background =#7F7
text_color =


decay_product =isotopes of yttrium#90
decay_symbol =Y
decay_mass =90
decay_mode1 =Beta decay
decay_energy1 =0.546
decay_mode2 =
decay_energy2 =
decay_mode3 =
decay_energy3 =
decay_mode4 =
decay_energy4 =
parent =
parent_symbol =
parent_mass =
parent_decay =
parent2 =
parent2_symbol =
parent2_mass =
parent2_decay =
spin =
excess_energy =
error1 =
binding_energy =
error2 =

Strontium-90 (90Sr) is a radioactive isotope of strontium, with a half life of 28.8 years. 90Sr undergoes beta decay with decay energy of 0.546 MeV to the yttrium isotope 90Y, which in turn undergoes beta decay with half life of 64 hours and decay energy 2.28 MeV for beta particles to 90Zr (zirconium), which is stable [Decay data from [http://www.nndc.bnl.gov National Nuclear Data Center] at the Brookhaven National Laboratory in the US.] . Note that 90Sr/Y is almost a perfectly pure beta source; the gamma photon emission from the decay of 90Y is so weak that it can normally be ignored.

90Sr finds extensive use in medicine and industry, as a radioactive source for thickness gauges and for superficial radiotherapy of some cancers. Controlled amounts of 90Sr and 89Sr can be used in treatment of bone cancer. As the radioactive decay of strontium-90 generates significant amount of heat, and is cheaper than the alternative 238Pu, it is used as a heat source in many Russian/Soviet radioisotope thermoelectric generators, usually in the form of strontium fluoride. It is also used as a radioactive tracer in medicine and agriculture. It is obtained during nuclear reprocessing of spent nuclear fuel.

90Sr is a product of nuclear fission. It is present in significant amount in spent nuclear fuel and in radioactive waste from nuclear reactors and in nuclear fallout from nuclear tests. For thermal neutron fission as in today's nuclear power plants, the fission product yield from U-235 is 5.8%, from U-233 6.8%, but from Pu-239 only 2.1%.

Together with caesium isotopes 134Cs, 137Cs, and iodine isotope 131I it was between the most important isotopes regarding health impacts after the Chernobyl disaster. Slightly elevated levels of 90Sr may be present in the vicinity of nuclear power plants.

Strontium has biochemical behavior similar to calcium. After entering the organism, most often by ingestion with contaminated food or water, about 70-80% of the dose gets excreted. Virtually all remaining strontium is deposited in bones and bone marrow, with the remaining 1% remaining in blood and soft tissues. Its presence in bones can cause bone cancer, cancer of nearby tissues, and leukemia. Exposition to 90Sr can be tested by a bioassay, most commonly by urinalysis.

In the vicinity of nuclear waste and nuclear test sites, strontium also enters the metabolism of plants in lieu of calcium. For example, specimens of chamisa growing in Bayo Canyon, near Los Alamos, New Mexico, exhibit a concentration of radioactive strontium 300,000 times higher than normal plants. Their roots reach into a nuclear waste treatment area that has been closed since 1963; the radioactive shrubs are "indistinguishable from other shrubs without a Geiger counter" Masco, Joseph. "The Nuclear Borderlands: The Manhattan Project in Post-Cold War New Mexico". [http://press.princeton.edu/titles/8185.html Princeton University Press, 2006] .] . The same happens with the tumbleweed plants at the Hanford Site; "crews armed with pitchforks" are employed to prevent the contaminated plants from spreading .

Accidental mixing of radioactive sources containing strontium with metal scrap can result in production of radioactive steel. Discarded radioisotope thermoelectric generators are a major source of 90Sr contamination in the area of the former Soviet Union.

References

External links

* [http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@na+@rel+strontium,+radioactive NLM Hazardous Substances Databank – Strontium, Radioactive]


Wikimedia Foundation. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • Strontium — (pronEng|ˈstrɒntiəm, ) is a chemical element with the symbol Sr and the atomic number 38. An alkaline earth metal, strontium is a soft silver white or yellowish metallic element that is highly reactive chemically. The metal turns yellow when… …   Wikipedia

  • Strontium — Rubidium ← Strontium → Yttrium Ca …   Wikipédia en Français

  • STRONTIUM — De Strontian, ville d’Écosse. Symbole chimique: Sr Numéro atomique: 38 Masse atomique: 87,62 Point de fusion: 769 0C Point d’ébullition: 1 384 0C Densité (à 20 0C): 2,54 Métal alcalinoterreux mou, de reflet argenté quand il est fraîchement coupé …   Encyclopédie Universelle

  • Strontium 90 — may refer to: *Strontium 90, a Strontium isotope *Strontium 90 (band) was a British band …   Wikipedia

  • Strontium-90 — A radioactive isotope of strontium produced by certain nuclear reactions, and constituting one of the prominent harmful components of radioactive fallout from nuclear explosions; also called {radiostrontium}. It has a half life of 28 years. [1913 …   The Collaborative International Dictionary of English

  • strontium 90 — n a heavy radioactive isotope of strontium having the mass number 90 that is present in the fallout from nuclear explosions and is hazardous because like calcium it can be assimilated in biological processes and deposited in the bones of human… …   Medical dictionary

  • strontium — [strän′shəm, strän′shē əm; stränt′ē əm] n. [ModL: so named (1808) by DAVY Sir Humphry, who first isolated it < STRONTIA + IUM] a pale yellow, metallic chemical element, one of the alkaline earth metals, resembling calcium in properties and… …   English World dictionary

  • strontium — light metallic element, 1808, coined in Modern Latin by English chemist Sir Humphry Davy (1778 1829) from Strontian, name of a parish in Argyllshire, Scotland, the site of lead mines where strontium was first found …   Etymology dictionary

  • Strontium — Stron ti*um, n. [NL. See {Strontia}.] (Chem.) A metallic element of the calcium group, always naturally occurring combined, as in the minerals strontianite, celestite, etc. It is isolated as a yellowish metal, somewhat malleable but harder than… …   The Collaborative International Dictionary of English

  • strontium 90 — strontium 90. См. стронций 90. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Strontĭum — Strontĭum, Element, zu den Metallen der alkalischen Erden gehörig; chemisches Zeichen Sr, Atomgewicht 43,84 (H = 1) od. 548 (O = 100). Findet sich in der Natur als Oxyd (Strontian) an Schwefelsäure od. Kohlensäure gebunden; der schwefelsaure… …   Pierer's Universal-Lexikon

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”