The third unit of the Saeul Nuclear Power Plant in South Korea has been commissioned.

The South Korean company KHNP (Korea Hydro & Nuclear Power) announced that the Saeul 3 reactor has reached first criticality, i.e., a stable chain reaction. This is the third of four planned APR-1400 reactors at this site to have entered the startup phase.

The Nuclear Safety and Security Commission (NSSC) confirmed that all necessary inspections were completed on April 10, while the reactor itself successfully started up two days later. According to plan, the reactor's power will gradually increase over the next six months.

Commercial operation is expected in the second half of 2026, after performance and safety tests are completed and when it reaches full power, Saeul 3 will cover about 1.7% of South Korea's total electricity consumption, or as much as 37% of the needs of the city of Ulsan.

Construction began in 2017, but was temporarily suspended for three months due to a change in government policy. Nevertheless, a special committee voted to resume works at the end of that year (59.5% in favor), citing energy supply stability as the primary reason – and all this makes Saeul 3 one of the fastest-built blocks of nuclear power plants outside China.

Moreover, the APR-1400 reactor is the leading South Korean design that is already being used successfully. In addition to four operating units in Korea itself (Saeul 1 and 2, Shin Hanul 1 and 2), the same technology has also been applied at the Barakah Nuclear Power Plant in the United Arab Emirates, where all four built units are already in commercial operation, and that these reactors will soon be located in the Czech Republic.