Chornobyl Disaster 40th Anniversary: Russian Aggression Threatens Decommissioning Efforts

Forty years ago, on April 26, 1986, an explosion at Reactor 4 of the Chornobyl nuclear power plant in northern Ukraine, then part of the Soviet Union, caused the world's worst nuclear disaster. The blast, occurring at 01:23 am during an aborted test, destroyed the reactor roof and released a massive cloud of radioactive waste. Radiation plumes drifted across Europe, with Belarus being the most affected. Soviet authorities evacuated Prypiat residents 36 hours later and only admitted the accident two days after the explosion, following detection of elevated radiation levels by Swedish scientists.

Approximately 30 first responders died from radiation exposure, and two were killed by the immediate explosion. Over 200,000 people were permanently displaced from an exclusion zone exceeding 2,500 sq/km, which remains in place. Chornobyl was decommissioned in 2000, but over 2,000 workers continue the decades-long process of waste disposal and infrastructure dismantling, managed by Ukraine's government.

Russia's full-scale invasion has severely compromised this work. Russian troops occupied the plant for five weeks, holding 300 staff captive. In February 2025, a Russian drone struck the New Safe Confinement (NSC) encasing Reactor 4, causing a fire and a 15 sq/m hole. This damage, temporarily patched, could cost €500 million to fully repair and has compromised the NSC's leak-tightness. Ukrainian Prosecutor General Ruslan Kravchenko reported routine Russian drone activity within 20 km of Chornobyl and 35 Kinzhal missiles detected near Chornobyl and Khmelnytskyi plants since 2022.

The IAEA reported in December that the NSC had lost its primary safety functions, emphasizing the need for timely restoration. The European Commission, marking the anniversary, urged Russia to cease attacks on Ukrainian nuclear facilities and comply with IAEA safety pillars. Russia has violated these pillars at both Chornobyl and Zaporizhzhia, where its forces continue to occupy the plant and have caused power losses and drone strikes on containment structures. The ongoing drone activity near Chornobyl makes full reconstruction investment unlikely until the war ends, leaving the site of the world's worst nuclear disaster at high risk.