Radiogenic decay

Radiogenic decay is the process by which radiogenic particles lose energy.

The detonation of a Druoda series 5 long-range tactical armor unit on a planetary surface in 2375 left high concentrations of radiogenic decay. 

In 2376, the rate of radiogenic decay on the Vaadwaur homeworld allowed Voyager personnel to determine that the planet had been bombarded 892 years ago.