Workers at the Savannah River Site say they have now removed a mysterious “cobweb-like” bacteria whose appearance has perplexed researchers at the former nuclear weapons complex since its discovery three years ago.
In 2011, employees working at the site near Aiken were surprised to find the white, string-like growth in a large pool at the L Disassembly Basin which is used to store spent nuclear fuel assemblies.
Scientists at both facilities determined that the “cobwebs” were made up of a broad variety of bacteria along with a few other types of microbes that were able to survive despite the radiation and lack of carbon in the pools. Researchers say they have spent the past two years monitoring the “cobwebs” for growth patterns and changes.
“They were non-harmful,” Savannah River Nuclear Solutions spokeswoman Lindsey Evans told South Carolina Radio Network. “However we were having a problem seeing (through the cobwebs) the top of the fuel bundles that have the identification numbers on them… So it was decided that it was best to go ahead and vacuum those up.”
Evans said it took about four months for a specially-designed vacuum to remove all of the bacteria and microbes. “It uses filters a lot like water filters found around your home,” she said. “We just basically stuck it down in the water and vacuumed it up.”
She added the machine had not been running constantly during that four-month timeframe.
“The floor of the basin is regularly vacuumed to remove debris,” L Basin Operations Support Engineer Rich Deible said in a statement. “Vacuuming the ‘cobwebs’ proved to be a new challenge, as we had never vacuumed the tops of fuel racks before.”
Scientists aren’t sure if the bacteria will return, since they don’t know the source of carbon that was fueling its growth in the first place. “If it was just murky water that had been sitting there for decades, we could understand there could be a food source, but it’s just the opposite,” SRNS spokesman D.T. Townsend told South Carolina Radio Network in a 2012 interview. “This is extremely purified water… It’s quite a mystery.”
He added that it was also unknown why the “cobwebs” had never appeared in the basin until 2011.
The L Basin underwater storage hold used fuel in a 3.4 million gallon pool. In 1998, SRS officials consolidated all of the site’s spent fuel in L Basin. The basin water protects workers from radiation.