Secular equilibrium

{
  "id": "MLC-T-CHM-010647",
  "term": "Secular equilibrium",
  "field": "Chemistry",
  "definition": "A state of radioactive equilibrium where a long-lived parent radionuclide decays to a shorter-lived daughter radionuclide, and the half-life of the parent is much greater than that of the daughter. In this condition, the activity of the daughter becomes equal to the activity of the parent. This equilibrium is often observed in natural decay chains, such as uranium-238 decaying to radium-226.",
  "subject": "Analytical Chemistry",
  "see_also": [
    "radioactive equilibrium",
    "activity",
    "half life",
    "precursor"
  ],
  "references": [
    "PAC, 1982, 54, 1533. 'Glossary of terms used in nuclear analytical chemistry (Provisional)' on page 1541 (https://doi.org/10.1351/pac198254081533)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/secular-equilibrium/"
}