Radioactive decay

Similar term(s): radioactive disintegration.

The decrease in the [radiation intensity] of any radioactive material with the passage of time due to the spontaneous emission of radiation from an atomic nucleus.

Source: University of Harvard Environmental Health & Safety  

The end product – called decay product, daughter product, daughter isotope or daughter nuclide – is a less energetic, more stable nucleus. Each decay process has a definite half-life.

Source: GreenFacts

Radiation - Radioactivity

Español: Desintegración radiactiva
Français: Désintégration radioactive

Chernobyl

Fukushima accident

Fukushima Consequences