Cracks found in all four OL3 feedwater pumps
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On 18 October, TVO announced that damage had been discovered in the internals of the feedwater pumps located in the plant's turbine island during maintenance and inspection work.
The feedwater pumps are Olkiluoto 3's largest pumps and are used to pump water from the feedwater tank into the steam generators. TVO said the cracks detected in the pumps have no impact on nuclear safety.
The company noted the structure of the feedwater pumps located in Olkiluoto 3's turbine island is commonly used in power plants. However, the pumps at OL3 have been designed for the plant unit's operations and are larger in size.
"The investigation is currently ongoing in several laboratories," TVO has now said. "The root cause of the cracks found in the pump impellers is still unknown."
The Areva-Siemens consortium constructed the OL3 plant under a fixed-price turnkey contract. They have joint liability for the contractual obligations until the end of the guarantee period of the unit. Construction of OL3 began in 2005, with completion of the reactor originally scheduled for 2009, but the project has had various delays and setbacks.
OL3 attained first criticality on 21 December last year and was connected to the grid on 12 March. The 1600 MWe pressurised water reactor is currently in an ongoing test production phase. It was operated at full capacity for the first time in late-September and is currently scheduled to start regular electricity production in December.
"The schedule for continuing the test production programme will be updated once the reasons for the damage and the repair method have been confirmed," TVO said.
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