In the early hours of April 26, 1986, a nuclear power plant in Ukraine exploded, shattering the silence of the night. This loud bang shook not only the Soviet Union, but also the whole world. The 4th reactor of the Chernobyl nuclear power plant suddenly burst, and tons of radioactive material were ejected, instantly turning an area of tens of kilometers into a danger zone. The Soviet government reacted quickly, immediately sending thousands of buses to evacuate the population and mobilizing a large number of planes to begin covering the reactors to control the spread of radioactive dust. Yet, as hundreds of planes flew over the plant, rescuers were confronted with an invisible enemy – the ubiquitous radiation. Tens of tons of concrete capping, thousands of sorties, what is the cost?
The moment of the explosion of the Chernobyl accident
At 1:23 a.m. on April 26, 1986, in the area of the 4th reactor of the Chernobyl nuclear power plant in the city of Pripyat, Ukraine, the quiet night was shattered by a huge explosion. At this moment, the alarm in the monitoring room suddenly sounded, and the tense atmosphere instantly enveloped the entire control room.
After a brief period of shock, the plant's staff quickly rushed into the emergency response. Due to the strong shock wave of the explosion, the equipment was badly damaged, the data on the display of the control system began to beat wildly, and the safety monitoring system of the reactor issued a continuous warning signal.
The shock wave caused by the explosion and the ensuing heat wave shattered the glass windows of buildings in the vicinity of the nuclear power plant. Heavy dust and rubble covered the corridors and operating rooms inside the power station. Firefighters and safety engineers at the plant, wearing protective suits and breathing apparatus, stormed the reactor building to try to contain the spreading fire and assess the specific damage to the reactor. They make their way in dim light and thin air, endure the heat and the threat of radioactive materials, and carry out fire-fighting and emergency containment tasks.
As the reactor's graphite blocks were ejected during the explosion, large amounts of radioactive dust and smoke began to emerge from the dilapidated building and spread to the surrounding environment. Alerted, external rescue teams rushed to the plant, including fire trucks and ambulances from nearby towns. Upon arrival at the scene, they immediately deployed water cannons and foam extinguishing systems, and despite the risk of radioactivity, rescuers remained steadfast in their rescue efforts.
Shortly after the accident, the top echelons of the Soviet government urgently convened a meeting in the capital, Moscow. Prime Minister Ryzhkov, after receiving an urgent briefing from Pripyat, quickly decided to set up a special emergency response team. He immediately assigned the head of the Main Energy Agency and top Soviet nuclear energy experts to join the team, along with several senior officials of the Ukraine government, to deal with the unprecedented nuclear accident.
In the afternoon, the emergency response team, made up of experts in various fields, was assembled without wasting any time and flew directly to the scene of the accident on a government plane. Immediately after the plane landed at a temporary military airfield near Pripyat, the team members were sent to the nuclear power plant. When they arrived, they found the scene in chaos, filled with radioactive smoke, and the fire brigade battling a rekindling graphite fire.
Mass evacuation operations
Considering the serious harm of these substances to the human body, the government decided that immediate action must be taken to carry out a large-scale evacuation of people. They assessed the scope of the impact and decided to evacuate not only the residents in the vicinity of the plant, but also the entire population within a 30-kilometer radius, which means that about 130,000 people would need to be evacuated in a short period of time.
The city of Pripyat, the closest residential area to the nuclear power plant, is home to about 50,000 people, most of whom are nuclear power plant workers and their families. The severity of the accident was initially unclear to the people of the city, but as time went on, there was a danger in the air that could not be ignored. Announcements and sirens began to echo over the city, informing residents to prepare for an emergency evacuation.
The military sprang into action, mobilizing thousands of buses from neighboring cities and villages to form a huge convoy and drive into the streets of Pripyat. To ensure the evacuation of every resident, the government has also mobilized three railways dedicated to transporting large numbers of residents out of high-risk areas. Transportation was arranged tightly and efficiently, with government officials, military personnel, railroad staff and local government volunteers coordinating to keep things in order.
The convoy stretched outward from the roads and railways around the nuclear power plant, and within four hours, tens of thousands of residents were successfully transferred away from the accident area. Every car was crowded with residents who had fled their homes, and the scene outside the window flashed quickly, gradually moving away from the city that was suffering from radioactive contamination.
Although these evacuees have moved away from the source of radiation, the rest of life is fraught with uncertainty. Most of them were carrying only the most basic necessities, and some were even unable to take anything with them. Although the temporary settlements provide basic shelter and food, life is far from stable.
With the end of the evacuation operation, the city of Pripyat turned into an empty city. The leak of radioactive material has left the once-thriving city deserted, with roads, schools, shops and residential areas quietly abandoned. Subsequently, the government sent troops and scientists into the area, established a strict quarantine zone that no unauthorized personnel were allowed to enter, and the entire city was sealed off and became a dead silence "no-go zone".
High-altitude throwing and plugging work
The day after the accident, the Soviet government realized that decisive measures must be taken to control the spread of radioactive materials. In order to prevent more radioactive dust from drifting into the atmosphere, the Soviet military quickly mobilized a large number of planes and helicopters and began a large-scale aerial throwing operation.
In the early morning of April 27, dozens of planes took off from various military bases and headed for the skies over the Chernobyl nuclear power plant. Coordinated by the ground command center, the pilots carried out tasks that they had never experienced before. They flew transport planes and helicopters, flew over the smoke over the nuclear power plant, and threw bags of sand, aluminum powder and boron carbide. These substances were precisely dropped on the wreckage of the reactor in an attempt to suppress the fire and reduce the spread of radioactive dust by burying them.
Each aircraft carries several tons of projectiles, requiring extreme precision for each mission. The aircraft had to maintain a low flight altitude to ensure that the drops accurately covered the exposed reactor area. These pilots are at great risk because in such close proximity to the reactor, the intensity of radiation is extremely high, and the slightest carelessness can lead to serious health problems. However, the urgency and importance of the task made it impossible for them to retreat. The dropping operation lasted several days, with each plane constantly going back and forth between the nuclear power plant and the temporary storage site. By the end of April, more than 100 aircraft had flown about 3,000 missions, dropping a total of about 5,000 tons of material into the reactor.
Of these, sand plays the most basic role of covering, while aluminium powder reacts chemically with high temperatures, helping to further reduce the temperature of combustion. Boron carbide is used to absorb excess neutrons and prevent further nuclear reactions. Although these measures have been effective in controlling the spread of fires and radioactive dust in the short term, the problem has not been fundamentally solved. The plant's fourth reactor is still in a dangerous state, and the high temperatures and radioactive materials inside continue to pose a threat to the outside world.
In order to completely plug the source of the leak, scientists and engineers have proposed a more long-term solution: seal the reactor with concrete and build a massive "sarcophagus" to completely isolate the broken reactor. The implementation of this project was extremely difficult because of the large amount of building materials required and the fact that all work had to be carried out in a high-radiation environment. First, the engineers needed to construct a massive reinforcement frame to support the concrete that was about to be poured in. Subsequently, the large concrete blocks will be stacked gradually, eventually forming a closed protective structure.
In December, the most critical capping task officially began. This time, the Mi-26, the most advanced and largest helicopter in the Soviet Union at that time, was needed to complete the lifting task. The Mi-26 was tasked with lifting a concrete roof weighing 35 tons onto the top of the sarcophagus. However, the helicopter was designed to have a capacity of only 20 tons, and to complete the mission, all unnecessary equipment was removed, reducing the dead weight of the aircraft and ensuring that it could withstand the overload of the task.
As the behemoth hovered over the nuclear power plant, tension in the ground command center and the operations team reached an extreme. The pilots had to place the heavy lid precisely in its intended position, and any mistake could cause problems with the entire sarcophagus structure or even completely seal the reactor. Despite the high risk and operational difficulties, the mission was successfully completed. The Mi-26 successfully put the top cover in place, putting a temporary end to the disaster.
International repercussions and long-term impact
A few days after the accident, on April 28, a nuclear power plant in Sweden monitored unusual radiation levels. At first, Sweden thought the problem might be with its own nuclear facilities. However, after verification, they found that everything was normal at their nuclear power plant, and they began to suspect that the radiation source came from abroad. The Government of Sweden immediately alerted neighbouring countries and the International Atomic Energy Agency to the spread of radioactive material and to promptly launch further investigations. After several days of testing, Sweden confirmed that the radioactive material originated in Chernobyl, Ukraine.
Detection stations in Northern and Eastern Europe have recorded the dispersal of radioactive material, and the path of the radiation cloud is becoming clear. Ukraine, Belarus and Poland were the first countries to be affected, and those areas closer to the core of the accident have seen a sharp rise in radiation levels in their soil and air, becoming direct victims of the accident. Farmland, pastures and drinking water sources have been contaminated, and crops and livestock in many areas have been found to contain excessive levels of radioactive material.
Environmental protection authorities and health agencies in France, Germany and other countries have reported that trace amounts of radioactive materials have been found in dairy products, cereals and other agricultural products tested. Due to the widespread circulation of these products, many governments have urgently introduced measures to restrict imports, especially for high-risk foods such as milk and meat, and France and Germany have taken the lead in banning the import of food from Eastern Europe to prevent their residents from being contaminated with radioactive materials.
In the long-term aftermath of the accident, environmental and health problems across Europe began to come to the fore. Radioactive materials not only have an impact on agriculture, but also the health of people who have been exposed to low doses of radiation for a long time. In the years following the accident, there was an increase in the incidence of cancer, leukemia and other radiation-related diseases in radiation-affected areas. In particular, those workers involved in the handling of the accident and those living in the area surrounding the nuclear power plant suffered severe health damage, and many died of various radiation illnesses in the years that followed.
References: [1] Liu Huoxiong. Western Education Research(Shaanxi),2023(9):82-84