Korean nuclear regulators have discovered microscopic cracks in tunnels that guide control rods in one of the reactors at the Yeonggwang nuclear power plant, in the southwestern part of the country.
It's raising new concerns about the nation's nuclear power sector, as the detection came just days after two reactors at the same plant were shut down to replace parts that had been provided with forged certificates.
The Korea Hydro and Nuclear Power Corporation said they had found cracks in six different tunnels in the reactor which had not been operating since October 18th for regular maintenance.
They've said they will now keep it shut indefinitely.
The state-run nuclear operator said there was no threat to public safety as the cracks had not caused any leaks.