New Nuclear Plants Planned for South Korea's Yeongnam Region Amid Grid Capacity Concerns

South Korea is grappling with a critical shortage of power transmission capacity, forcing the curtailment of electricity from both nuclear and renewable energy sources. This situation is exacerbated by plans to build new nuclear power plants, including two large-scale reactors and one small modular reactor, in the Yeongnam region, specifically in Yeongdeok and Gijang counties. Critics question the feasibility of these projects given the already strained grid and the "concentration of power sources" in the region.

The number of times nuclear power output was controlled due to transmission issues surged to 37 last year, a tenfold increase from just three in 2023. Similarly, solar power output curtailments rose to 88, up from 31 the previous year. This creates a "zero-sum" competition between nuclear and renewable energy, with approximately a quarter of renewable energy generation being wasted. As of May last year, only 26.9 GW of the 35.8 GW of renewable energy connection applications were granted, meaning a significant amount of electricity is generated but cannot be transmitted.

The primary cause is the insufficient capacity of the transmission network. The East Coast's transmission capacity stands at 11.6 GW, while the connected generation capacity is 17.4 GW, leaving a deficit of 5.8 GW. Korea Electric Power Corporation (KEPCO) plans to expand this capacity to 19 GW through the East Coast-ShinGapyung High-Voltage Direct Current (HVDC) transmission line project. However, local resident opposition continues to hinder these crucial infrastructure upgrades, with 18 out of 52 ongoing KEPCO power grid construction projects experiencing delays.

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It usually takes over 10 years to build new transmission lines. 2.8 GW, the installed capacity of the two new large nuclear reactors, requires two 345 kV transmission lines, but there are many delays due to resident opposition. In Yeongdeok, a new transmission line must be built from scratch, making it more complex.

Amidst these challenges, the plan to build two additional large nuclear reactors in Yeongdeok is particularly contentious. The Gyeongbuk province, where Yeongdeok is located, already boasts the highest electricity self-sufficiency rate in the country at 228%. Furthermore, 20 out of South Korea's 26 operating nuclear reactors are concentrated in the Yeongnam region, including Busan, Ulsan, Gyeongju, and Uljin.

Experts express concern that new nuclear sites are being selected without thorough consideration of the power grid's capacity. Professor Jeon Young-hwan of Hongik University's Department of Electronic Engineering noted that establishing new transmission lines typically takes over a decade. He questioned the government's strategy of constructing new facilities without adequately considering grid operations, especially when plans for transmission lines for the upcoming Shinul 3 and 4 reactors, due to be completed by the end of the year, are still uncertain.

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Given that the construction plans for transmission lines for Shinul 3 and 4, which are scheduled for completion by the end of the year, are still uncertain, it is questionable whether the government's approach of constructing facilities without considering grid operations is appropriate.