South Korea’s Nuclear Safety & Security Commission (NSSC) has approved the operation of the unit 3 at Saeul NPP in Ulju, Ulsan. This marks the first operational permit for a new nuclear reactor in South Korea since Shin Hanul unit 2 in September 2023.
The NSSC passed the Saeul 3 nuclear reactor operational permit proposal with five votes in favour and one against. “After comprehensively reviewing the design safety of the reactor building, accident response facilities, radiation impact assessments, and operational capabilities of the Saeul 3 reactor, we confirmed that it meets the licensing criteria under the Nuclear Safety Act and approved its operation,” the Commission said. During a meeting earlier in December, NSSC had postponed a decision due to insufficient information on the accident management plan submitted by Korea Hydro & Nuclear Power (KHNP).
Saeul 3 is a new APR1400 model with a 60-year design life – the fifth such reactor to apply for an operational permit in South Korea. Originally named Shin Hanul unit 5, construction began in June 2016. However, under the Moon Jae-in administration’s nuclear phase-out policy, construction was halted in 2017 for a three-month public deliberation process before resuming.
The project faced significant delays, taking 9.7 years from construction permit to operational approval. Before the Moon administration, the average time from construction to operational permits for 23 reactors was 5.2 years. However, reactors permitted under Moon’s government took significantly longer – Shin Hanul Unit 2 (February 2019, 11 years), Shin Hanul Unit 1 (July 2021, 9.7 years), and Shin Hanul Unit 2 (September 2023, 11.9 years).
The Saeul-3 reactor incorporates enhanced safety features compared to previous models. It is the first reactor designed to withstand extreme external shocks, such as aircraft impact. Its wall thickness was increased by 15 cm to 137 cm, while auxiliary buildings surrounding the reactor were thickened by 30cm to 180cm. It also added an alternating AC diesel generator to prepare for power outages during earthquakes. The used nuclear fuel storage capacity was designed to hold three times the amount of previous reactors – 60 years’ worth – allowing all spent fuel generated during the reactor’s operational lifespan to be stored on-site.
This is the first operational permit for a new reactor since the inauguration of President Lee Jae-myung’s administration. According to a nuclear industry source: “The Lee Jae-myung government’s stance on nuclear power had been ambiguous, but this approval for Saeul 3 has strengthened confidence that reactors under construction or planned will proceed as scheduled.”
Following the NSSC’s approval, KHNP will load fuel into the Saeul 3 reactor and conduct a six-month trial operation. Commercial operation is expected to begin around August 2026.
Approval for new reactors is now expected to accelerate with the government prioritising AI data centre construction. According to the 11th Basic Plan for Electricity Supply and Demand, data centre peak additional power demand will jump from 0.5 GWe in 2025 to 4.4 GWe in 2038.
Shin Hanul unit 4, slated for completion next year. NSSC plans to review its permit in the second half of 2026. The Shin Hanul units 3&4 were scrapped under the Moon administration but received construction permits in September 2024, with a target for commercial operation in 2033.
