[Reporter’s Notebook] How Renewable Energy and Nuclear Power Can Coexist

Flexible Operation of Nuclear Power Plants Emerges as Key Issue
at Government Energy Mix Policy Forum
Korean Nuclear Plants Also Capable of Flexibility
Potential for Harmonious Integration with Renewables

Following the previous event on December 30, the '2nd Policy Forum on the Desirable Energy Mix' will be held on January 7. The government plans to finalize whether to proceed as planned with the construction of two new large-scale nuclear power plants, as decided in the 11th Basic Plan for Electricity Supply and Demand, based on the outcomes of these two policy forums and public opinion surveys.

In this second forum, the flexible operation of nuclear power plants is expected to be a primary topic. In the first forum, some environmentalists opposed the construction of new nuclear plants, arguing that expanding nuclear power, which is considered an inflexible energy source, would conflict with renewable energy.

Renewable energy sources such as solar and wind power are highly variable depending on weather conditions. To complement renewables, power sources capable of flexible output adjustment are necessary. Opponents argue that nuclear power is unsuitable for this role.

The perception that nuclear power is an inflexible energy source stems from a misunderstanding. Overseas, nuclear plants have long been operated flexibly. France, where nuclear power accounts for 70% of electricity generation, is a prime example. In France, nuclear output is reduced when renewable energy generation is high and increased when it is low. Nuclear output can be adjusted from 100% down to 20% within a single day.

The Korean-designed APR1400 reactor was equipped with flexible operation capabilities from the design stage. However, until now, output has only been limited to 80% in exceptional cases. In Korea, nuclear power's share is around 30%, so large-scale output reductions, as seen in France, have not been necessary.

To adjust nuclear output, operators can change the position of control rods inserted into the reactor core or regulate the concentration of boric acid dissolved in the coolant. Alternatively, they can adjust the amount of steam supplied to the generator while maintaining reactor output.

However, it is not immediately possible to expand the range and frequency of output restrictions domestically. Technologies suited to local conditions must be developed, and regulations need to be updated. The domestic nuclear industry has been developing flexible operation technology since July last year.

Coal and liquefied natural gas (LNG) each account for 30% of the nation's total electricity generation. All coal-fired power plants are scheduled to be closed by 2040, and the share of LNG power generation will gradually decrease. Is it possible to fill this gap entirely with renewable energy?

At the first forum, Minister of Climate, Energy, and Environment Kim Sunghwan admitted the difficulties of the energy transition, stating, "Frankly, when I look at the daily electricity supply, it is hard to find clear answers."

Under domestic conditions, achieving carbon neutrality with only renewable energy is nearly impossible. If the flexible operation capabilities of nuclear power are effectively utilized, a harmonious energy mix with renewables will be possible.