A small hydrogen fire at the San Onofre nuclear power plant on Friday caused no injuries, no damage and no release of radioactive materials into the atmosphere, according to Southern California Edison.
The fire, which was extinguished in about an hour, occurred during maintenance on equipment used to process gases extracted from the reactor coolant system.
According to an SCE statement, the release of the gas resulted in a small amount of radioactive material within the plant.
"Appropriate precautions to protect workers involved have been taken," the statement said, adding that the incident has been reported to the Nuclear Regulatory Commission. "Nobody received significant radiation exposure."