strontium90yttrium90

Strontium-90 (Sr-90) is a radioactive isotope of strontium with mass number 90. It is produced primarily as a fission product in nuclear reactors and in nuclear weapons tests, and it can persist in the environment for decades. Sr-90 decays by beta-minus emission to yttrium-90 (Y-90) with a half-life of about 28.8 years. The emitted beta particles have a maximum energy of about 0.546 MeV.

Yttrium-90, the daughter nuclide, has a half-life of about 64 hours and decays by beta emission to stable zirconium-90 (Zr-90). Its beta radiation has a maximum energy of 2.28 MeV, with an average energy around 0.93 MeV. Because Sr-90 decays relatively slowly and the Y-90 daughter is a strong beta emitter, the decay chain delivers significant radiation over time.

Chemically, strontium behaves similarly to calcium, so Sr-90 tends to be incorporated into bone tissue when ingested or inhaled. This bone-seeking behavior makes exposure hazardous, increasing the risk of bone cancer and leukemia. Health protection involves shielding, containment, and avoidance of intake.

Applications and significance: Sr-90 itself has been used as a heat source in some radioisotope thermoelectric generators and industrial devices. The medical relevance centers on its decay product, Y-90, which is widely used in radiotherapy, most notably in Y-90 microsphere treatments for liver cancer. While Sr-90 is not a clinical therapeutic, its decay chain provides a source of Y-90 for medical applications and historical industrial uses.

Safety and regulation: Due to its long half-life and bone-seeking properties, handling and disposal of Sr-90 require strict regulatory controls, proper shielding, and environmental monitoring.