The 40th Anniversary of Chernobyl: A Legacy of Disaster and New Threats

A drone strike in February 2025 has damaged the protective shield over Reactor 4, raising fresh fears about nuclear safety in a war zone.

On April 26, 1986, an explosion at Reactor 4 of the Chernobyl Nuclear Power Plant in Ukraine released radioactive material across Europe. Now, 40 years later, the site faces a new challenge: war.

The 1986 Disaster

Explosion and Immediate Response

On April 26, 1986, a routine safety test at the Chernobyl Nuclear Power Plant—located in what is now Ukraine—triggered a catastrophic power surge and steam buildup. The explosion destroyed Reactor 4 and released radioactive smoke and steam for over ten days, contaminating areas across Europe, particularly in neighboring Belarus. Helicopters dropped sand, clay, and lead to contain the fire.

The Soviet Union did not publicly acknowledge the accident until April 28, when a 20-second announcement stated that one reactor was damaged and remedial actions were being taken. The public disclosure came only after radiation alarms were triggered in Sweden, over 1,000 kilometers away.

"They told us we would return home in three days. Many never did." — Evacuee accounts from the exclusion zone.

Evacuation and Human Impact

Approximately 350,000 people were evacuated from the exclusion zone, including residents of towns like Pripyat and surrounding villages. Evacuees reported being told they would return home in three days, but many never did.

The official death toll from the incident is 31. Thousands of deaths have been attributed to cancer caused by radiation exposure. In 2005, a study by several UN agencies concluded that 4,000 people could die as a result of the accident, with other estimates suggesting a higher number.

Three men—Alexei Ananenko, Valeri Bezpalov, and Boris Baranov—volunteered on May 4, 1986, to drain flooded water from under the reactor. Baranov lived until 2005; Ananenko and Bezpalov remain alive as of the latest reports.

Cleanup and Long-Term Response

As many as 600,000 "liquidators" from the Soviet Union participated in containment and cleanup over four years. The Soviet Union constructed a concrete sarcophagus over the damaged reactor with a 30-year operational lifespan.

Reactors 1, 2, and 3 continued operating after the accident. Reactor 3, the last operational unit, was decommissioned in 2020.

The Exclusion Zone and Environmental Changes

The Chernobyl Exclusion Zone covers 2,600 square kilometers bordering Belarus. The nearby city of Pripyat, founded in 1970, housed workers for the power plant. The city had 160 buildings, 13,500 apartments, and five schools. It remains abandoned, with buildings derelict and overgrown.

Within the exclusion zone, wildlife has thrived in the absence of humans. Species include Przewalski's horses, brown bears, lynx, red deer, and wolves. Some organisms have adapted to radiation:

• A black fungus grows better in radioactive environments.
• Green tree frogs have evolved darker skin.
• Wolves show altered immune systems and genetic changes that may resist cancer.

Despite adaptation, individual animals experience high cancer rates, smaller brains, cataracts, and genetic mutations.

The Red Forest, named for rust-colored trees after the explosion, remains highly radioactive. Drone surveys indicate that in some areas, a person could receive a year's recommended radiation dose in under an hour. Forest fires could spread toxic smoke and ash beyond the exclusion zone.

About 100–200 elderly self-settlers still live in the zone. Up to 3,000 scientists work shifts monitoring contamination and managing the plant.

February 2025 Drone Strike

Event Details

On February 14, 2025, at 1:59 a.m., a drone with an explosive warhead struck the outer layer of the New Safe Confinement (NSC) structure covering Reactor 4 at the Chernobyl nuclear power plant. Ukrainian officials attributed the strike to a Russian drone; Russia denied the accusation and alleged Ukraine staged the attack.

The drone caused a fire on the exterior of the NSC, which took firefighters over two weeks to fully extinguish. No increase in radiation levels was detected outside the arch, and no injuries were reported.

Damage Assessment and Repairs

The New Safe Confinement, built in 2016–2019 at a cost of approximately 2 billion euros and designed to last 100 years, requires repairs estimated at 500 million euros. The structure's primary safety functions, including confinement capability, have been compromised, according to the International Atomic Energy Agency (IAEA).

Denys Khomenko, deputy director for technical operations, stated that highly contaminated areas around reactor 4 limit worker exposure to minutes or hours, complicating repairs. A large panel was temporarily patched over the hole, but further work is needed.

IAEA inspectors found no permanent damage to the shield's load-bearing structures or monitoring systems, and some roof repairs have been completed. IAEA Director General Rafael Grossi stated that "timely and comprehensive restoration remains essential to prevent further degradation and ensure long-term nuclear safety."

"The risk is low," said Professor Jim Smith, an environmental expert from the University of Portsmouth, "as contaminated dust is contained within the original concrete sarcophagus."

Ongoing Risks

Professor Jim Smith, an environmental expert from the University of Portsmouth, stated that the principal hazard at the site involves the disturbance of radioactive dust, but indicated that "the risk is low" as contaminated dust is contained within the original concrete sarcophagus, which is itself covered by the newer protective shield.

Ukraine's state prosecutor reported that since June 2024, radars detected 92 Russian drones flying within a 5 km radius of the shield. Other vulnerable sites include a nuclear fuel storage facility near reactor 4, not designed to withstand aerial impacts.

The war has postponed plans to dismantle the reactor. About 2,250 employees continue to work at the plant. The city of Slavutych was built to house evacuees and still has about 20,000 residents.

War-Related Nuclear Safety Concerns

Russian forces occupied the Chernobyl plant for nearly three weeks in February–March 2022 during the invasion of Ukraine, reportedly exposing staff to excess radiation.

The ongoing war has raised concerns about nuclear safety, with Russian forces active near both Chernobyl and the Zaporizhzhia nuclear power plant. The IAEA has been assessing Ukraine's energy infrastructure since early December 2024, including inspections of electrical substations critical for reactor cooling and other safety systems.

Russia reportedly conducted airstrikes on the city of Kremenchuk, an industrial hub in central Ukraine.