South Korea’s nuclear watchdog announced a sweeping probe on atomic plants across the country after finding forged safety documents and has shut down two reactors as part of the investigation.

It emerged that safety certificates for more than 7,600 items procured by state-run Korea Electric Power Corp., which runs all 23 of South Korea’s nuclear power stations, were allegedly forged. The Ministry of Knowledge Economy was forced to shutdown two reactors on Monday. Kepco chief executive Kim Joong-kyum offered to resign following Monday’s announcement, according to a ministry official.

The government claimed that the parts in question do not pose a serious security danger because they were not used in the most sensitive parts of the reactor. The Nuclear Safety and Security Commission said it would ensure that the investigation and replacement of uncertified parts would not disrupt power supply. However, more closures might be necessary, raising the prospect of a power shortage as the country braces itself for another cold winter.

Analaysts said the scandal could undermine Seoul’s efforts to increase nuclear exports to emerging markets, including Turkey and Vietnam, and a $20 billion civil nuclear deal with UAE as well as a potential nuclear deal with Finland next year.

“The reason why we got the UAE deal is because of their trust of our nuclear safety, thanks to our high operating ratio. But these technical noises would likely hinder the ongoing talks to export more nuclear reactors,” Yu Duk-sang, an analyst at Dongbu Securities, told the Financial Times.