Recent satellite image of Chernobyl site showing sarcophagus on the right and the
arched top covering on the left, awaiting completion of assembly;
image courtesy of Google.

Zone of Alienation: The Chernobyl Disaster, April 26, 1986
| published April 27, 2015 |

By Kevin Robbie Thursday Review contributor

During the 1980’s, the United States and Soviet Union (USSR) were locked in an arms race which included the development, refinement and production of nuclear weapons. Each side possessed enough warheads and delivery vehicles to wipe out civilization several times over. People around the world went about their business with a mushroom cloud figuratively hanging over their heads like a Damoclean sword. In reality, the biggest nuclear threat—and radioactive cloud—was caused by an explosion on April 26, 1986. However, the explosion did not result from an outbreak of nuclear war or the detonation of a weapon, but from a catastrophic accident at the Chernobyl plant in Soviet Russia. The Chernobyl nuclear facility is located in Chernobyl, a town in the northern Kiev oblast in Ukraine. The area is now referred to the Chernobyl Exclusion Zone. The town was originally founded in the twelfth century and was granted “city” status in 1941.

In early 1986, Chernobyl had a population around 15,000 and nearby Pripyat—a somewhat larger town—a population of 45,000. (Most employees of the plant lived in one of those two locations.) Chernobyl had been fought over during the Russian Civil War in the early 1920’s and the area also suffered under Stalin’s brutal collectivization program which followed. Chernobyl was occupied by the Germans from 1941-1943. Lush with once fertile soil, it was populated mostly by farmers in 1986.

Construction of the power plant, known as type RBM-1000 with four reactors, began in 1970, two miles outside of the town. This class of reactors used graphite to maintain the chain reactions and cooled the reactors with water. Reactor 1 was commissioned and went online in 1977. All four reactors were completed by 1983. Each reactor produced 1,000 megawatts of energy, or about 10% of Ukraine’s electricity. Chernobyl was the first nuclear power plant on Ukrainian soil.

Typically, reactors of this type could take many years to complete. Indeed, by 1986, the design of Chernobyl’s reactors was considered outdated and they required frequent testing for safety and reliability, far more than the routine tests when they were originally constructed. An extensive round of thorough tests was scheduled for April 1986. Reactor 4 was set for testing first, in order to test the procedures for an automatic shutdown, a procedure requiring a gradual reduction of the temperature of the reactor core. According to plant procedures, this particular test was to be completed while the day shift was still on duty. However, another Ukrainian power plant unexpectedly went offline, requiring Chernobyl to continue producing power. This unanticipated event delayed the start of reactor four’s test.

By the time the night shift assumed operation of the plant, the reactor test was underway but behind schedule. The night shift had limited time to prepare for continuing the test due to the late change in the procedures. Thus, their actions during the test inadvertently put reactor 4 into an unstable state known as “reactor poisoning,” caused by a dangerous flux of neutrons and resulting in an unstable core temperature and a reduction in the flow of coolant. The reactor was outside the safety envelope prescribed by its designers. As the core’s power output decreased, technicians inserted the control rods too far.

Thus, the core’s power dropped precipitously, and the improperly trained night staff—unaware of the reason and blindside by severity of the problem—were unable to respond appropriately. The core became more unstable, triggering numerous alarms. But those alarms were largely ignored in the interest of preserving the reactor’s power level, which to the night crew seemed the more critical issue.

Several minutes later, a button was pushed in order to initiate an emergency shutdown, possibly in an effort to end the test but also to stop the temperature in the core from rising too quickly. Within seconds, a massive power spike occurred, rapidly overheating the core. The normal power output for the reactor was 3,000 megawatts but the power surge raised the level to 30,000.

At 1:23 a.m., local time, an explosion occurred in one of the reactor’s steam boilers. A 2,000-ton metal plate, to which the reactor was anchored, was blown straight up through the reactor building’s roof. A second explosion, more powerful than the first, then occurred, breaching the reactor’s containment vessel, terminating the nuclear chain reaction and dispersing the core. Various theories have been proposed regarding the cause of the second explosion, ranging from hydrogen produced moments before the first explosion, to a second steam event. The most likely explanation may be that a graphite moderator ignited. The moderator stabilizes the rate of the fission of atoms, sustaining the chain reactions which are necessary for the ultimate goal of producing energy. As a result, a fire quickly broke out, caused by a rapid and sudden flow of air through the overheated core.

The second explosion ejected extremely hot particles of fuel into the air, as well as poisonous fission products such as strontium-90, caesium-137 and iodine-131. Later that night, residents of the area reported actually seeing the radioactive cloud. Firefighters were immediately called in and even from as far away as Kiev. By daybreak, the fires had been contained except for the blaze inside the reactor, which burned for several days. Damage to the reactor site was severe and news of the disaster spread rapidly but the enormity of the catastrophe had not yet begun to sink in.

Within the first minutes and hours, radioactive clouds began to spread their poisonous reach across hundreds of square miles of the Ukraine, then into neighboring Belarus and Russia, and even across parts of Eastern Europe. Radiation levels showed measurable spikes in a number of cities and towns hundreds of miles away.

To this day, there is controversy and confusion about the true death toll. The United Nations officially recognizes 31 deaths from the Chernobyl reactor disaster; records compiled during the Soviet era in Moscow record the fatalities at about 50. The U.S. Nuclear Regulatory Commission’s website breaks down the death toll as follows: out of a total of 600 employees at the plant, 28 workers dead from severe radiation sickness within the first months; with three more who died at the site. In each case, these numbers reflect primarily workers at the facility, killed by either the first or second explosion or in the subsequent fires, or emergency services personnel and firefighters killed in the minutes immediately after the alarm went out.

But many independent studies, European examinations, and several unofficial totals by groups like Greenpeace place the genuine death toll much higher, perhaps as high as 100,000—if one counts the fatalities which came weeks, months and years later. In the hours after Moscow received word of the reactor explosion and subsequent fires, Kremlin leaders sent thousands of additional workers from a wide area—firefighters, soldiers, police, rescue personnel, construction workers, engineers—into the area around Chernobyl to help with containment, evacuation and clean-up. But many of those first- and second-responders were sent into the poisonous region without proper protective gear or hazardous materials clothing, and many others entered the area around the troubled reactor with little more than a pair of rubber work boots and a gas mask. And though mass evacuations were already under way within hours of the explosions, thousands of civilians did not immediately leave the area. Many others who did leave quickly were nonetheless exposed to dangerous levels of radiation. In the weather conditions prevalent at the time, still thousands more people spread out over a one thousand mile arc stretching toward Eastern Europe may have been exposed to fallout from the clouds of smoke and drifting fumes.

Complicating any accurate analysis of the long term health after-effects: several rivers and extensive wetlands run adjacent to accident site, including the Prypyat River, which flows into the Dnieper a few miles to the south. A massive area of wetland formations sits slightly southeast of Chernobyl, at the confluence of numerous creeks and rivers.

For these reasons, and more, an accurate reckoning with the death toll may never be known.

In the days and weeks after the initial disaster, the Soviet authorities forcibly evacuated 115,000 people from a heavily contaminated area in an 18 mile radius of the facility. By mid-May of 1986, only selected workers and containment personnel were allowed into that zone. Homes, businesses, farms, docks, boats and cars, and entire apartment buildings and schools were abandoned completely. To contain the toxic fires, Soviet helicopters dumped millions of pounds of dirt and sand on the wreckage of the facility. Repairs were impossible. Once the fires and fumes were mostly contained, heavy construction began on a massive tomb made of concrete and sand—called the sarcophagus—to enclose the entire facility. Under the extremely dangerous conditions at the site, the sarcophagus was hastily constructed (it now requires repairs and renovation, which could take several years to complete).

Though the initial evacuation zone displaced 115,000 from homes, apartments and farms, Soviet authorities later moved still more people from a wider area measuring some 40 miles in diameter. The entire region was sealed off, and became known as the Zone of Alienation, or Zone of Exclusion. To date, clean-up and repairs required the efforts of more than a half million construction workers and engineers, working over the decades. According to U.N. and NRC reports, only a small number of these workers were exposed to lethal levels of radiation. By the end of the 1980s, workers were only allowed into the area if properly outfitted with outerwear sufficient for the hazardous duty.

A little known fact of the incident is that a few years later—desperately in need of power—engineers and workers reactivated two of the original four reactors. But they were all shut down over time, and the last remaining reactor was powered down in 1999 (a political promise made by Ukraine’s then-President Leonid Kuchma) as Russian and Ukrainian oil and gas output, coupled with new efficiencies in hydro-electric output, rendered the continued operations at Chernobyl too costly to maintain.

Among the unforeseen health effects of the disaster were the higher-than normal percentage of children who lived in the areas nearby—but outside—the Exclusion Zone, in the Ukraine or in Belarus, who suffered from cancer at various stages of their childhood, teenage and young adult years. Doctors believe that the children drank milk or ate dairy products contaminated by cows who consumed grasses and feed which had soaked up larger-than-expected levels of radiation. Though the evidence is unclear on how many of the children who suffered with cancers such as leukemia, liver cancer or stomach cancer can trace their afflictions to Chernobyl, the link to the extremely high rate of thyroid cancer is well-documented. To date, more than 6000 thyroid cancer cases have been diagnosed among that original pool of kids, but increasingly effective forms of treatment have raised the recovery rate to nearly 98%.

According to the NRC, doctors and scientists over time may conclude that a higher-than average rate of cancer among those who worked within the Exclusion Zone will also be able to be linked directly to the events at Chernobyl.

Vast areas of forest and wetlands near Chernobyl now provide scientists with the ability to closely study the short-term and long-term effects of radiation—on trees, plant life, and animal life. Post-accident radiation levels, which were predicted in the late 1980s to remain deadly for centuries, have actually stabilized to within some tenuous levels of tolerance, allowing such strange oddities as bus tours of the area and some forms of limited tourism, even on foot. News documentaries have also reported on the arrival by some residents to their original homes and farms, though such aberrant forms of return migration have not been approved by Ukrainian authorities.

Photo of abandoned downtown area of Prypyat showing hotel and passenger bus station on the right, and empty apartment buildings on the left and center.
Photo courtesy of Artyomiy Titov.

Part of the improvements to the sarcophagus—the heaviest of the work which began in 2006—include the construction of a massive, arched tent-like structure of steel and concrete, designed to more effectively contain radiation leakage. This enormous shroud is being assembled on a set of rails, and once completed will be rolled slowly atop the existing concrete tomb, then anchored securely to a wide concrete and steel sheathe. The new structure is being designed and built using newer, contemporary tools and construction elements, is earthquake resistant, and is expected to remain intact for at least 100 years.

(Additional reporting on this article by R. Alan Clanton)

Related Thursday Review articles:

Relics of the Cold War; R. Alan Clanton; Thursday Review; December 10, 2014.

Kiev Says Russian Troops Crossing Border; R. Alan Clanton; Thursday Review; February 21, 2015.