BELL BEND - Workers at PPL's Susquehanna nuclear power plant disconnected its Unit 1 nuclear reactor from the regional power grid early Thursday, part of a planned outage during which the company plans to modify blades on its turbines, which have had problems with cracks developing in recent years. The modifications to be done on the turbines "are the first-phase of a long-term plan that is expected to resolve the turbine blade issues," the company said in a press release. Workers made the same modifications to Unit 2 during its regularly scheduled refueling outage, which is still ongoing. "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," said Timothy S. Rausch, PPL Susquehanna senior vice president and Chief Nuclear Officer. Both units at the plant north of Berwick are expected back in service by the start of summer, according to the press release.