noun
natural radioisotope
Technical term used in nuclear physics, chemistry, and environmental science. Refers to a radioactive isotope that occurs naturally, as opposed to one produced artificially.
天然放射性同位体の一つであるカリウム40は、岩石中に広く存在する。
Potassium-40, one of the natural radioisotopes, is widely present in rocks.
この地域の地下水から天然放射性同位体が検出された。
Natural radioisotopes were detected in the groundwater of this area.
Compound of 天然 (natural), 放射性 (radioactive), and 同位体 (isotope). The term is a direct calque from English 'natural radioisotope'.