30 years ago, one of the largest man-made disasters on Earth took place - an explosion at the 4th power unit of the Chernobyl Nuclear Power Plant. Despite the enormous scale of the catastrophe, radioactive emissions into the atmosphere amounted to only 5% of the total amount of radioactive elements in a nuclear reactor, and 95% are currently buried in the bowels of the destroyed reactor and covered with the so-called. the Shelter object - a sarcophagus built in a record six months between May and November 1986. However, the service life of the facility is about to expire, and it is gradually deteriorating. The total area of the cracks in the structure exceeds 1000m2. At the time of construction, the estimated service life was 30 years.
The New Safe Confinement (NSC) is a multifunctional complex for transforming the Shelter into an environmentally friendly system. The new arch object will run into the 4th power unit of the Chernobyl NPP and the Shelter object along special guide rails in the fall of 2016. The NSC has been under construction since 2007.
The first thermal explosion took place, knocking out the upper part of the reactor - a plate weighing 1,000 tons. A few seconds later, the second explosion finally destroyed the reactor, releasing 190 tons of radioactive substances into the atmosphere, including isotopes of uranium, plutonium, iodine and cesium. Two employees of the station were killed, more than 30 fires occurred.
(c) screenshots from the movie "Moths"
The first object "Shelter". Construction history.
Initially, 18 projects of the protective structure were considered. They can be roughly divided into two groups. The first of them included those in which it was supposed to build an independent completely sealed building of huge dimensions around the block - an arch with a span of 230 m, or a dome with a span of up to 120 m. The second group of projects proposed to maximize the use of the preserved walls and other structures of the destroyed block for the construction of a protective shell. The newly erected walls and roof were to be based on these structures.
The studies and technical and economic calculations showed that the work on the first option will last 1.5-2 years and will require huge costs, while the work on the second will take several months and significantly less costs.
The second approach was chosen. It allowed significant gains in cost and speed of construction (design and construction was completed in 6 months, an unprecedented case in world practice). But this option also required the laying of over 200 thousand tons of concrete and the installation of over 10 thousand tons of metal structures.
The payment for the win was not only the huge collective dose received by the builders and installers, but also the fundamental shortcomings of the facility itself. The need to erect new structures in the immediate vicinity of the destroyed block in huge radiation fields forced the use of remote technology. It was impossible to use welding to connect many critical structures, and remote mounting did not allow large metal structures to be fitted exactly to each other.
All this was the reason for the first of the major drawbacks of the "Shelter" - leaks, a large number of cracks (their total area, according to subsequent calculations, was estimated at 1000 m2).
Radiation fields and rubble did not make it possible to assess, according to all the rules, the strength of many of the supports - old structures that had been exposed to an explosion and fire. And the main bearing beams of the structure under construction were based on these structures.
The use of remote concreting methods has led to the fact that large masses of concrete did not hit the designated place. They leaked into the destroyed building, making it difficult or even impossible to enter many premises and to reconnoitre them.
The second drawback is the undefined strength of the supports supporting the main load-bearing beams of the Shelter. As for the newly erected structures - load-bearing beams, pipe run over the central hall, steel roof panels, etc., they were designed and executed in accordance with building codes and regulations, therefore, the strength of these structures themselves is beyond doubt. Their durability is limited by the lack of the possibility of periodic inspection and restoration of the anti-corrosion coating. Therefore, in the "Conclusion on the reliability and durability of the coating structures, as well as the radiation safety of the reactor compartment of unit N4 of the Chernobyl nuclear power plant", presented to the Government Commission on October 11, 1986, it is said:
"Considering the low corrosion rate under the operating conditions of structures, with the completed protective coatings, their service life can be considered ensured:
- from pipes 30-40 years old,
- from beams for 30 years. "
Unfortunately, later these figures were often called for the service life of the entire object, and not only for the bearing capacity of new metal structures, and the time of 30 years was indicated as the guaranteed time of the safe state of the Shelter object.
After the first work on cleaning the area around the block, construction began on the perimeter of the 4th power unit of "pioneer" protective walls made of reinforced concrete: about 6 meters high - from the side of the dam (northern side of the block) and about 8 meters - from the southern and western sides.
"Pioneer" protective walls were designed to ensure the safety of construction and installation work on the construction of the "Shelter".
Inside the building, the first steps in the construction of the Shelter were the erection of partitions and walls separating the damaged 4th block from the 3rd block.
27 metal pipes with a diameter of 1220 mm and a length of 34.5 m are laid on the beams, and a roof made of profiled flooring is arranged above the pipes - 6 spatial blocks:
The Shelter object was accepted by the government commission in December 1986.
Shelter object. 30 years later.
The peculiarities of the Shelter object are determined by its potential hazard, which is much greater than allowed by the norms and rules for facilities containing nuclear and radioactive materials. The situation is further complicated by the fact that the safety assessment of any nuclear power and industrial facility is based, as a rule, on the practical experience of operating such or a similar facility. "Shelter" has no similar analogues.
From 1986 to the present day, no more than 60 percent of the premises of the Shelter (Block B) have been investigated. The rest of the premises are inaccessible either due to high radiation fields, or due to impenetrable barriers that arose during an explosion that resulted in the destruction of structures and the appearance of lava-like fuel-containing materials, as well as when concrete was pumped during the period of direct construction of the Shelter. Thus, a significant part of the object remains an unexplored area, which is one of the most serious risks today.
The potential danger of the Shelter object for the environment and humans is determined by the following factors:
The presence of nuclear materials in the amount of about 185 tons, in relation to which there are no means of active influence on their criticality, and the absence of reliable physical barriers to the spread of radioactivity into the environment. Today it can be considered established that about 95% of the fuel that was in the reactor at the time of the accident remained inside the Shelter. Now its total activity is approximately 16 million curies. It has been established that the irradiated nuclear fuel inside the Shelter is in the form of the following modifications:
Fragments of the core (APF);
- lava-like fuel-containing materials (LFCM);
- finely dispersed fuel (dust), hot fuel particles;
- secondary uranium minerals formed from solutions of FCM in the form of crystalline new formations.
As a result of the 1986 accident, part of the structures of the reactor block, deaerator stack, turbine hall and others were destroyed. In the western zone, the wall has a deviation in the western direction up to 50 cm, in some places it has faults. Such a condition in the event of an earthquake of 4.3 points on the Richter scale can lead to the fall of part of the roof of the "sarcophagus". In the southern zone, above the 24.3 m mark, the deaerator stack frame, which holds a significant amount of debris and building materials, deviated from the vertical by about 1.5 m. And although during the construction of the sarcophagus this place was reinforced with metal supports, calculations show that in In the event of an earthquake, there is a risk of their falling towards the turbine hall, which will entail the release of radioactive dust into the environment through the formed fault. Scientists have calculated that the value of the probable risk of such an event for 1 year is 0.24, which significantly exceeds the standard value recommended by the IAEA for nuclear power facilities.
As a result of the high level of humidity in the Shelter's premises, reinforced concrete structures are saturated with water, which leads to their gradual destruction. Steel structures are largely damaged by corrosive processes. The deformation process continues. Analysis of the state of building structures indicates the presence of critical zones that are sensitive even during small earthquakes and other natural phenomena that are possible in the conditions of the location of the ChNPP industrial site.
On February 12, 2013, several hanging slabs collapsed over the power unit's turbine room, the collapse area was about 600 square meters
In 2011, the old pipe was dismantled, immersed under the sarcophagus, after having dismantled part of its roof. And they built a new ventilation pipe.
Model of the 4th power unit of the Chernobyl NPP and what is now under the Shelter object:
New Safe Confinement (NSC)
The New Safe Confinement is a multifunctional complex for transforming the Shelter Object into an ecologically safe system.
According to the conceptual design, the NSC includes: - the main structure, consisting of an arched structure, the span of which in the north-south direction is 257.44 m, height 108.39 m, length 150 m, foundations, western and eastern end walls, necessary support and auxiliary systems;
- technological building, which includes areas for decontamination, fragmentation and packaging, sanitary locks, workshops and other technological premises;
- auxiliary facilities.
Construction began in 2007. Initially, it was assumed that the project would be ready by 2012-2013, but due to a lack of funding, the launch date of the facility was pushed back to 2017.
The main functions of the NBK:
1. Limitation of radiation impact on the population, personnel and the environment by established boundaries, both under the condition of normal operation of the Shelter object, and in the event of a violation of normal operation, emergencies and accidents, including accidents in the process of dismantling unstable structures and future handling of fuel materials (FCM) and radioactive waste (RW).
2. Limiting the spread of ionizing radiation and radioactive substances that are inside the OS.
3. Technological support, that is, creating conditions for dismantling unstable structures, future extraction of fuel and lubricants and radioactive waste, removal of accumulated water, ensuring the implementation of measures for the control and maintenance of the Shelter and its industrial site.
4. Control of all parameters of the "Shelter" object state and control of technological processes.
5. Physical protection, that is, preventing unauthorized access to FCM and radioactive waste and ensuring the functioning of the IAEA safeguards system.
NSC construction stages:
The history of the Arch installation began on February 13, 2012, when the first batches of the main metal structures were delivered to the ChNPP site.
The first lift was carried out on November 24, 2012, as a result of which +5300 tons of metal structures were successfully lifted. The height of the Eastern part of the Arch after the first jacking up was 53 meters.
The second lift was performed on June 13, 2013 The operation was successful. At that time, the mass of the structure was 9100 tons.
The third ascent of the Arch differed from previous operations, therefore it included several stages. The first stage is jacking up the Arch to a height of no more than 110 meters. This operation was performed on September 14-16, 2013. After that, the installation of the side segments of the arch, as well as the supporting parts, was carried out. At the same time, the Arch was in limbo. In parallel, the tracks of the approaching and other auxiliary structures were mounted on the foundations of the assembly zone. On October 11, 2013, the process of transferring the load from the Arch to the foundation was performed.
On July 24, 2015, the connection of the western and eastern parts of the Arch was completed.
In 2016, the following works are being carried out:
Installation of metal structures is in progress (metal structures) Arches
- Delivery of steel structures of the arch to the site is in progress.
- The delivery of elements of the eastern bridge of the main crane system is underway. Contractor is performing reverse structural collection of the east bridge.
- Work is underway to arrange the external and internal space of the NSC: External underground engineering networks (construction part: power supply, water supply and sewerage, cable laying).
In November 2016, it is planned to move the Arch to the Shelter object of the 4th power unit of the ChNPP.
The design life of the NSC is 100 years.
Here is a very visual short one-minute video about the construction process and the idea of Confinement:
https://www.youtube.com/watch?v=MPYcU7Uno9o- follow the link to YouTube if the video is not playing.
The territory of NSC installation can be entered only on such a retro LAZ:
This is how the NSC Arch and the 4th power unit look now from different sides.
The NSC service life is 100 years. At the moment there is no understanding, not everything is clear with the technologies that can be used to clean the contents of the Shelter object and everything that is buried under it. They talk about the possible use of robots for work in the future under the roof of the NSC.
Chernobyl nuclear power plant today.
This is an aerial panorama.
Chernobyl and Pripyat.
I took this footage from a Kiev-Vilnius plane a couple of years ago.
It is only 2 km from the center of Pripyat to the 4th power unit of the Chernobyl nuclear power plant. He possesses some kind of inexplicable magnetism, in the exclusion zone you always gaze at this technogenic monster.
If you are planning a trip to Chernobyl and Pripyat, be sure to be in time before the end of this year! According to the construction schedule of the NSC (New Safe Confinement), the arch will cover the 4th power unit of the Chernobyl NPP in November 2016, and it is worth seeing it in its current state 30 years after the disaster.
But the photo on the left in the distance is the 4th power unit and the sarcophagus, on the right is the arch of the NBK, which will run over the old sarcophagus along the rails in the fall.
I am under the New Safe Confinement Arch.
Here, from me to the 4th power unit of the Chernobyl Nuclear Power Plant, 400 meters.
The radiation level here is as follows:
The Chernobyl nuclear power plant currently employs 2,400 employees who work on a rotational basis, staying in the exclusion zone of the Chernobyl nuclear power plant for 15 days and living in the city of Chernobyl. The last operating reactor of the Chernobyl NPP was shut down in 2000, but the process of their decommissioning will take place until 2063.
Another 800-1000 people are employed daily in the construction of the NSC facility.
ChNPP Administration:
Another 200 people are involved in the construction of ISF-2, this is the second large construction site on the territory of the Chernobyl nuclear power plant. HOYAT-2 is a "dry type" Spent Nuclear Fuel Storage Facility. The storage facility will be put into operation this year, the goal is to store and dispose of 23 thousand nine meter rods with nuclear fuel, which were used in the operation of the Chernobyl nuclear power plant, which are now stored in water reservoirs.
Such a train with a special container car for transporting nuclear fuel rods between power units and ISF-2 is already being tested at the Chernobyl NPP. I will talk about the construction of ISF-2 in one of the following reports this week.
Pripyat.
Pripyat is a unique place!
From the rooftops of sixteen-story buildings, the nuclear power plant is in full view. You can visually assess the size of the arch - the new safe confinement. A must-see for everyone who loves abandonment and industrial. I was here in 2006, 10 years ago, and I see how, over this decade, nature is slowly but surely winning over man. Trees sprout buildings, asphalt turns into grass.
Last year, 17 thousand tourists visited the Chernobyl exclusion zone. Tourism is one of the main vectors of development for the coming years as part of the exclusion zone rebranding program.
I will tell and show you tomorrow how Pripyat looks like 30 years after the evacuation of the population.
To be continued...
The consortium of French construction companies "Novarka" on Tuesday, November 29, completed the process of installing a new safe confinement (NSC) - an arch-sarcophagus, which should protect the fourth power unit of the Chernobyl nuclear power plant, destroyed during the disaster in 1986. According to Interfax, according to the project, the service life of this facility is designed for 100 years and cost 1.5 billion euros.
“We welcome the completion of this phase of the Chernobyl NPP transformation as a symbol of what we are able to achieve together through strong, decisive and long-term efforts. We applaud our Ukrainian partners and contractor, and we also thank all the donors of the Chernobyl Shelter Fund, whose contributions have made today's success possible. This spirit of cooperation gives us confidence that the project will be completed on time and within budget in one year, "said Suma Chakrabarti, President of the European Bank for Reconstruction and Development (EBRD), quoted by RIA Novosti at the ceremony.
The Ukrainian president, Petro Poroshenko, was not left out of business either, saying that the "Russian threat" was worse than the Chernobyl disaster. "No one could have imagined that the Chernobyl test would not be the worst and not the worst that Ukraine would have to go through. And that Ukraine is building an arch and a safe confinement in a war, when it is defending itself from Russian aggression," Poroshenko said.
The construction of the new sarcophagus is financed by a special fund managed by the EBRD on behalf of international donors, the largest of which is the European Union, which has so far allocated 750 million euros for Chernobyl projects.
EU High Representative for Foreign Affairs Federica Mogherini, Deputy President of the European Commission for the Energy Union Maros Sefcovic, EC Member for Neighborhood Policy and EU Enlargement Negotiations Johannes Hahn, EC Member for International Cooperation and Development Neven Mimica and EC Member for climate and energy Miguel Arias Cañete.
It is reported that all NSC systems are planned to be tested until November 2017, after which the arch will be put into operation. Next, Ukraine will have to dismantle unstable structures and extract fuel-containing materials in order to turn the nuclear power plant into an environmentally friendly facility.
However, today the Minister of Ecology and Natural Resources of Independent Ostap Semerak told reporters that Kiev would ask international partners to assist in dismantling the damaged power unit. "I would like to say that we expect technical support, scientific support, technical support in the dismantling of the fourth power unit," he said, noting that it would be difficult for Ukraine to cope with such a task on its own.
In the fall of 2015, Bouygues and Vinci, members of the consortium, completed the preliminary assembly of the arched sarcophagus, then it was disassembled and delivered to the station, where it was reassembled in a clean area near the 4th power unit of the Chernobyl nuclear power plant and, with the help of a special system, was "pushed" onto the object.
According to Bouygues, the arch is larger than Paris' Stade de France, weighing five times the weight of the Eiffel Tower. The height of the new sarcophagus reaches the level of an approximately 30-storey building - 110 m, the length of the structure is 165 m, and the weight is 36.2 thousand tons.
The body of the arch will be covered with a special covering, which will protect the old sarcophagus from external influences and will serve as protection for the environment and the population. The building will also be equipped with a high-tech ventilation system and a temperature and humidity control system.
Recall that on April 26, 1986, the fourth power unit of the Chernobyl nuclear power plant exploded. During the first three months after the accident, about 30 people died. Almost 8.4 million residents of Belarus, Ukraine and Russia were exposed to radioactive exposure. Around the Chernobyl nuclear power plant, a so-called 30-kilometer exclusion zone was created, from which two cities were completely evacuated - Pripyat and Chernobyl, as well as 74 villages.
The first sarcophagus ("Shelter") above the emergency power unit was erected shortly after the explosion, but in recent years the structure began to collapse.
The first sarcophagus, the Shelter object, was erected over the fourth block destroyed by the explosion of the reactor at the cost of life and health of 90 thousand workers in record time - 206 days from the moment of the accident and was put into operation in November 1986. This was done to prevent the spread of radioactive elements throughout the world. Indeed, according to scientists, 80% of the total amount of radioactive elements contained in the reactor still remain under the sarcophagus.
The sarcophagus of the Chernobyl nuclear power plant is designed for 30 years
The Shelter Object was originally supposed to be only a temporary solution to the problem of the spread of radioactive substances - its service life was calculated for 30 years.
But what is hidden inside the Chernobyl sarcophagus
There are many rooms and rooms under the sarcophagus. Some of them were created after the accident to service the sarcophagus and carry out all kinds of measurements and research - as a rule, they are separated from the destroyed reactor hall by thick concrete walls through which radiation does not penetrate. Another part of the rooms is the former premises of the Fourth Power Unit. It was possible to penetrate into some of them only in the early nineties, I came across descriptions of these rooms - "rickety ceilings, traces of soot on the walls, furniture moved from the explosion, a thick layer of dust on all objects, a background radiation of about 2 roentgens per hour." And in the third rooms (especially in those rooms that are located under the reactor hall) it has not yet been possible to get into what is happening there now - no one knows.
ChNPP reactor hall:
And the reactor hall itself looks something like this. The photo shows a concrete reactor lid, which was thrown by an explosion in 1986, and it fell back in this position. The tubes protruding from the cover are the so-called fuel assemblies, and the cone-shaped elements on top are sensors-monitors for monitoring radiation levels.
Dosimetrists under the sarcophagus of the Chernobyl nuclear power plant:
Dosimetrist Alexander Kupny and his colleagues have repeatedly descended under the rubble of the fourth power unit of the Chernobyl NPP. The radiation levels are high there. Protective suits and masks must be worn. It is impossible to stay in the sarcophagus for a long time. This can be very harmful to your health. But you need to check the status of the Shelter in any case.
Fuel masses under the Chernobyl sarcophagus
After the accident, about 80% of the fuel masses remained under the Shelter, which have a high radioactive background. In 1986, all this was poured with concrete and lead. So everything has remained to this day.
On April 26, 1986, a reactor exploded in the fourth power unit of the Chernobyl nuclear power plant, located on the territory of the Ukrainian SSR. More than half a million people were involved in the liquidation of the accident. Many of them seriously undermined their health due to radiation, some died in the first months after the start of work.
In terms of economic damage, the number of people killed and injured, the accident is regarded as the largest in the nuclear power industry.
The idea to close the torn vent of the reactor arose almost immediately after the explosion. By November 1986, the Shelter, better known as the Sarcophagus, was erected over the fourth power unit. Installation work was supervised by Soviet engineer Vladimir Rudakov. Like many other liquidators, he soon died from the effects of radioactive exposure.
The old sarcophagus was, in fact, a large concrete box (it took 400 thousand cubic meters of concrete mix and 7 thousand tons of metal structures to build it). Erected in a hurry, it nevertheless held back the further spread of radiation from the reactor for 30 years. However, its floors and walls were already dilapidated and began to collapse: for example, in 2013, suspended slabs with an area of 600 sq. m above the machine room. According to the authorities, however, this did not entail an increase in the background radiation. But
there are about 200 tons of radioactive materials under the roofs of the sarcophagus, and further destruction can lead to serious consequences.
The first sarcophagus has another serious drawback: its design does not allow working with radioactive waste accumulated inside. But until all the stuffing of the exploded reactor is removed and disposed of, this object will remain dangerous. In addition, the sarcophagus had to be protected from rain and snow, which could cause unforeseen chemical reactions.
Construction of the second sarcophagus began in 2007. It was planned that it would be a movable arch that would cover the reactor along with the old sarcophagus, after which it would be possible to dismantle, decontaminate and dispose of the remains of the power unit. Initially, the project was going to be completed by 2012/13, but the deadline has shifted due to financial problems.
A new sarcophagus, called the "New Safe Confinement" (from the English. сonfinement- "restriction"), became the largest ground mobile structure.
The funds for the project were allocated by Ukraine, Russia and a number of Western countries. In total, more than $ 2 billion was spent on the construction. The work was supervised, and the technical contractor was the French company VINCI Construction Grand Projects, part of the Bouygues group of companies, one of the largest construction companies in Europe. On account of Bouygues - the construction of a tunnel under the English Channel, the construction of Terminal 2 at Charles de Gaulle Airport, the reconstruction of the Main Building in Moscow and many more projects.
The service life of the new Shelter is estimated at 100 years. Its length is 165 m, height - 110, width - 257. The structure weighs 36.2 thousand tons. About 3 thousand workers were engaged in the construction. Since it was dangerous to build an arch directly above the old sarcophagus, it was erected piece by piece at an assembly site near the power plant. The assembly and lifting of the elements of the first half of the arch lasted from 2012 to 2014; by 2015, the second half was also assembled. After that, both parts were connected into a single structure. By November 2016, the installation was fully completed.
On November 14, the process of sliding the arch onto the power unit began. Over the course of several days, the arch was slowly moved with the help of jacks along special rails. Finally, on November 29, the push was successfully completed. On this occasion, the authorities held ceremonial events with the participation of politicians and representatives of the curator bank.
“Let everyone see today what Ukraine and the world can do, uniting, how we can protect the world from nuclear pollution and nuclear waste”,
- said the President of Ukraine at the ceremony.
During the construction, the workers faced certain difficulties. In particular, they had to dismantle the ventilation pipe through which air was supplied to the buildings of the third and fourth power units. The pipe suffered from the explosion of the reactor and could fall on the roof of the sarcophagus at any moment.
For dismantling, a special super-heavy German crane with a lifting capacity of 1.6 thousand tons had to be used. The pipe was successfully cut into six fragments, dismantled and buried in the building of the 3rd power unit. Almost $ 12 million had to be spent on these actions.
The new sarcophagus is planned to be commissioned in another year, by November 2017. During this time, the equipment will be connected and tested, the structure will be sealed and transferred under the control of the ChNPP administration.
