Third unit at South Korea's Saeul nuclear power plant reaches criticality for the first time

The new South Korean unit Saeul 3 has reached an important milestone ahead of entering commercial operation. The APR-1400 reactor, with an installed capacity of 1400 MW, has reached criticality for the first time. Before officially entering service, the unit will undergo tests at various power levels. KHNP began construction of the unit in April 2017.

South Korean company Korea Hydro & Nuclear Power has announced an important milestone in the commissioning of the new Saeul 3 nuclear unit. The APR-1400 reactor reached criticality for the first time on 13 April, marking a stable nuclear fission chain reaction. The company received an operating licence for Saeul 3, with an installed capacity of 1400 MW, at the end of last year and subsequently began loading nuclear fuel.

"The initial start-up of the reactor is a preparatory phase before full-scale electricity generation. The trial operation will be carried out in accordance with strict standards and procedures. Safety will be the top priority throughout the process. We will carry out thorough checks to ensure that the unit can enter commercial operation in the second half of the year," a KHNP representative said.

Engineers plan to gradually increase the output of the third unit at the Saeul nuclear power plant (formerly also known as Shin-Kori) over the next six months. Once they have verified the performance of key equipment and safety systems at 100% output, Saeul 3 will begin commercial operation.

South Korea's five-year nuclear hiatus

South Korea began construction of the Saeul 3 nuclear unit in April 2017, and construction of its sister unit Saeul 4 began in September 2018. Work on both units continued despite the anti-nuclear policy of the country's former president (in office 2017- 2022). The country subsequently returned to its nuclear plans and officially began construction last year on the third unit at the Shin-Hanul nuclear power plant, with another unit at the site set to begin construction this year. The country plans to bring two more units online by 2038.

"This achievement is attracting even greater attention amid the energy supply instability caused by the recent escalation of tensions in the Middle East. Nuclear power is considered a source of energy with a stable fuel supply and relatively little exposure to price fluctuations," KHNP added in a press release.

Nuclear power plants currently account for just under a third of the country's generation mix, while the new unit is expected to contribute just under 2%. South Korea currently operates four APR-1400 reactors, commissioned between 2016 and 2024. KHNP supplied another four of these units for the Barakah nuclear power plant in the United Arab Emirates.