 This video is the third in a series on the Chernobyl disaster. The first video started with the precursor event, the Leningrad 1975 meltdown. The second video, titled Chernobyl Part 1, covers the fateful failure of the RBMK at Chernobyl Number 4. And finally, this video, which will look at the aftermath and clean up from one of the world's worst pollution events. I'd recommend watching the previous two videos if you haven't done so already. But now, let's begin the final episode of my Chernobyl series. It is February 2022 and Russian soldiers have crossed the Belarusian-Ukrainian border and have been ordered to occupy the Chernobyl Exclusion Zone. The site offers political capital in the Russian invasion. It has the potential to be a future bargaining chip for any negotiations, but maybe more importantly, it represents a logistic benefit. In that, it is in a direct line between Belarus and Kiev. The Ukrainian guards are arrested and bundled into a basement. The technical staff, however, are allowed to continue their work keeping the site relatively safe. All around the site of the 1986 Chernobyl disaster, Russian soldiers dig in. They excavate trenches and make dugouts. Either from ignorance, blindly following orders, or the fear of catching a Ukrainian bullet have led these men to be digging up some of the world's most contaminated soil. Reportedly, they even dig up parts of the infamous Red Forest, although an estimated 1500 soldiers have been told to hold the area, a reported 10,000 vehicles have driven through the Exclusion Zone, potentially spreading contaminated soil for hundreds of miles. Towards the end of March, and with hopes of a lightning invasion of Ukraine fading away, the soldiers are ordered to withdraw. This is the most recent chapter in the Chernobyl story, but it only represents a small part of the legacy that continues to cast a shadow over the region. My name is John and today we're looking at the cleanup and containment of the Chernobyl nuclear reactor disaster. It is April 1986 and Soviet authorities are desperately trying to take stock of the unfolding nightmare at Chernobyl nuclear power station. In the immediate days and weeks after reactor 4's failure, focus was firmly put on trying to contain the spread of radiation. This involved the use of personnel to remove debris from the turbine hall roof in preparation for the construction of the sarcophagus, as well as miners working below the reactor hall to install a shield to prevent the core from melting through to the water table. These people were known as the liquidators, but as I alluded to in my previous video, this was just the tip of the human iceberg. You see the term liquidator is actually a bit of a catchall that covers the first response teams all the way to the police, on the streets, directing personnel and vehicles. And the doses they received reflected the work they undertook, with an official death toll of 28 from radiation sickness in 1986. Some 600,000 would be involved in the wider region cleanup activities between 1986 and the present day, but in the immediate aftermath of the core uncovering and 10 day fire, a massive region wide project was beginning to form, in evacuation and decontamination of a 30 kilometer radius exclusion zone. The Soviet authorities were eager to begin cleaning activities as quickly as possible. In a case of trying to snatch some kind of victory from the jaws of defeat. If the affected regions could be repopulated quickly, then maybe, just maybe, it would soften the international embarrassment and reclaim some glory for the socialist utopia the USSR claimed to be. However, this ambition to clean up as quickly as possible came at a cost, much like the men sent to top the roofs of the reactor buildings to collect contaminated rubble, the exclusion zone would require people, and lots of them, to work for hours, days, weeks and months on end amongst the fallout. Needless to say, the health of many would become a long lasting legacy. The exclusion zone was initially an arbitrary 30 kilometer radius around reactor 4, and was split up into 3 areas, and as such, different protective clothing and precautions were required, the first of which was a 10 kilometer radius around the nuclear plant, and was designated the black zone. This had radiation levels of over 200 microcevets an hour, if you were evacuated from here, you'll never be allowed to return home. The next area was called the red zone, and had radiation levels of between 50 and 200 microcevets an hour, and here evacuees might be able to return once radiation levels normalize. The final area was the blue zone, with levels between 50 and 30 microcevets an hour. Here, children and pregnant women were evacuated throughout 1986. The region was home to approximately 120,000 people, spread out amongst Pripyat, the city built for the workers at the plant, Chernobyl, and just under 200 smaller settlements. A total of 92,000 would be evacuated throughout the summer, but the number would rise in the wider region, with children being evacuated as far away as Kyiv. As a side note, the exclusion zone was home to a pretty horrific local landmark, known as the Partisan Tree, and was essentially used by the Nazis as their very own Ukrainian Tibern Tree. Soviet soldiers and partisans were hung from the tree during the Second World War by the invading Germans. It is an extraordinary looking tree, I mean just look at this picture. It is the stuff of nightmares, and actually survived 1986 by quite a few years, all the way into the 1990s, surprising as it was only 1600 meters from reactor 4. Its striking trident shape became somewhat of a local icon, but I digress. As time went on, the boundaries of the zones began to follow the areas more contaminated than arbitrary lines on the map. You see the wind in the following days and weeks after the disaster dictated the hot spots of contamination. Although the plant was in Ukraine, some of the most affected areas were in Belarus. As time went on, the exclusion zone would expand, encompassing an area of 2,600 km2. But contamination wasn't limited to just the exclusion zone. Officially to enter the exclusion zone, you would need to pass multiple checkpoints and sanitation stations. The closer you got to the black zone, the more protective equipment was required from a simple mask at the end of the zone to full hazmat towards the epicentre. But as the full scope of the cleanup work became ever more apparent for the liquidators, some of these rules were relaxed. The zone by the summer increasingly looked like a military camp, with cleanup teams billeted in tents. Some higher-ranking officials, however, had taken up residence in the abandoned city of Chernobyl, where the nuclear power plant got its name from. As April gave way to May, and some of the areas had been evacuated, the mass clean-up began. The task of cleaning up the area would officially, and I say in quotation marks, start off by a team of dosimetrists driving through the area in a specially shielded vehicle. They would work out the safest way to enter and exit an area. As well as get readings of the radiation any workers would be exposed to. This would determine how long a worker could operate in an area. A limit of 25 runtguns was set. Once this was reached, the worker should be rotated to a different role away from any contaminated area. Although in reality, this limit was exceeded, where the ready supply of willing volunteers gradually dwindles away. Once given the okay to enter, liquidators would have a free-stage process of cleaning up. The first was to remove the top layer of soil. The official depth was 30 centimetres, but reports seem to suggest that as little as 10 centimetres was taken in some places and as much as 50 centimetres in others. Ranging from hand tools up to diggers, the liquidators removed the soil and placed it into metal containers that were sent to a radioactive waste dump. The soil was contaminated with but not limited to strontium 90, cesium 137 and plutonium. The next stage was to soak everything, houses, roads, heavy equipment and vehicles in a special solution. The water then was as best as possible collected and again placed in metal containers to be sent to a waste facility. The final stage was to spray the ground with another solution which created a film to encapsulate radioactive dust to then be scooped up and again sent to a waste facility. But that is really just the tip of the iceberg. In many areas within the exclusion zone, houses had to have their roofs removed and replaced, roads had to be machine washed or even re-asphalted, fences replaced, water pipes removed and replaced and new wells dug. Up to 60,000 buildings were cleaned including 500 population centres of varying sizes. Conditions for the workers were not great, which led to many volunteers refusing to work. Every person was meant to be issued with a personal dosimeter, but unsurprisingly due to the vast scale of the cleanup project, this didn't happen. Many continued to be housed or better described not housed in tents, even after proper accommodation was apparently allocated. In November 1986, control of the cleanup and remediation project was taken over by a new production association, COBINAT. The organisation was based in Chernobyl City and was tasked with operating and decommissioning the NPP. Continuation of decontamination efforts, run the supply lines into the zone and oversee the construction of a new city outside the zone for displaced persons. The city would be called Slavutage, but we will come back to this a bit later. One of the most polluted areas known as the Red Forest, 10 square kilometres of woodland had its pine trees bulldozed and buried. The area was then covered in sand and replanted with new pine saplings. The area got its name from the colour the trees went after becoming contaminated and subsequently dying. But where did the liquidators come from? Well really, it was a mixture. The initial attendants were ordered to be there, for example the firefighters, miners, transport workers, police and military personnel. Reservists were also employed and any who refused were socially and politically punished. But a large proportion were volunteers. Some were drawn by the money on offer, others a sense of public duty, and many were students, training to become firefighters, police or ambulance workers. There were many cases of liquidators keeping on working past their 25 runtkins due to the lack of replacement and with others continuing due to bravado. The overexposed liquidators have cast a long shadow over the region and has become a medical and social issue even till today. It is estimated that 600,000 people deemed liquidators took part in the cleanup. Needless to say, this has proven a terrible headache for healthcare infrastructure in the region. Liquidators would work on different parts of the exclusion zone for many decades to come. Strangely, although abandoned, Pripyat Swimming Pool was kept in use until 1998 for exercise for inner zone workers. Depending on who's asked, the time required for the exclusion zone or locally known as a zone of alienation to become habitable again ranges from between 320 and 10,000 years. The former figure was from the Ukrainian government and the latter from Greenpeace. Wildlife within the exclusion zone flourished with nature taking back the previously human occupied areas. With no pesky people around to encroach upon their habitat, animals populations have soared. With even bear sightings, animals that were pretty rare pre-1986, studies on birds from the more contaminated areas have shown to have smaller brains than that of species from healthier areas. Vutation deformations have been observed and population densities are noted to be lower in higher contaminated areas. Throughout the cleanup of the different zones and their eventual return to nature, the Chernobyl nuclear power plant loomed in the distance, including its often forgotten still running reactors. But what of the other reactors? The self-deconstruction of Unit 4 didn't negate the need to safely operate the other three operational reactors. It didn't even immediately put an end to Units 5 and 6 which were planned and under construction. Based with the prospects of energy shortages, reactors 1, 2 and 3 were allowed to continue operation by the local authorities. The USSR had no choice anyway as its economy wasn't in the best shape and with nuclear power any option would cost a lot of money. If they shut down and decommissioned the reactors, they would incur the cost of dismantling and dealing with the waste, something that has recently started at the Dungeon S nuclear power plant in Kent. Needless to say, they needed more nuclear waste like a hole in the head. Also, once gone, where are you going to get a power source to pick up the deficit the closure of Chernobyl would create? You'd have to build multiple more conventional power plants, all of which costs money. This left, at least for the short term, the less costly option of keeping the remaining reactors online. Because at Chernobyl the reactors were of two designs, being that 1 and 2 were of first generation and 3 and 4 were of second generation, RBMK, the units were paired up. This meant to safely operate Unit 3, the connecting areas with 4 had to be filled in with concrete, but the early 90s would see another accident at Chernobyl. Just a couple of months after Ukrainian independence was declared, Unit 2 experienced a fire in its turbine hall on the 11th October 1991. The event wrote off Unit 2, resulting in it requiring decommissioning. The fire showed the ongoing risk of operating the plant. The first generation RBMK design was showing its age, and after the fire was most certainly proving to be a liability. Because of this, a deal was struck between several international agencies, including the IAEA, requiring Chernobyl NPP to be shut down and decommissioned. This started in 1996 with Unit 1 going offline, followed by Unit 3 four years later. On the 15th December 2000, the president of Ukraine, Lenid Kuchma, turned off reactor number three in an official ceremony. Although now officially shut down, there was an even bigger issue to deal with. All of that used fuel. The origin site was not sufficient for all the additional waste, meaning a new site was required. In 1999, a contract to construct a dry waste management area designated ISF-2 was signed. 12 years later, construction began, being completed in 2017. ISF-2 became the world's largest nuclear fuel storage facility, and is estimated to be able to hold more than 21,000 fuel assemblies for at least 100 years. I mentioned in my Chernobyl Part 1 video the construction of the sarcophagus, but this wasn't the magic bullet of containment. I mean, it wasn't ever intended to be permanent, because of the speed in which it was built, and the amount of radiation it would be subjected to, that would eventually cause damage to the structure. Such intensity was the radiation during the sarcophagus' construction. That crane operator cabs had to be lined with thick lead shielding, and even then working times were closely monitored. The sarcophagus made use of some of the walls of the reactor building to support the main roof beam. This helped with the speed of installation, and although reinforced in places, serious damage had been received during the accident. Multiple boreholes were drilled into the roof to facilitate exhausting and filtering of radioactive gases. When it was completed in November 1986, the sarcophagus held in 200 tonnes of reactive lava-like corium, 30 tonnes of highly contaminated dust, and 16 tonnes of uranium and plutonium. By 1988, assessments of the structure showed its life expectancy to be a maximum of 30 years. This was probably ambitious, and as such, the international community started to show signs of wanting to help. Soon enough, a more refined form of confinement was beginning to be conceived. The sarcophagus was the best in a bad situation, and a new safe confinement was intended to go over the sarcophagus and the reactor building. After being successfully installed, the original confinement structure will then be demolished. It is truly an impressive idea, requiring the newly independent Ukrainian government to hold an international competition for proposals to replace the sarcophagus in 1992, but it would take over a decade of planning and design competitions. But in 2004, a tender was announced, generating two bids. Sadly, this wouldn't lead to much. Eventually, a consortium of French companies would be awarded the contract in September 2007, 21 years after Unit 4 turned its fuel into molten lava. Construction costs were estimated at $1.4 billion, with a project timeline of five years. Spoiler alert, they may have had to have doubled that. But let's look at the design of the new confinement structure. The 100-year life expectancy structure consists of 13 arches, assembled 12.5 meters apart, with a height of 110 meters. Between the arches, a tubular steel lattice was built, which was then clad with three layers, totaling a thickness of 10 meters. Polycarbonate panels cover each arch to prevent the accumulation of radioactive particles, and warm air is circulated to reduce the risk of corrosion. The structure's width is 165 meters, and is long enough to cover the entirety of Unit 4 and its sarcophagus. The height is oversized to allow machinery to be attached to the arches to allow for dismantling of the original structure. Even more fascinating is that it was built not over the reactor, but to its side, meaning that upon completion of construction, it was designed to slide over Unit 4. It was built on retaining walls independent from the damaged reactor building, allowing for a full demolition of the old structure. Construction began in 2010 and two years later the first steel sections were beginning to be erected. In April 2014, the first steel section was moved into a parking position to allow further arch construction. And two years later, in April 2016, the final arch was completed. Just a few months after that, the vast structure was getting ready to be moved into its final resting place. After 15 days of movement, on the 29th November 2016, the new containment structure was in position. But yet again, another two years would be needed to finish off the project officially, when it ended in July 2019 with the sarcophagus being sealed under the monumental steel structure. At the time of its movement, it was the largest movable man-made structure in the world, and the project's final price tag was over 2.1 billion euro. Although delayed, it is a success. But this only marks the start of the reactor's dismantling project. Dust within the shelter is constantly monitored with hundreds of sensors all throughout the structure. The radiation exposure of staff is recorded and tallied up, allowing for a maximum yearly dose of 20 millisieverts, or apparently 12 minutes of standing on the sarcophagus roof. So far, the whole disaster has cost $68 billion and has affected millions of lives, and it looks like it will continue to do so. Less than 100 deaths are officially linked to the disaster. But the long-term effects have caused increased numbers in thyroid cancers, birth defects and infant mortality. In 2019, a gradual but worrying rise in neutron rates started to be recorded. These were thought to be coming from the depths of the damage fuel in the reactor hall. It is thought, strangely, that the drying of water in the reactor hall basement, instead of stopping a chain reaction by removing a moderator, was actually doing the opposite. Although to much relief, the steady increase of neutron started to peter out in 2021. Unit 4's ability to surprise the international community is clearly still a looming spectre, reminding us we still aren't finished. Covid, of course, affected work on sites slowing down remediation works. But just as we thought things couldn't get any worse, the risks of one of the world's most contaminated sites came back into the news headlines. And this brings us back to the Russian soldiers in the exclusion zone. During the initial occupation of the Ukrainian-Russian war, power was cut to the power station for three days, requiring technicians to beg, borrow and steal fuel to power generators. But with Russia changing its target from Kyiv to the Donbas, soldiers left the exclusion zone. Their occupation has made the site far more dangerous, as in their wake, landmines and contaminated equipment has been left behind. But although the occupation of the region represents a political and environmental disaster, amazingly scenes of defiance were shown in the city of Slavych, the home of many evacuees from Pripyat. Russian troops entered the city and detained the mayor Yuri Formityev. Outrage by this, locals took to the streets to protest the occupation. Even flashbangs and warning shots from the Russian forces failed to disperse the crowd. Seeing such resistance to occupation, the soldiers agreed to leave and release the mayor. After the Russian withdrawal from the exclusion zone, Ukrainian soldiers and National Guards went into examine the abandoned dugouts and trenches. Little precautions seem to have been taken by the soldiers and it is likely this will come back to haunt them in later life. Some of the radiation monitors found dates back to the 1950s and were far from capable of providing any benefit. Contamination is likely to be spread to Belarus throughout Ukraine and even back to Russia. Chernobyl would likely be in news cycles for decades to come as political, scientific and economic uncertainty can all affect the management and clean up operations. Right work goes without saying with such a massive disaster as Chernobyl, this video is just the tip of the molten uranium iceberg and I strongly recommend having a look at the references in the video description for further reading. This should be my last video on Chernobyl but will probably change when we find out the true scale of the Russian army's contamination spread.