The head of Korea Hydro and Nuclear Power apologized Sunday over the recent internal data leaks at the country’s nuclear reactors and a gas leak at the construction site of an atomic reactor that killed three workers.

The executive also tried to reassure the public, stressing that all of its plants were safe from cyberattacks.

“The cyberattacks have been persistent but I assure you that the nuclear plants are being safely guarded,” said Cho Seok, chief executive of the KHNP, the operator of the nation’s 23 nuclear reactors, at a press conference.

“Some hacking attempts to infiltrate the KHNP’s internal networks have been detected but they will not have any impact on plant operations as we are taking the proper defense measures,” he added. 

Cho also said he did not plan to step down, as he was responsible for handling the situation.

Regarding the impact on the plants, the chief said the hacking may have succeeded if the intention was to cause a social uproar, but that in terms of material damage, it achieved nothing more than damaging four of the KHNP’s personal computers.
On five occasions between Dec. 15 and 23, an anonymous antinuclear group posted diagrams and operating manuals of local nuclear reactors on Twitter. The personal information of some 10,000 KHNP employees was also released online.

The group demanded that the government shut down three nuclear power reactors starting Dec. 25. Otherwise, it threatened to commence cyberattacks on the KHNP to paralyze the nation’s atomic energy supply.

South Korean officials have not ruled out the possible involvement of North Korea, but Pyongyang on Sunday denied any role in the hacking, calling the allegation “a groundless scheme.”

Meanwhile, three workers died on Friday after inhaling toxic gas at the construction site of the unit 3 reactor at Gori, the country’s largest nuclear power complex, in Ulsan, southeast of Seoul. Construction of the reactor was about 99 percent complete.

The state-run nuclear operator ruled out any connection between the deaths and the cyberattack threats.

Amid the growing public fears, the government has been on emergency standby since Monday.

On Wednesday, a joint investigation team of government and prosecution officials said a suspect in the hacking attack was found to have used multiple Internet protocol addresses based in China.

Korean investigators asked Chinese authorities to help identify the suspected IP addresses the hackers used in the Chinese city of Shenyang, which is close to North Korea.

By Park Han-na and news reports (hnaprk@heraldcorp.com)