The Chernobyl Nuclear Power Plant – officially named the Vladimir Ilyich Lenin Nuclear Power Plant – was built near the city of Pripyat in the north of Ukraine, which was then part of the Union of Soviet Socialist Republics, or USSR. The plant consisted of four RBMK-1000 reactors (with two more under construction in 1986), each capable of producing 1,000 megawatts of electric power, totaling about 10% of Ukraine's electricity.
It was the third Soviet RBMK (Russian: Reaktor Bolshoy Moshchnosti Kanalnyy, translated "high-power channel-type reactor") nuclear power plant - and the first in Ukraine. Chernobyl’s newest reactor, number 4, was put into service in 1983 but had failed a critical safety test three times.
Countdown to Tragedy
In the early morning hours of Saturday, April 26, 1986, the fourth test - a simulation of an electrical power outage – would unexpectedly be it's last.
But before this fourth attempt, an unexpected 10-hour delay meant an unprepared operating shift crew was on duty. During the planned decrease of reactor power, done in preparation for the test, the electrical output unexpectedly dropped to near-zero. Working fast to fix the situation, the operators were only able to partially restore the specified power needed for the test but did so in a way that created a potentially unstable condition called a “high positive void coefficient” within the reactor.
Not fully understanding the situation, the operators continued with the electrical test undaunted. Upon concluding the test, the crew triggered a reactor shutdown, but a combination of unstable conditions and reactor design flaws instead caused an uncontrolled nuclear chain reaction and power surge. Superheated cooling water instantly vaporized, and the reactor core exploded, throwing fire and radioactive debris into the sky.
Air Power...
The resulting open-air reactor core fire release considerable airborne radioactive contamination. In response, the Soviet military called in an armada of Mil Mi-8s helicopters to carry and drop radiation-absorbing materials – a mixture of boron carbide, clay, dolomite, lead, and sand – on to the burning heap. An estimated 600 pilots were called to fly short, 20-minute sorties. By the end of the initial ordeal, more than 1,800 “bombing run” flights were flown as pilots received potentially lethal doses of radiation that went completely off the scale of their dosimeters.
For nine days – the flames continued as the helicopters dumped more than 5,000 metric tons of absorbent. And the same time, using oil well drilling equipment, liquid nitrogen was injected into the soil under the reactor, freezing the ground to prevent the reactor from sinking downwards akin to “China syndrome,” and also stabilize the nuclear plant’s foundation.
On May 4,the fire was deemed ‘contained’ – but not after it released a radioactive cloud of contamination that spread across parts of the USSR and Western Europe – roughly the same amount of contamination as the initial explosion.
Most of the helicopters used to dump the boric acid/sand mixture were severely irradiated from the recovery work. Nearly all had to be abandoned, left in giant "machine cemetery" junkyards to decay like the radioactive isotopes found in the 30 Kilometer Exclusion Zone around Chernobyl.
Containment
While partially effective, nuclear scientists and environmental researchers worked to find a new, better way to contain the radiation. Building a massive concrete enclosure around the reactor, officially called the Object Shelter but informally dubbed the “Sarcophagus,” was determined to be the best course of action.
By July of 1986, three construction cranes were erected to help build the new structure. But radioactive dust was everywhere, slowing the progress. As summer gave way to autumn, helicopters continuously flew in and around the reactor and construction site, air-dropping polyvinyl acetate (PVA) glue to keep the dust from becoming airborne. The resulting mass, once dried, could then be cut, rolled, and removed from the area by volunteer soldiers, jokingly called “bio-robots.”
“Some of the cranes were literally hanging in the void without support,” recalled Colonel Oleg Chichcov years after the disaster. At the time a Mi-26 helicopter instructor, he was dispatched as part of the response effort. “I had been assigned to a mission area, but I refused until the cranes had been made safe.”
In Service to Others...
Other helicopter crews were called in from throughout the Soviet Union to assist. Pilots and navigators from the occupation of Afghanistan were ordered to Ashgabat, thinking that it was rest, only to be urgently sent directly to Kyiv - non-stop.
Amongst them was Captain Vladimir Konstantinovich Vorobyov (ВОРОБЙОВ). The youngest member of a large family in Yaroslavl, a city northeast of Moscow, the 30-year-old pilot (3rd class), was a veteran of the invasion of Afghanistan – having survived the shootdown of one helicopter for which his received the Order of the Red Star. Having been stationed in the Siberian city of Chita in the Trans-Baikal Military District of the Ministry of Defense of the USSR, the married father of two joined the Chernobyl effort in September of 1986.
On October 2, 1986, Vorobyov would be assigned as the second helicopter in a two-ship formation. The lead copter, a Mi-24 designated “Cup 1” and flown by Vyacheslav Zheronkin - would dump bulk sand and lead material, and the second – “Cup 2” -would apply the PVA latex glue. As each helo did its tasks, the other would provide an additional set of eyes to help with precision targeting, as well as watch for obstacles.
With him was his navigator, senior lieutenant Alexander Yungkind (ЮНГКИНД). Initially ordered to serve in Afghanistan, he had become unwell and was advised to delay. The father of a one-year-old girl, Yungkind’s wife told him – shortly before he left for Chernobyl – that she was pregnant with another child.
Rounding out the Mi-8’s flight crew was Senior Lieutenant Leonid Khristich (ХРИСТИЧ), serving as the flight engineer. Also a veteran of the Afghan war, the married father of two children was nearly shot down in the conflict when enemy fire torn through his helicopter’s fuel tanks. Thanks to some quick thinking on his part, he covered the leaks with his hands until the pilot could safely land in Soviet-controlled territory.
Captain V. K. Vorobyov
Senior Lieutenant A. Y. Yundkind
Senior Lieutenant L. I. Khristich
First Ensign N. A. Ganzhuk
Helping to load the two-and-a-half tons of material into each helicopter’s external buckets was 26-year-old warrant officer Nikolai Ganzhuk (ГАНЖУК). A native of Lutsk, he was an experienced mechanic but specialized in loading weaponry. Assigned to the Soviet Army’s 51st Separate Guards Helicopter Regiment, he was invited at the last second to join Vorobyov and the crew of Cup 2 – helping them carry out their day’s mission.
Signs and Portents...
Shortly before the pair of helicopters were to take off on the day’s mission that morning, a photographer from the “Red Star” military newspaper, Igor Kostin, arrived, wanting to take pictures of the two crews. Zheronkin declined to opportunity, citing it as bad luck before a flight – but Vorobyov agreed.
The two helicopters worked a non-stop cycle: take off from the railyard, fly 20 minutes to the reactor, dump your load, fly back to the yard, refuel and reload with materials. Repeat.
Dodging the cables hanging from the cranes was made easier due to each line being flagged. But as the day continued, the flags became more challenging to spot and – eventually – disappeared altogether.
As the sun was becoming low on the horizon, shortly after 5 p.m., the unthinkable would happen.
Wrapping Up a Day’s Work…
At the same time, a cameraman from West Siberia, Victor Grebenyuk, stopped in his car to record the Mi-8 sortie. His task was to capture the history of the recovery work, and the sight of the two helicopters working was certainly notable.
In Cup 2, Vorobyov radioed guidance to Zheronkin in Cup 1, saying things like, “Come on a little to the right, you still have three meters to the wall.”
The directions gave little room for error. The flight engineer on Zheronkin’s helicopter exclaimed, “Go ahead, go ahead, stop - I see the foot of the crane.” And at that moment, Zheronkin thought that he was so close to the crane, he could open his cockpit door, reach out, and touch it.
With Cup 1’s task primary task completed, Zheronkin maneuvered away from the target area. At the same time, on the ground, Grebenyuk started to film as Vorobyov’s helicopter, Cup 2, moved into a position to drop its plastic payload.
But the angle of the sun in the sky blinded Vorobyov, and the lack of any apparent reference marks between his helicopter and the crane’s cables became a volatile mix. Within seconds, the main rotor blades of Cup 2 begin to strike the wires, shattering on impact and throwing parts of the helicopter in every direction.
Without the force of lift to counter the effects of gravity, Cup 2, and its crew of four, plummet down a hundred meters into the burnt remains of Chernobyl Reactor #4, alongside an exterior wall. Helpless, all that Zheronkin could do was watch the stricken Mi-8 fall.
In a panic, the commander yells into the radio, “Regroup and return to base.” While Zheronkin requested to land immediately to check on his comrades, it was denied, and he flew his Mi-24 back to Goncharovsk.
A few hours later, shortly before midnight, Major Zheronkin returned to the crash site of Cup 2 with the assignment of recovering the crew’s remains. Arriving in another Mi-8, he waited as each of his comrades were loaded aboard before departing for the airfield in nearby Kyiv. The remains, having been near the reactor for several hours, pegged the helicopter’s radiation dosimeters – encouraging Zheronkin to fly that the Mi-8 top speed of 320 kilometers per hour.
Aftermath
All four members of the Mi-8’s crew were posthumously awarded the Order of the Red Star, presented to Soviet military personnel in peacetime for ensuring public safety. And while a special committee was commissioned to investigate the cause of the accident, with representatives from Soviet Committee for State Security – better known as the Komitet Gosudarstvennoy Bezopasnosti or the KGB – no report on the accident was ever released to the public.
Near the helipad at Chernobyl, a memorial was built to remember to the crew of Cup 2. Constructed with the only known (at the time) piece of debris that survived the accident, a helicopter blade that was thrown from the crash site, it bears a brass plaque at the base with the names of the four men killed that day in October of 1986.
In November of 1986, the construction of the Object Shelter was completed. Requiring more than 400,000 cubic meters of concrete and 7,300 tons of metal framework, the structure was designed to be temporary, lasting up to 30 years. It was an imperfect build, however, as it allowed for more than 1,000 square meters of openings, which let potentially radioactive dust to escape and water to seep into the enclosure.
Ukrainian filmmaker Vladimir Shevchenko used the footage collected at Chernobyl to make a documentary about the disaster entitled “Chernobyl: Chronicle of Difficult Weeks”. He is widely credited with having captured the crash of Cup 2 on film, but these claims are unproven and unlikely, as he left Chernobyl in August of 1986 to begin editing his movie. No footage of the Mi-8 accident appears in the film, and Grebenyuk’s footage was not released until years later.
The radiation the director was exposed to while documenting the recovery efforts would sicken him, and he died six months later on March 30, 1987, from radiation poisoning. The raw film itself has since been branded the 'most dangerous roll of film ever,' and the camera used to shoot it had to be encased in a lead-lined casket and was stored at a facility close to Kyiv.
The pregnant widow of Cup 2’s flight navigator gave birth to a son, named Sasha, in 1987.
In the years that followed, details about the extent of the disaster began to become public, and many Soviet citizens became increasingly disillusioned with their government. Empowered by Glasnost ("openness and transparency") and loosened restrictions surrounding public dissent, grassroots movements began to spring up in Ukraine. Coupled with food shortages and economic strain due to the ongoing Soviet occupation of Afghanistan, a new Ukrainian independence movement sprang into action.
On August 24, 1991, Ukraine officially declared itself an independent country, which was confirmed by the citizens in a referendum on the Act of Declaration of Independence, held on December 1, 1991. Passed with over 90% approval, the departure of the second-most powerful republic in the Soviet Union both economically and politically - behind only Russia - ended any chance of Soviet President Mikhail Gorbachev keeping his nation together.
The Soviet Union officially dissolved on December 26, 1991.
In 1994, the United States’ Nuclear Regulatory Commission published an article by then-MIT graduate student (now Doctor) Alexander R. Sich, entitled “Chernobyl Accident Management Actions.” Appearing in Volume 35, Issue #1, of the “Nuclear Safety” technical progress journal, Sich was critical of the Soviet response to the Chernobyl accident and determined the helicopter drops in April and May were mostly ineffective. He surmised that the pilots aimed at the wrong target, a red glow which proved not to be the core, that was located about 50 feet away.
According to Sich’s research, the core extinguished itself after completely melting through the 6-foot reactor shield and spilling into a lower level where it spread out sufficiently to cease the nuclear reaction.
In the mid-1990s, the widows and families of the four men killed aboard Cup 2 finally learned the truth as to how they died. The men’s death certificates simply state the place of death as the Chernobyl district of the Kyiv region, and the cause of death as multiple fractures of the skeleton bones – with no mention of involvement with the recovery effort. With the new information in hand, the families were able to apply for and receive financial benefits, in gratitude for their loved ones’ service.
In 1996, Alexander Timchenko, then the chairman of the Ukrainian Union of Veterans of Afghanistan and Chernobyl, filmed a documentary. In it, he recorded a brief moment with Sasha Jungkind, the then-ten-year-old son of Cup 2’s flight navigator. The correspondent asked the boy: “What would you like to become?”
“A pilot,” the child answered. “The main thing is to fly.”
In 2004, design work began for a replacement to the Chernobyl sarcophagus. The new building, called the New Safe Confinement, encapsulated the previous enclosure and also allowed the disassembly of the dead reactor. With construction beginning in September of 2010, the 31,000-ton steel-tube arch was completed in July of 2019.
Also, in 2019, the HBO mini-series “Chernobyl” aired. The series’ second episode depicted a helicopter crash early in response to the explosion of reactor #4, based on the “Cup 2” accident, despite it occurring nearly six months later. In the scene, the crash of the helicopter, while attempting to fly over the reactor, was blamed on the intense radiation – which was not the cause of the actual accident.
However, helicopter video footage taken at the time does show static pops and distortions caused by the concentrated radiation level above the reactor core, and there were reports of pilots getting radiation sickness from their missions.
On December 6, 2017, a work crew dismantling the Chernobyl Sarcophagus found a part of the crashed Mi-8’s tail. The possibility of removing and decontaminating it for use as a museum object is currently being studied.
Today, the official Soviet/Russian death toll from the accident stands at 31. Still, it is widely agreed upon by medical experts that thousands have died later as a result of radiation exposure. The Ukrainian government pays benefits to tens of thousands of the families of men who have died as a result of the Chernobyl disaster, most of whom worked as “liquidators” – post-disaster clean-up workers.
The remaining three of the four Chernobyl plant reactors continued to operate after the disaster but were all powered down by 2000. It is expected that the reactors will be fully decommissioned by the year 2022, and the clean-up completed by 2065.
The resulting open-air reactor core fire release considerable airborne radioactive contamination. In response, the Soviet military called in an armada of Mil Mi-8s helicopters to carry and drop radiation-absorbing materials – a mixture of boron carbide, clay, dolomite, lead, and sand – on to the burning heap. An estimated 600 pilots were called to fly short, 20-minute sorties. By the end of the initial ordeal, more than 1,800 “bombing run” flights were flown as 
Containment
Shortly before the pair of helicopters were to take off on the day’s mission that morning, a photographer from the “Red Star” military newspaper, Igor Kostin, arrived, wanting to take pictures of the two crews. Zheronkin declined to opportunity, citing it as bad luck before a flight – but Vorobyov agreed.
In the years that followed, details about the extent of the disaster began to become public, and many Soviet citizens became increasingly disillusioned with their government. Empowered by Glasnost ("openness and transparency") and loosened restrictions surrounding public dissent, grassroots movements began to spring up in Ukraine. Coupled with food shortages and economic strain due to the ongoing Soviet occupation of Afghanistan, a new Ukrainian independence movement sprang into action. 
In 2004, design work began for a replacement to the Chernobyl sarcophagus. The new building, called the New Safe Confinement, encapsulated the previous enclosure and also allowed the disassembly of the dead reactor. With construction beginning in September of 2010, the 31,000-ton steel-tube arch was completed in July of 2019.
On December 6, 2017, a work crew dismantling the Chernobyl Sarcophagus found a part of the crashed Mi-8’s tail. The possibility of removing and decontaminating it for use as a museum object is currently being studied.
