South Korea may soon face a power shortage with the scheduled shutdown of another nuclear reactor for maintenance while temperatures continue to rise, officials said Sunday.

According to officials from the Korea Power Exchange (KPX), the country's power reserves are expected to drop to around 3 million kilowatts this week.

The officials said the reserves level will likely drop to less than 3 million kilowatts in the following week. A power shortage warning is issued when the reserves dip to below 4 million kilowatts.

Such an outlook comes as a 700,000-kilowatt nuclear reactor at the Wolsong Nuclear Power Plant, located some 400 kilometers southeast of Seoul, is set to undergo regular maintenance from Saturday, further reducing the country's total generation capacity.

The country was forced to halt the operation of two nuclear reactors last week for faulty control cables that were allegedly supplied under fake test results and quality warranties. The government has also postponed the scheduled operation of two new nuclear reactors.

The Ministry of Trade, Industry and Energy has announced a set of painstaking measures to cut the country's electricity consumption, but it has also said the measures may not be enough to completely rule out the possibility of the power reserves running out, causing a nationwide blackout.

The country's total generation capacity remains at around 76.7 million kilowatts while its peak demand is expected to reach up to 78.7 million kilowatts, the ministry said.

Meanwhile, the state-run nuclear plant operator, the Korea Hydro and Nuclear Power Co., said the operation rate of the country's nuclear power plants has dropped to below 80 percent for the first time in its history.

In the first four months of the year, the country's 23 nuclear reactors in operation produced some 47.85 million kilowatts of electricity, or 79.16 percent of their total capacity.

The country's operation rate of nuclear power plants reached a record high of 95.5 percent in 2005 and had remained well above 90 percent until 2012 when two reactors had to be shut down for faulty parts supplied under fake quality warranties. (Yonhap News)