Unit 2 at Diablo Canyon nuclear power plant was returned to full power Monday after it was shut down five days earlier due to an influx of sea salps, a jellyfish-like creature.

The plant's cooling water intake screens had become clogged with the small marine creatures. Shutting the unit down was a safety precaution, plant managers said.

The plant's other reactor remains offline after it was shut down early last week for a regularly scheduled refueling outage.