BERWICK, Pa. (AP) — Susquehanna nuclear power plant operators said Sunday that they found a water leak in one of its units.

The plant, located in Luzerne County near Berwick, Pa., is owned jointly by PPL Susquehanna LLC and Allegheny Electric Cooperative Inc.

Susquehanna closed the unit on Saturday for inspection of the turbine blades, suspecting they may have developed small cracks. On Sunday, operators briefly declared an "unusual event" after finding water leaking inside a room in the plant's reactor building.

This is the lowest of the four emergency classifications established by the U.S. Nuclear Regulatory Commission.

The leak was contained and the unit remains shut down. The company said the event had no effect on public safety and required no public action.

Timothy S. Rausch, senior vice president and chief nuclear officer for PPL Susquehanna, said the company traced the cause of the water leak to a valve on one of the plant's multiple cooling systems; other cooling systems were operational throughout the event. He said the company plans to conduct a full investigation of the incident.

PPL Susquehanna is a unit of publicly traded PPL Corp.