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Naturally occurring strontium is nonradioactive and nontoxic at levels normally found in the environment, but 90 Sr is a radiation hazard. [4] 90 Sr undergoes β − decay with a half-life of 28.79 years and a decay energy of 0.546 MeV distributed to an electron, an antineutrino, and the yttrium isotope 90 Y, which in turn undergoes β − decay with a half-life of 64 hours and a decay energy ...
The longest-lived of these isotopes, and the most relevantly studied, are 90 Sr with a half-life of 28.9 years, 85 Sr with a half-life of 64.853 days, and 89 Sr (89 Sr) with a half-life of 50.57 days. All other strontium isotopes have half-lives shorter than 50 days, most under 100 minutes.
The mean strontium content of ocean water is 8 mg/L. [50] [51] At a concentration between 82 and 90 μmol/L of strontium, the concentration is considerably lower than the calcium concentration, which is normally between 9.6 and 11.6 mmol/L. [52] [53] It is nevertheless much higher than that of barium, 13 μg/L. [11]
The only stable nuclides having an odd number of protons and an odd number of neutrons are hydrogen-2, lithium-6, boron-10, nitrogen-14 and (observationally) tantalum-180m. This is because the mass–energy of such atoms is usually higher than that of their neighbors on the same isobaric chain, so most of them are unstable to beta decay .
strontium-90: 28.79 909 curium-243: 29.1 920 caesium-137: 30.17 952 10 9 seconds (gigaseconds) isotope half-life years 10 9 seconds bismuth-207: 32.9 1.04 titanium-44: 63
Mass Half-life (years) Typical source Helium: 3 - stable - Air, water, and biota samples for bioassays: Carbon: 14: 5,730: Radiocarbon dating of organic matter, water Iron: 55: 2.7: Produced in iron and steel casings, vessels, or supports for nuclear weapons and reactors Strontium: 90: 28.8: Common fission product Technetium: 99: 214,000 ...
Source of most of the decay heat from years to decades after irradiation, together with 90 Sr. 6.0507%: Technetium: 99 Tc: 211 ky: Candidate for disposal by nuclear transmutation. 5.7518%: Strontium: 90 Sr: 28.9 y: Source of much of the decay heat together with 137 Cs on the timespan of years to decades after irradiation.
Niobium-95, with a half-life of 35 days, is initially present as a fission product. The only stable isotope of niobium has mass number 93, and fission products of mass 93 first decay to long-lived zirconium-93 (half-life 1.53 Ma). Niobium-95 will decay to molybdenum-95 which is stable.