By Olha Chepil | 2026-04-24

Forty years ago, a reactor exploded in the dead of night at a Soviet nuclear power plant. The Soviet government's response was not to warn anyone -- it was to monitor rumors, hold May Day parades and falsify medical records.

On April 26, the Ukrainian National Chernobyl Museum in Kyiv marks the anniversary with a major exhibition and newly declassified archives. The documents reveal both the cover-up and the courage of those who responded.

The museum has remounted a large exhibition and opened access to classified telegrams, situation reports and internal documents. Together, they sketch a portrait of a system that prioritized secrecy over survival -- and of the firefighters, doctors and service members who worked at the site of the explosion with incomplete information and at mortal risk.

A system that chose silence

The warning signs came early.

On March 26, 1986, a month before the catastrophe, the newspaper Literaturna Ukraina published a piece by journalist Lyubov Kovalevskaya detailing systemic construction violations at the fifth and sixth reactors: missed deadlines, defective materials, shortcuts. As editor of the plant's official newspaper, Kovalevskaya had inside access. Her conclusion was dangerous: without changes, an accident was inevitable.

The government's response was swift. She was called before party officials, threatened with expulsion from the Communist Party and forced to resign. According to Yanina Shvachko, deputy director of the Ukrainian National Chernobyl Museum, reactor start-ups were regularly adjusted to land on holidays. The fourth reactor was commissioned on Power Engineer's Day.

"The reactors were commissioned hastily in order to coincide with the holidays," Shvachko told Kontur. "Then three months later, they discovered serious mistakes that had slipped in when the third and fourth units were started up."

When the fourth reactor exploded overnight on April 26, 1986, internal measurements showed over 200 roentgen per hour -- a fatal dose over several hours of exposure. But official reports submitted by plant director Viktor Bryukhanov described normal conditions and routine monitoring.

The Soviet Union stayed silent for 36 hours. On the evening of April 28, the TV newscast "Vremya" ran a 14-second report. The New York Times had already put the story on its front page. The Soviet newspaper Radianska Ukraina buried a brief Council of Ministers statement on page 3.

Declassified Ministry of Internal Affairs archives, now under study by the museum, show that in the first hours after the explosion, KGB officers from the seventh directorate, responsible for external surveillance, were dispatched to the nearby city of Pripyat. Their mission was not rescue. It was to monitor public sentiment and identify "alarmists."

In Kyiv alone, 20 vehicles operated daily and 125 operators tracked and reported rumors about the accident to leadership. Militia stopped residents trying to leave Pripyat before the official evacuation order and sent them back.

"We have an outgoing encrypted telegram saying that any information about the events at the Chernobyl nuclear power plant must be communicated only through an encrypted connection," Shvachko said.

A parade through poison

The most consequential decision came days later. To demonstrate the situation was under control, Moscow pressured the party leadership of Soviet Ukraine to proceed with the traditional May Day parades. The Kyiv authorities objected. Moscow held firm.

Background radiation levels in Kyiv at the time were more than 200 times above normal. Whole families, children included, lined the parade route. Within days, hospitalizations surged. On the morning of May 3, Ukrainian data show 911 people were admitted with symptoms of radiation damage.

The next day, the number rose to 1,345, including 330 children. Radiology wards overflowed. Patients were transferred to hospitals outside the city.

The government then issued an order directing physicians to record "dysautonomia" in medical files rather than radiation exposure. When even that wasn't enough, the health ministry of the Ukrainian Soviet Socialist Republic (SSR) raised radiation exposure standards, nearly doubling them, to avoid documenting the real scale of harm. Initial diagnoses were removed or replaced.

"It was easier to change the standards" than to reveal the actual picture, Shvachko said.

Nature recovers, war returns

Almost four decades on, the exclusion zone has become Europe's largest natural reserve. Elk, deer, wolves, lynx and occasional brown bears now roam the territory.

Denys Vyshnevskiy, head of the scientific department of the Chernobyl Radiation and Ecological Biosphere Reserve, has worked there for 25 years.

"The nature here has been recovering since the 1990s," he told Kontur.

Russia's full-scale invasion in 2022 brought new disruption. Russian troops seized the plant territory, operated equipment in radioactive forests and robbed researchers of everyday items -- microwaves, kettles, computers and clothing -- later sold for scrap metal.

The threats have continued since the zone was liberated. On Feb. 14, 2025, a Russian drone struck the protective structure over the fourth reactor.

"I once personally witnessed what Russia is doing," Vyshnevskiy said. "I had gone out to work, I was standing in a field, and in the sky I could hear buzzing. There was a cruise missile flying, then another one, then Shaheds. They often go through the Chernobyl zone, and then continue on across Ukraine."

Meanwhile, the Ukrainian National Chernobyl Museum has built a digital space to collect personal testimonials.

"We're talking about Chernobyl not just as a catastrophe but also a trauma that society was able to overcome," museum director Vitalina Martynovska told Kontur.

The accident forced a reckoning in nuclear energy worldwide. Construction halted on multiple atomic facilities after 1986, and in 1990 a moratorium on new nuclear power plants was introduced. Chernobyl gave professional practice a new concept: safety culture -- the individual and collective responsibility of staff for every action and its consequences.