‘Hot wasps’ found at US nuclear facility in South Carolina

COLUMBIA – Four radioactive wasp nests have been discovered at a South Carolina nuclear facility, according to federal officials.

The first nest, which was found by workers at the Savannah River Site early in July, was recently disclosed in a report from the Department of Energy, which owns the site. The facility, near Aiken, South Carolina, produced materials for nuclear weapons throughout the Cold War. Three additional nests have since been discovered at the site, officials told The New York Times on Aug 1.

“The US Department of Energy is managing the discovery of four wasp nests with very low levels of radioactive contamination,” Mr Edwin Deshong, the manager of the department’s Savannah River operations office, said in an e-mailed statement. “The nests do not pose a health risk to SRS (Savannah River Site) workers, the community or the environment.”

But the discovery raised questions about the extent of the environmental contamination at the site, said Professor Timothy Mousseau, a biologist at the University of South Carolina who studies organisms and ecosystems in radioactive regions of the world, including Chernobyl in Ukraine and Fukushima in Japan.

“This is an indicator that there are contaminants spread across this area that have not been completely encased and protected,” Prof Mousseau said.

The discovery of additional radioactive nests, he added, indicates “that much greater effort must be made to assess the possible risks and hazards of what appears to be a significant source of radioactive pollutants.”

Here’s what to know:

What is the Savannah River Site?

The Savannah River Site, formerly known as the Savannah River Plant, sits on 800 sq km in the sand hills of South Carolina, close to the Georgia border. The facility was built in the 1950s to produce materials for nuclear weapons. For decades, the site produced plutonium and tritium, key components of hydrogen bombs.

The production of materials for nuclear weapons ramped down after the end of the Cold War, and the Department of Energy began cleaning up the site in 1996. But the process has dragged on well past its initially projected completion date. Officials now say that clean-up activities will be complete by 2065.

In 2018, the first Trump administration announced plans to repurpose an unfinished building at the site to produce plutonium “pits” – the cores of nuclear weapons. Production is expected to begin in the 2030s.

What did workers find?

Workers at the site routinely monitor the grounds for signs of radioactivity. On July 3, they discovered a radioactive wasp nest on a post near a tank used to store nuclear waste. “The wasp nest was sprayed to kill wasps, then bagged as radiological waste,” the federal report said. “The ground and surrounded area did not have any contamination.”

But the report omitted key details, Prof Mousseau said, including the absolute level of radioactivity in the nest and the specific isotopes that were found, which would provide clues about the source of the contamination.

Three additional nests were subsequently discovered during “routine work activities”, a spokesperson for the Department of Energy said in an e-mail on Aug 1.

How did the nests become radioactive?

It is not entirely clear, but the initial Department of Energy report said that the radioactivity resulted from “on-site legacy radioactive contamination”, rather than from a leak or “loss of contamination control”.

That is a reasonable explanation, said Prof Mousseau, who has studied birds at the site. “There’s some legacy radioactive contamination sitting around in the mud in the bottom of the lakes or, you know, here and there,” he said.

The report did not disclose the species of wasp involved, but many wasps make their nests out of wood that they chew into a pulp. It was not far-fetched to imagine that they came across some contaminated rotting wood that had escaped previous detection and used the material to make their nest, Prof Mousseau said.

How alarming is the discovery of radioactive wasp nests?

Wasps do not typically travel far from their nests, Prof Mousseau said, and the “hot wasps”, as he called them, probably posed little direct risk to the public.

But there are other potential risks. “The main concern relates to whether or not there are large areas of significant contamination that have escaped surveillance in the past,” he said.

“Alternatively, this could indicate that there is some new or old radioactive contamination that is coming to the surface that was unexpected.”

In 2017, workers found radioactive bird droppings on the roof of a building at the site, and birds can carry radioactivity long distances, spreading it across the landscape, Prof Mousseau said.

The wasp nests are a “red flag” that should lead to more surveillance and investigation, he added.

“We would like to know a lot more about what this actually represents, and just how common it is and whether there is any evidence of these radionuclides being moved through the ecosystem,” Prof Mousseau said. NYTIMES