Utility officials said they shut down Unit 1 on Monday morning after a small radioactive water leak was found. They say there is no threat to employees or the public.
Duke Energy spokeswoman Valerie Patterson says the leak is confined to the airtight, steel-lined concrete containment building. She says the leak was less than a gallon of water every 10 minutes.
The water cools the reactor. Engineers first discovered the leak Friday and spent the weekend trying to pinpoint the location and severity of the problem.
Fluctuations in the water used to turn turbines and create electricity shut down Unit 3 for three days last month.