Workers at a site in South Carolina that once made key parts for nuclear bombs in the United States have found a radioactive wasp nest but officials said there is no danger to anyone.

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

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.