A nuclear power plant, whose operation had been suspended for an inspection, experienced a temporary cutoff in the power supply, an accident which, if prolonged, could have caused a horrendous disaster. No less serious was that the accident had been covered up for more than a month.

The power failure at the Busan-based Gori-1 nuclear power plant happened at 8:34 p.m. on Feb. 9, reportedly because the procedure of safety checks on the power supply was not followed as directed by the manual.

During a check on the plant’s circuit breaker, an inspector accidentally cut off the power supply from the outside, which should have automatically started a diesel-powered generator immediately. But it did not because the generator was out of order.

In that case, the inspector should have manually started an ACC DG, another emergency generator. But he did not. Instead, he spent 12 minutes restoring the power supply from the outside. If the first blackout the nation experienced had been prolonged, it could have caused a nuclear meltdown, a nightmare Japan experienced when a tsunami hit the Fukushima nuclear power plant a year ago.

Korea Hydro and Nuclear Power, the operator of nuclear power plants, reported the accident to the Nuclear Safety and Security Commission, not immediately but on Monday. It says it received the report from the Gori power plant March 10. The Gori plant may have continued to keep it secret if it had not received an inquiry from a member of the Busan city council March 9. He was doing some digging on the case after overhearing about the incident.

Given the gravity of the accident, however, it is an enigma that there was no whistleblower though 60 to 100 employees were reportedly in the know. Was it because they kept silent, fearing a backlash ahead of the Nuclear Security Summit on March 26-27?

Since the Fukushima disaster, the Korean government has repeatedly vowed to take every precaution possible to prevent a nuclear accident. But the Gori case shows that the nation has failed to learn lessons from the Fukushima meltdown.

It goes without saying that nuclear safety cannot be over-emphasized. The Nuclear Safety and Security Commission will have to conduct painstaking safety checks on all of the 21 nuclear reactors in operation and their auxiliary facilities and take all precautions conceivable. The nuclear watchdog also needs to determine who in the line of safety supervision should be held accountable for the attempted cover-up.