South Africa's state-owned power utility Eskom announced on Monday that 91 workers were contaminated with a small amount of radiation while doing maintenance work at the Koeberg nuclear power plant near Cape Town.

Eskom spokeswoman Karen de Villiers said during maintenance on Koeberg Unit One, 91 workers tested positive for cobalt 58 as they left the site on Sept. 12.

After this testing, the workers had body scans to search for the radiation.

She said it is believed that they were contaminated with airborne radiation, possibly from dust particles.

For two days the site was shut down while tests were conducted.

De Villiers said the radiation the workers were exposed to was low, about 0.5 percent of the annually allowed exposure limit.

"Frankly, they would pick up more radiation from a couple of plane trips to Johannesburg," she said.

Cobalt 58 was a "very short-lived radiation" and would leave the bodies of the workers easily, De Villiers added.

The workers will continue to be monitored in the coming weeks.

Eskom also counseled the workers on the contamination, she said.

"We had a chat with the workers because the issue was an emotional one," said De Villiers.