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Official trailer for Chernobyl
Hearing the words Chernobyl, many people think of the world's worst nuclear accident in 1986. Yes, when these five words appear on the list of recent popular dramas, I believe many people will want to see how people will reproduce this century disaster through film and television dramas after decades.
Yes, HBO recently launched a drama-quality TV series "Chernobyl", which has aired three episodes so far, and the rating of the whole drama is as high as 9.7 points.
Poster of the Chernobyl TV series
So, today's "Heat Encyclopedia", we go back to 1986 to understand the causes and consequences of the Chernobyl nuclear accident.
<h1>The world's largest nuclear accident</h1>
The Chernobyl nuclear accident was a nuclear reactor rupture accident that occurred on April 26, 1986 at the Chernobyl Nuclear Power Plant in Pripyat, Ukraine, Usser Union. The accident was the worst nuclear power accident in history and the first major accident to be rated as the highest level seven incident by the International Nuclear Incident Classification Scale. Mainly because when the reactor is tested for power supply, due to design defects and insufficient operator training, the power increases sharply, destroys the reactor, and releases a large amount of radioactive material into the environment. The initial vapor explosion killed two people, and the etiology and cause of death of most of the victims in succession were attributed to the high-energy radiation released in the accident, but the effects of the small amount of radiation dust are still debated.
Stills from Chernobyl
At 1:23 a.m. local time on April 26, 1986, reactor No. 4 of the Chernobyl nuclear power plant near Pripyat in Ukraine exploded. Successive explosions sparked fires and released large amounts of high-energy radioactive material into the atmosphere, and this radioactive dust covered a large area. The disaster released more than 400 times the radiation dose of the atomic bombing of Hiroshima during World War II. Clouds contaminated with radioactive dust drift to numerous areas, including parts of the western Soviet Union, Western Europe, Eastern Europe, Scandinavia, the British Isles and parts of eastern North America. In addition, Ukraine, Belarus and Russia were severely contaminated with nuclear contamination, forcing the evacuation of more than 336,000 residents. Official Soviet reports say about 60 percent of the areas contaminated with radioactive dust are located in Belarus. Economically, the catastrophe cost a total of about $200 billion (inflation has been calculated) and was the most costly disaster in recent history.
The accident raised worldwide safety concerns about the Soviet nuclear power industry and slowed down a series of nuclear power projects. At the same time, the incident made the Soviet government's information disclosure more transparent. The CIS and its independent states after the collapse of the Soviet Union, including Russia, Ukraine, and Belarus, still pay a heavy price for the pollution problems left over from the Chernobyl incident. The accident has caused unimaginable negative impacts on the local and even global ecology, and the number of deaths caused by the incident alone is difficult to accurately calculate for a variety of reasons, among which the deliberate concealment of the former Soviet Union made the statistical work very difficult. In fact, the soviet authorities, shortly after the incident, prohibited doctors from mentioning the cause of death of "radiation" on death certificates.
In a 2005 report on the Chernobyl incident, produced by the Chernobyl Forum, led by the International Atomic Energy Agency and the World Health Organization, 56 people died (47 relief workers, 9 children with thyroid cancer) and estimated that an additional 4,000 of the approximately 600,000 people exposed to high-radiation substances would die of cancer. This data includes the number of deaths that will result from thyroid cancer in 4,000 children diagnosed (in the experience of Belarus, the survival rate of this cancer is close to 99%). Greenpeace estimates the total number of casualties at 93,000, but cites data from a recent report that suggests that separate incidents in Belarus, Russia and Ukraine may have caused 200,000 additional deaths between 1990 and 2004, but this figure is not sourced from peer-reviewed academic papers. Although evacuation areas and some restricted areas are still somewhat regulated, most of the affected areas are already considered safe to live and economically active, and the amount of "radiation tourism" for abandoned cities near here is still growing.
<h1>A catastrophe caused by a "small test"</h1>
Under normal conditions, 6% of the power of a nuclear fission reactor comes from the waste heat of the reaction product. After initiating an emergency shutdown, waste heat continues to be generated despite the chain reaction stopping, so the cooling system must continue to operate to avoid core meltdown.
Each unit at the Chernobyl nuclear power plant is equipped with three backup diesel generators, but it takes an additional 60 to 75 seconds to warm up when it starts. During emergency shutdowns and grid anomalies, a one-minute window period is a major safety concern for the Chernobyl power plant.
The solution proposed at the time was to take advantage of the inertia of the vapor turbine. After an emergency shutdown, the steam turbine continues to rotate for a short period of time, and according to the analysis, this residual turbine momentum can generate power supply pump operation for 45 seconds, which is exactly to support the power demand during the empty window period. In order to test this concept, the Chernobyl power plant planned to carry out a fourth test in 1986 with the fourth machine that was about to enter the old age after three failed tests.
The problem of the empty window period, which has not been properly resolved after the operation of the Chernobyl nuclear power plant, is a key improvement project for the power plant management. Perhaps it is precisely because of this pressure that the managers on site are still insisting on conducting a fourth test in the face of problems.
On the day of the incident, after the test began, there was a small power station jumping without warning, and the Kiev power grid dispatching unit asked Chernobyl to give priority to supporting the evening peak power consumption and postpone the reduction of output. The factory agreed, so the test was postponed until late that night. The postponed test did not begin until the next shift, so the already trained early shift personnel left work one after another, and the night shift and the big night shift alternated, in order to prepare for the test before the handover, it was decided to reduce the power extremely quickly. The duty officer was Alexander Fyodorovich Akimov, and the operator was Leonid Fyodorovich Toptunov, who had only been promoted to senior engineer three months earlier.
At 12:05 a.m. on April 26, the output power dropped to 700MW, but the phenomenon of "reactor toxication" caused by the excessive speed caused the reactor to gradually stop the reactor reaction. Subsequently, the control room personnel were ordered to turn off the control rod automatic control system, and then to manually control the extraction of a large number of control rods.
A series of tricks and tricks have made the reactor extremely unstable. According to the operating specifications, at least 28 control rods need to be retained and inserted to ensure safety in emergency situations, but only 18 are inserted at this time. The automatic SCRAM shutdown system and many autonomous/passive safety functions are turned off, leaving only the manual emergency shutdown system. The reactor was configured beyond the safe range of the original design, and with just a little disturbance, it was enough to lead to destruction.
In the special design of the RBMK graphite mitigation reactor in Chernobyl, there is a fairly high "void coefficient", which means that when there is no water and only water vapor, the reduced neutron absorption effect will rapidly increase the power of the reactor, in this case forming a dangerous positive cycle: the vapor bubble increases, reducing the efficiency of the water absorption neutron, which in turn leads to an increase in the output power; and the increase in output power leads to more bubbles. The automatic control system tried to prevent the positive cycle from happening, but it only had control of the 12 control rods left, so it could not do anything about it.
At 1:23:40 a.m., according to the records of SKALA's central control system, the AZ-5 button was pressed, activating the emergency shutdown system. The reason for activating the AZ-5 is still unknown, either as an emergency measure in response to a sharp rise in temperature or as a purely end-of-test shutdown procedure. Whether the AZ-5 was pressed during the alarm bell or when it was peaceful is still a matter of opinion.
After the AZ-5 button is pressed, all the control rods that were extracted begin to be reinserted back into the reactor. The control rod moves at a speed of 0.4 meters per second, and it takes 18 to 20 seconds to fully insert the 7-meter-high core. The design of the RBMK reactor control rod is also a big problem. The bottom end of the control rod is connected to a piece of graphite that promotes chain reactions. Originally designed to allow the graphite underneath to facilitate and evenly chain reactions when the control rod is withdrawn. But this also causes that when the control rod is initially inserted, the graphite at the tail end replaces the water that absorbs the neutrons below, which promotes the reaction rate instead. It wasn't until the control rod was inserted deep enough that the reaction rate was finally suppressed and decreased. This counterintuitive phenomenon of "rising first and then falling" was discovered by the Ignalina nuclear power plant in Lithuania in 1983, but because the shutdown was successfully completed, this phenomenon was not taken seriously afterwards.
7 seconds after the emergency shutdown start-up, the graphite part causes a sharp increase in power, and the core temperature is too high to deform some of the fuel rods, blocking the control rod pipes, so that the control rod can only be inserted by one-third. The graphite stuck between the cores continued to promote chain reactions, rising to 530MW in less than a few seconds. The high heat further produces high-pressure vapor, prompting the fuel rod to rupture and melt, and the vapor pressure increases rapidly, at which point the reactor power is estimated to be 30,000 MW, reaching 10 times the normal output power. The final measured output power of the control panel was 33,000MW. Finally, because the vapor pressure was too high, it led to a large-scale steam explosion, blowing up the upper cover of the reactor 2,000 tons in one go, and the coolant pipe burst and blew through a large hole in the roof. In order to reduce costs, and because of its large size, the reactor was built in a single protective layer, which allowed radioactive contaminants to enter the atmosphere after the reactor pressure vessel burst after a steam explosion. This was the first explosion most people heard. The explosion destroyed more fuel lines, a large amount of steam gushed out, and the continuous loss of cooling water continued to increase the output power of the reactor.
The second explosion occurred two to three seconds after the first explosion, and the core exploded in this explosion, thus stopping the chain reaction. However, after oxygen was combined with extremely high temperature reactor fuel and graphite moderators, it immediately caused a burning graphite fire. A very large amount of radioactive dust is generated, which spreads and contaminates the area of radioactive materials to a wider area.
After the explosion, the fourth machine building was blown in half, the reactor core was directly exposed to the atmosphere, and a blue-and-white light in the center of the core shot into the night sky, which was the appearance of the atoms in the air excited by ionization returning to the unexcited state.
The blue-and-white beam of light after the nuclear accident depicted in Chernobyl
<h1>If the disaster is not taken seriously</h1>
The situation was irreparable at this point, but after the explosion, it did not attract the attention of the Soviet authorities. The message from Moscow's nuclear experts and Soviet leaders was that "the reactor was on fire, but it did not explode," and the Soviet government was slow to respond officially.
It was only 34 hours after the accident that some villages close to the nuclear power plant began to evacuate, and the government sent troops to force people to evacuate. At that time, hundreds of times the lethal amount of nuclear radiation was measured in the village near the scene, and the radiation value was still rising. But this still did not attract attention, and experts preferred to believe that it was the failure of the machine that measured radiation.
Because the Soviet government feared causing panic among the people, the residents were not told the full truth of the matter. In Pripyat, May Day was celebrated with great fanfare, and Vladimir Vasilyevich Shelbitsky, the first secretary of the Communist Party of Ukraine, also brought his family to the ceremony. Many had absorbed deadly amounts of radiation before they were evacuated.
On Saturday, April 26, 1986, an accident occurred at 1:23 a.m., and nikolai Ivanovich Ryzhkov, chairman of the Council of Ministers of The USSR, received a telephone report from the Minister of Energy of the USSR, Anatoly Ivanovich Majolec, that the Provisional Emergency Committee of the Soviet Government was established at 11 a.m. on the same day.
Throughout the day on April 26, the Soviet Meteorological, Hydrological, Radiation and Public Health Monitoring Department quickly formed a dispatch of monitoring personnel to carry out radiation environment monitoring within a radius of 1,000 km, and dispatched more than 500 helicopters to collect air samples to detect radiation doses, providing basic data for the decision of the Soviet government committee on a large evacuation.
At 20:00 that night, the experts of the Provisional Committee, after obtaining evidence from the scene, decided to evacuate all the residents of the city of Pripyat. 1,000 buses and 3 railway trains were mobilized.
On the morning of April 27, General Vladimir Karpovich Pikarov, commander of the Soviet Chemical Corps, led 2,600 nuclear protection units and 400 special vehicles to the scene of the accident by transport aircraft and helicopters. From April 27 to May 6, helicopters dropped more than 5,000 tons of firefighting materials on Reactor 4. The dose released by radioactive material was reduced from 12 000 kBq to 100 kBq.
At noon on April 27, more than 1,000 buses and three special trains used to evacuate residents arrived, and the evacuation of all residents began at 11 o'clock on the same day. In order to evacuate the residents quickly, the Government informed them to carry only the most necessary items. At 15:00 on the same day, all 53,000 inhabitants of the cities of Pripyat and Chernobyl were evacuated to the town of Bolegna and other places.
The evacuation of Pripyat began at 2 p.m. on April 27, with an emergency evacuation broadcast locally:
Attention, attention... Dear comrades, the Municipal People's Committee has issued a notice that harmful radiation has been released as a result of an accident at the Chernobyl nuclear power plant in the city of Pripyat. The Party, the Soviets, the military units have taken the necessary measures. However, in order to ensure the absolute safety of the people, especially the safety of children, it is necessary to temporarily evacuate citizens to the Kiev region to avoid difficulties. For this purpose, today, on 27 April, the residential apartments will be provided with evacuation buses from 2 p.m. and will be escorted by militia officials and representatives of the executive committee of the municipal party committee. It is recommended that you bring: ID card, basic household items and necessary food. Executive committees for businesses and facilities will provide lists of workers who remain to keep the city running. All residential buildings will be guarded by militia during the evacuation. Comrades, when you leave your home temporarily, please do not forget to close the windows and cut off the power, gas and taps. Please remain calm and orderly during the temporary evacuation.
In the months that followed, the Soviet government sent countless manpower and material resources to finally extinguish the reactor fire and control the radiation. However, these people responsible for cleaning have also suffered serious radiation injuries; one of the reasons is the technical limitations of remote control robots, coupled with the failure of electronic circuits of remote control robots due to severe radiation lines, so the cleaning of many of the most polluted sites still relies on human labor.
On April 28, the evacuation of residents within a radius of 10 km began. On April 28, the Politburo of the Central Committee of the Communist Party of the Soviet Union held a plenary meeting to discuss disaster relief. On the same day, Soviet television announced the news of the Chernobyl nuclear accident to the public in a news program at 21:00. All Soviet radio and television stations broadcast classical music in silence to pay tribute to the victims of the accident.
On April 29, the Emergency Action Group of the Politburo of the CPSU headed by chairman of the Council of Ministers, Ryzhkov, was set up to take full responsibility for the disaster relief work in Chernobyl, and held two meetings every day to summarize the situation and make decisions. The government committee decided to evacuate all residents within a 30km radius of the nuclear power plant, and by May 6 all 135,000 residents, 367 people diagnosed with acute radiation sickness and 34 people with severe illness were evacuated.
A meeting of the Politburo of the CPSU Central Committee was held on the afternoon of 30 April to discuss whether to cancel the May Day event the following day. Scientists report that radioactivity levels in the city of Kiev are still normal. The meeting decided to shorten the May Day celebration in Kiev city the next day from the normal 4 hours to 2 hours. The reality is that on May 1 the wind direction changed and the Kiev region was contaminated.
Within a week of the accident, helicopters dumped 5,000 tons of borax from the air into the reactor core, halting the chain reaction.
On May 2, Ligachev, member of the Politburo of the CPSU Central Committee, and Ryzhkov, chairman of the Council of Ministers, arrived in Chernobyl and took up their posts in the Chernobyl District Committee building and the Provisional Committee of the Soviet Government located here, and decided to evacuate all residents within 30 km.
Twenty years after the accident, the surface of reactor FOUR's sarcophagus still has an irradiance of 750 mSv, which is much higher than the safety value of 20 mSv, and the welders who reinforce the sarcophagus rotate every two hours of work. The average irradiance in the quarantine area is still greater than 100 mSv.
On May 2, three volunteers undertook the almost certainty of a death-defying task: diving into the flooded basement of Reactor 4, opening the drainage gates to avoid thousands of tons of hot graphite blocks and core melt from inside Unit 4 at temperatures of up to 1,200°C, and then encountering highly radioactive wastewater accumulated in the basement causing a water vapor explosion, and the 5,000 tons of fire extinguishing material thrown by the helicopter added an additional burden to the shattered structure of the building. According to Anaenko's dictation, after the floodgates were opened, 20,000 tons of high-lying wastewater in the basement were pumped with a fire pump and drained by May 8. As originally predicted, a few months later, the radioactive melt from the core actually burned through the floor. Fortunately, thanks to the efforts of these three heroes, the radioactive cooling water in the pool has long been emptied. The molten matter just fell into the empty basement, and there was no water vapor explosion.
The Provisional Committee of the Government of the USSR conducted preventive medical examinations for 5 million people in Ukraine and Belarus, and more than 500,000 people were permanently registered for prevention and treatment. In the following year or so of emergency rescue, senior leading cadres at the vice-chairman level of the Council of Ministers, Such as Ivan Stepanovich Siraev, Yuri Dmitryevich Maslyukov, and Lev Alexievich Voronin took turns on duty in Chernobyl.
The Deputy Minister of Water Resources of the USSR, Polad Agievich Polad-Zaj, led the organization of a large-scale water conservancy protection project, and more than 130 embankments were built to protect all rivers in an area of 1,500 square kilometers, preventing radioactive dust from flowing into the Pripyat River with rainwater and endangering the hinterland of the lower Dnieper River.
Outside the 30 km radius of the quarantine area is a lightly polluted evacuation zone with an average irradiance of about 60 mLentgen and up to 150-200 mLentgen at specific locations. Further afield is the lightly polluted quasi-evacuation zone, with an average irradiance of about 30 mSv.
Soviet Chernobyl Accident Rescue Medal (left) with medal
Soviet scientists braved high radiation to enter the Reactor Iv building to investigate the possibility of a new chain reaction or explosion. Probes are placed from outside the reactor by drill pipes to monitor the temperature and radioactivity of various parts of the reactor. A 2-meter-diameter molten reactor core with a diameter of several hundred tons was found in the basement of the reactor with extremely high radioactivity.
On May 7, 1986, the rescue and disaster relief entered the stage of eliminating the impact of the accident. At this time, 195 tons of graphite and nuclear fuel were still boiling under the buried pressure of 5,000 tons of fire extinguishing materials. The Government Council decided on two measures: the construction of an artificial heat protection horizontal layer and the construction of a "sarcophagus".
In August 1986, the rescue and disaster relief entered the post-processing stage. The Soviet government recruited a large number of rescuers to participate in the rescue work at the scene of the Chernobyl accident. In 1986 and 1987 alone, 240,000 people attended. By December 1986, the Soviet government had built a "sarcophagus" on Reactor No. 4 to seal off the accident site. In total, 600,000 Soviets received the Chernobyl Accident Rescue Medal and Medal.
<h1>Centuries-long influence</h1>
Soviet accident reports indicate that the Chernobyl No. 4 reactor has a total of 180 to 190 tons of uranium dioxide and nuclear waste from the nuclear reaction. They estimate that about 5 to 30 percent of these substances flow outside. But according to the cleaners who have been to the sarcophagus reactor for follow-up treatment, only about 5%-10% of the material remains in the reactor. Photos of the reactor show that the reactor is completely empty. Because of the high temperature caused by the fire, many radioactive materials rushed into the atmosphere and spread in all directions.
The radioactive dust leaked from the meltdown of the atomic furnace drifted through Russia, Belarus and Ukraine, as well as parts of Europe, such as Turkey, Greece, Moldova, Romania, Lithuania, Finland, Denmark, Norway, Sweden, Austria, Hungary, the Czech Republic, Slovakia, Slovenia, Poland, Switzerland, Germany, Italy, Ireland, France (including Corsica) and the United Kingdom.
Immediately after the accident, 203 people were taken to hospital for treatment, of which 31 died, of which 28 died of excessive radiation. Most of those who died were firefighters and ambulance crews because they were unaware of the dangers of radiation contained in the accident. In an effort to control the spread of radioactive soot from nuclear power, the authorities immediately sent 135,000 people to evacuate their homes, about 50,000 of whom were residents of the town of Pripyat near Chernobyl. The health unit predicts that the proportion of people who receive cancer from 5–12 Ibeck radiation will increase by 2% over the next 70 years. In addition, 10 people have been exposed to radiation and died of cancer as a result of the accident.
The long-term impact of the explosion at the nuclear power plant on the residents of Chernobyl has been controversial. After the accident, people's health problems were mainly affected by the radioactive material "iodine-131". Currently, there are concerns that strontium-90 and cesium-137 from 20 years ago will also pollute the soil. Moreover, the soils on the outermost surface of plants, insects, and mushrooms absorb cesium-137. So some scientists worry about the centuries-old effects of nuclear radiation on locals.
Many studies have found that children in Belarus, Ukraine and Russia also have a rapid increase in the proportion of thyroid cancer. According to statistics from the post-mortem survey of the Atomic Bombing in Japan, leukemia in the Chernobyl region is expected to increase in the coming years. But until now, the increase in the number of leukemia cases has not been statistically extrapolated and is related to radiation leakage.