South Korea has shut down two nuclear reactors and suspended the restart of two others after an investigation found they were using substandard parts.
Seoul's nuclear safety watchdog insisted Tuesday there is no danger of a radiation leak due to the suspect components, which it says were provided with fake quality certificates.
Authorities shut down reactors at the Gori nuclear complex and Wolseong plant. They also delayed the resumption of operations of a reactor under maintenance and the start of another new reactor because of the same issue.
Last year, a corruption scandal involving thousands of suspect parts under fake warranties prompted a nationwide inspection of South Korea's nuclear plants.
With the latest shutdowns, only 13 of the country's 23 nuclear reactors are online, raising fears of a power shortage during the upcoming warmer months.
South Korea relies on nuclear power for more than one-third of its electricity. But the scandals, combined with the 2011 nuclear disaster in nearby Japan, have many South Koreans questioning whether the risks of nuclear power outweigh the benefits.