On April 26, 1986, the explosion of Reactor No. 4 at Chernobyl triggered the most serious civil nuclear disaster ever recorded. Nearly forty years later, the Russian invasion of Ukraine in February 2022 brought Chernobyl back to the center of global attention. Military occupation, disturbance of the highly radioactive Red Forest, fires in contaminated areas, and damage to the protective arch by a Russian drone have all revived radiological risks. Despite ongoing uncertainty, Ukrainian authorities are now considering partial reuse of the exclusion zone, including the installation of Small Modular Reactors and storage of nuclear waste.
1. A review of the facts
On April 26, 1986, Reactor No. 4 at the Chernobyl nuclear power plant in Ukraine exploded during a safety test. The reactor core melted down, releasing a radioactive cloud into the atmosphere. A 30-kilometer exclusion zone was established around the site, and approximately 350,000 people were evacuated. Hundreds of thousands of “liquidators” were deployed to contain the disaster under extreme conditions; many subsequently died from radiation exposure. The accident is classified as Level 7 on the International Nuclear Event Scale — the maximum level — making it the most serious civil nuclear disaster ever recorded.
2. Containment of the reactor
An initial concrete sarcophagus was constructed in 1986 to entomb the reactor’s remains. In 2016, this was covered by a metal arch designed to contain radioactive materials and stabilize the original, highly fragile sarcophagus. This structure is also intended to facilitate the eventual decommissioning of the reactor.
Nearly forty years after the disaster, the Russian invasion of Ukraine in February 2022 returned Chernobyl to the center of global attention.
3. Russian occupation and radiological consequences
3.1. Disturbance of the zone and health concerns
The Russian army seized control of the site on the first day of the conflict. Armored vehicles entered the exclusion zone, specifically traversing the “Red Forest.” Off-limits since 1986, the forest earned its name from the color of the pine trees killed by intense radiation. It remains one of the most contaminated places on Earth. For several weeks, Russian vehicles disturbed radioactive dust, while troops churned the soil to dig trenches and build fortifications. These activities caused a local increase in radiation levels, raising concerns regarding the health of the Russian forces stationed there for a month.
3.2. Forest fires and deterioration of the radiological situation
The radiological situation in and around the exclusion zone also deteriorated due to forest fires in contaminated areas, exacerbated by military activity. The occupation prevented firefighters from deploying, making it impossible to limit the re-aerosolization of radioactive particles.
4. Damage to the protective arch and radiation monitoring
In February 2025, the protective arch was damaged by a Russian drone strike. By December, IAEA (International Atomic Energy Agency) inspectors confirmed that the steel structure had been punctured and could no longer fully perform its primary radiation-blocking function, though the load-bearing elements and monitoring systems sustained no permanent damage.
Meanwhile, the ASNR (Nuclear Safety and Radiation Protection Authority) has been regularly monitoring radioactivity levels across Ukraine since the start of the conflict. Data analysis has shown no increase in radioactivity in the immediate vicinity of the plant, and ambient radioactivity in the zone remains stable. Nevertheless, the IAEA recommends restoring the integrity of the protective shield to ensure maximum security for the site and the surrounding ecosystem.
5. Toward a reuse of the exclusion zone?
Despite the ongoing uncertainty, future projects for the exclusion zone are under consideration. In a report presented in March 2026, the State Agency of Ukraine on Exclusion Zone Management (SAUEZM) stated that radioactivity levels remained generally stable throughout 2025. Based on these figures, the agency is considering the installation of two Small Modular Reactors (SMRs) in villages located within the exclusion zone, less than 10 kilometers from the Chernobyl plant. The exclusion zone could also serve as a storage site for radioactive waste and spent nuclear fuel.
6. Frequently asked questions
Why is the Chernobyl accident classified at the maximum level of the nuclear scale?
The Chernobyl accident is classified at Level 7 of the International Nuclear Event Scale (INES) — the maximum level — due to the reactor core meltdown, the massive release of a radioactive cloud into the atmosphere, the evacuation of 350,000 people, and the large number of liquidators who died from radiation exposure. This classification is shared only with the Fukushima disaster of 2011.
What radiological risks did the Russian occupation of Chernobyl create?
The occupation generated several risks: armored vehicles disturbed radioactive dust in the Red Forest, troops churned contaminated soil to build fortifications, and forest fires broke out in contaminated areas without firefighters being able to intervene. These activities caused a local increase in radiation levels and led to the re-aerosolization of radioactive particles into the atmosphere.
Is the Chernobyl protective arch still functional after the drone strike?
The arch was damaged by a Russian drone in February 2025 and can no longer fully perform its radiation-blocking function. IAEA inspectors confirmed the steel structure was punctured, though load-bearing elements and monitoring systems sustained no permanent damage. The IAEA recommends restoring the integrity of the structure as soon as possible to ensure maximum site security.
Has radioactivity increased around Chernobyl since the start of the conflict?
According to the ASNR, which has been regularly monitoring radioactivity across Ukraine since February 2022, no significant increase has been detected in the immediate vicinity of the plant. Ambient radioactivity in the zone remains generally stable, although local and temporary rises were observed during soil disturbances and fires in contaminated areas.
What projects are planned for the Chernobyl exclusion zone?
According to the SAUEZM’s March 2026 report, with radioactivity levels having remained stable in 2025, Ukraine is considering installing two Small Modular Reactors (SMRs) in villages within the exclusion zone, less than 10 kilometers from the plant. The zone could also become a storage site for radioactive waste and spent nuclear fuel.