Chernobyl nuclear accident

The 1986 accident at the Chernobyl nuclear power plant drastically changed the lives of thousands of residents in northern Ukraine and southern Belarus. It also raised questions about the future of the plant itself; the ecological, human health, economic, and political repercussions of the incident; and the future of nuclear power programs worldwide.

THE EVENT: Explosion of a nuclear power reactor at the Chernobyl power plant in the Soviet Union

DATE: April 26, 1986

On April 26, 1986, nuclear power reactor number 4 exploded at the Chernobyl Nuclear Power Plant, located about 15 kilometers (9 miles) from the small town of Chernobyl in the republic of Ukraine. As the core of the reactor began to melt, an explosion occurred that blew the top off the reactor and sent a wide trail of radioactive material across large parts of what was then the Soviet Union as well as much of Eastern and Western Europe. More than 116,000 people were evacuated within a 30-kilometer (19-mile) radius, and more than two dozen people died due to acute radiation syndrome (also known as radiation sickness).

In addition to the political, social, and economic aftermath of the explosion, the consequences of human inability to prevent or contain widespread damage were evident in the environment in the years following the Chernobyl disaster. A major release of radioactive materials into the atmosphere occurred during the first ten days following the explosion. Radioactive plumes reached many European countries within a few days, increasing radiation levels to between ten and one hundred times normal levels. Over time, the contaminated lithosphere created a new biogeographical province characterized by irregular and complicated patterns of radioactivity in Belarus, Ukraine, and Russia, the countries most affected. In spite of some success in efforts to slow the flow of certain soluble radionuclides into the Black and Baltic seas, as well as into the Pripet, Dnieper, and Sozh Rivers (all of which contribute water to the Kyiv water reservoir), much contamination occurred that only the passage of time could resolve.

Contamination Effects

The effects of the radioactive contamination on vegetation have varied depending on the species. Damage to coniferous forests was more than ten times greater than that to oak forests and grass communities, and more than one hundred times greater than the damage to lichen communities. Ten years after the explosion, pine forests still had high levels of radionuclides in the uppermost layer of the forest floor, while birch forests had considerably lower levels. Large numbers of highly contaminated trees were felled, and restrictions were placed on cutting and using the wood in industry and for fuel. Likewise, the degrees of radiation damage and the doses absorbed varied among plant communities. In addition to killing or damaging plant life, the radiation disturbed the functioning of plant reproductive systems, resulting in sterility or decreases in both seed production and fertility. Other effects involved changes in plant chlorophyll, necessary for removing carbon dioxide from the air, and the process of decomposition.

Among animals, lower life-forms have been found to have higher radiosensitivity levels; that is, mammals are less sensitive to radioactivity than are birds, reptiles, and insects. The severity of damage also depends on whether it is external or internal. The impact of environmental contamination may be less severe for animals than for plants because of the ability of animals to move from place to place and make selective contact with the environment. Irradiation can have a wide range of effects among animal species, including death, reproductive disturbances, decrease in the viability of progeny, and abnormalities in development and morphology.

The contamination of aquatic ecosystems by Chernobyl radiation was considerable. The contamination of freshwater ecosystems has fallen with time, but continuing contamination has been evidenced by factors such as a transfer of radionuclides from bottom sediments and erosion of contaminated soil into water sources. Some restrictions have been placed on fishing in contaminated aquatic ecosystems.

The consequences of the Chernobyl accident for agriculture were severe. Drastic changes in land-use and farming practices became necessary as a result of contamination. As with other life-forms affected by radiation, the degree of contamination varies; in the case of agriculturally related contamination, damage depends on such things as the type of soil and the biological peculiarities of different plant species. As Ukraine produced 20 percent of the grain, 60 percent of the industrial sugar beets, 45 percent of the sunflower seeds, 25 percent of the potatoes, and about 33 percent of all the vegetables used in the former Soviet Union, the problem of soil contamination following the accident was serious. Furthermore, the problems extended beyond the borders of Ukraine: The contamination affected the reindeer herds of Scandinavia and sheep breeding in mountainous regions of the British Isles.

The scale of the contamination of the environment by the Chernobyl accident was so enormous that the task of protecting the population was not entirely successful. The long-term health effects of environmental contamination are caused only in part by external radiation. Scientists studying the problem believe that the majority of health problems in affected areas will be caused by the consumption of contaminated agricultural products, particularly dairy products.

By the beginning of the 2020s, debates in the scientific community continued over the impact of the Chernobyl nuclear disaster on wildlife and their populations in the exclusion zone. Studies in the area had been ongoing, particularly following 2016, the year in which the cesium-137 nuclides released during the accident were calculated to have reached their half-lives. While some noted that animal populations and biodiversity had increased since the disaster, seeming to indicate levels of adaptation and that the absence of human interaction outweighed the long-term effects of radiation, such findings were often disputed. In the mid-2020s, some studies of microscopic worms and wolves inhabiting the area drew interest in the potential for natural or evolutionary radiation resistance.

Chernobyl Today

Construction of the Chernobyl New Safe Confinement (NSC), which was designed to replace the previous steel and concrete sarcophagus that was constructed around the destroyed nuclear reactor in 1986, began in 2010; the structure was moved into place over the site in November 2016. After testing and other procedures, it began an extent of operations in 2019. The Chernobyl NSC is designed to prevent radioactive materials from leaking into the environment from the reactor complex for one hundred years. Twenty-five years after the Chernobyl accident, in 2011, concentrations of cesium-137 in food products produced in areas surrounding the Chernobyl nuclear power plant were generally below international standards for action. However, some areas in the region continued to suffer from radionuclide contamination, and radiation levels can vary widely. After an especially large forest fire, eventually contained, spread within the area of the restricted zone around Chernobyl in 2020, concerns had grown as inspection services reported a drastic increase in radiation levels close to the reactor site; however, it was also noted that the radiation spikes were not detected further out, including in cities such as Kyiv.

Three groups of people faced the highest exposure to radiation due to the Chernobyl accident: the clean-up crew, known as liquidators, who worked in the immediate vicinity of the reactor in the two years following the accident; the over 100,000 individuals who were living in and evacuated from the area surrounding the Chernobyl reactor in 1986; and the approximately 270,000 residents of strictly controlled zones (SCZs), areas with high levels of radioactive cesium. More than one hundred liquidators were diagnosed with acute radiation sickness; twenty-eight liquidators died in 1986 due to the effects of radiation exposure, and an additional nineteen died by 2005. In the long term, there was a significant increase in the incidence of thyroid cancer among residents of the area who were children and adolescents at the time of the accident, and, as of 2018, according to a study conducted by the UN Scientific Committee on the Effects of Atomic Radiation, an estimated five thousand cases of thyroid cancer registered between 1991 and 2015 had been attributed to radiation exposure due to the Chernobyl accident. Most of these thyroid cancer cases are due to the consumption of milk that was contaminated with iodine-131 in the weeks following the accident. A significantly increased risk of leukemia among the most highly exposed liquidators has also been reported. According to the World Health Organization, there may be up to four thousand additional cancer deaths among the liquidators, evacuees, and residents of the SCZs over their lifetime, representing a 3 to 4 percent increase over the normal incidence of cancers from all causes. Additional health effects related to the Chernobyl accident include an elevated risk of cataracts and cardiovascular disease. A 2005 study by the United Nations attributed fifty-six deaths to radiation exposure from Chernobyl.

The Chernobyl accident galvanized the antinuclear movement and prompted significant changes to reactor designs, nuclear regulations, and emergency response measures worldwide. Public access to the Chernobyl Exclusion Zone, which covers more than one thousand square miles surrounding the Chernobyl Nuclear Power Plant, continued to be restricted due to the elevated levels of radiation detected there, although the site remained a place of interest to scientists and, increasingly, to tourists.

In 2021, despite the existence of the NSC, concerns were heightened once more upon scientific reports detailing the detection of increased neutron amounts and smoldering fission reactions within a specific, inaccessible area of the plant. Experts continued to monitor the situation to determine whether any action needed to be taken depending on the level of threat, including of future accidents, such smoldering reactions posed.

Shortly after Russia launched a war through an invasion of Ukraine in February 2022, it was reported that Russian soldiers had taken over the site of the station within the exclusion zone and had set up nearby camps and fortifications. Though the troops had moved out of the area by early April, experts noted that their presence and the use of military vehicles such as tanks had resulted in an increase in the site's detected radiation levels over the period of occupation. According to reports, radioactive dust had been disturbed and the soldiers were most likely exposed to radiation.

In Popular Culture

Even years after the accident at Chernobyl, authors and screenwriters returned to the disaster to explore its lasting physical and emotional impact both locally and worldwide. The Nobel Prize–winning book Voices from Chernobyl: The Oral History of a Nuclear Disaster, by Svetlana Alexievich, was first published in Russian as Tchernobylskaia molitva in 1997 before being translated into English in 2005, and in 2019, Adam Higginbotham published Midnight in Chernobyl: The Untold Story of the World's Greatest Nuclear Disaster. Also in 2019, HBO began airing the miniseries Chernobyl, which was not only critically acclaimed but became a ratings hit for the premium cable network. By the beginning of the 2020s, reports indicated that such renewed popular attention had only increased the number of people traveling to visit the site and the surrounding areas, leading to further debates about the ethical nature of allowing tourists near the site. The year 2022 saw the release of HBO's documentary Chernobyl: The Lost Tapes.

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