The incident took place in the city of Ulsan, located approximately 400 kilometers (248 miles) south-east of Seoul. The plant is operated by Korea Hydro & Nuclear Power (KHNP), a subsidiary of the state-controlled Korea Electric Power Corp (KEPCO).
KEPCO is on high alert following recent cyberattacks targeting the company. However, Choi Hee-ye, a company spokeswoman, said that Friday incident was not related to cyberterrorism, according to the Associated Press.
Moreover, hackers recently threatened KEPCO, claiming that they can disable the control systems of its power plants.
On Thursday, South Korea launched an investigation into a cyberattack on Wolseong, another nuclear power plant operated by KHNP. Investigators have not ruled out Pyongyang’s involvement in the attack.