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Strontium 90

Chemical Symbol: Sr-90 Half-Life: 28.79 years
Atomic Number: 38 Decay Constant: 0.024076 years-1
Mass Number: 90 (52 neutrons) Decay Mode: Beta
U.S. NRC Exempt Quantity Limit: 0.1 μCi (3.7 kBq) IAEA Exempt Quantity Limit: 0.27 μCi (10 kBq)

Betas From Sr-90

End-Point Energy (keV)

Intensity (%)




  • Health Physics and Radiological Health, 4th Edition by Thomas E. Johnson PhD, Brian K. Birky Ph.D.
  • National Nuclear Data Center database –
  • Table of Radioactive Isotopes (ToRI) database – http:/


Prepared by:

Spectrum Techniques, LLC.