View source for Physics:Strontium-90

{{short description|Radioactive isotope of strontium}}
{{Infobox isotope
 | alternate_names =
 | symbol =Sr
 | image = Strontium 90 (test source) in tin.jpg
 | image_caption = Strontium-90 test source in [[Chemistry:Tin|tin]]
 | mass_number =90
 | mass = 89.9077279(16){{AME2020 II |ref}}
 | num_neutrons =52
 | num_protons =38
 | abundance = [[Physics:Synthetic radioisotope|syn]]
 | halflife = {{val|28.79|u=years}}
 | decay_product =isotopes of yttrium#90
 | decay_symbol =Y
 | decay_mass =90
 | decay_mode1 =[[Physics:Beta decay|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 =
 | binding_energy =
}}

'''Strontium-90''' ({{SimpleNuclide|strontium|90}}) is a [[Physics:Radioactive|radioactive]] [[Physics:Isotopes of strontium|isotope of strontium]] produced by [[Physics:Nuclear fission|nuclear fission]], with a [[Physics:Half-life|half-life]] of 28.8 years. It undergoes [[Physics:Beta decay|β<sup>−</sup> decay]] into [[Physics:Yttrium-90|yttrium-90]], with a [[Physics:Decay energy|decay energy]] of 0.546&nbsp;MeV.<ref name="nucleardata">{{cite web |url=http://nucleardata.nuclear.lu.se/toi/nuclide.asp?iZA=380090 |title=Table of Isotopes decay data |publisher=[[Organization:Lund University|Lund University]] |access-date=2014-10-13}}</ref> Strontium-90 has applications in medicine and industry and is an [[Physics:Isotope|isotope]] of concern in [[Physics:Nuclear fallout|fallout]] from nuclear weapons, nuclear weapons testing, and nuclear accidents.<ref name="EPA">{{cite web |url=http://www.epa.gov/rpdweb00/radionuclides/strontium.html#environment |title=Strontium &#124; Radiation Protection &#124; US EPA |publisher=EPA |date=24 April 2012 |access-date=18 June 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120511030249/http://www.epa.gov/rpdweb00/radionuclides/strontium.html |archive-date=11 May 2012}}</ref>

==Radioactivity==
Naturally occurring [[Chemistry:Strontium|strontium]] is nonradioactive and nontoxic at levels normally found in the environment, but <sup>90</sup>Sr is a radiation hazard.<ref name="ATSDR">{{citation |url=http://www.atsdr.cdc.gov/toxprofiles/tp159.pdf |title=TOXICOLOGICAL PROFILE FOR STRONTIUM |publisher=Agency for Toxic Substances and Disease Registry |date=April 2004 |access-date=2014-10-13}}</ref> <sup>90</sup>Sr undergoes [[Physics:Beta decay|β<sup>−</sup> decay]] with a [[Physics:Half-life|half-life]] of 28.79 years and a [[Physics:Decay energy|decay energy]] of 0.546 [[Physics:Electronvolt|MeV]] distributed to an [[Physics:Electron|electron]], an antineutrino, and the [[Chemistry:Yttrium|yttrium]] isotope [[Physics:Yttrium-90|<sup>90</sup>Y]], which in turn undergoes [[Physics:Beta decay|β<sup>−</sup> decay]] with a half-life of 64 hours and a decay energy of 2.28 MeV distributed to an electron, an antineutrino, and [[Chemistry:Zirconium|<sup>90</sup>Zr]] (zirconium), which is stable.<ref>Decay data from [http://www.nndc.bnl.gov National Nuclear Data Center] at the Brookhaven National Laboratory in the US.</ref> Note that <sup>90</sup>Sr/Y is almost a pure [[Physics:Beta particle|beta particle]] source; the gamma photon emission from the decay of <sup>90</sup>Y is so infrequent that it can normally be ignored.

<sup>90</sup>Sr has a [[Physics:Specific activity|specific activity]] of 5.21&nbsp;[[Becquerel|TBq]]/g.<ref name="RPD">{{cite book |title=Radionuclide and Radiation Protection Data Handbook 2002 |isbn=978-1-870965-87-3 |year=2002 |first1=D. |last1=Delacroix |first2=J. P. |last2=Guerre |first3=P. |last3=Leblanc |first4=C. |last4=Hickman |publisher=Nuclear Technology Publishing |edition=2nd}}</ref>

{{Medium-lived fission products}}

==Fission product==
<sup>90</sup>Sr is a product of [[Physics:Nuclear fission|nuclear fission]]. It is present in significant amount in [[Physics:Spent nuclear fuel|spent nuclear fuel]], in [[Physics:Radioactive waste|radioactive waste]] from [[Physics:Nuclear reactor|nuclear reactor]]s and in [[Physics:Nuclear fallout|nuclear fallout]] from nuclear tests.
For thermal neutron fission as in today's nuclear power plants, the [[Physics:Fission product yield|fission product yield]] from [[Physics:Uranium-235|uranium-235]] is 5.7%, from [[Physics:Uranium-233|uranium-233]] 6.6%, but from [[Physics:Plutonium-239|plutonium-239]] only 2.0%.<ref name="IAEALiveChart">{{cite web |url=https://www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html |title=Livechart - Table of Nuclides - Nuclear structure and decay data |publisher=IAEA |access-date=2014-10-13}}</ref>

===Nuclear waste===
Strontium-90 is classified as high-level waste. Its 29-year half-life means that it can take hundreds of years to decay to negligible levels. Exposure from contaminated water and food may increase the risk of [[Medicine:Leukemia|leukemia]] and bone cancer.<ref name=Potera>{{cite journal |last=Potera |first=Carol |title=HAZARDOUS WASTE: Pond Algae Sequester Strontium-90 |journal=Environ Health Perspect |date=2011 |volume=119 |issue=6 |pages=A244 |pmid=21628117 |doi=10.1289/ehp.119-a244|pmc=3114833 |doi-access=free }}</ref> Reportedly, thousands of capsules of radioactive strontium containing millions of curies are stored at Hanford Site's Waste Encapsulation and Storage Facility.<ref>https://www.energy.gov/sites/prod/files/2014/04/f14/OAS-L-14-04.pdf "Long-Term Storage of Cesium and
Strontium at the Hanford Site"  Inspector General Report No. OAS-L-14-04 . March 2014.</ref>

=== Remediation ===
Algae has shown selectivity for strontium in studies, where most plants used in [[Earth:Bioremediation|bioremediation]] have not shown selectivity between calcium and strontium, often becoming saturated with calcium, which is greater in quantity and also present in nuclear waste.<ref name=Potera/>

Researchers have looked at the bioaccumulation of [[Chemistry:Strontium|strontium]] by ''[[Biology:Scenedesmus|Scenedesmus spinosus]]'' ([[Biology:Algae|algae]]) in simulated wastewater. The study claims a highly selective [[Earth:Biosorption|biosorption]] capacity for strontium of ''S. spinosus'', suggesting that it may be appropriate for use of nuclear wastewater.<ref>{{cite journal |title=Biosorption of Strontium from Simulated Nuclear Wastewater by Scenedesmus spinosus under Culture Conditions: Adsorption and Bioaccumulation Processes and Models |journal=Int J Environ Res Public Health |date=2014 |doi=10.3390/ijerph110606099|doi-access=free |last1=Liu |first1=Mingxue |last2=Dong |first2=Faqin |last3=Kang |first3=Wu |last4=Sun |first4=Shiyong |last5=Wei |first5=Hongfu |last6=Zhang |first6=Wei |last7=Nie |first7=Xiaoqin |last8=Guo |first8=Yuting |last9=Huang |first9=Ting |last10=Liu |first10=Yuanyuan |volume=11 |issue=6 |pages=6099–6118 |pmid=24919131 |pmc=4078568 }}</ref>

A study of the pond alga ''[[Biology:Closterium|Closterium moniliferum]]'' using stable strontium found that varying the ratio of [[Chemistry:Barium|barium]] to [[Chemistry:Strontium|strontium]] in water improved strontium selectivity.<ref name=Potera/>

==Biological effects==

===Biological activity===
Strontium-90 is a "[[Physics:Bone seeker|bone seeker]]" that exhibits biochemical behavior similar to [[Chemistry:Calcium|calcium]], the next lighter [[Chemistry:Group 2 element|group 2 element]].<ref name="ATSDR" /><ref name="NRCglossary">{{cite web |url=https://www.nrc.gov/reading-rm/basic-ref/glossary/bone-seeker.html |title=NRC: Glossary -- Bone seeker |publisher=US Nuclear Regulatory Commission |date=7 May 2014 |access-date=2014-10-13}}</ref> After entering the organism, most often by ingestion with contaminated food or water, about 70–80% of the dose gets excreted.<ref name="EPA" /> Virtually all remaining strontium-90 is deposited in [[Biology:Bone|bone]]s and [[Biology:Bone marrow|bone marrow]], with the remaining 1% remaining in blood and soft tissues.<ref name="EPA" /> Its presence in bones can cause bone cancer, cancer of nearby tissues, and [[Medicine:Leukemia|leukemia]].<ref>https://dhss.delaware.gov/dhss/dph/files/strontiumfaq.pdf {{Bare URL PDF|date=March 2022}}</ref> Exposure to <sup>90</sup>Sr can be tested by a [[Earth:Bioassay|bioassay]], most commonly by urinalysis.<ref name="ATSDR" />

The [[Biology:Biological half-life|biological half-life]] of strontium-90 in humans has variously been reported as from 14 to 600 days,<ref>{{citation |chapter-url=http://hanford-site.pnnl.gov/envreport/2001/env01_45.pdf |title=Hanford Site 2001 Environmental Report |chapter=4.5 Fish and Wildlife Surveillance |last1=Tiller |first1=B. L. |publisher=DOE |year=2001 |access-date=2014-01-14}}</ref><ref>{{citation |url=http://www.osti.gov/bridge/servlets/purl/10136486-6sLptZ/native/10136486.pdf |title=Ecotoxicity Literature Review of Selected Hanford Site Contaminants |doi=10.2172/10136486 |publisher=DOE |last1=Driver |first1=C.J. |year=1994 |access-date=2014-01-14}}</ref> 1000 days,<ref>{{cite web |url=http://www.areaivenvirothon.org/freshwaterecology.htm |title=Freshwater Ecology and Human Influence |publisher=Area IV Envirothon |access-date=2014-01-14}}</ref> 18 years,<ref>{{cite web |url=http://www.epi.alaska.gov/eh/radiation/RadioisotopesInFood.pdf |title=Radioisotopes That May Impact Food Resources |access-date=2014-01-14 |publisher=Epidemiology, Health and Social Services, State of Alaska}}</ref> 30 years<ref>{{cite web |url=http://www.gsseser.com/FactSheet/Strontium.pdf |title=Human Health Fact Sheet: Strontium |publisher=Argonne National Laboratory |date=October 2001 |access-date=2014-01-14}}</ref> and, at an upper limit, 49 years.<ref>{{cite web |url=http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/biohalf.html |title=Biological Half-life |publisher=HyperPhysics |access-date=2014-01-14}}</ref> The wide-ranging published biological half life figures are explained by strontium's complex metabolism within the body. However, by averaging all excretion paths, the overall biological half life is estimated to be about 18 years.<ref>{{cite book |chapter-url=http://www.fourmilab.ch/etexts/www/effects/eonw_12.pdf |title=The effects of Nuclear Weapons |last1=Glasstone |first1=Samuel |last2=Dolan |first2=Philip J. |year=1977 |access-date=2014-01-14 |chapter=XII: Biological Effects |page=605}}</ref>

The elimination rate of strontium-90 is strongly affected by age and sex, due to differences in bone metabolism.<ref name="ShaginaBougrov2006">{{cite journal |last1=Shagina |first1=N B |last2=Bougrov |first2=N G |last3=Degteva |first3=M O |last4=Kozheurov |first4=V P |last5=Tolstykh |first5=E I |title=An application of in vivo whole body counting technique for studying strontium metabolism and internal dose reconstruction for the Techa River population |journal=Journal of Physics: Conference Series |volume=41 |year=2006 |issue=1 |pages=433–440 |issn=1742-6588 |doi=10.1088/1742-6596/41/1/048|doi-access=free |bibcode=2006JPhCS..41..433S }}</ref>

Together with the caesium isotopes [[Physics:Isotopes of caesium#Caesium-134|<sup>134</sup>Cs]] and [[Physics:Caesium-137|<sup>137</sup>Cs]], and the iodine isotope [[Physics:Iodine-131|<sup>131</sup>I]], it was among the most important isotopes regarding health impacts after the Chernobyl disaster.
As strontium has an affinity to the [[Biology:Calcium-sensing receptor|calcium-sensing receptor]] of parathyroid [[Biology:Cell|cell]]s that is similar to that of calcium, the increased risk of [[Biology:Chernobyl liquidators|liquidator]]s of the Chernobyl power plant to suffer from primary hyperparathyroidism could be explained by binding of strontium-90.<ref name=BoehmNEJM>{{cite journal|vauthors=Boehm BO, Rosinger S, Belyi D, Dietrich JW |title=The Parathyroid as a Target for Radiation Damage|journal=New England Journal of Medicine|date=August 2011|volume=365|issue=7|pages=676–678|doi=10.1056/NEJMc1104982|pmid=21848480|doi-access=free}}</ref>

==Uses==

===Radioisotope thermoelectric generators (RTGs)===
The radioactive decay of strontium-90 generates a significant amount of heat, 0.95&nbsp;W/g in the form of pure strontium metal or approximately 0.460&nbsp;W/g as [[Chemistry:Strontium titanate|strontium titanate]]<ref>{{cite report |title=Properties of Selected Radioisotopes |url=https://ntrs.nasa.gov/citations/19680020487 |id=19680020487 |year=1968 |work=[[Organization:NASA|NASA]] |last1=Harris |first1=Dale |last2=Epstein |first2=Joseph |access-date=15 May 2023 }}</ref><!-- Note: source is self-contradictory with different tables with wildly different specific powers.--> and is cheaper than the alternative [[Physics:Plutonium-238|<sup>238</sup>Pu]]. It is used as a heat source in many Russian/Soviet [[Physics:Radioisotope thermoelectric generator|radioisotope thermoelectric generator]]s, usually in the form of strontium titanate.<ref name="NRPA2005">{{citation |title=Assessment of environmental, health and safety consequences of decommissioning radioisotope thermal generators (RTGs) in Northwest Russia |url=http://www.nrpa.no/dav/c600d1d288.pdf |number=StrålevernRapport 2005:4 |year=2005 |publisher=Norwegian Radiation Protection Authority |location=Østerås |last1=Standring |first1=WJF |last2=Selnæs |first2=ØG |last3=Sneve |first3=M |last4=Finne |first4=IE |last5=Hosseini |first5=A |last6=Amundsen |first6=I |last7=Strand |first7=P}}</ref> It was also used in the US "Sentinel" series of RTGs.<ref name=OTA94>{{cite web |title=Power Sources for Remote Arctic Applications |date=June 1994 |location=Washington, DC |publisher=U.S. Congress, Office of Technology Assessment |url=http://govinfo.library.unt.edu/ota/Ota_1/DATA/1994/9423.PDF |id=OTA-BP-ETI-129}}</ref>

===Industrial applications===
<sup>90</sup>Sr finds use in industry as a radioactive source for thickness gauges.<ref name="EPA" />

===Medical applications===
<sup>90</sup>Sr finds extensive use in medicine as a radioactive source for superficial radiotherapy of some cancers. Controlled amounts of <sup>90</sup>Sr and [[Physics:Strontium-89|<sup>89</sup>Sr]] can be used in treatment of bone cancer, and to treat coronary [[Medicine:Coronary stent#Restenosis|restenosis]] via [[Medicine:Brachytherapy#Blood vessels|vascular brachytherapy]]. It is also used as a [[Biology:Radioactive tracer|radioactive tracer]] in medicine and agriculture.<ref name="EPA" />

===Aerospace applications===
<sup>90</sup>Sr is used as a [[Engineering:Blade inspection method|blade inspection method]] in some helicopters with hollow blade spars to indicate if a crack has formed.<ref name="helo">{{cite web |title=Wireless blade monitoring system and process |url=https://patents.google.com/patent/US7176812B1/en}}</ref>

===Radiological warfare===
{{Further|Biology:Radiological warfare}}
In April 1943, [[Biography:Enrico Fermi|Enrico Fermi]] suggested to [[Biography:J. Robert Oppenheimer|Robert Oppenheimer]] the possibility of using the radioactive byproducts from enrichment to contaminate the German food supply. The background was fear that the German atomic bomb project was already at an advanced stage, and Fermi was also skeptical at the time that an atomic bomb could be developed quickly enough. Oppenheimer discussed the proposal with [[Biography:Edward Teller|Edward Teller]], who suggested the use of strontium-90. [[Biography:James B. Conant|James Bryant Conant]] and [[Biography:Leslie Groves|Leslie R. Groves]] were also briefed, but Oppenheimer wanted to proceed with the plan only if enough food could be contaminated with the weapon to kill half a million people.<ref>{{Cite book|last1=Rhodes|first=Richard|url=http://worldcat.org/oclc/1096260191|title=The making of the atomic bomb|date=2012|publisher=Simon & Schuster|isbn=978-1-4711-1123-5|pages=510ff|oclc=1096260191|}}</ref>

==<sup>90</sup>Sr contamination in the environment==
Strontium-90 is not quite as likely as [[Physics:Caesium-137|caesium-137]] to be released as a part of a nuclear reactor accident because it is much less volatile, but is probably the most dangerous component of the radioactive fallout from a nuclear weapon.<ref name="hyperphysics">{{cite web |url=http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/fisfrag.html#c5 |title=Nuclear Fission Fragments |publisher=HyperPhysics |access-date=18 June 2012}}</ref>

A study of hundreds of thousands of deciduous teeth, collected by Dr. [[Biography:Louise Reiss|Louise Reiss]] and her colleagues as part of the [[Biology:Baby Tooth Survey|Baby Tooth Survey]], found a large increase in <sup>90</sup>Sr levels through the 1950s and early 1960s. The study's final results showed that children born in St. Louis, Missouri, in 1963 had levels of <sup>90</sup>Sr in their deciduous teeth that was 50 times higher than that found in children born in 1950, before the advent of large-scale atomic testing. Reviewers of the study predicted that the fallout would cause increased incidence of disease in those who absorbed strontium-90 into their bones.<ref>{{cite journal|last=Schneir|first=Walter|title=Strontium-90 in U.S. Children|journal=The Nation|date=April 25, 1959|volume=188|issue=17|pages=355–357}}</ref> However, no follow up studies of the subjects have been performed, so the claim is untested.

An article with the study's initial findings was circulated to U.S. President [[Biography:John F. Kennedy|John F. Kennedy]] in 1961, and helped convince him to sign the Partial Nuclear Test Ban Treaty with the {{wipe|United Kingdom}} and [[Place:Soviet Union|Soviet Union]], ending the above-ground nuclear weapons testing that placed the greatest amounts of [[Physics:Nuclear fallout|nuclear fallout]] into the atmosphere.<ref name=Reiss>Hevesi, Dennis. [https://www.nytimes.com/2011/01/10/science/10reiss.html "Dr. Louise Reiss, Who Helped Ban Atomic Testing, Dies at 90"], ''{{wipe|The New York Times}}'', January 10, 2011. Accessed January 10, 2011.</ref>

The Chernobyl disaster released roughly 10&nbsp;[[Becquerel|PBq]], or about 5% of the core inventory, of strontium-90 into the environment.<ref>{{citation |url=https://www.oecd-nea.org/rp/reports/2003/nea3508-chernobyl.pdf |chapter-url=https://www.oecd-nea.org/rp/chernobyl/c02.html |title=Chernobyl: Assessment of Radiological and Health Impacts |chapter=II: The release, dispersion and deposition of radionuclides |publisher=[[Organization:Nuclear Energy Agency|NEA]] |year=2002}}</ref> The Kyshtym disaster released strontium-90 and other radioactive material into the environment. It is estimated to have released 20 MCi (800 PBq) of radioactivity. The Fukushima Daiichi disaster had from the accident until 2013 released 0.1 to 1 PBq of strontium-90 in the form of contaminated cooling water into the [[Earth:Pacific Ocean|Pacific Ocean]].<ref name="PovinecAoyama2013">{{cite journal |last1=Povinec |first1=P. P. |last2=Aoyama |first2=M. |last3=Biddulph |first3=D. |last4=Breier |first4=R. |last5=Buesseler |first5=K. |last6=Chang |first6=C. C. |last7=Golser |first7=R. |last8=Hou |first8=X. L. |last9=Ješkovský |first9=M. |last10=Jull |first10=A. J. T. |last11=Kaizer |first11=J. |last12=Nakano |first12=M. |last13=Nies |first13=H. |last14=Palcsu |first14=L. |last15=Papp |first15=L. |last16=Pham |first16=M. K. |last17=Steier |first17=P. |last18=Zhang |first18=L. Y. |title=Cesium, iodine and tritium in NW Pacific waters &ndash; a comparison of the Fukushima impact with global fallout |journal=Biogeosciences |volume=10 |issue=8 |year=2013 |pages=5481–5496 |issn=1726-4189 |doi=10.5194/bg-10-5481-2013 |display-authors=3|bibcode=2013BGeo...10.5481P |doi-access=free |hdl=1912/6245 |hdl-access=free }}</ref>

==See also==
* [[Physics:Gray (unit)|Gray]] and [[Physics:Sievert|Sievert]]
* Lia radiological accident
* Radiation poisoning
* [[Chemistry:Strontium|Strontium]]
* [[Physics:Yttrium-90|Yttrium-90]]

==References==
{{reflist|30em}}

==External links==
*{{cite web |url=https://pubchem.ncbi.nlm.nih.gov/source/hsdb/7403 |work=Hazardous Substances Data Bank (HSDB) |title=Strontium, Radioactive |publisher=pubchem.ncbi.nlm.nih.gov |access-date=15 May 2023 }}

[[Category:Isotopes of strontium|Strontium-090]]
[[Category:Radioisotope fuels]]
[[Category:Radioactive contamination]]

{{Sourceattribution|Strontium-90}}