Causes of the accident At power unit No. 4 of the Chernobyl nuclear power plant on April 26, 1986 at 01:23:40, the reactor operator pressed the reactor shutdown button. After that, the reactor, instead of stopping, began to rapidly increase its power, turned into a kind of nuclear bomb, and exploded at 1 hour 23 minutes 47 seconds. After 1-2 seconds, a second explosion followed, and the reactor collapsed. The accident occurred due to design flaws in the control rods. nuclear reactor. These rods were made in such a way that when they were introduced into the reactor core, they did not slow down the nuclear reaction, as they should, but, on the contrary, accelerated it for several seconds.
The accident at the Chernobyl nuclear power plant was the largest environmental disaster of the twentieth century. The radiation emitted during the explosion made a life-threatening area of 5 million hectares, occupied mainly by rural fields. A dangerous amount of radionuclides has accumulated in the silt of the Pripyat and Dnieper rivers, the Kyiv reservoir. Decades after the accident, their content is 10-100 times higher than the permissible levels. Today, the danger is not only the sarcophagus of the fourth power unit, which transmits radiation to the outside. Around the Chernobyl nuclear power plant there are more than 100 nuclear waste repositories. The consequences of the man-made disaster affected the health of several generations and will continue to be felt for many years to come.
Pripyat is a satellite city at the Chernobyl nuclear power plant. Was built to serve nuclear power plant. After assessing the scale of radioactive contamination, it became clear that the evacuation of the city of Pripyat was necessary. The evacuation was carried out on April 27, 1986, only 36 hours after the explosion. People were forbidden to take things with them, many were evacuated to home clothes. To avoid panic, people were told that they would return home in three days. Pets were not allowed to be taken with them. Now, it is a ghost town located in northern Ukraine, 3 km from the Chernobyl nuclear power plant near the border with Belarus. As a result of the accident, a 30-kilometer exclusion zone was created, hundreds of small settlements were buried with heavy equipment.
Mutation like
Memory The liquidators worked gradually in the danger zone: those who had accumulated the maximum allowable dose of radiation left, and others came to take their place. Most of the work was completed in the first year. The total number of liquidators was about 600 thousand people. Many monuments were erected in memory of the Chernobyl accident and as a tribute to the liquidators. The monument to Nizhny Novgorod residents - participants in the liquidation of the consequences of the disaster was opened on September 10, 2009 at the Old Fair Cathedral.
In the city of Chernobyl, a monument to firefighters was erected, near the fire station. Firefighters from this unit were among the first to arrive at the scene of the accident.
ACCIDENT At about 1:24 on April 26, 1986, an explosion occurred at the 4th power unit of the Chernobyl nuclear power plant, which completely destroyed the reactor. The reason for this was the performance of safety tests at an ultra-low power of 200 MW, while the norm is 700 MW. When the power level fell too low, an unstoppable increase in power was provoked by pressing the emergency shutdown button, resulting in the destruction of 4 units. The building of the power unit partially collapsed. Subsequently, the remnants of the core melted. A mixture of molten metal, sand, concrete and fuel particles spread over the sub-reactor rooms. The accident resulted in the release of environment radioactive substances, including isotopes of uranium, plutonium, iodine-131 (half-life 8 days), cesium-134 (half-life 2 years), cesium-137 (half-life 33 years), strontium-90 (half-life 28 years) .
Some facts: the reactor installation did not actually comply with the safety standards in force at the time of design and even had unsafe design features Insufficient safety analysis Insufficient attention to independent safety review Operating procedures are not adequately justified in the safety analysis Insufficient and ineffective communication of important safety information, both between operators and between operators and designers Insufficient understanding by personnel of their plant's safety related aspects materials in construction, in order to reduce the cost of construction, which affected the extinguishing of the building of the power unit (extinguishing continued all night, many firefighters received lethal doses of radiation) Safety was in the 2nd plan ...
Disadvantages of the RBMK-1000 reactor The reactor becomes practically uncontrollable at ultra-low power, it is necessary to shut it down immediately, but the result was unforeseen ... A large number of pipelines and various auxiliary subsystems require a large number of highly qualified personnel; The need for channel-by-channel regulation of flow rates, which may lead to accidents associated with the termination of the coolant flow through the channel; Higher load on operational personnel associated with a large number of nodes (for example, shut-off and control valves); A larger amount of activated structural materials due to the large size of the core and the metal consumption of RBMK, which remain after decommissioning and require disposal.
In the first hours after the accident, many did not realize how badly the reactor was damaged, so an erroneous decision was made to ensure the supply of water to the reactor core to cool it. These efforts were futile, as both the pipelines and the core itself were destroyed, which required work in areas with high radiation. Other actions of the station personnel, such as extinguishing local fires in the station premises, measures aimed at preventing a possible explosion on the contrary, were necessary. Perhaps they prevented even more serious consequences. During the performance of these works, many employees of the station received large doses of radiation, and some even lethal. The release led to the death of trees near the nuclear power plant on an area of about 10 km²
Firefighters did not allow the fire to spread to the third block (the 3rd and 4th power units have single transitions). Of the means of protection, firefighters had only a combat jacket (canvas robe), a helmet and mittens. It was impossible to work in gas masks due to the high combustion temperature; firefighters removed them already in the first 10 minutes. Instead of a fire-resistant coating, as was required by the instructions, the roof of the engine room was filled with ordinary combustible bitumen. At about 2 o'clock in the morning, the first firefighters were struck. They began to show weakness, vomiting, "nuclear sunburn", and after removing the mittens, the skin was removed from their hands. Assistance was provided to them on the spot, at the station's first-aid post, after which they were transferred to the city hospital of Pripyat. On April 27, the first group of 28 people injured was sent by plane to Moscow, to the 6th radiological hospital. Almost no fire truck drivers were injured.
The first official announcement was made on television on 28 April. A rather dry report reported the fact of the accident and two dead, the true extent of the disaster began to be reported later. After assessing the scale of radioactive contamination, it became clear that the evacuation of the city of Pripyat would be required, which was carried out on April 27. In the first days after the accident, the population of the 10-kilometer zone was evacuated. In the following days, the population of other settlements of the 30-kilometer zone was evacuated. It was forbidden to take things with you, many were evacuated in home clothes. In order not to fan the panic, it was reported that the evacuees would return home in three days. Safe paths for the movement of columns of the evacuated population were determined taking into account the already obtained radiation survey data. Despite this, neither on April 26 nor April 27 did the residents warn of the existing danger and did not give any recommendations on how to behave in order to reduce the impact of radioactive contamination.
Specialists sent to carry out work on the emergency unit and around it, as well as military units, both regular and composed of urgently called up reservists, began to arrive in the 30-kilometer zone around the Chernobyl nuclear power plant. All of them later began to be called "liquidators". The liquidators worked in the danger zone in shifts: those who had accumulated the maximum allowable dose of radiation left, and others came to take their place. The main part of the work was carried out in 1986 - 1987, about 240,000 people took part in them. The total number of liquidators (including subsequent years) amounted to about 600,000. Bless THEM…
Geographical location of the Chernobyl NPP The Chernobyl NPP is located in the eastern part of the Belarusian-Ukrainian Polissya in northern Ukraine, 11 km from the border with Belarus, on the banks of the Pripyat River, which flows into the Dnieper. To the west of the three-kilometer sanitary protection zone of the nuclear power plant is the abandoned city of Pripyat, 18 km southeast of the station is the former regional center the abandoned city of Chernobyl, 110 km to the south is the city of Kiev.
Chernobyl accident Chernobyl accident destruction on April 26, 1986 of the fourth power unit of the Chernobyl nuclear power plant, located on the territory of the Ukrainian SSR (now Ukraine). The destruction was explosive, the reactor was completely destroyed, and a large amount of radioactive substances was released into the environment. On April 26, 1986, the Chernobyl nuclear power plant of the Ukrainian SSR
Causes of the Chernobyl accident The reactor did not meet safety standards and had dangerous design features; low quality of operation regulations in terms of safety; the ineffectiveness of the regulatory and oversight regime for safety in nuclear power, the general lack of safety culture in nuclear matters both at the national and local levels; there was no effective exchange of information on safety both between operators and between operators and designers, the personnel did not have sufficient understanding of the features of the plant that affect safety; the personnel made a number of mistakes and violated the existing instructions and test program.
Medical consequences of the Chernobyl accident Thyroid cancer and other thyroid pathology Leukemia Other than thyroid cancer, solid cancers Non-cancerous and non-thyroidal effects: – Mortality attributed to the Chernobyl accident – Psychiatric and psychological consequences and effects in the central nervous system – Reproductive effects and children's health - Cataracts - Cardiovascular diseases - Immunological effects
Four main mechanisms of public exposure external dose due to the passage of a radioactive cloud, internal dose due to inhalation of radioactive materials from the cloud and resuspended particles, external dose from radioactive material deposited on soil and other surfaces, internal dose from ingestion food products and water
Radiation-induced effects on plants and animals Acute radiation effects (death of plants and animals due to radiation, loss of reproduction, etc.) and long-term effects (changes in biodiversity, cytogenetic anomalies) were observed in the affected areas.
Radioactive Contamination of the Environment The main releases from Unit 4 of the Chernobyl nuclear power plant lasted ten days and included radioactive gases, condensed aerosols and a large amount of fuel particles.
Agricultural environment Different kinds agricultural plants, in particular leafy vegetables and greens, were also contaminated with radionuclides to varying degrees depending on the levels of deposition and the stage of growth. Direct deposition on plant surfaces has been a problem for almost two months.
RESULTS The results of the implementation of the Chernobyl programs show that the problem of overcoming the consequences of the Chernobyl disaster is objectively long-term in nature: A large amount of work has been done to clarify the radiation situation, environmental, medical, demographic, economic and social characteristics the territories and contingents affected by the accident. At present, it is possible to reliably predict the situation in contaminated areas. Work has been carried out to protect the population, including measures in the field of agriculture and forestry, sanitary protection, decontamination and improvement of settlements. At the same time, programs were implemented to improve medical care for the population, to provide specialized medical care, social protection citizens affected by the accident. Thanks to natural processes and the work done, there was an objective improvement in the radiation situation in all areas that were subjected to radioactive contamination. In the slightly polluted territories of Belgorod, Voronezh, Kursk, Lipetsk, Leningrad, Penza, Ryazan, Tambov, Ulyanovsk regions and Mordovia, it can be considered normalized.
The Russian Scientific Commission on Radiation Protection adopted the "Concept of Radiation, Medical, Social Protection and Rehabilitation of the Population Russian Federation exposed to accidental irradiation", which creates a scientific basis for rehabilitation work in the recovery phase and involves changing the principles of zoning the affected territories and ongoing activities. High-risk groups have been identified - the liquidators of the years and the child population of the most contaminated areas of the Bryansk, Kaluga, Oryol and Tula regions. For these categories of the population, long-term medical supervision is necessary.
Tasks for the restoration of the Chernobyl zone health protection and medical rehabilitation of citizens exposed to radiation as a result of the Chernobyl disaster; socio-psychological rehabilitation of citizens exposed to radiation; radiation monitoring in radioactively contaminated areas; reduction of dose loads on the population and environmental improvement of territories; socio-economic rehabilitation of the population of contaminated territories.
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Presentation on the topic:
slide number 1
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slide number 2
Description of the slide:
At about 1:24 am on April 26, 1986, an explosion occurred at the 4th power unit of the Chernobyl nuclear power plant, which completely destroyed the reactor. The reason for this was the performance of safety tests at an ultra-low power of 200 MW, while the norm is 700 MW. When the power level fell too low, an unstoppable increase in power was provoked by pressing the emergency shutdown button, resulting in the destruction of 4 units. The building of the power unit partially collapsed. Subsequently, the remnants of the core melted. A mixture of molten metal, sand, concrete and fuel particles spread over the sub-reactor rooms. As a result of the accident, radioactive substances were released into the environment, including isotopes of uranium, plutonium, iodine-131 (half-life 8 days), cesium-134 (half-life 2 years), cesium-137 (half-life 33 years), strontium -90 (half-life 28 years).
slide number 3
Description of the slide:
Some facts: The reactor facility did not actually comply with the safety standards in force at the time of design and even had unsafe design features Insufficient safety analysis Insufficient attention to the independent review of safety Operating procedures are not properly justified in the safety analysis Insufficient and ineffective exchange of important safety information, as between operators, and between operators and designers, insufficient understanding by the personnel of the aspects of their plant related to safety, the use of COMBUSTIBLE materials in construction, in order to reduce the cost of construction, which affected the extinguishing of the building of the power unit (extinguishing continued all night, many firefighters received lethal doses of radiation)
slide number 4
Description of the slide:
Disadvantages of the RBMK-1000 reactor The reactor becomes practically uncontrollable at ultra-low power, it is necessary to shut it down immediately, but the result was unforeseen ... A large number of pipelines and various auxiliary subsystems require a large number of highly qualified personnel; The need for channel-by-channel regulation of flow rates, which may lead to accidents associated with the termination of the coolant flow through the channel; Higher load on operational personnel associated with a large number of nodes (for example, shut-off and control valves); A larger amount of activated structural materials due to the large size of the core and the metal consumption of RBMK, which remain after decommissioning and require disposal.
slide number 5
Description of the slide:
In the first hours after the accident, many did not realize how badly the reactor was damaged, so an erroneous decision was made to ensure the supply of water to the reactor core to cool it. These efforts were futile, as both the pipelines and the core itself were destroyed, which required work in areas with high radiation. Other actions of the station personnel, such as extinguishing local fires in the station premises, measures aimed at preventing a possible explosion on the contrary, were necessary. Perhaps they prevented even more serious consequences. During the performance of these works, many employees of the station received large doses of radiation, and some even lethal. The release led to the death of trees near the nuclear power plant on an area of about 10 km²
slide number 6
Description of the slide:
Firefighters did not allow the fire to spread to the third block (the 3rd and 4th power units have single transitions). Of the means of protection, firefighters had only a combat jacket (canvas robe), a helmet and mittens. It was impossible to work in gas masks due to the high combustion temperature; firefighters removed them already in the first 10 minutes. Instead of a fire-resistant coating, as was required by the instructions, the roof of the engine room was filled with ordinary combustible bitumen. At about 2 o'clock in the morning, the first firefighters were struck. They began to show weakness, vomiting, "nuclear sunburn", and after removing the mittens, the skin was removed from their hands. Assistance was provided to them on the spot, at the station's first-aid post, after which they were transferred to the city hospital of Pripyat. On April 27, the first group of 28 people injured was sent by plane to Moscow, to the 6th radiological hospital. Almost no fire truck drivers were injured.
slide number 7
Description of the slide:
The first official announcement was made on television on 28 April. A rather dry report reported the fact of the accident and two dead, the true extent of the disaster began to be reported later. After assessing the scale of radioactive contamination, it became clear that the evacuation of the city of Pripyat would be required, which was carried out on April 27. In the first days after the accident, the population of the 10-kilometer zone was evacuated. In the following days, the population of other settlements of the 30-kilometer zone was evacuated. It was forbidden to take things with you, many were evacuated in home clothes. In order not to fan the panic, it was reported that the evacuees would return home in three days. Safe paths for the movement of columns of the evacuated population were determined taking into account the already obtained radiation survey data. Despite this, neither on April 26 nor April 27 did the residents warn of the existing danger and did not give any recommendations on how to behave in order to reduce the impact of radioactive contamination.
slide number 8
Description of the slide:
Specialists sent to carry out work on the emergency unit and around it, as well as military units, both regular and composed of urgently called up reservists, began to arrive in the 30-kilometer zone around the Chernobyl nuclear power plant. All of them were later called "liquidators". The liquidators worked in the danger zone in shifts: those who had accumulated the maximum allowable dose of radiation left, and others came to take their place. The main part of the work was carried out in 1986-1987, about 240,000 people took part in them. The total number of liquidators (including subsequent years) was about 600,000.
