Operators at Pennsylvania Power & Light Co.'s Susquehanna nuclear plant are preparing to restart Unit 2 after investigating and correcting an electrical problem and a problem with a diesel generator.
On July 14, a loose connection caused a circuit breaker to fail to close. That led plant operators to shut down Unit 2 manually, said Herbert D. Woodeshick, PP&L's special assistant to the president for Susquehanna.
"Following routine maintenance while the unit was still operating, one connection in the circuit breaker box was not properly connected," Woodeshick said. The problem has been corrected.
"During an investigation, plant management determined that the incident occurred because employees did not properly complete the work. Also, employees did not properly complete a required follow-up check of the work," Woodeshick said.
Independent investigations of the incident were conducted by plant personnel and PP&L's Independent Safety Evaluation and Corporate Audit Services groups to determine the cause. These investigations determined that these events were due to inattention to detail, not to any deliberate act, Woodeshick added.
Because the incident was similar to one that happened in mid-June in which employees doing work on one of the plant's five backup diesel generators failed to align switches properly, PP&L decided to keep Unit 2 shut down until a thorough investigation was completed.
"The diesel generators were available to start automatically as they are designed to do, but the misalignment was not consistent with normal operating procedures," said Woodeshick, "because it would have caused one of the diesels to run low on fuel in a few hours. We could have manually operated switches to add fuel to the diesel if necessary."
Investigators determined that an employee misaligned the diesel generator switches as he was putting the generator into service, and three other employees failed to find the mistake in subsequent inspections.
Events such as these are unusual at the nuclear plant, Woodeshick said, and the utility took immediate action to prevent a recurrence. "Employees did not follow required procedures, and we're taking action to prevent that from happening in the future," he said.
Among the steps being taken are meetings with all employees at the plant at which management's expectations for employee conduct at the facility are being reiterated. Also, some employees involved were placed on administrative leave and others have been assigned to other PP&L work locations pending continuing review of the issues involved.
PP&L has performed the inspections again, increased supervisory oversight and instituted a stepped-up inspection program as a result of the incidents, Woodeshick said. The company has informed the Nuclear Regulatory Commission about the incidents and the follow-up actions.
Unit 2 will return to service following completion of the appropriate corrective actions required for startup, Woodeshick said. PP&L continues to evaluate the incidents and will take the corrective actions that are deemed prudent.
Unit 1 at the plant continues to operate at full power.