Four radioactive wasp nests may indicate previously undetected environmental contamination at the decades-old Savannah River Site. Here’s what to know.

Employees who routinely check radiation levels at the Savannah River Site near Aiken found a wasp nest on July 3 on a post near tanks where liquid nuclear waste is stored.

The hazardous insect abode was located near a set of tanks filled with liquid nuclear waste, although the team didn’t detect any leaks. Instead, experts believe the nest set off Geiger counters through what’s known as “onsite legacy radioactive contamination.