Korea Electric Power Corp. is walking a tightrope, as its electricity reserves frequently fall to dangerous levels these days. It cannot rule out the possibility of a blackout, as demand for power remains unexpectedly high as the nation is gripped by a scorching heat wave.

With the summer holiday season entering full swing at the end of July, KEPCO had expected power demand to subside. But a protracted period of scorching days and tropical nights continues to push up power demand, resurrecting the ghost of not just a series of small-scale blackouts but widespread outages.

Last year, the nation experienced rolling blackouts as KEPCO, the government-invested utility, suspended the provision of power, successively from one small area to another, to conserve electricity when supply fell to a dangerous level. If it wishes to avoid a second series of rolling blackouts, it will have to do all it can do in its capacity ― including requests to businesses to stop operations during peak hours.

KEPCO normally maintains 4 million kW to 5 million kW in reserve. But on Monday, the Korea Power Exchange issued a warning of an impending danger when the electricity reserve fell below 3 million kW, the first since the rolling blackouts on Sept. 15 last year. KEPCO had to take emergency measures ― including the temporary suspension of power supply to 234 business concerns and the purchase of an additional 420,000 kW from private power generators. The Korea Power Exchange sent out messages about the declining reserves to the public with the help of TV networks.

Had the reserves dropped below the 1 million kW mark as they did last September, the state utility would have started rolling blackouts. If no action had been taken, the administration says, the reserves would have been reduced to less than 1 million kW.

The worst is yet to come if the conservation campaign the administration is carrying out fails to produce an intended result. The Ministry of Knowledge Economy believes the nation could be exposed to a grave blackout risk during the second and third weeks of this month, still a sultry season, during which most families will have returned from their summer vacations. Demand for power, the ministry says, would peak if families should ignore the energy-saving campaign and keep the air-conditioned room temperatures too low.

Against this backdrop, the Reactor-1 of the Kori Nuclear Power Plant in Busan, which had gone through security checks since March, resumed operation on Monday. The Ministry of Knowledge Economy says its power generation will climb to its full capacity of 580,000 kW on Friday.

The reactor was shut down when the cover-up of a safety breach was reported on March 12. The Nuclear Safety and Security Commission, which had since conducted a four-month safety inspection, approved its restart. The commission’s decision was supported by an expert team from the International Atomic Energy Agency.

To put residents’ fear about safety to rest, their representatives and nuclear experts recommended by Korea Hydro & Nuclear Power were allowed to have another round of inspections. They concluded it had “no internal defects deserving any attention.” Still, antinuclear activists were opposed to the reactor’s restart.

In announcing the reactor’s restart at a news conference, Minister Hong Suk-woo said it was not a matter of whether or not it was safe. He was right when he said, “From the beginning, it was a matter of how safe people felt.”

The 580,000 kW of electricity will be of great help. Still, it will not be enough to avert a blackout unless families turn down the air-conditioned room temperatures. That is the reason why they will have to be encouraged to participate in the civic campaign for energy conservation, which will continue until Sept. 21.

Voluntary participation in the campaign can make a difference, as witnessed during its trial run on June 21. At the time, as much as 5 million kW was saved. Moreover, energy conservation is a worthy cause that should last long after the electricity shortage is relieved when a 3 million kW thermal power plant is dedicated in the second half of next year.