The fractures found at the Yeonggwang nuclear power complex in South Korea have been described as ‘not serious’ by an official at the country’s nuclear watchdog.
The damage has not led to a leak but power shortages are now feared as the reactor has been switched off as a precaution.
The cracks were found during maintenance work on control rod tubes at a unit in the Yeonggwang nuclear complex, where two other reactors were recently shut down for several months to replace unvetted components.
The affected reactor had been shut down on October 18 for regular maintenance work, which normally takes just over a month.
"This is the first time these type of cracks have been discovered, but there was no radioactive leak," Nuclear Safety and Security Commission (NSSC) spokeswoman Shim Eun-Jung told AFP.
"We believe the extent of the cracks is not serious, although a further inspection is required," Shim said, adding that the reactor would remain offline until early January at the earliest.
On Monday, the government said it was shutting down two other reactors at Yeonggwang to replace thousands of "non-core" parts that had been provided with forged quality and safety warranties.
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