Sr90Y90

Strontium-90 (Sr-90) is a radioactive isotope of strontium with a half-life of 28.8 years. It decays by beta emission to Yttrium-90 (Y-90), which itself is a highly radioactive isotope with a half-life of 64 hours. Y-90 then decays by beta emission to stable Zirconium-90 (Zr-90). The beta particles emitted by Sr-90 and Y-90 are energetic, with maximum energies of 0.546 MeV for Sr-90 and 2.28 MeV for Y-90. Sr-90 is a common fission product found in nuclear reactor fuel and is also produced in nuclear weapons explosions. Due to its chemical similarity to calcium, Sr-90 can be incorporated into bone tissue if ingested or inhaled, posing a long-term internal radiation hazard. Its presence in the environment is primarily a concern from past atmospheric nuclear weapons testing and accidental releases from nuclear facilities. Its properties make it useful in certain industrial applications, such as thickness gauging and in radioisotope thermoelectric generators (RTGs) for powering spacecraft, although its use is carefully regulated due to its radioactivity.