Government Plans to Expand Output Control Range of Nuclear Power Plants to 10%

Minister of Climate, Energy and Environment Kim Sung-hwan announced that nuclear power plants will be utilized as a “flexible energy source.” At present, nuclear power plants operate at full capacity around the clock as a “base-load power source,” but this means they would be operated by adjusting output according to demand. The interpretation is that the government intends to reduce the share of nuclear power during daytime hours, when renewable energy generation such as solar power surges, in order to increase the utilization of renewable energy. However, concerns have been raised that existing nuclear plants were not designed with frequent output adjustments in mind, which could undermine nuclear safety.

At a press briefing held at Government Complex Sejong on Dec. 1, Minister Kim said, “In the spring and fall, power demand will likely be met solely by nuclear power and renewable energy,” adding, “Research and development (R&D) is underway to convert nuclear power into a flexible energy source.”

Currently, power authorities divide power plants into base-load power sources and flexible power sources to balance electricity supply with demand. Minimum daily power demand is covered by base-load sources — nuclear power plants and coal-fired power plants — while the additional demand that surges during the day is filled by flexible sources such as solar power plants and liquefied natural gas (LNG).

The problem is that if the share of renewable energy generation increases going forward, there may be times in spring and autumn, when demand is low, in which electricity demand is met solely by renewable energy. In such a case, if the output of nuclear power plants is not sufficiently controlled, the entire national power grid could become overloaded and a blackout, or massive power outage, could occur. Currently, South Korea limits the output control range of nuclear power plants to around 3 percent, but the government’s goal is to raise it to 10 percent. It is known that France is the only country in the world that utilizes nuclear power plants as a flexible energy source, because nuclear power accounts for more than 65 percent of its market.

Lee Ki-bok, president of the Korean Nuclear Society, cautioned, “If the direction shifts to artificially reducing nuclear output for the purpose of using more renewable energy, it would not be desirable.”