South Korea has approved 10-year operating extensions for the Kori-3 and Kori-4 reactors, restoring a potential 1.9 gigawatts of electricity to a grid under pressure from AI data centres and semiconductor production. The catch: the reactors are not expected back in service until 2027, and the extensions include years already spent shut down.
Watch Desk analysis
What happened
The Nuclear Safety and Security Commission approved the extensions for the two reactors in Busan, which had been shut after their original licences expired. Korea JoongAng Daily reports that Kori-3 is authorised to operate until September 2034 and Kori-4 until August 2035.
Korea Hydro & Nuclear Power says it aims to restart them in phases during the first half of 2027, after inspections and replacement of ageing equipment. If they return early next year, the article estimates they would have about seven and eight years of actual operation left, respectively, rather than a fresh decade.
Why it matters
The approval links an immediate, if not immediate-to-switch-on, source of electricity to South Korea’s plans for AI data centres and chip manufacturing. The article puts the reactors’ combined capacity at 1.9 gigawatts, enough for 19 large data centres rated at 100 megawatts each. That is meaningful capacity, though it does not settle how much power will ultimately reach new computing facilities or when.
The decision also shows the limits of treating nuclear extensions as a quick fix. The reactors need work before restarting, and commissioners raised concerns about risks including simultaneous accidents, climate change and spent-fuel storage. More electricity is useful; the engineering and safety questions do not vanish just because demand has a very shiny new customer.
Our read
This is a significant infrastructure decision for the AI build-out, not proof that data-centre demand can be met by extending old reactors alone. The practical takeaway is to watch the restart timetable alongside the safety reviews and the wider grid plan. Power capacity counts most when it is available, and this capacity still has a few steps to clear.
What to watch
- Whether Kori-3 and Kori-4 restart in phases during the first half of 2027, as KHNP says it aims to do.
- How regulators address the safety and spent-fuel concerns raised during deliberations.
- Whether South Korea’s next long-term electricity plan includes further nuclear capacity to serve data centres and semiconductor production.
Discussion spark: Should South Korea lean more on extending existing reactors to supply AI and semiconductor growth, or should safety, waste and the reactors’ limited remaining operating years weigh more heavily?
Sources and evidence
- Source update (28 October 2026, 07:10 UTC)
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