It’s the 29th anniversary of the Chernobyl nuclear disaster today. Here’s what happened. (148 Pictures)


The Chernobyl Nuclear Power Plant, officially known as the V. I. Lenin Nuclear Power Station during the Soviet era, began construction in 1970 at a remote region near Ukraine’s swamp-filled northern border, 15 kilometres north-west of the small town of Chernobyl. The plant’s location was chosen because of its relative proximity to Ukraine’s capital while still being a safe distance away, a ready water supply – the River Pripyat – and the existing railway line that ran from Ovruc in the West to Chernigov in the East.


It was the first nuclear power station ever to be built in the country, and was considered to be the best and most reliable of the Soviet Union’s nuclear facilities.



To oversee the titanic operation, 35-year-old turbine expert and loyal communist Viktor Bryukhanov was plucked from his position as Deputy Chief Engineer at the Slavyanskaya thermal power station in Eastern Ukraine, and appointed as Chernobyl’s Director. He is the man second from left.


Concurrent to the construction of the power station, the Soviet Union’s ninth Atomograd – Russian for ‘atomic city’ – named Pripyat was being erected 3 kilometres away, for the specific purpose of housing the ambitious station’s 50,000 operators, builders, support staff and their families.


It was one of the ‘youngest’ cities in the Soviet Union, with an average age of only 26. Convincing experienced workers from more populous parts of the Soviet Union to move to such a remote location proved challenging, so many of Chernobyl's workers came straight from college/university.


Because Pripyat was new and carried with it the prestige of a nuclear power station, it was afforded many modern luxuries other Soviet cities sometimes did without.


It had all the facilities you would expect of a modest-sized city. In addition to a hospital and its nearby clinics, there were 15 kindergartens, 5 schools, a vocational school/college and a school of music and the arts for the children, with 1 expansive park and 35 smaller playgrounds for them to play in.


Further entertainment was found at any of the city’s 10 gyms, 3 swimming pools, 10 shooting ranges, 2 stadiums, 4 libraries and a cinema, or by reading Pripyat’s own newspaper.


Retail came in the form of 25 shops including a bookshop, a supermarket and various smaller food stores, a sports shop, a shop selling TVs, radios and other electronics, and a large shopping centre on the city’s central square.


For down-time there were 27 canteens, cafés and restaurants distributed throughout the city. All in all, it was a very nice place to live compared to many other locations in the Soviet Union.


A wedding couple in front of Pripyat's city sign.


Children playing in main square.



This must have been taken quite close to the accident, as the ferris wheel in the background wasn't officially due to open until 2 days after the explosion.





The town held parades praising the nuclear power station. This truck has a representation of the reactor control room on its front.



This is the famous swimming pool.


Bus station


Lenin on a parade truck.



A few kilometers from Pripyat was a new type of over-the-horizon (OTH) radar system, used as part of the Soviet ballistic missile early-warning network. The system operated from July 1976 to December 1989. Two Duga-3 radars were deployed, the other in eastern Siberia.


Starting in 1976 a new and powerful radio signal was detected worldwide, and quickly dubbed the Woodpecker by amateur radio operators.Triangulation quickly revealed the signals came from Ukraine. Confusion due to small differences in the reports being made from various military sources led to the site being alternately located near Kiev, Minsk, Chernobyl, Gomel or Chernihiv. All of these reports were describing the same deployment, with the transmitter only a few kilometers southwest of Chernobyl


Construction at the power station continued throughout the year.


Although complications put the plant 2 years behind schedule, the first reactor – Unit 1 – was commissioned on the 26th of November 1977, following months of tests. Three more reactors followed: Unit 2 in 1978, Unit 3 in 1981, and Unit 4 in 1983.


Erecting the power lines.


Here we can see Unit 3 has been completed and the iconic vent chimney is being put into place.


All four reactors were of the relatively new RBMK-1000 type, which stood for Reaktor Bolshoy Moshchnosti Kanalnyy ("High Power Channel-type Reactor" in English). Measuring a massive 7 metres tall by 11.8 metres wide, with each capable of outputting 1000 Megawatts (MW) of electrical power via two 500MW steam turbogenerators, they were unusually large reactors. A further two were under construction at the time of the accident in 1986, with Unit 5 expected to be completed later that year. Here is a diagram showing how the RBMK system works.


Vertical graphite blocks surrounding the fuel channels slow down the speed of the moving neutrons in the fuel, because slowed neutrons are far more likely collide with uranium-235 nuclei and split. In other words, the graphite moderator creates the right environment for a chain reaction to occur. Think of the graphite as oxygen in a conventional fire: even with all the fuel in the world, there will be no flame without oxygen.


This diagram shows how the building is laid out, including where the pumps, steam separators and turbines are.


Here you can see engineers working on the water pipes below where the reactor will be.


Reactor construction, you can start to see how big the RBMK is here.


Fueling the reactor.


Brand new fuel rods are fairly harmless.


This was printed a few years before the accident.


Once the power station was up and running, all staff entering and exiting the complex had to go through these radiation detectors. They're still used at the site today.


Here you can see one of the gigantic pumps used to feed water into the core. Water is pumped into the bottom of the reactor at a very high pressure (approximately 1000psi, or 65 atmospheres), where it boils and passes up, out of the reactor and through a condensator which separates steam from water. The remaining water is pushed through another pump and fed back into the reactor.


On the right is a refueling machine. Once it is positioned over the right fuel channel, it withdraws the fuel rod and replaces it with a fresh one.


The completed turbine hall. Steam from the condensator enters these steam turbines, which turn and generate electricity. Having passed through the turbogenerator, the steam is condensed back into water and fed back to the pumps, where it begins its cycle again.


Here is one of the control rooms. There's one control room for each reactor – 4 in all at Chernobyl.


Nuclear reactors have to be constantly fed with a huge volume of water by pumps. In the event that there's ever a problem with the electricity supply, the pumps would stop, so enormous diesel engines like this one were there as a backup. Unfortunately, these engines took almost a minute to reach capacity, and couldn't be relied upon by themselves.


In the early morning of April 26th 1986, a team of men at the power station were testing a safety feature of the RBMK design that allowed to system to power the pumps by itself for that vital minute before the diesel engines took over. This was done by taking electricity generated by the risidual steam in the turbines to power the pumps.


This is the only good image I've ever found of the power station from the angle it's most commonly now seen from.


This is Leonid Toptunov, one of the control room operators. He made a mistake when switching from manual to automatic control of the control rods, causing them to descend much further into the core than intended. This resulted in an almost total shutdown of the reactor. Safety procedures required that the operators fully shutdown the reactor, as the RBMK became unstable at very low power.


Unfortunately for the whole world, the Deputy Chief Engineer in charge of the test – Anatoly Dyatlov – insisted that they continue. The men struggled to bring the reactor up to power, and then commenced the test. Toptunov saw that the reactor readings were heading for danger, so he told the man seen here, senior engineer Alexander Akimov.


At precisely 01:23:40, Akimov pressed the emergency shutdown button. 18 seconds later, the reactor exploded.


Valeriy Khodemchuk, seen here on the left, was in the south-side pump room and was killed instantly when it was destroyed by the explosion.


This is the first photograph ever taken of the accident, and the only photo that survives from the morning of the accident. Igor Kostin was a photographer from Kiev who became world famous for his images of the the clean-up operation. The image is very noisy because the radiation was destroying the film in his camera. Of all the shots he took on that flight, this is the only one that wasn't ruined.


This is a wonderful diagram illustrating just how intense the radioactivity was after the accident.


This model from the plant's own visitor centre shows how the internal structure of the building now looked.


The plant's own firemen immediately rushed into action. The explosion had started fires all over the site, which threatened to destroy the nearby Unit 3. These brave souls climbed onto the roof overlooking the destroyed reactor and fought fires for hours as the radiation destroyed their bodies.


This isn't a photograph, but it is a very accurate recreation of the building that morning. You can clearly see the upper biological shield has been completely dislodged and is resting at a sharp angle.


Bryukhanov, in a panic, repeatedly told his superiors in Moscow that the accident was only minor and that the reactor was still intact.


The smoke is a mixture of incredibly radioactive particles venting into the atmosphere. This cloud would spread radioactivity across Europe.


The outside world remained ignorant of the accident at Chernobyl until the morning of Monday the 28th of April, when a sensor detected elevated radiation levels on engineer Cliff Robinson as he arrived for work at Sweden’s Forsmark Nuclear Power Plant, over 1,000 kilometers away.


Following the news, global media had a fit and made wild assumptions about the accident. In fact, only 2 men had died at the time when these were published.


A special government commission consisting of Party officials and scientists were on their way to assess the situation, and would arrive over the following 24 hours. The leader of this commission was this man, Boris Shcherbina, Deputy Chairman of the Council of Ministers of the USSR – a relatively unknown politician, since Moscow thought this was a minor accident at this point.


The most prominent scientific member of the commission was 49 year old Academician Valerii Legasov, seen on the left. Legasov held a Doctorate in Chemistry and was something of a prodigy, having enjoyed an unprecedented rise within Soviet scientific circles to become the First Deputy-Director of the prestigious I. V. Kurchatov Institute of Atomic Energy who designed the technology in the RBMK-1000. Even though he was not a specialist in nuclear reactors, he was a highly intelligent, experienced and influential figure, both within the Communist Party and the global scientific community at the time.


Their most pressing concern was that the reactor core could be still undergoing nuclear fission, and could get so hot that it would melt its way through the entire structure of the building and into the earth below, which may could have triggered a second, far more massive explosion. It was Legasov who suggested using helicopters to drop sand mixed with boronic acid to neutralise the reaction.


Here you can see how much material was dropped by the fleet of helicopters. Unfortunately, almost all of it completely missed its target, and what little did reach the reactor only served to cut off the cooling heat-exchange between the core and the atmosphere. The core temperature increased. During the operation, one of the helicopters crashed. There's a video of the crash here:


Miners were brought in to dig a 150 meter tunnel underneath Unit 4, where a special refrigeration device would be installed below the building, in an attempt to cool the core. They worked 24 hours a day and achieved their goal in a month, but many of them later died from exposure, and their refrigeration device was never used – the core cooled down by itself.


The residents of Pripyat knew there had been an accident, but had no idea how severe it was, and went about their day as usual on the Saturday of the 26th. Word spread throughout the day that something serious had gone wrong. In order to prevent panic, no information was provided about what had happened at the plant. Those who tried to leave town soon discovered that police had set up roadblocks to stop anyone going into or out of the area.


On the morning of the 27th, as the radiation levels in Pripyat peaked, Legasov remarked that, “mothers could be seen pushing prams and children were playing in the street – just like any other Sunday.” The order to evacuate was finally given at 11am on April 27th, 34 hours after the accident. These two photos are from shortly after the evacuation.


As seen in the previous photo, all the radioactive cars were gathered together at the edge of the city.


Pripyat was fenced off.


Since pieces of the reactor had landed on the roof and radiation there was far too intense for people to work around the plant, remote control machinery was brought in from throughout the Soviet Union (and later Germany and Japan – America offered equipment specially designed for this sort of situation, but were turned down).



This included the STR-1, a rover the Russians had designed to land on the moon.


Some machines succumbed to the radiation. Hardened vehicles like the STR-1 survived it, but then became tangled in the debris.


Tractors were customised with lead panelling and used on the roof of the turbine hall, but they were too unwieldy to be used on the highest parts of the building.


On the roof.


There was no alternative – men would go in their place.


Using suits with lead panels sewn into them, men dubbed 'Bio-Robots' ran up to the roof to shovel debris into the breach.


Each man was only able to work for 40 seconds before their radiation dosage became too high. Only around 10% of the work on the roof was accomplished by actual machines – the rest being done by 5,000 men, according to Yuri Semiolenko, the Soviet official responsible for the decontamination of the plant.


Here you can see the radiation eating into the camera's film from below.


The Bio-Robots' sacrifice allowed work to begin on erecting an enormous enclosure – soon to become known as the Sarcophagus – to seal Unit 4 off from the world. One of the largest and most difficult civil engineering tasks in modern history, there had never been such an important building designed and built in such a short time, under such extreme conditions. It was to stand 170 metres long, 66 metres tall, and envelop the whole of block 4. The Sarcophagus needed the strength to withstand Ukrainian weather for an estimated 20 years – time to develop a more permanent solution – and contain the astronomical levels of radiation within


Heavy machinery, specially customised with radiation resistant cabs, like the one seen here and previous, were brought in to help with the construction.


While this was ongoing, pilots flew Mi-26 helicopters (the largest helicopter ever built) around the clock, spraying a special coagulant chemical across the area.


This sealed radioactive particles to the ground, enabling quick removal and burial. In total, 300,000m³ of earth was dug up and buried in pits, which were then covered over with concrete.



Construction continued for months. Once people reached their dosage limit, they were paid and sent home.


There was a huge concern that the molten reactor core could melt its way into the flooded basement. On May 4th, three incredibly courageous volunteers in wet suits dove into the basement together. The divers were an engineer named Alexei Ananenko, who knew the location of the venting valves, and two soldiers named Valeri Bezpalov and Boris Baranov, one of whom held a light. They were aware of what was at stake, and apparently knew it was a suicide mission, but were promised that their families would be well taken care of. The light failed and the poor men had to swim and find the valves by hand in pitch darkness. The valves were successfully located and opened, and the bubbler pool was drained of its 20,000 tons of water by the fire brigade, but all three men were suffering from radiation sickness even as they climbed out of the water, and each later died



This is a view from inside the damaged turbine hall.


All vehicles entering and leaving the 30km exclusion zone were meticulously cleaned and measured for radioactive particles.



The poor firemen who had first battled the flames on the night of the explosion were dying of radiation syndrome one by one. They had been flown to a specialist radiation hospital in Moscow, called Hospital No. 6


It’s often stated that radiation has no taste, but the men who absorbed the highest doses at Chernobyl all reported a metallic taste in their mouths immediately upon exposure, so it seems that if the dose is high enough to kill you, you will definitely taste it. While every person’s body reacts slightly differently, the following is a good general indicator of the consequences of extreme doses of radiation.


You’ll begin to vomit and feel nauseous almost immediately, and within a short space of time, your tongue and eyes will swell, slowly followed by the rest of your body. You’ll feel weakened, as if the strength has been drained from you. If you have received a high dose of direct exposure – as in this scenario – your skin will turn dark red within moments, a phenomenon often called nuclear sunburn. Within an hour or two of exposure, you’ll gain a pounding headache, a fever and diarrhoea, after which you’ll go into shock and pass out.


After this initial bout of symptoms, there is often a latent period during which you will start to feel like you’re recovering. The nausea will recede, along with some swelling, though other symptoms will remain. This latent period varies in duration from case to case, and of course it depends on the dose, but it can last a few days. It’s cruel, because it gives you hope, only to then get much, much worse. The vomiting and diarrhoea will return, along with delirium. There will be an unstoppable, excruciating pain throughout your body, from your skin down to your bones, and you’ll bleed from your nose, mouth and rectum. Your hair will fall out, your skin will tear easily, crack and blister, and then slowly turn black.


Your bones will rot, forever destroying your body’s ability to create new blood cells. As you near the end, your immune system will completely collapse, your lungs, heart and other internal organs will begin to disintegrate, and you’ll cough them up. Your skin will eventually break down completely, all but guaranteeing infection. One man from Chernobyl reported that when he stood up his skin slipped down off his leg like a sock. At high doses, radiation will change the very fabric of your DNA, turning you quite literally into a person other than the one you were before. And then you’ll die, in agony.


The official USSR figures state that 30 men and one female security guard died as a direct consequence of the accident. That list only covers the people who were at the site within the first few hours of the explosion and who quickly died of acute radiation syndrome or burns, and ignores all military personnel who died due to exposure from the clean-up operation, civilians living in the surrounding area, and many others outwith the military who entered the zone shortly after the accident (journalists, doctors etc). Those whose bodies were recovered are buried in welded zinc coffins, to prevent their radioactive remains from contaminating the soil.


The Chernobyl zone had by now transformed into a huge clean-up operation, involving hundreds of thousands of people, who came to be called Liquidators.


Passenger ships were sailed up the Dnieper River and moored nearby, to provide accommodation for the more lucky and higher ranking Liquidators.


The less fortunate were billeted in vast fields of tents, a few kilometers from the plant.


One of their tasks was to dig up and replace all of the topsoil in Pripyat.



The cars from the city were gradually buried in vast pits of other radioactive machinery.



Workers were supposed to wear their full protective gear – and facemask – but many didn't.


Some were given 3 sets of clothing, but were then required to wear the same 3 sets for 6 months. Others exhibited a rather care-free attitude towards their own future health. “Our protective gear consisted of respirators and gas masks, but no one used them because it was 30°C outside”, says Ivan Zhykhov. “If you put those on it would kill you. We signed for them, as you would for supplementary ammunition, and then forgot all about it.”



This is a famous shot taken by Igor Kostin, of a Liquidator who has discovered a baby abandoned in a country home.


The swimming pool was deliberately kept open to provide some stress-relief and relaxation for the workers.



Everything had to be cleaned.


The work took months. To make matters worse, each time it rained within 100km of the plant new spots of heavy contamination appeared, brought down from the still highly radioactive clouds above.


By the end of 1986 more than 600 villages and towns in the region had been decontaminated.


Those that couldn't be properly decontaminated were simply buried.


By this time, the construction of the Sarcophagus was completed.


In all, more than 400,000m³ of concrete and 7,300 tons of steel were used in its construction, which lasted 206 days, concluding in late November 1986.


A big test came that winter. If the snow on top of the reactor building melted, they had a big problem. It didn't.


The area was completely sealed off to the outside world, and remains so today.



For 6 months following the accident, as the Sarcophagus was under construction, a team of courageous scientists from the Kurchatov Institute of Atomic Energy re-entered Unit 4 as part of an investigation aptly-named Complex Expedition.


“Everyone was afraid of one thing: an explosion might happen again, because the reactor was out of control” recalls Viktor Popov, the nuclear physicist in charge of the expedition. “Were conditions inside the reactor such that another catastrophe might occur?”


They explored the plant’s ruined and unpowered sub-levels with flashlights and cotton masks. “At that time,” says Popov, “there were no places in [Unit 4] that were not dangerous, not by normal human standards. We entered fields of 100, 200, 250 roentgens an hour. This kind of situation could crop up unexpectedly. You’re walking down a corridor and the levels are not too bad; 1 to 5 roentgens per hour. Then you turn a corner and suddenly it’s 500 roentgens! You have to turn and run for it.”


In December – six months after the accident – the group of scientists finally found some fuel, with the help of remote cameras poking through a long hole drilled into a wall. It was still emitting extreme radioactivity. “It made us treat it with the utmost respect,” remembers Yuri Buzulukov, another expedition scientist. “To approach it meant certain death.”


Here you can see the tops of the water pumps poking out of the debris.


The science team next needed a closer look at the reactor itself, so they brought in oil industry engineers to begin drilling through the reactor’s reinforced-concrete containment structure. They finally broke through in the summer of 1988, after the end of 18 months of drilling in harsh conditions. “There were many theories about what we might find there,” says Buzulukov, “but everyone agreed there would be damaged reactor core: graphite blocks interspersed with distorted fuel rods. But once a hole had been drilled in the side of the reactor vessel, the sight that met our eyes was totally unexpected. The reactor was completely empty.”


In 1991, the exhausted and stressed members of the expedition decided there was little alternative but to venture into what was left of Unit 4’s reactor hall to look for themselves – the risk of a possible second explosion was too great.


After clambering over shattered graphite blocks blown out of the reactor and shovelled off the roof, they discovered steaming concrete, heated by the fuel beneath it. Upon further inspection, they saw radioactive lava – an astonishing find. On their way back, as they passed through a shattered corridor adjacent to the bottom of the reactor, in an area of 1,000R/h, they saw that the lower biological shield had crushed the wall beneath it. The final missing piece of the puzzle fell into place.


This is what had happened on that fateful morning: the explosion that blew off the reactor lid also dislodged special serpentine sand and concrete from within the thick walls surrounding the RBMK. In that same moment, a powerful shockwave forced the entire bottom half of the core assembly – including the lower biological shield – downward by several meters into the space below.


Over the course of about a week, intense heat generated by the fire and beta decay gradually increased until it reached temperatures sufficient to melt the fuel assembly, which poured out and bonded with the sand/concrete mix to form a kind of radioactive lava called corium. This lava then passed through pipes, ducts and between cracks in the damaged structure to the rooms beneath.


This diagram illustrates the event, showing where the fuel came to rest.


A piece of the cooled lava/fuel. I don't know how this man could have possibly approached it, so I assume this was probably taken around 1991, when it wouldn't have been quite so lethal. Even then, he will have had to run into and out of the room immediately.


An image of the ruined turbine hall.


In 1987, global attention turned to the Soviet elite who faced the task of deciding who would be held responsible for the Chernobyl disaster, and what the appropriate response would be. Six men were put on trial in July, including (from front to back), Bryukhanov (plant manager), Dyatlov (Deputy Chief Engineer, and the man responsible for forcing the test to continue), and Nikolai Fomin, the plant's Chief Engineer.


Soviet leaders were supplied information originating from V. P. Volkov, head of the Kurchatov Institute’s RBMK safety research group, which made it very clear that the accident was a result of critical design flaws, but the idea that Soviet reactors were anything less than perfect could never be admitted to the world. The USSR was founded on a belief in science and had always taken pride in being a technological superpower, there was fear among the Council of a possible public backlash against nuclear power, as had occurred in America after Three Mile Island.


The Chairman of the panel of judges had no interest in hearing about defects of the reactor. Scherbina and Legasov’s original government commission had discovered these defects and concluded that the reactor was at fault, but the only sections of their report given any credence by the judges were those criticising the operators. So-called ‘independent experts’ were, in fact, hand-picked men from the various Institutes responsible for the reactor’s creation in the first place – the very same men who had a vested interest in seeing their work exonerated.


All six men were found guilty and sent to prison. Bryukhanov and Dyatlov were released early due to poor health. Chief Engineer Nikolai Fomin was declared insane in 1990, and transferred to a psychiatric hospital. Astonishingly, after he recovered he was allowed to return to work at the Kalinin Nuclear Power Plant near Moscow.


Legasov took a very strong stance against the official story that the plant's staff were entirely to blame. His resistance ruined his career. With his reputation in tatters, his health ravaged by the radiation he absorbed at Chernobyl, his disillusionment with his country’s unwillingness to focus more on safety, and feeling the weight of so many dead on his shoulders, he hung himself on the second anniversary of the disaster – the day after his proposal for a reformed Soviet scientific community was rejected.


Meanwhile, Pripyat lay abandoned, and remains so to this day.




Over the years, animal mutations started to appear – DNA corrupted by the radiation.



None of the machines used during the operation to clean up the zone could ever be used again, as they had become highly radioactive. They lay in vast metal fields for years, before they were gradually taken away and buried in pits.


An image of the Unit 4 control console as it appears today.


The Sarcophagus was never intended as a permanent solution. Rather, the concern at the time was to erect a structure which would confine the radioactive release as rapidly as possible. As a consequence, it never fit together seamlessly and, in any case, only had an estimated life of around 20 years – a time frame which has long since expired. In 1997 a plan funded by 46 different countries and organisations for a replacement – dubbed the New Safe Confinement (NSC) – was set in motion with an estimated cost of €2 billion. Construction began in 2011. Here you can see the first section being raised.


The enormous, one-of-a-kind arch, 250m wide by 165m long, the NSC will weigh a colossal 30,000 tons, and is being assembled from prefabricated sections at a special holding ground 400 metres west of Unit 4. The first half was completed at the end of March 2014, as seen here. Upon completion of the second half, the two pieces will be combined and slid along purpose-built tracks over the existing Sarcophagus. It will be the largest movable structure ever built. Unlike the original Object Shelter, this new confinement has been built to last an estimated 100 years, by which time most of the decommissioning work on Unit 4 should be concluded.


As part of this operation, Chernobyl's iconic chimney was removed last year. 🙁


Pripyat as it appears today. I visited the city in 2011, and found it to be a most profound experience. When I got back I began to research and write a book both about the accident and my own journey there.


The book came from my own frustration at the existing books on the subject, which I found very inaccessible for those unfamiliar with the topic and nuclear engineering in particular. I've now finished writing what I want to write, but I need to hire the services of an editor to polish it. I can't afford to pay for this, so I've had to shelve the project.Since people have been asking me about it a lot today, I've decided to make it available for 24 hours as a physical book. You can find it here: or here: for a hard cover version.


Someone lights a candle at the Chernobyl memorial in Slavutych, the town built to replace Pripyat. Akimov can be seen on the left.

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