Ra228

Radium-228, denoted as 228Ra, is a radioactive isotope of the element radium (atomic number 88) with a mass number of 228. It is produced in the decay of thorium-232 and is a member of the thorium decay series that ultimately leads to lead-208. 228Ra has a half-life of about 5.75 years, making it a relatively long-lived radionuclide compared with many other radium isotopes.

The principal decay mode of 228Ra is beta decay to actinium-228 (228Ac). 228Ac itself has a much shorter half-life, about 6.15 hours, and decays by beta emission to thorium-228 (228Th), which continues down the decay chain toward stable lead. As a member of a radioactive series, 228Ra contributes to the radiological activity of thorium-bearing materials and environments where thorium and its daughters accumulate.

Natural occurrence and production: 228Ra occurs in trace amounts in minerals containing thorium and uranium and is found in environments where thorium-232 decays. It can also be produced in radiochemical laboratories or as part of research into thorium fuel cycles and related decay chains.

Hazards and safety: 228Ra is a radiological hazard if ingested, inhaled, or absorbed. It emits beta radiation and, through its daughter products, gamma radiation, contributing to external and internal dose. Handling, shielding, and disposal follow appropriate regulatory requirements for radioactive materials.

Uses: due to its moderate half-life and placement in the thorium decay chain, 228Ra is mainly of interest for research, radiochemical standards, and environmental studies related to thorium-bearing materials rather than consumer applications.