chernobyl disaster 1986 case study

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By: Editors

Updated: April 23, 2021 | Original: April 24, 2018


Chernobyl is a nuclear power plant in Ukraine that was the site of a disastrous nuclear accident on April 26, 1986. A routine test at the power plant went horribly wrong, and two massive explosions blew the 1,000-ton roof off one of the plant’s reactors, releasing 400 times more radiation than the atomic bomb dropped on Hiroshima. The worst nuclear disaster in history killed two workers in the explosions and, within months, at least 28 more would be dead by acute radiation exposure. Eventually, thousands of people would show signs of health effects—including cancer—from the fallout.

The Chernobyl disaster not only stoked fears over the dangers of nuclear power, it also exposed the Soviet government’s lack of openness to the Soviet people and the international community. The meltdown and its aftermath drained the Soviet Union of billions in clean-up costs, led to the loss of a primary energy source and dealt a serious blow to national pride.

Then-Soviet leader Mikhail Gorbachev would later say that he thought the Chernobyl meltdown, “even more than my launch of  perestroika , was perhaps the real cause of the collapse of the Soviet Union five years later.”

chernobyl disaster 1986 case study

Where Is Chernobyl?

Chernobyl is located in northern Ukraine, about 80 miles north of Kiev. A small town, Pripyat, was constructed a few miles from the site of the nuclear plant to accommodate workers and their families.

Construction of the Chernobyl power plant began in 1977, when the country was still part of the Soviet Union. By 1983, four reactors had been completed, and the addition of two more reactors was planned in subsequent years.

What Happened at Chernobyl?

A routine exercise to test whether an emergency water cooling system would work during a power loss started at 1:23 a.m. on April 26.

Within seconds, an uncontrolled reaction caused pressure to build up in Reactor No. 4 in the form of steam. The steam blasted the roof off the reactor, releasing plumes of radiation and chunks of burning, radioactive debris.

About two to three seconds later, a second explosion hurled out additional fuel. A fire started at the roof of Reactor No. 3, risking a breach at that facility. Automatic safety systems that would normally have kicked into action did not because they had been shut down prior to the test.

READ MORE:  Chernobyl Disaster: The Meltdown by the Minute

chernobyl disaster 1986 case study

Firefighters arrived at the scene within minutes and began to fight the blaze without gear to protect them from radiation. Many of them would soon number among the 28 killed by acute radiation exposure.

Eyewitness accounts of the firefighters who had helped battle the fires described the radiation as “tasting like metal,” and feeling pain like pins and needles on their faces, according to the CBC documentary series, Witness . Days later, many of those firefighters would be dead.

It wasn’t until 5 a.m. the following day that Reactor No. 3 was shut down. Some 24 hours later, Reactors No. 1 and 2 were also shut down.

By the afternoon of April 26, the Soviet government had mobilized troops to help fight the blaze. Some were dropped at the rooftop of the reactor to furiously shovel debris off the facility and spray water on the exposed reactor to keep it cool.

The workers were picked up within seconds to minimize their radiation exposure. It would take nearly two weeks to extinguish all the fires using sand, lead and nitrogen.

chernobyl disaster 1986 case study

Pripyat Evacuated

Meanwhile, life went on as usual for almost a day in the neighboring town of Pripyat. Aside from the sight of trucks cleaning the streets with foam, there were initially few signs of the disaster unfolding just miles away.

It wasn’t until the next day, April 27, when the government began evacuations of Pripyat’s 50,000 residents. Residents were told they would be away for just a few days, so they took very little with them. Most would never return to their homes.

Soviet Secrecy

It took days for Soviet leadership to inform the international community that the disaster had occurred. The Soviet government made no official statement about the global-scale accident until Swedish leaders demanded an explanation when operators of a nuclear power plant in Stockholm registered unusually high radiation levels near their plant.

Finally, on April 28, the Kremlin reported that there had been an accident at Chernobyl and that authorities were handling it. The statement was followed by a state broadcast detailing the U.S. nuclear accident at Three Mile Island and other nuclear incidents in western countries.

Three days later, Soviet May Day parades to celebrate workers went ahead as usual in Moscow, Kiev and Belarus’ capital Minsk—even as hazardous amounts of radiation were still streaming from the wrecked power plant.

Most people, even within the Ukraine, were still unaware of the accident, the deaths, and the hasty evacuations of Pripyat.

READ MORE: The Chernobyl Cover-Up: How Officials Botched Evacuating an Irradiated City

Chernobyl Disaster Spewed Radiation

The damaged plant released a large quantity of radioactive substances, including iodine-131, cesium-137, plutonium and strontium-90, into the air for over a period of 10 days.

The radioactive cloud was deposited nearby as dust and debris, but was also carried by wind over the Ukraine, Belarus, Russia, Scandinavia and other parts of Europe.

In an attempt to contain the fallout, on May 14, Soviet leader Mikhail Gorbachev ordered the dispatch of hundreds of thousands of people, including firefighters, military reservists and miners, to the site to aid in clean-up. The corps worked steadily, often with inadequate protective gear, through 1989 to clear debris and contain the disaster.

chernobyl disaster 1986 case study

Chernobyl Sarcophagus

Over a hurried construction period of 206 days, crews erected a steel and cement sarcophagus to entomb the damaged reactor and contain any further release of radiation.

As former liquidator, Yaroslav Melnik, told the BBC in January 2017, “We worked in three shifts, but only for five to seven minutes at a time because of the danger. After finishing, we’d throw our clothes in the garbage.”

Starting in 2010, an international consortium organized the building of a bigger, more secure sarcophagus for the site. The 35,000-ton New Safe Confinement was built on tracks and then slid over the damaged reactor and existing sarcophagus in November 2016.

After the installation of the new structure, radiation near the plant dropped to just one-tenth of previous levels, according to official figures. The structure was designed to contain the radioactive debris for 100 years.

chernobyl disaster 1986 case study

Chernobyl Elephant’s Foot

Deep within the basement of Reactor 4 lies the Chernobyl Elephant’s Foot, a huge mass of melted concrete, sand and highly radioactive nuclear fuel.

The mass was named for its wrinkled appearance, which reminded some observers of the wrinkled skin of an elephant’s leg and foot.

In the 1980s, the Elephant’s Foot gave off an estimated 10,000 roentgens of radiation each hour, enough to kill a person three feet away in less than two minutes. By 2001, that rate had dropped to roughly 800 roentgens per hour.

How Many People Died in Chernobyl?

Ukraine’s government declared in 1995 that 125,000 people had died from the effects of Chernobyl radiation. A 2005 report from the United Nations Chernobyl Forum estimated that while fewer than 50 people were killed in the months following the accident, up to 9,000 people could eventually die from excess cancer deaths linked to radiation exposure from Chernobyl.

As of 2005, according to the Union of Concerned Scientists , some 6,000 thyroid cancers and 15 thyroid cancer deaths had been attributed to Chernobyl.

Health effects from the Chernobyl disaster remain unclear, apart from the initial 30 people the Soviet government confirmed killed from the explosions and acute radiation exposure. No official government studies were conducted following the explosion to assess its effects on workers, the liquidators and nearby populations.

A 2011 study by the U.S. National Institutes of Health concluded that exposure to radioactive iodine-131 from Chernobyl fallout was likely responsible for thyroid cancers that were still being reported among people who were children or adolescents at the time of the accident.

chernobyl disaster 1986 case study

Chernobyl Exclusion Zone

Apart from the ever-unfolding human toll from the disaster, the Chernobyl accident also left behind a huge area of radiation-tainted land.

A 770-mile-wide Chernobyl Exclusion Zone around the site isn’t considered safe for human habitation and can’t be used for logging or agriculture due to contaminated plants and soil. By 2017, however, entrepreneurs found a new use for the territory.

In December 2017, a Ukrainian-German company, Solar Chernobyl, announced construction of a massive solar power plant in the abandoned territory. The one-megawatt power plant, built just a few hundred feet from the damaged Reactor 4, was fitted with 3,800 photovoltaic panels. The Ukrainian government said that a collection of companies planned to eventually develop up to 99 more megawatts of solar power at the site.

That’s a lot of power, but still not close to the former output of the ruined nuclear power plant. At the time of the accident Chernobyl’s four reactors could generate 1,000 megawatts each .

Chernobyl Animals Thrive

Meanwhile, wildlife, including boars, wolves, beavers and bison, showed signs of flourishing at the Chernobyl site, according to an April 2016 study .

The researchers pointed out that while radiation exposure couldn’t be good for the animals, the benefits of the absence of humans outweighed radiation risk.

Chernobyl Today

Humans, on the other hand, aren’t expected to repopulate the area any time soon. Ukrainian authorities have said it will not be safe for people to live in the Chernobyl Exclusion Zone for more than 24,000 years.

Today tourists can visit the site, which appears frozen in time, apart from signs of looting, natural weathering and the encroachment of nature.

“Chernobyl: The True Scale of the Accident,” September 5, 2005, World Health Organization . Chernobyl Accident 1986, updated November 2016, World Nuclear Association “Health Effects of the Chernobyl Accident: An Overview,” April 2006, World Health Organization . “Chernobyl’s Legacy 30 Years On,” by Tom Burridge, April 26, 2016, BBC News “Higher Cancer Risk Continues After Chernobyl,” March 17, 2011, National Institutes of Health . “How Many Cancer Deaths Did Chernobyl Really Cause?” by Lisbeth Gronlund, Union of Concerned Scientists . “Animals Rule Chernobyl Three Decades After Nuclear Disaster,” by John Wendle, April 18, 2016, National Geographic . “A Nuclear Disaster That Brought Down an Empire,” April 26, 2016, The Economist . “World’s Largest Moveable Steel Structure Shelters Sarcophagus at Chernobyl,” April 27, 2017, PhysOrg/Pacific Northwest National Laboratory . “Pictures: ‘Liquidators’ Endured Chernobyl 25 Years Ago,” by Marianne Lavelle, April 27, 2011, National Geographic . “Chernobyl: Timeline of a Nuclear Nightmare,” by Kim Hjelmgaard, USA Today . “A Vast New Tomb for the Most Dangerous Disaster Site in the World,” by Christian Borys, January 3, 2017, BBC Future Now . “The Lessons of Chernobyl May Be Different Than We Thought,” by Ryan Faith, April 26, 2016, Vice News . “25 Years After Chernobyl, We Don’t Know How Many Died,” by Roger Highfield, April 21, 2011, New Scientist . “Chernobyl’s Transformation Into a Massive Solar Plant Is Almost Complete,” by David Nield, January 13, 2018, Science Alert . “The Famous Photo of Chernobyl’s Most Dangerous Radioactive Material Was a Selfie.” January 24, 2016, Atlas Obscura .

chernobyl disaster 1986 case study

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Engineering Ethics - Chernobyl’s Case Study

The Chernobyl disaster was nuclear accident that occurred at Chernobyl Nuclear Power Plant on April 26, 1986. A nuclear meltdown in one of the reactors caused a fire that sent a plume of radioactive fallout that eventually spread all over Europe.

Chernobyl nuclear reactor plant, built at the banks of Pripyat river of Ukraine , had four reactors, each capable of producing 1,000 MWs of electric power.

On the evening of April 25 th 1986 , a group of engineers, planned an electrical engineering experiment on the Number 4 Reactor. With their little knowledge on Nuclear physics, they thought of experimenting how long turbines would spin and supply power to the main circulating pumps following a loss of main electrical power supply.

Following is an image of the Chernobyl nuclear power plant.

chernobyl disaster 1986 case study

What Led to the Disaster?

Let us now see what led to the disaster.

The reactor unit 4 was to be shut down for routine maintenance on 25 April 1986. But, it was decided to take advantage of this shutdown to determine whether, in the event of a loss of station power, the slowing turbine could provide enough electrical power to operate the main core cooling water circulating pumps, until the diesel emergency power supply became operative. The aim of this test was to determine whether cooling of the core could continue in the event of a loss of power .

Due to the misconception that this experiment belongs to the non-nuclear part of the power plant, it was carried out without a proper exchange of information between the testing department and the safety department. Hence the test started with inadequate safety precautions and the operating personnel were not alerted to the nuclear safety implications of the electrical test and its potential danger.

The Experiment

According to the test planned, the Emergency Core Cooling System (ECCS) of the reactor, which provides water for cooling the reactor core, was shut down deliberately.

For the test to be conducted, the reactor has to be stabilized at about 700-1000 MW prior to shut down, but it fell down to 5000 MW due to some operational phenomenon. Later, the operator working in the night shift committed an error, by inserting the reactor control rods so far. This caused the reactor to go into a near-shutdown state, dropping the power output to around 30 MW.

Since this low power was not sufficient to make the test and will make the reactor unstable, it was decided to restore the power by extracting the control rods, which made the power stabilize at 200 MW. This was actually a violation to safety law, due to the positive void co-efficiency of the reactor. Positive void coefficient is the increasing number of reactivity in a reactor that changes into steam. The test was decided to be carried out at this power level.

Actually, the reactors were highly unstable at the low power level, primarily owing to the control rod design and the positive void coefficient factors that accelerated nuclear chain reaction and the power output if the reactors lost cooling water.

The following image shows the reactor 4 where the experiment was conducted. This picture was taken after everything was restored.

Emergency Core Cooling System

At 1:23, on April 26 th 1986, the engineers continued with their experiment and shut down the turbine engine to see if its inertial spinning would power the reactor’s water pumps. In fact, it did not adequately power the water pumps and without the cooling water the power level in the reactor got surged.

The water pumps started pumping water at a slower rate and they together with the entry to the core of slightly warmer feed water, may have caused boiling (void formation) at the bottom of the core. This, along with xenon burn out, might have increased the power level at the core. The power level was then increased to 530 MW and continued to rise. The fuel elements were ruptured and lead to steam generation, which increased the positive void coefficient resulting in high power output.

The high power output alarmed the engineers who tried to insert all the 200 control rods, which is a conventional procedure done in order to control the core temperature. But these rods got blocked half the way, because of their graphite tip design. So, before the control rods with their five-meter absorbent material, could penetrate the core, 200 graphite tips simultaneously entered the core which facilitated the reaction to increase, causing an explosion that blew off the 1,000-ton heavy steel and concrete lid of the reactor, consequently jamming the control rods, which were halfway down the reactor. As the channel pipes begin to rupture, mass steam generation occurred as a result of depressurization of the reactor cooling circuit.

As a result, two explosions were reported. The first one was the initial steam explosion. Eventually, after two to three seconds, a second explosion took place, which could be possibly from the build-up of hydrogen due to zirconium-steam reactions.

All the materials such as Fuel, Moderator and Structural materials were ejected, starting a number of fires and the destroyed core was exposed to the atmosphere. In the explosion and ensuing fire, more than 50 tons of radioactive material were released into the atmosphere, where it was carried by air currents. This was 400 times to the amount of radioactive materials released at the time of Hiroshima bombing.

Fatal Effects of the Disaster

The Chernobyl Nuclear Power Plant disaster in Ukraine, is the only accident in the history of commercial nuclear power to cause fatalities from radiation.

There were many fatal effects due to the radiation released. A few of the effects are listed below −

Two workers had died. One immediately got burnt to ashes after the accident, while the other was declared dead at the hospital within few hours of admission.

28 emergency workers and staff died within 4 months of the accident due to the thermal burns and the radiation effect on their bodies.

This accident created 7,000 cases of thyroid cancer.

Acute radiation syndrome (ARS) was diagnosed in 237 people, who were on-site and involved in cleaning up

The land, air and ground water were all contaminated to a great extent.

The direct and indirect exposure to radiation led to many severe health problems such as Downs Syndrome, Chromosomal Aberrations, Mutations, Leukemia, Thyroid Cancer and Congenital Malfunctions, etc.

A number of plants and animal faced destruction as after-effect.

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Lessons of Chernobyl

chernobyl disaster 1986 case study

Published June 7, 2019

National Review Online

By Mona Charen

O n the morning of April 28, 1986, an employee of the Forsmark nuclear power plant an hour north of Stockholm was returning from a restroom break when his shoes set off the radiation alarm. Soon klaxons were sounding everywhere. Technicians scoured the plant. No leak. After performing chemical and other analysis, they determined that the radiation wasn’t coming from Forsmark. It wasn’t even coming from Sweden. It was fallout from Chernobyl, 700 miles away.

The excellent HBO series  Chernobyl  offers an overdue glimpse into the leviathan of lies that was the Soviet system. Some have nitpicked that a composite character was created or that the trial scene at the end wasn’t historically accurate, but these exercises in poetic license don’t detract from the overall impact, and are, in any case, openly acknowledged, not concealed.

Lies were the Soviet regime’s native tongue. From the annual “record” grain harvests to the  Katyn Forest  massacre; from the Gulag to  Lysenkoism  to the shootdown of KAL007 to the  Holomodor ; the system was a black hole from which truth could not escape.

When Sweden demanded an explanation of the radiation, the Soviets denied that anything was amiss. Days later, when other European governments were detecting fallout and when U.S. satellites had photographed Chernobyl’s smoldering roof, the official news agency grudgingly acknowledged that an accident had killed “two people” but that “the situation had now been stabilized and [is] under control.” A later (post-Soviet) Ukrainian parliamentary report described such reassurances as “disinformation” of “almost Mephistophelean proportions.” The reactor was open and spewing radioactivity. Scores were already dead, more were dying an agonizing death from acute radiation poisoning, and thousands were inhaling and eating and drinking the radioactive isotopes that would cause miscarriages, stillbirths, and thyroid and other cancers. As  The   Economist summarized, “Chernobyl led to thousands of deaths, including the Soviet Union.”

While Communist Party officials were bundling their families out of Ukraine, the people were kept in the dark. Doses of potassium iodide, if administered within ten days, can protect against thyroid cancer. But there was no program to distribute the medicine. The Ukrainian surgeon general asked that people be warned to at least stay inside, wash their vegetables, avoid drinking milk, and take other precautions, but the Central Committee demanded that May Day parades proceed as usual, along with outdoor weddings and bike races. On May 1 in Kiev, as invisible fallout rained down, children in shirtsleeves marched past reviewing stands that usually held Soviet officials. They stood empty.

The Soviets kept their eye on the ball — deceit. Phone lines were cut to Chernobyl to prevent unauthorized truth from escaping, while the official machinery of propaganda revved up. As Robert McConnell reported  in  National Review , a Soviet television “news” report showed a photo of the damaged reactor and explained, “As you can see for yourself, there is no enormous destruction that some Western agencies are writing about, or no great fires, as there are no thousands of dead . . .” The air and water in Kiev were safe, the Soviet government said. For good measure, the TASS  news agency added that the U.S. had experienced “2,300 nuclear accidents and breakdowns in 1979 alone.”

While the world reeled from reports of a massive nuclear plume dropping poison whichever way the wind blew; while frantic but secret efforts were underway in Soviet Ukraine to stanch the flow; and while 220,000 people had to flee their homes (leaving livestock and pets behind as the HBO series dramatizes in sad detail), the official statements from the Kremlin were as noxious as the site itself. Denouncing a “Poisoned Cloud of Anti-Sovietism,”  Moscow News  pointed the finger at a “premeditated and well-orchestrated campaign” to “cover up criminal acts of militarism by the USA and NATO against peace and security.”

The catastrophe was a direct result of official lies. The Chernobyl reactor, like others of Soviet design, lacked several key safety features — but operators were kept in ignorance.

It is hard to know just how many people were killed outright or suffered later cancers and other pathologies because of the accident. The Soviet state directed that only the most severe cases of radiation sickness be noted in patients’ records. Estimates of deaths vary from several thousand to hundreds of thousands. As tragic as they were, those deaths were a tiny fraction of the millions starved, shot, and worked to death by the Soviet Union.

It was among the most soul-crushing of regimes in human history and lies were at the core of its corruption. The Soviet Union is gone, but deceit lives on. The Chernobyl  series is a timely reminder and a metaphor: Lying, when it becomes a way of life, is radioactive.

© 2019

Mona Charen is a senior fellow at the Ethics and Public Policy Center.

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Thirty-Five Years Later, a First Responder at the Chernobyl Disaster Looks Back

In her new book, Alla Shapiro shares her experience of one of the worst nuclear disasters in history

Jennifer Nalewicki

Travel Correspondent


April 26, 1986, started off like any other day for Alla Shapiro. The pediatrician, then 32 years old, was at work in the Pediatric Hematology Unit at the Children’s Hospital in Kiev, Ukraine. But everything changed when she learned that an explosion had occurred 80 miles north at the Chernobyl Nuclear Power Plant , just outside the city of Pripyat. In the hours that followed, hundreds of children arrived at the hospital by bus seeking treatment.

As a front-line worker, it was the first time that Shapiro and her colleagues were faced with treating patients during a disaster of Chernobyl's magnitude. Unfortunately, the Soviet government didn’t have any nuclear disaster protocols in place, and basic supplies were severely limited, leaving medical professionals to improvise and adapt. In the days and weeks that followed, Shapiro discovered that the government was misleading the public about its handling of the explosion, which was caused by a flawed reactor design, according to the World Nuclear Association .

The explosion occurred at 1:23 a.m. during a routine maintenance check of the plant's electrical system, when operators went against safety protocols and shut down parts of the control system that were necessary to run the plant safely. The result was an unexpected sudden surge in power due to excess steam building up in one of the reactors. The accident killed two plant workers immediately, but soon dozens more would perish from acute radiation sickness , including emergency workers and firefighters who were sent to the scene. Over the years, thousands of people would succumb to radiation contamination from the explosion, with the number of total deaths unknown since many people died years and decades after the fact. Cancer, particularly thyroid cancer , would become a common link among survivors, including Shapiro, who, now in her late 60s, is a cancer survivor herself. A pproximately 20,000 cases of thyroid cancer were registered from 1991 to 2015 in regions affected by the Chernobyl accident, according to a report published by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The high numbers are due to the fallout from the explosion, with winds carrying toxic particles as far away as Switzerland .

Preview thumbnail for 'Doctor on Call: Chernobyl Responder, Jewish Refugee, Radiation Expert

Doctor on Call: Chernobyl Responder, Jewish Refugee, Radiation Expert

Dr. Alla Shapiro was a first physician-responder to the worst nuclear disaster in history: the explosion at the Chernobyl Nuclear Power Station in Ukraine on April 26, 1986. Information about the explosion was withheld from first responders, who were not given basic supplies, detailed instructions, or protective clothing. Amid an eerie and pervasive silence, Dr. Shapiro treated traumatized children as she tried to protect her family.

On the tragedy’s 35th anniversary, Shapiro shares her story from the frontlines of Chernobyl in a new book called Doctor on Call: Chernobyl Responder, Jewish Refugee, Radiation Expert . In her memoir, Shapiro discusses not only the disaster, but also her experience immigrating to the United States with her extended family and her work as a leading expert at the U.S. Food and Drug Administration in developing medical countermeasures against radiation exposure. Her work is a testament to the importance of preparedness, especially in the face of adversity. Even now in retirement, Shapiro continues to work tirelessly in strengthening the preparedness of the United States against nuclear disaster. She's currently a consultant and an advisory board member for Meabco A/S, an international pharmaceutical company, that's developing a novel drug that could potentially protect humans from harmful doses of radiation. She's also conducting webinars for scientists and medical care providers who are interested in the health effects of radiation on humans.

Shapiro spoke with Smithsonian about her personal experience during one of the worst nuclear disasters in history, the Soviet government’s failure to act swiftly and transparently during the catastrophe, and her thoughts on the handling of the Covid-19 pandemic today.

book cover photo

What was going through your head as hundreds of children arrived at your hospital for treatment after the Chernobyl explosion?

I really didn’t have time to get scared or to get prepared. We saw the children arriving in a panic and in tears. It was a stressful event, but you have to act and do what you have to do. The negative thing was that we didn’t have any instruction, knowledge or training in radiation, so we exercised our [medical] background and did what we could. We also didn't have enough supplies and proper protective clothing to wear during examinations.

Since a similar disaster was never recorded in medical history books, and there were no guidelines in place for how to handle the situation, you had to innovate. Can you give an example of how you improvised?

We tried to comfort the children. It was only much later that we learned the psychological impact [of the disaster]. We told them funny stories and hugged them, which worked quite well. And then we looked at what we were facing—if children were coughing, at first we didn’t know why. In pediatrics, if a patient has a cough, most likely a fever will follow, but not in this case. We soon realized that the cough wasn’t related to any virus or infection. It was because the children were lacking oxygen, and their lungs were plugged with dust that possibly contained radiation particles. Many of the children waited outside for hours for the buses to arrive to bring them to the hospital. There were a lot of mistakes made [in the aftermath of the disaster], but one of the biggest was the lack of knowledge and understanding, [which resulted in] children being left outside to breathe this radioactive air. So, we started giving them oxygen. Since we didn’t have enough [individual oxygen tanks] for everyone, we made tents out of bed sheets and pumped oxygen in and had the children sit inside the tents.

Chernobyl Nuclear Power Plant

The Soviet government withheld information pertaining to the explosion and its aftermath, and even spread rumors about the situation. How did this affect you?

It was very hard psychologically, especially knowing that some of the information being spread came from either government officials or through rumors. Lots of people, physicians in particular, have colleagues in different locations [that were sharing information with one another]. A close friend of mine was called into work on a Saturday, which was unusual for him. He was handed a dosimeter, the device used to measure [ionizing] radiation, and used it to measure the levels in tap water. He called me and told me not to use the tap water, not even to brush my teeth. It was nothing official, since he wasn’t allowed to tell anyone about his findings. I immediately shared this information with friends and colleagues. This is how information spreads despite all the warnings given [by the government] if you tell the truth. It was a huge risk for him to do what he did; he could’ve lost his job.

You often faced anti-Semitism as a Jewish doctor, which ultimately led to you immigrating with your family to the United States. What was that transition like coming here?

It wasn’t difficult for me, because I was by default so fond of [the United States]; I wanted to get here so badly. Plus, our family got an extremely warm welcome from the Jewish community when we arrived in Washington, D.C. We made friends in a couple of weeks, and quite a few of them are still some of our best friends. The welcoming we received took some fears off my mind, although not having a job and not having the credentials that would allow me [to practice medicine here], plus taking care of a little girl and my elderly grandmother, all contributed to my anxiety and uncertainty. Not every family had this kind of welcome. Some [refugee] families ended up in the far west where locals weren’t so familiar with immigrants and how to accept them and even if they should accept them. There was a fear that they would take their jobs. However, we were blessed, and we never wanted to leave Washington, D.C.; I considered it home from day one.

old photo

As a medical professional, how did your experience in Chernobyl prepare you for your work with the FDA developing disaster readiness protocols?

This experience taught me a lot. The main point is that people—not just physicians, but the general public—need knowledge of what’s happening. Unfortunately, in [the United States], physicians don’t have good and proper training in radiation. Without knowledge in this field, people can’t do anything, but fortunately we do have experts in the area of radiation. When I worked with the FDA, I had meetings with the Departments of Defense and Health and Human Services on how to prepare our country in case of a nuclear disaster. There are guidelines and [mock explosion] exercises that take place every other year that pretend that a nuclear explosion occurs in a major city. What I witnessed [at Chernobyl] helped me realize that strong communication between the government and the public and doctors is necessary, otherwise it can cause bad outcomes.

You compare the U.S government’s lack of preparedness during the Covid-19 pandemic to the Soviet Union’s mishandling of the Chernobyl explosion. What do think can be learned from both of these two global tragedies?

We need to analyze very critically what happened and why. Each disaster, regardless of whether it’s nuclear or a viral pandemic, has lots of things in common, and we need to be aware of this. There needs to be strong communication not only within the country, but also amongst international communities. So much depends on our preparedness, and so many deaths could’ve been avoided at Chernobyl. And the same with Covid-19. The former Soviet Union didn’t know how to prepare for such a disaster. The United States did know how to prepare, but failed to do it.

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people in protective clothing using devices to measure for radiation

The cleanup of the area surrounding the Chernobyl nuclear disaster is expected to continue for decades, while parts may remain uninhabitable for thousands of years.

The Chernobyl disaster: What happened, and the long-term impacts

The accident at a nuclear power plant in Ukraine shocked the world, permanently altered a region, and leaves many questions unanswered.

On April 25 and 26, 1986, the worst nuclear accident in history unfolded in what is now northern Ukraine as a reactor at a nuclear power plant exploded and burned. Shrouded in secrecy, the incident was a watershed moment in both the Cold War and the history of nuclear power . More than 30 years on, scientists estimate the zone around the former plant will not be habitable for up to 20,000 years .

The disaster took place near the city of Chernobyl in the former USSR, which invested heavily in nuclear power after World War II. Starting in 1977, Soviet scientists installed four RBMK nuclear reactors at the power plant, which is located just south of what is now Ukraine’s border with Belarus.

a nuclear reactor

A few months after reactor 4 of the Chernobyl nuclear power plant went up in toxic flames in 1986, it was encased in a concrete and steel "sarcophagus" to contain the radioactive material inside. That aging structure, seen here, was covered with a larger, newer containment housing in 2016.

On April 25, 1986, routine maintenance was scheduled at V.I. Lenin Nuclear Power Station’s fourth reactor, and workers planned to use the downtime to test whether the reactor could still be cooled if the plant lost power. During the test, however, workers violated safety protocols and power surged inside the plant. Despite attempts to shut down the reactor entirely, another power surge caused a chain reaction of explosions inside. Finally, the nuclear core itself was exposed, spewing radioactive material into the atmosphere.

Firefighters attempted to put out a series of blazes at the plant, and eventually helicopters dumped sand and other materials in an attempt to squelch the fires and contain the contamination. Despite the death of two people in the explosions, the hospitalization of workers and firefighters, and the danger from fallout and fire, no one in the surrounding areas—including the nearby city of Pripyat , which was built in the 1970s to house workers at the plant—was evacuated until about 36 hours after the disaster began.

Publicizing a nuclear accident was considered a significant political risk, but by then it was too late: The meltdown had already spread radiation as far as Sweden, where officials at another nuclear plant began to ask about what was happening in the USSR. After first denying any accident, the Soviets finally made a brief announcement on April 28.

a boy at a medical exam

A child who was only one-year old at the time of the Chernobyl disaster undergoes an ultrasound test to see if there are any long-term effects of possible radiation exposure.

Historic disaster

Soon, the world realized that it was witnessing a historic event. Up to 30 percent of Chernobyl’s 190 metric tons of uranium was now in the atmosphere, and the Soviet Union eventually evacuated 335,000 people, establishing a 19-mile-wide “exclusion zone” around the reactor.

At least 28 people initially died as a result of the accident, while more than 100 were injured. The United Nations Scientific Committee on the Effects of Atomic Radiation has reported that more than 6,000 children and adolescents developed thyroid cancer after being exposed to radiation from the incident, although some experts have challenged that claim .

International researchers have predicted that ultimately, around 4,000 people exposed to high levels of radiation could succumb to radiation-related cancer, while about 5,000 people exposed to lower levels of radiation may suffer the same fate. Yet the full consequences of the accident, including impacts on mental health and even subsequent generations, remain highly debated and under study.

What remains of the reactor is now inside a massive steel containment structure deployed in late 2016. Containment efforts and monitoring continue and cleanup is expected to last until at least 2065.

An aerial picture of buildings

The city of Pripyat was built to house workers of the nuclear power plant in the 1970s. It has been an abandoned ghost town since the accident, and is now used as a laboratory to study fallout patterns.

Long-term impacts

The impact of the disaster on the surrounding forest and wildlife also remains an area of active research. In the immediate aftermath of the accident, an area of about four square miles became known as the “Red Forest” because so many trees turned reddish-brown and died after absorbing high levels of radiation.

Today, the exclusion zone is eerily quiet, yet full of life. Though many trees have regrown, scientists have found evidence of elevated levels of cataracts and albinism, and lower rates of beneficial bacteria, among some wildlife species in the area in recent years . Yet, due to the exclusion of human activity around the shuttered power plant, the numbers of some wildlife, from lynxes to elk, have increased . In 2015, scientists estimated there were seven times more wolves in the exclusion zone than in nearby comparable reserves, thanks to humans’ absence.

The Chernobyl disaster had other fallout: The economic and political toll hastened the end of the USSR and fueled a global anti-nuclear movement. The disaster has been estimated to cost some $235 billion in damages . What is now Belarus, which saw 23 percent of its territory contaminated by the accident, lost about a fifth of its agricultural land. At the height of disaster response efforts, in 1991, Belarus spent 22 percent of its total budget dealing with Chernobyl.

Today, Chernobyl beckons to tourists who are intrigued by its history and its danger. But though Chernobyl symbolizes the potential devastation of nuclear power, Russia never quite moved beyond its legacy—or its technology. As of 2019, there are still 11 operational RBMK reactors in Russia.

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30 years After the Chernobyl Nuclear Accident: Time for Reflection and Re-evaluation of Current Disaster Preparedness Plans

Lydia b. zablotska.

University of California, San Francisco, San Francisco, CA USA

It has been 30 years since the worst accident in the history of the nuclear era occurred at the Chernobyl power plant in Ukraine close to densely populated urban areas. To date, epidemiological studies reported increased long-term risks of leukemia, cardiovascular diseases, and cataracts among cleanup workers and of thyroid cancer and non-malignant diseases in those exposed as children and adolescents. Mental health effects were the most significant public health consequence of the accident in the three most contaminated countries of Ukraine, Belarus, and the Russian Federation. Timely and clear communication with affected populations emerged as one of the main lessons in the aftermath of the Chernobyl nuclear accident.

As we near the 30-year mark of the worst nuclear power plant accident known to mankind, it is an opportune time to pause and critically reflect upon lessons learned as well as to think how we could utilize this knowledge to improve current disaster preparedness and management plans. Chernobyl nuclear power plant’s geographical location in Ukraine—less than 20 km from the borders of two other post-Soviet countries of Belarus and the Russian Federation, close to densely populated urban areas—could provide pertinent information for a variety of scenarios considered by public health officials in drawing nuclear disaster preparedness plans, particularly with regards to a “dirty” bomb.

The accident at the Chernobyl (Ukrainian spelling “Chornobyl”) nuclear power plant on April 26, 1986, was due to a planned scientific experiment which went awry and resulted in the release of radioactive materials into the air for about 10 days. 1 Due to the prevailing wind patterns (in the Western and Northern directions in the first days after the accident and then in all directions), the long-range transport of various radionuclides caused serious contamination of the regions both close to the site of the accident but also throughout Europe. Scientific reports by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) have emphasized that three population groups in the three most affected countries had the highest levels of radioactive contamination and were at risk of long-term health effects from radiation exposures: (1) recovery operation workers (“liquidators” or “cleanup workers,” n  = 530,000); (2) evacuees from contaminated areas ( n  = 115,000); and (3) inhabitants of contaminated areas ( n  = 6,400,000). 2 The last group received low radiation doses equivalent to approximately one whole-body computed tomography (CT) scan. 2 In addition to these three groups, those living further away from the place of the accident both in the three most contaminated countries but also in Europe number almost 600 million people, with radiation exposure doses comparable to one annual background radiation dose. 2

Risk projection studies conducted a decade after the accident estimated that about 9 to 10,000 deaths from leukemia, and solid cancers might be expected over life in the most exposed populations in Ukraine, the Russian Federation, and Belarus. 1 To date, epidemiological studies of the long-term effects of the Chernobyl accident have mainly focused on the three most severe health outcomes which emerged in the 30 years after the accident: (1) leukemia in cleanup workers; (2) cataracts and cardiovascular diseases (CVD) in cleanup workers; and (3) thyroid cancer and non-malignant diseases in those exposed as children and adolescents. Several recent reports have argued, however, that psychological consequences became the major health effect of the Chernobyl nuclear accident. 2 , 3 Below, we summarize the current knowledge of the long-term health effects for various population groups exposed in the aftermath of the Chernobyl accident and point to knowledge gaps as well as future directions for research.

Leukemia in Chernobyl Cleanup Workers

Previous studies of radiation-exposed populations reported increased risks of leukemia associated with exposures to high doses of radiationr, 4 but several questions remained about the effects of exposures to low doses of radiation. Initial studies of Chernobyl cleanup workers reported increased incidence rates of leukemia, 5 – 7 but no increase was reported in the general population in contaminated areas. 8 Increased risks of leukemia, although not statistically significant, were reported from a study of Chernobyl cleanup workers from Belarus, Russia, and Baltic countries. 9 Similar findings were reported for Russian cleanup workers from the analysis based on the official reported doses and the Chernobyl Registry-based leukemia diagnoses. 10

We recently reported the results of 20-year follow-up of a cohort of 110,000 cleanup workers from Ukraine. 11 A significant association between protracted radiation exposure at low doses and leukemia incidence was identified. The mean cumulative radiation doses were lower than reported for the atomic bomb survivors from Japan, 4 and the estimated radiation risks were lower, although comparable, given the range of statistical uncertainty. About 16 % of leukemia cases among Chernobyl cleanup workers was attributed to radiation exposure from cleanup activities in the Chernobyl 30-km zone. 11 Examination of the effects of non-radiation risk factors showed that increased risks of leukemia in this cleanup worker population could not be explained by lifestyle factors such as smoking and alcohol consumption or non-Chernobyl occupational exposures to pesticides and solvents, although there were some indications of increased risks due to petroleum exposures. 12 No associations with risk factors other than radiation were found for chronic lymphocytic leukemia (CLL).

Until recently, the majority of epidemiological studies of radiation-exposed populations, whether from occupational, 13 environmental, 4 or therapeutic exposures, 14 – 16 reported no radiation risk for CLL. The radiogenic risk for CLL has important public health implications because it is the most prevalent type of leukemia in Western populations. 17 In a reversal of previous findings, our study indicated elevated radiation risk estimates among cleanup workers for both CLL and non-CLL. 11 There is now an emerging consensus on CLL radiogenicity, 18 – 20 but the magnitude of risks remains unknown. We also recently reported that higher radiation doses and younger age at first exposure to radiation during Chernobyl cleanup work were associated with significantly shorter survival of CLL cases. 21 The median age at diagnosis was 57 years compared to the median age at diagnosis in the U.S. of 72 years. 22 Further investigations are needed to develop a better understanding of the association between radiation and CLL, which is the most common type of leukemia in this cleanup worker population.

Cataracts and CVD in Chernobyl Cleanup Workers

Cataracts are believed to be a deterministic effect of radiation exposure and their severity varies depending on the radiation dose. 23 The Ukrainian-American Chernobyl Ocular study reported a dose-related increase in the rate of cataracts in cleanup workers from Ukraine. 24 Importantly, the study challenged the previously suggested threshold of 1 gray (Gy) and reported a threshold of no more than 0.7 Gy. As a result of this singular investigation, the International Commission on Radiological Protection recommended a change in the threshold dose for the eye lens and dose limits for the eye for occupationally exposed persons from 1 to 0.5 Gy. 23 However, uncertainties in individual dosimetry and absence of confirmation studies in other cleanup worker populations temper the certainty of findings.

Previous studies of radiation-exposed populations indicated increased risks of the circulatory system, but the mechanism is not completely understood. 25 Radiation risks of CVD mortality have been reported for high-dose exposures above 0.5 Gy, but the evidence for lower doses is mixed. 26 To date, increased risks of CVD have been reported only for Russian Chernobyl cleanup workers based on data from the Russian National Medical and Dosimetric Registry and require further investigation. 27

Thyroid Cancer and Other Thyroid Diseases

At the time of the Chernobyl accident, it was known that exposures to external ionizing radiation in childhood and adolescence were associated with increased risk of thyroid cancer, 4 , 28 but risks following internal exposure to radionuclides were much less well known. We established two parallel screening cohort studies in Ukraine and Belarus, with each involving about 12,000 subjects who were exposed to radioactive fallout, chiefly iodine-131 ( 131 I), from the Chernobyl accident as children or adolescents. 29 The cohorts have undergone periodic standardized screening for thyroid cancer and non-malignant diseases of the thyroid. The Ukranian 30 – 32 and Belarusian 33 studies have shown a significantly increased risk of thyroid cancer which was similar in magnitude to the risk associated with external radiation exposure. 4 , 28 Evidence from other smaller population-based case-control studies confirms a causal relationship between the observed increase in thyroid cancer risk and exposure to 131 I from the Chernobyl fall out. 34 – 36

Research from our group has also introduced 37 and later confirmed 38 a novel idea that radioactive iodine contamination of those exposed as children and adolescents causes not only cancer but also benign tumors of the thyroid gland. Our studies also provided evidence on the importance of young age at exposure as a modifier of this risk. 38 The consistency in the results obtained from the two cohorts, in which benign follicular adenomas were ascertained by standardized examinations and pathology reviews, 39 strengthens the evidence of the radiation risks of this benign tumor. Future studies are needed to clarify the effects of radiation exposures on other non-malignant thyroid disorders for which the evidence has been mixed to date. 40 – 42

Psychological Effects

Initial delays by the Soviet government to provide timely information to the affected populations, seeming absence of disaster preparedness plans, and chaotic evacuations in the months after the accident at the power plant, created a climate of distrust and wide-spread frustration. In the years after the accident, sensationalist media reports about the health effects of radiation only increased the fears among those exposed. These effects were compounded by severe social and economic upheaval in the three countries most affected by the nuclear accident from the disintegration of the Soviet Union in 1991 and the subsequent disruption of existing government structures designed to deal with the nuclear accident consequences.

Several reports recently concluded that mental health effects were the most significant public health consequence of the accident. 2 Neuropsychological and psychological impairments associated with radiation exposure have been reported for those exposed as children, in particular poor self-rated health as well as clinical and subclinical depression, anxiety, and post-traumatic stress disorder. 3 The excess morbidity rate of psychiatric disorders among cleanup workers in the first year after a disaster was reported at 20 %, 3 and the rates of depression and post-traumatic stress disorder remained elevated decades later. 43 Many of the lingering effects were due to continuing worries about the adverse health effects of radiation exposures and to paucity of mental health care in affected regions. Future research is needed to clarify the incidence and prevalence of mental disorders in various exposure groups and the dose-dependent associations for individual mental health effects.

In summary, clinical and population-based studies conducted after the Chernobyl accident have provided unique insights into the associations between radiation exposures and long-term health risks of leukemia, CVD, and cataracts among cleanup workers and of thyroid diseases in those exposed as children and adolescents. While the long-term mental health effects were the most significant public health consequence of the accident, few scientific studies were conducted and no longitudinal studies. One of the main lessons of the aftermath of the Chernobyl nuclear accident is the recognition of importance of delivering timely information to the affected populations and of having clear communication strategies embedded in disaster preparedness and mitigation plans. 44 Based on the experiences after the Chernobyl accident and after other events, such as September 11 Terrorist Attacks in New York City, 45 it is imperative to integrate psychological support and psychiatric treatment for the affected populations with existing medical screening and treatment programs. Measures aimed at increasing resilience at the individual and population levels should be included in disaster preparedness, response, and management plans. Such plans should also include education and training of key personnel in health departments on actions to take with regards to risk communication, population needs assessment, establishment of treatment referral centers, and conduct of targeted outreach. The Chernobyl experience indicates that the psychological sequelae persist for a very long time, so future research should determine the radiation dose-response for mental health effects and the possible modifying effects of mitigating measures.


Dr. Zablotska was supported by the NCI grant R01CA197422.

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Assessments of the radiation effects from the Chornobyl nuclear reactor accident

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The accident at the Chornobyl nuclear reactor that occurred on 26 April 1986 was the most serious accident ever to occur in the nuclear power industry. The reactor was destroyed in the accident and considerable amounts of radioactive material were released to the environment. The accident caused the deaths, within a few weeks, of 30 workers and radiation injuries to over a hundred others. In response, the authorities evacuated, in 1986, about 115,000 people from areas surrounding the reactor and subsequently relocated, after 1986, about 220,000 people from Belarus, the Russian Federation and Ukraine. The accident caused serious social and psychological disruption in the lives of those affected and vast economic losses over the entire region. Large areas of the three countries were contaminated with radioactive materials, and radionuclides from the Chornobyl release were measurable in all countries of the northern hemisphere.

Among the residents of Belarus, the Russian Federation and Ukraine, there had been up to the year 2005 more than 6,000 cases of thyroid cancer reported in children and adolescents who were exposed at the time of the accident, and more cases can be expected during the next decades. Notwithstanding the influence of enhanced screening regimes, many of those cancers were most likely caused by radiation exposures shortly after the accident. Apart from this increase, there is no evidence of a major public health impact attributable to radiation exposure two decades after the accident. There is no scientific evidence of increases in overall cancer incidence or mortality rates or in rates of non-malignant disorders that could be related to radiation exposure. The incidence of leukaemia in the general population, one of the main concerns owing to the shorter time expected between exposure and its occurrence compared with solid cancers, does not appear to be elevated. Although those most highly exposed individuals are at an increased risk of radiation-associated effects, the great majority of the population is not likely to experience serious health consequences as a result of radiation from the Chornobyl accident. Many other health problems have been noted in the populations that are not related to radiation exposure.

Release of radionuclides

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Maps of radionuclide deposition

Download detailed maps from the UNSCEAR 2000 report

  • Surface ground deposition of caesium-137 on the territories of Belarus, Russian and Ukraine (1.1 MBytes)
  • Surface ground deposition of caesium-137 in Europe (2.2 MBytes)

The radionuclides released from the reactor that caused exposure of individuals were mainly iodine-131, caesium-134 and caesium-137. Iodine-131 has a short radioactive half-life (eight days), but it can be transferred to humans relatively rapidly from the air and through consumption of contaminated milk and leafy vegetables. Iodine becomes localized in the thyroid gland. For reasons related to the intake of milk and dairy products by infants and children, as well as the size of their thyroid glands and their metabolism, the radiation doses are usually higher for them than for adults.

Average effective doses to those persons most affected by the accident were assessed to be about 120 mSv for 530,000 recovery operation workers, 30 mSv for 115,000 evacuated persons and 9 mSv during the first two decades after the accident to those who continued to reside in contaminated areas. (For comparison, the typical dose from a single computed tomography scan is 9 mSv). Maximum individual values of the dose may be an order of magnitude and even more. Outside Belarus, the Russian Federation and Ukraine, other European countries were affected by the accident. Average national doses there were less than 1 mSv in the first year after the accident with progressively decreasing doses in subsequent years. The average dose over a lifetime in distant countries of Europe was estimated to be about 1 mSv. These doses are comparable to an annual dose from natural background radiation (the global average is 2.4 mSv) and are, therefore, of little radiological significance.

The exposures were much higher for those involved in mitigating the effects of the accident and those who resided nearby. Those exposures are reviewed in great detail in the UNSCEAR assessments.

Health effects

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The Chornobyl accident caused many severe radiation effects almost immediately. Of 600 workers present on the site during the early morning of 26 April 1986, 134 received high doses (0.8-16 Gy) and suffered from radiation sickness. Of these, 28 died in the first three months and another 19 died in 1987-2004 of various causes not necessarily associated with radiation exposure. In addition, according to the UNSCEAR 2008 Report, the majority of the 530,000 registered recovery operation workers received doses of between 0.02 Gy and 0.5 Gy between 1986 and 1990. That cohort is still at potential risk of late consequences such as cancer and other diseases and their health will be followed closely.

The Chornobyl accident also resulted in widespread radioactive contamination in areas of Belarus, the Russian Federation and Ukraine inhabited by several million people. In addition to causing radiation exposure, the accident caused long-term changes in the lives of the people living in the contaminated districts, since the measures intended to limit radiation doses included resettlement, changes in food supplies and restrictions on the activities of individuals and families. Later on, those changes were accompanied by the major economic, social, and political changes that took place when the former Soviet Union broke up.

For the last two decades, attention has been focused on investigating the association between exposure caused by radionuclides released in the Chornobyl accident and late effects, in particular thyroid cancer in children. Doses to the thyroid received in the first few months after the accident were particularly high in those who were children and adolescents at the time in Belarus, Ukraine and the most affected Russian regions and drank milk with high levels of radioactive iodine. By 2005, more than 6,000 thyroid cancer cases had been diagnosed in this group, and it is most likely that a large fraction of these thyroid cancers is attributable to radioiodine intake. It is expected that the increase in thyroid cancer incidence due to the Chornobyl accident will continue for many more years, although the long-term increase is difficult to quantify precisely.

Among Russian recovery operation workers with higher doses there is emerging evidence of some increase in the incidence of leukaemia. However, based on other studies, the annual incidence of radiation-induced leukaemia would be expected to fall within a few decades after exposure. In addition, recent studies of the recovery operation workers indicate that opacities of the eye lens might be caused by relatively low radiation doses.

Among the 106 patients surviving radiation sickness, complete normalization of health took several years. Many of those patients developed clinically significant radiation-induced cataracts in the first few years after the accident. Over the period 1987-2006, 19 survivors died for various reasons; however, some of these deaths were due to causes not associated with radiation exposure.

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Apart from the dramatic increase in thyroid cancer incidence among those exposed at a young age, and some indication of an increased leukaemia and cataract incidence among the workers, there is no clearly demonstrated increase in the incidence of solid cancers or leukaemia due to radiation in the exposed populations. Neither is there any proof of other non-malignant disorders that are related to ionizing radiation. However, there were widespread psychological reactions to the accident, which were due to fear of the radiation, not to the actual radiation doses.

There is a tendency to attribute increases in the rates of all cancers over time to the Chornobyl accident, but it should be noted that increases were also observed before the accident in the affected areas. Moreover, a general increase in mortality has been reported in recent decades in most areas of the former Soviet Union, and this must be taken into account when interpreting the results of the accident-related studies.

The present understanding of the late effects of protracted exposure to ionizing radiation is limited, since the dose-response assessments rely heavily on studies of exposure to high doses and animal experiments. Studies of the Chornobyl accident exposure might shed light on the late effects of protracted exposure, but given the low doses received by the majority of exposed individuals, any increase in cancer incidence or mortality will be difficult to detect in epidemiological studies.

The accident at the Chornobyl nuclear power plant in 1986 was a tragic event for its victims, and those most affected suffered major hardship. Some of the people who dealt with the emergency lost their lives. Although those exposed as children and the emergency and recovery workers are at increased risk of radiation-induced effects, the vast majority of the population need not live in fear of serious health consequences due to the radiation from the Chornobyl accident. For the most part, they were exposed to radiation levels comparable to or a few times higher than annual levels of natural background, and future exposures continue to slowly diminish as the radionuclides decay. Lives have been seriously disrupted by the Chornobyl accident, but from the radiological point of view, generally positive prospects for the future health of most individuals should prevail.

Chornobyl Forum 2005

From 2003 to 2005 Committee's experts participated in the work of the Chernobyl Forum, whose conclusions ( Summary report of the Chernobyl Forum ) essentially concur with those of the UNSCEAR 2000 report .

UNSCEAR publications

The Committee has been involved from early on in the assessment of radiation exposures and health effects from the accident.

UNSCEAR 1988 Report, annex D - Exposures from the Chernobyl accident, and appendix to annex G - Acute radiation effects in victims of the Chernobyl accident

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In 1988 it issued its first study of acute radiation effects in victims of the Chernobyl accident ( UNSCEAR 1988 Report, appendix to annex G ), which reviews experience gained in treating the immediate radiation injuries of workers and firemen who dealt with the initial emergency. The Committee also published an account of the accident, and its global fallout and exposures ( UNSCEAR 1988 Report, annex D ). Soon after the accident, the dispersion of radionuclides and the resulting radiation exposures had been measured and evaluated throughout the affected regions. The Committee made use of those data to evaluate the average individual and population doses for affected regions, and for the northern hemisphere as a whole.

UNSCEAR 1993 Report, annex B - Exposures from man-made sources of radiation

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In 1993 the Committee issued an assessment of exposures from man-made sources of radiation (UNSCEAR 1993 Report, annex B), which summarizes the findings of the more detailed assessment of the UNSCEAR 1988 Report, annexes D and G on the exposures and effects of the Chernobyl accident.

UNSCEAR 2000 Report, annex J - Epidemiological evaluation of radiation-induced cancer

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In 2000 the Committee issued a more detailed assessment of radiation levels and effects: Exposures and effects of the Chernobyl accident ( UNSCEAR 2000 Report Volume II, annex J ). Evaluating the exposures received by the people who had been evacuated or who were still residing in the areas most affected by the accident required much time and effort. The initial measurements were supplemented by information on matters such as the location and diet of the people in each settlement. The accumulation of data on any late health effects also required time.

UNSCEAR 2001 Report - Hereditary effects of radiation

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In 2001 Committee also published findings related to possible genetic effects of radiation exposures resulting from the Chernobyl accident ( UNSCEAR 2001 Report ).

UNSCEAR 2008 Report, annex D - Health effects due to radiation from the Chernobyl accident

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In 2011, the Committee published a report, entitled "Health effects due to radiation from the Chernobyl accident" ( UNSCEAR 2008 Report, annex D ). The findings are based on more than two decades of experimental and analytical studies of the radiation consequences of the Chernobyl accident for health of the exposed populations and for the environment. The data reviewed, including numerous dosimetric measurements and results of analytical epidemiological studies, allowed a comprehensive evaluation of the human exposure levels and radiation-induced health effects at that time.

Chernobyl 2017 White Paper - Evaluation of data on thyroid cancer in regions affected by the Chernobyl accident

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In 2018, the UNSCEAR secretariat published a White Paper evaluating thyroid cancer data in regions affected by the Chernobyl accident to guide the Scientific Committee's future programme of work. The publication recapitulates previous findings of the Scientific Committee on this matter, reports the latest data provided by the three most affected countries (Belarus, the Russian Federation and Ukraine), summarizes key literature of the past ten years, and makes an assessment of the cases of thyroid cancer that could be attributed to radiation exposure.

UNSCEAR 2020/2021 Report, annex B, appendix B - Comparison between various attributes and consequences of the accidents at Chernobyl and Fukushima Daiichi nuclear power stations

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The Committee also summarised the key radiological data from the Fukushima and Chernobyl accidents in the UNSCEAR 2020/2021 Report, annex B , appendix B - comparison between various attributes and consequences of the accidents at Chernobyl and Fukushima Daiichi nuclear power stations.

Secretary General reports on the accident

A/65/341: optimizing the international effort to study, mitigate and minimize the consequences of the chernobyl disaster.

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In 2010, in accordance with General Assembly resolution 62/9 on the strengthening of international cooperation, the Secretary-General submitted to the General Assembly the report "Optimizing the international effort to study, mitigate and minimize the consequences of the Chernobyl disaster" ( A/65/341 ).

A/RES/71/125: Persistent legacy of the Chernobyl disaster

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In 2019 the Secretary General submitted a report in accordance with General Assembly resolution A/RES/71/125 on the persistent legacy of the Chernobyl disaster and provides an update on the progress made in the implementation of all aspects of the resolution.

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Chernobyl: A Manmade Disaster

  • 15 May 2024
  • By: Basma Fawzy
  • Energy - Disaster - Pollution - Atom - Power

chernobyl disaster 1986 case study

Planet Earth is often plagued by natural disasters, from volcanoes and earthquakes, to hurricanes and tsunamis, natural disasters can be truly horrendous. Yet, more often than not, manmade disasters wreak even more havoc. This article is about Chernobyl, one of the worst manmade disasters of all time.

Before going into details about Chernobyl, let us know more about nuclear power plants. As we know, a power plant is built to generate power (electricity); in a nuclear plant, electricity is generated through nuclear fission, with uranium fuel at the core of a nuclear reactor. During nuclear fission, atoms are split then heat is produced; the heat is used to create steam, which is used in spinning the turbines, eventually generating electricity. For additional information concerning nuclear power plants, check out “ Is Nuclear Energy the Answer to Global Warming? ”.

Though Chernobyl was the first nuclear power plant in Ukraine, it was not the first in the Soviet Union; the plant had four RBMK-1000 reactors, which were built during 1970s and 1980s. The date 26 April 1986, was a tragic day for those operating the Chernobyl Nuclear Power Plant and for anyone in its proximity when the fourth reactor exploded, emitting dangerous radiations into the atmosphere.

The accident partially occurred due to a faulty design of the reactor; however, human error cannot be disregarded. During maintenance, safety procedures were not properly followed when operators wanted to check if the reactor could be cooled down during power outage. As a result, a surge of power inside the reactor led to the fateful explosion, which unfortunately led to the exposure of the nuclear core.

Death claimed many lives as a direct result of the explosion; yet, the implications of the exposure of a nuclear core, which amounts to 30% of Chernobyl’s uranium, were not limited to death. Huge numbers of people and other creatures suffered from Acute Radiation Syndrome resulting from exposure to high amounts of radiation over a short period of time. Moreover, children who consumed dairy products from cows that fed on contaminated grass developed thyroid cancer.

After the explosion of the Reactor, and in order to contain the damage, thousands of people were evacuated; until now, no one is allowed inside the area where the Reactor exploded and around it, which is known as the “Exclusion Zone”. It is estimated that the affected area can be habitable only after 20,000 years. On the other hand, affected areas around the Exclusion Zone have witnessed serious efforts for rehabilitation. As several countries were affected by that disaster—namely Belarus, Russia, and Ukraine—the scale of the disaster merited international cooperation.

chernobyl disaster 1986 case study

Chernobyl Exclusion Zone. Image by Freepik .

One of the organizations that took the initiative to support the affected communities was the International Atomic Energy Agency (IAEA). The initiative known as the Chernobyl Forum was launched in cooperation with five UN organizations, the World Bank and the governments of the affected countries. The purpose was to scientifically evaluate the accident and provide solutions and recommendations involving special health care programs and controlling environmental damage.

Furthermore, on its website, the United Nations (UN) has included the economic rehabilitation of Chernobyl disaster affected areas as one of the goals in action under the Goal 8 of Sustainable Development: Decent Work and Economic Growth. Indeed, the UN has taken the lead in rehabilitating the area, creating “A Chernobyl Trust Fund” in 1991. The UN has also named the ten years from 2006–2016 the “Decade of Recovery and Sustainable Development of the Affected Regions.” Thanks to these efforts, nowadays, more than three decades following the disaster, the economic revival in the area is visible, with some spots becoming leading destinations for investors.

Addressing environmental and economic issues has not been enough though; people’s fears and concerns also had to be addressed, and the knowledge of how to deal with the situation had to be delivered to them. To that end, UN Agencies dedicated USD 2.5 million to raise awareness and deliver vital information to affected communities. The initiative attempts to transform scientific information into practical advice that the communities could use to lead a safe life. It is a long journey, but with proper international collaboration efforts, these areas can return back to normal.

Despite the potential dangers, nuclear power plants are considered an environmentally-friendly energy solution because they do not emit greenhouse gases. If the Chernobyl disaster was of any significance, it was to inform people how deadly nuclear energy can be if not well-managed, and how careful we should be when handling nuclear power plants.

Cover Image by ASphotofamily on  Freepik .


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