PPL Susquehanna modifies turbines to fix blade cracking issue

18 June 2013

Operators reconnected the Unit 1 reactor at the Susquehanna nuclear power plant to the regional electric grid on 14 June, after completing improvements that will address the turbine issues experienced at the plant over the past several years. Workers made the same modifications to Unit 2 during its regularly scheduled refueling outage.

"We will continue to monitor the performance of the turbines on both units over the next few years to confirm the modifications are working as designed," said Timothy S. Rausch, senior vice president and Chief Nuclear Officer.

Operators at PPL's Susquehanna nuclear power plant disconnected Unit 1 from the regional power grid on 9 May at the start of a scheduled outage to install turbine modifications. The modifications are the first phase of a long-term plan that is expected to resolve the turbine blade issues that have affected plant operations in recent years.

Unit 2 was shut down for two weeks starting 30 May 2012 to replace 'a small number' of cracked turbine blades discovered during a planned inspection earlier in the year. Although no cracks were discovered in unit 1 at the time, extra diagnostic instrumentation was installed.

In October 2012 Susquehanna reduced output on both units 1 and 2, and shut down unit 1 for a three-week additional turbine inspection, to confirm data provided by instrumentation installed in May 2012 about turbine blade cracking.

"Consistent with best practices in the nuclear power industry, we've been very systematic and deliberate in our approach to this issue, from conducting periodic inspections to replacing turbine blades when appropriate and installing diagnostic equipment to monitor for conditions that may lead to cracking," Rausch said then.

"As a result of these efforts and our ongoing, detailed engineering analysis, we are in the final stages of verifying the causes of the cracking and implementing both short-term and long-term measures to resolve the cracking issues," Rausch said.

PPL Susquehanna lowered operating power levels of both units as a temporary measure to reduce the potential for cracking to occur or worsen.

Unit 2 returned to service June 5, having completed an eight-week refueling and maintenance outage. PPL employees and more than 1,000 supplemental workers replaced about 40 percent of the Unit 2 reactor fuel during the outage. They performed extensive inspections and testing of plant equipment, systems and technology. They inspected and replaced several pieces of the unit's turbine assembly, making improvements that address turbine blade issues that have affected the plant in recent years. In addition, crews replaced a 24-ton motor and pump that helps circulate coolant water through the reactor. PPL continually invests in plant equipment to keep Susquehanna in excellent material condition.

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