What happened

The IAEA said it was informed a drone struck the cooling tower of reactor unit No. 1 at Russia's Kursk Nuclear Power Plant on 17 September. Rosatom described the damage as minor secondary-circuit damage — the cooling tower rejects waste heat and is separate from the reactor vessel, spent-fuel pool or control room — and said the unit continued operating at full capacity with radiation levels unchanged and no fire reported. IAEA Director General Rafael Grossi urged maximum military restraint near nuclear sites to avoid the risk of an accident. Russian officials attributed the strike to Ukraine; Ukraine had not publicly claimed it as of the following evening, and the damage assessment has not been independently verified by satellite imagery. No casualties were reported. Kursk NPP was previously struck in August 2025, when a drone damaged an auxiliary transformer and forced a 50% output cut at another unit.

When cited sources give different casualty, damage or spill figures for this event, they’re reported side by side above rather than merged into one number. See how confidence levels work.