Forty years after the Chernobyl nuclear disaster, Bulgaria remains deeply marked by that experience. As the only country in the socialist bloc to take no protective measures, it paid a heavy price. The fallout exposed the cynicism of the communist regime and shaped the country’s environmental and democratic awakening.
At 1:23 AM on 26 April 1986, reactor number four at the Chernobyl Nuclear Power Plant in the USSR suffered a catastrophic core failure and exploded, destroying part of the facility. The reactor core was left exposed, releasing large quantities of radioactive substances into the atmosphere. More than 200,000 people were evacuated from the surrounding areas in the months that followed.
Carried by the wind, the radioactive plume contaminated large parts of Europe, with the heaviest fallout in Ukraine, Belarus, and Russia. Emissions continued until 5 May, creating clouds of caesium-137 and other isotopes, the concentration of which diminished with distance but still affected vast territories. The plume reached the Balkans on 1 May.
At the time, Dimitar Vatsov was a 15-year-old high school student in Sofia. “Just after the radioactive rains, the Komsomol [the youth organisation of the Bulgarian Communist Party, modeled after the Soviet Komsomol] sent my class to work in the fields,” he recalls. “Every morning, a bus would pick us up to harvest spinach and chives”.
Until 7 May, Bulgarian authorities made no public announcement about the disaster. Subsequent official statements claimed that environmental contamination was minimal and required no special measures. Four of Vatsov’s classmates later died of cancer.
That experience left him deeply scarred. Now a philosopher and professor at the New Bulgarian University in Sofia, last autumn he launched a seminar entirely devoted to the consequences of the Chernobyl disaster in Bulgaria, bringing together historians, journalists, and nuclear physicists.
“Bulgaria was the only country in the socialist bloc that took no measures following the disaster,” he explains. Even though Bulgaria ranks only eighth among the countries most affected by radiation according to a UN report, it suffered the highest rate of thyroid cancer among children outside the former USSR. “As a philosopher, this singularity led me to reflect on truth, on the ethics of political discourse, and, more broadly, on the cynicism of the communist regime at the time.”
A Bulgarian Blackout
Bulgaria stands out as the country where information was most heavily censored, and no meaningful action was taken.
After the Chernobyl incident, information was carefully filtered in Eastern Bloc countries to minimize the perceived risks of the disaster while preserving the prestige of the USSR. For example, in Czechoslovakia, the word katastrofa was deliberately avoided in the early stages, while the term havárie (“disaster”) was used sparingly and generally without qualifiers. Official reports emphasized Soviet expertise and heroism, the rapid containment of the incident, and the alleged exaggeration of events by “Western imperialist media.” Still, Bulgaria stands out as the country where information was most heavily censored, and no meaningful action was taken.
“Ceaușescu – one of the most authoritarian dictators of the time – warned Romanians on May 2 about the risk of contamination. In Yugoslavia, pregnant women and children were asked to stay indoors, and basic precautions were recommended, such as washing fresh food. In Bulgaria, it was a complete blackout,” says Vatsov.
Nuclear physicist Georgi Kaschiev, who worked at the Kozloduy nuclear power plant in northwestern Bulgaria, remembers those days vividly: “The only statement we received was that there had been a fire at Chernobyl, and that it had been extinguished”. But thanks to a large antenna installed on his building, Kaschiev was able to receive Yugoslav television broadcasts. “Reports from Sweden and Finland quickly suggested that the incident was far more serious than what was being officially acknowledged. Western media aired satellite images from the United States showing the destroyed reactor, maps tracing the radioactive cloud, and reports that Yugoslavia had sent planes to evacuate its students from Kyiv.”
By the end of April, Kaschiev and his colleagues had understood that the cloud was moving towards Bulgaria. Between 1 and 2 May, radiation levels rose to 10 times the natural background, especially after rainfall. As the silence of public authorities persisted, panic spread privately: engineers warned relatives to take basic precautions. They were often met with disbelief. Subsequent analyses of food samples, including milk from Bulgarian farms, confirmed extreme contamination.
Analyses of food samples, including milk from Bulgarian farms, confirmed extreme contamination.
Archival documents now accessible show that the Bulgarian government closely monitored the evolution of the disaster and the extent of contamination in Europe and within Bulgaria. This involved analyzing foreign press coverage, intelligence reports, and daily radiation measurements across the country. For Vatsov, the Politburo of the Bulgarian Communist Party feared that revealing the true extent of contamination would cause panic and potentially spark political unrest and demonstrations, as had happened in Poland. “Beyond that, I can only describe it as a form of moral debility on the part of the ruling elites, who showed contempt for the rest of the population.”
Petko Kovachev, an environmental activist who was doing his compulsory military service in 1986, recalls that the army acted swiftly: “We suddenly stopped eating fresh food and were served canned goods in the mess hall. Outdoor activities were cancelled, and we were ordered to measure radiation levels around the base using Geiger counters.” However, these safety precautions didn’t come with greater clarity. “We were never told what was happening and were expected to follow orders without question. It was only years later that I fully grasped the scale of the disaster.”
The Cynicism of the Nomenklatura
The handling of the Chernobyl aftermath in Bulgaria exposed stark inequalities in access to information and health protection. At the top of the hierarchy stood the nomenklatura – high-ranking party officials, political police, administrators, and military officers. During the crisis, they had privileged access to meals and provisions distributed through the government-run Rila Hotel in central Sofia. The Politburo was supplied with deep-sourced mineral water and imported food, including lamb from Australia and vegetables from Egypt and Israel, to avoid radioactive contamination.
According to Vatsov, the upper echelon of this nomenklatura – around 300 people – was never endangered, as special measures were taken by agencies responsible for their security and well-being. “The military applied less stringent measures, but still ones that reduced exposure. The rest of the population was kept in complete ignorance.”
The upper echelon of this nomenklatura was never endangered, as special measures were taken by agencies responsible for their security and well-being.
Symbolic of the government’s cynicism was the decision to regularly hold the Labour Day parade on 1 May. Many children marched in Sofia despite the threat of radioactive rain. Numerous propaganda sports events were also held nationwide during that month, and “voluntary brigades”, mostly composed of 15- to 25-year-olds, performed their outdoor tasks such as agricultural or construction work. An estimated 365,000 young people were exposed in this way.
On 10 May, after a meeting at the Ministry of Energy in Sofia, Kaschiev visited his sister-in-law. Children were playing outside in front of the block, while the adults chatted casually. When he urged them to keep the children indoors and not let them play in the sandpit, his warning was dismissed. “They accused me of trying to sow panic,” he recalls. “Someone even told me I was probably a Western agent and threatened me to warn the authorities.”
Regardless of the measures taken, which were often insufficient, all the countries of the Eastern Bloc, including Czechoslovakia and Hungary, maintained the compulsory May Day parades. In Poland, too, May 1st celebrations took place as planned, with the government publicly denying any health risk. But at the same time, Polish authorities were distributing iodine and restricting milk sales. The swift distribution of iodine, which began on the afternoon of 29 April, is often cited as a model response to a radioactive emergency. It remains the largest preventive medical intervention ever carried out in such a short period: within three days, 18.5 million people, including adults and children, received iodine solution.
Scientists and Environmental Activism
Just after the fall of the regime, Kovachev learned more about the Chernobyl disaster and its consequences from an exhibition organised by Sofia University physicists. Already under communism, some of them were part of informal environmental networks that would later become Ecoglasnost, an organisation Kovachev joined as a student.
Ecoglasnost was founded in the spring of 1989, just months before the fall of communism. It was a civic movement focused on environmental protection that emerged from the political liberalization inspired by Soviet glasnost. In the autumn, it organised petitions and public demonstrations, including the 3 November rally in Sofia, widely regarded as one of the first open civic mobilizations against the communist regime. The movement soon expanded its demands to include civil liberties and democratic reforms. In December 1989, Ecoglasnost became the first officially recognized non-communist political organisation in Bulgaria and later played a key role in structuring the democratic opposition by joining the Union of Democratic Forces (a political party that united several organisations opposing the communist government). It also initiated the first inspections of the Kozloduy nuclear power plant.
The involvement of the scientific community in environmental struggles contributed to the regime’s weakening in its final years. It had initially manifested itself in Ruse, northern Bulgaria, where air pollution from a chemical plant across the border in Romania sparked widespread protests in 1987. From this movement emerged the Public Committee for the Protection of the Environment of Ruse, the first informal organisation tolerated under communism, which played a decisive role in early national mobilizations and the democratic transition.
Around the same time, the discovery of radioactive material in the form of “hot particles” in Bulgaria – evidence of the scale of the Chernobyl catastrophe – prompted several physicists to closely monitor the crisis and study its consequences. The Sofia University exhibition Kovachev visited in December 1989 was the result of that research and monitoring.
Similar movements also occurred in other countries of the socialist bloc, such as Hungary and Czechoslovakia. They combined the commitment of certain scientists with awareness of ecological and democratic issues.
Scientists documented contamination and exchanged information informally, while official communication remained limited.
As radiation levels rose in late April and early May 1986, Hungarian scientists and health professionals documented contamination and exchanged information informally, while official communication remained limited and reassuring. The widening gap between expert knowledge and public messaging created moral dissonance among professionals torn between scientific integrity and loyalty to the state. In this context, environmental concerns became a coded language, expressing demands for accountability and transparency. This fed into reformist networks that later shaped Hungary’s negotiated transition to democracy.
In former Czechoslovakia, the Chernobyl catastrophe also helped galvanize ecological movements that later became key actors in the 1989 Velvet Revolution. Although the regime was among the most repressive in the Eastern Bloc, it tolerated environmental activism more than overt political dissent, viewing concerns about pollution, water contamination, or landscape degradation as relatively harmless and difficult to censor.
The Second Wave of Contamination
With Bulgarian authorities failing to take action, cows, sheep, and goats continued grazing on contaminated pastures and consuming radioactive fodder until the spring of 1987. Dairy products from this food chain remained in circulation, leading to a “second wave” of contamination that is estimated to account for nearly 30 per cent of total exposure. This situation – unique in the history of the Chernobyl disaster – helps explain Bulgaria’s exceptionally high rates of thyroid cancer among very young children.
Retired physicist Liliana Prodanova, then working at the Institute of Solid State Physics, only found out about the seriousness of the situation in mid-May. “My husband was vice-rector of the Technical University of Sofia. I was myself specializing in silicon research, so we perfectly understood the implications of such contamination. We quietly took precautions, such as systematically washing food. We also removed contaminated soil around our countryside cottage. That year, we didn’t plant anything.”
Prodanova recalls that she and her colleagues were often asked by friends to measure the radioactivity of yogurt intended for children, using the instruments at the physics institute. “We did it discreetly, without seeking official authorization.”
The nomenklatura, by contrast, was fully aware of the risk. It tested the Bulgarian dairy products it consumed and imported the rest from abroad. Around the royal palace of Vratsa on the outskirts of Sofia, then occupied by party officials, pastures were mown in May to prevent contamination. The hay, however, was redistributed to livestock cooperatives supplying the capital, which went on to produce contaminated dairy products.
Kaschiev recalls that the physicists at the Kozloduy nuclear power plant used a specialised research laboratory to develop their own measuring instruments. They designed a device to assess thyroid radiation exposure. “Those who had not taken precautions in early May, especially people who were away on holiday at the time, were exposed to contamination levels up to 10,000 times higher than ours. At the beginning of May, I stocked up on as much cheese and powdered milk as I could. That also probably helped protect us during the second wave,” he says.
The Chernobyl Dissidents
According to Vatsov, there were no real dissidents in Bulgaria before the Chernobyl accident. “The conscience of having been deceived by the authorities and exposed to serious health risks shaped the political engagement of an entire generation, particularly within the scientific community.”
Kaschiev is a good example of this. Chernobyl shaped both his political involvement and his professional path. His anger at the regime’s moral and political failures led him to focus on nuclear safety. From the late 1980s onward, he shifted from reactor physics to risk assessment, first as a safety critic within the plant, then as a university lecturer and nuclear inspector. In 1997, he was appointed as head of Bulgaria’s national nuclear regulatory laboratory.
In other socialist countries, the Chernobyl disaster also became a spark for opposition to the regime. In Poland, it turned into a powerful anti-nuclear movement. Fears over the disaster quickly turned into opposition to the planned Żarnowiec nuclear power plant, sparking nationwide protests that drew in ecological groups, local activists, and dissidents such as Lech Wałęsa, who later became the country’s first democratically elected president. In a 1990 referendum held alongside local elections, more than 86 per cent of voters rejected the Żarnowiec project, leading the government to cancel it later that year. As political scientist Kacper Szulecki notes, these mobilizations both reflected and accelerated broader social and generational shifts, while further undermining Moscow’s legitimacy in Poland.
Although the disaster left a lasting mark on Bulgarian society, it did not result in a large-scale anti-nuclear movement. The Kozloduy plant, refurbished and still operating today, is widely regarded as a source of national pride and a guarantee of energy independence. The catastrophic handling of the Chernobyl disaster mainly exposed the indecency and cynicism of the communist regime, as well as the irrationality of its ideology.
The catastrophic handling of the Chernobyl disaster mainly exposed the indecency and cynicism of the communist regime, as well as the irrationality of its ideology.
In December 1991, after the fall of the regime, the Sofia Supreme Court convicted former Health Minister Lyubomir Shindarov and former Deputy Prime Minister Grigor Stoichkov of criminal negligence for deliberately misleading the public. After a lengthy appeal process, their sentences were reduced to two and three years in prison, respectively. They are the only senior officials of the Bulgarian regime to have been properly prosecuted and sentenced to prison terms for the handling of the Chernobyl disaster.
Nuclear physicist Atanas Krastanov, a young researcher in the 1980s who witnessed the disaster’s mismanagement by the authorities, believes that nuclear energy as such is not the problem. He emphasises that “the Chernobyl accident was primarily the result of human error” and notes that “it was not initially a nuclear explosion, but a thermal explosion caused by pressure buildup.” Today, Krastanov works as an expert at the Disaster, Accident and Crisis Prevention Center of Nadezdain Sofia. He recently co-authored a documentary film on the subject, due to be released this autumn in Bulgaria.
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What Future for Nuclear?
Environmental activist Petko Kovachev, affiliated with the NGO Za Zemiata and anti-nuclear networks, challenges this interpretation. “The human error argument is not valid,” he argues. “Human error lies at the root of most industrial and nuclear accidents. That does not mean nuclear energy is safe.” He adds that popular support for nuclear power in Bulgaria is driven mainly by concerns over energy independence and low electricity costs, rather than by scientific or ethical considerations.
Against this backdrop, construction of a new nuclear power plant in Belene, in northern Bulgaria, may yet move forward. Despite strong opposition from environmental groups and local populations, a national referendum in 2013 approved the project. After being abandoned and revived several times – primarily for geopolitical reasons, as the original project involved a Russian third-generation reactor – the project could now be carried out by France’s Framatome and the U.S.-based General Electric. A plan to sell the reactors already built in Belene to Ukraine (with the aim of replacing the Zaporizhzhia nuclear power plant currently under Russian control) has been abandoned. Bulgaria now considers the power plant as a potential source of electricity for future data centers.
In addition, two new reactors are planned at the Kozloduy site, to be built by Canadian companies. Commissioned in 1970, the plant now operates only its two most recent reactors, dating from 1988 and 1993; the older ones were shut down in the 2000s under pressure from the European Union, which made their closure a prerequisite for Bulgaria’s accession. Once described as one of the world’s most dangerous nuclear power plants, Kozloduy now meets all the safety requirements set by the International Atomic Energy Agency (IAEA). The site is also home to a nuclear waste disposal facility, which is expected to be operational by 2027. However, environmental activists regularly denounce the lack of transparency surrounding industrial decisions, damage, and accidents affecting the power station.
Georgi Kaschiev is deeply critical of the state of nuclear governance in Bulgaria. He describes the Belene nuclear project as a “financial catastrophe” and says it serves primarily as a vehicle for corruption. At Kozloduy, he points to worsening conditions: rising costs for spare parts and maintenance, declining energy output below international recommendations, and technical failures such as leaks in the steam generator of Unit 6. “The safety culture is clearly deteriorating,” he warns.
This article was first published in the Green European Journal. It was written as part of the Thematic Networks of PULSE, a European initiative to promote transnational journalistic cooperation. The Heinrich Böll Foundation is thankful for the opportunity to republish it.
