Operators at the plant disconnected the unit from the regional power grid for the modification works, which are part of the first phase of a long-term plan to resolve the turbine blade issues that have been affecting plant operations in recent years.

The nuclear plant located in Luzerne County about seven miles north of Berwick, is co-owned by PPL Susquehanna and Allegheny Electric Cooperative.

The plant is operated by PPL Susquehanna.

PPL Susquehanna senior vice president and chief nuclear officer Timothy S Rausch said, "Our conservative approach to resolve the issue by carefully monitoring blade performance and investing in the needed modifications reflects our commitment to the safe operation of the plant."

Workers at the plant have also made the same modifications to Unit 2, during the ongoing scheduled refueling outage.

Both units of the Susquehanna nuclear plant are expected to resume operations by June.