The emergency power generator at a nuclear power plant in Yeonggwang, South Jeolla Province was found to have malfunctioned during a special checkup last month, stoking controversy over another possible attempted cover-up.

The diesel power generator at the Yeonggwang-2 unit stopped a minute and 14 seconds after it was manually started for an examination on March 28, and the governor of Yeonggwang knew about it but did not report it to the public or nongovernmental watchdogs.

This comes after authorities at a nuclear power plant in Gori, Busan, had tried to conceal a power failure in February for more than a month.

Two emergency power generators are on standby at every nuclear power plant so they can start operating within 10 seconds in case of a power blackout.

The generator at the Yeonggwang-2 unit came to a halt with an alert for low-cooling water pressure, which the Korea Hydro and Nuclear Power Co. explained on Sunday was due to malfunctioning of the pressure switch.

“The actual pressure of the engine cooling water was normal, but the switch had malfunctioned,” the KHNP said in a statement, adding that it replaced the switch and completed the test on the generator.

“Such alerts do not stop the generator during blackouts or other emergency situations. So it could have supplied power in case of an emergency.”

The defect was fixed in about five hours, thereby meeting the rules that emergency power generator problems should be fixed within 72 hours after discovery, the KHNP said.

The government said all diesel power generators were functioning normally as it announced the results of its inspection on emergency power generators in 16 atomic power plants nationwide last month.

Chung Ki-ho, governor of Yeonggwang, confirmed the malfunctioning on the day it happened during a visit to the plant, but did not announce it, prompting anti-nuclear groups to file a complaint with the county office.

The KHNP said the case was not subject to public disclosure.

By Kim So-hyun (sophie@heraldcorp.com)