Radioactive contamination of the biosphere is the excess of the natural level of radioactive substances in the environment. Nuclear explosions and leakage of radioactive components as a result of accidents at nuclear power plants or other enterprises can cause it. Currently, according to the International Atomic Energy Agency (IAEA), the number of operating reactors in the world reached 426 in their total electrical capacity of about 320 GW (17% of global electricity production).
Nuclear power provides more or less environmentally cleaner performance compared with other power systems, because it eliminates the harmful emissions (ash, silica, carbon, and sulfur and nitrogen oxides al.). In France, for example, the rapid build-up of nuclear power plants in recent years has significantly reduced emissions of sulfur dioxide and nitrogen oxides in the energy sector by 71% and 60%, respectively. However, in general, the world has seen a tendency to reduce the construction of new nuclear power plants.
The use of atomic energy is the reality of our days. Now, nuclear arsenals have reached a size that threatens the destruction of life itself on Earth. It’s time to realize that the preservation of human civilization is a matter of all states, a nuclear war will inevitably affect everyone.
However, and the peaceful atom carries a lot of danger. This is evidenced by the consequences of accidents at nuclear facilities. Therefore, all countries together must ensure that the possibility of accidents in the operation of nuclear facilities was reduced to zero.
April 26, 1986 at the Chernobyl nuclear power plant was an accident. As a result of the destruction of the reactor and its core, dozens of millions of curies of radioactive substances have entered the environment. In the first 2-3 days of the accident, the most powerful outflow of radioactive products was observed. The height of the jet of radioactive release on April 27, according to aircraft data, exceeded 1200 m. In total, there were two salvo emissions. The radioactivity release capacity was 100 times higher than in the explosion of two atomic bombs dropped by the United States on the Japanese cities of Hiroshima and Nagasaki in 1945. The expiration of the highly radioactive gas-aerosol jet from the exposed core due to ignition of the graphite masonry of the reactor continued for 10 days. Separation of fragment radioactivity towards its enrichment by biologically significant radioactive isotopes of cesium has occurred. Discarded at the time of the accident radioactive material spread in a westerly direction, then stream from the reactor zone contributed to the spread of pollution in the north-west of the BSSR, and later – in the north and east, in the south-east and south. The Gomel and Mogilev regions of Belarus, the Kiev and Zhytomyr regions of Ukraine and the Bryansk region of Russia underwent the most severe radioactive contamination. In total, this is an area of 155,000 km2 and a population of 7.1 million people (3 million of whom are children). The radioactivity of the emission cloud reached a value of 50 million curies (Ki). Change in the first 7-10 days of wind direction by 180 degrees led to a wide spread of radioactivity. In places of rainfall, significant “spots” of radioactive contamination were formed. Formation of radioactive “trace” and “spots” continued throughout May. Noticeable loss of radioactivity from the rains reached Austria, Germany, Italy, Norway, Sweden, Poland, Romania, and Finland.
The reactor of Unit 4 of the Chernobyl NPP was completely destroyed and was an open and life-threatening powerful source of radiation and aerosol pollution. In the first days after the accident, the question arose about the construction of a structure that was supposed to prevent the spread of radionuclides from the destroyed reactor and protect the adjacent territory from penetrating radiation. It was decided to build a temporary localizing shell, known as the object “Shelter” or “Sarcophagus”.
Under the erected sarcophagus, the main quantity of radionuclides has been concentrated: according to maximum estimates, about 180 tons of nuclear fuel has been buried here. In addition to fuel-containing masses, a large number of radioactive materials are concentrated in the “Shelter” facility, consisting of the remains of a destroyed reactor, reactor graphite, metal and building structures of the power unit.
After the collapse of the USSR in December 1991. a crisis situation arose when Ukraine remained one on one with the object located on its territory and previously located in the all-Union subordination and had to solve the problem of a planetary scale itself. All responsibility for the elimination of the consequences of the accident and the shelter of the destroyed power unit fell on Ukraine.
The Chernobyl tragedy was not of a “prototype” in nature and nature of the change in the quality of the natural environment in the zone and in the vicinity of the nuclear power plant, and it was difficult for specialists to predict certain phenomena that should be expected in areas affected by radiation. Here is one of them; in the summer of 1988, in large areas around Kiev, especially to the north of it, the mass death of oak trees began. Famous oak groves from the horizon to the horizon drooped with yellow crowns. In the spring and summer of 1986, the birds left not only the 30-kilometer zone: around the Chernobyl for many tens of kilometers there were no bird voices. Two years was enough to make a small nondescript butterfly – a wide-mole moth bred in such quantity that it destroyed huge massifs of oak groves growing in those places.
The zone of high radiation contamination near Leningrad appeared in 1986 as a result of precipitation of Chernobyl radioactive fallout. In the summer of 1988, Leningraders had the opportunity to use the services of a radiation-monitoring laboratory to test fungi for radioactivity. In 15% of the mushroom pickers, the mushrooms turned out to be “dirty”; in others, the device recorded “the radiation background slightly inflated, but within the limits of the permissible”. With an organized inspection in the Leningrad markets, more than 500 kilograms of fungi “radiation dirty” were seized.
Radioactive products entered the water basins as a result of deposition on the water surface, runoff from polluted terrain, migration with groundwater. Academician B. Paton reported, “More than half of the radioactive substances released into the atmosphere as a result of the accident settled and concentrated in a 30-km zone, with the bulk at a depth of 1 to 5 cm”, (Paton B). The other scientist Yisrael acknowledged, “The total area of zones with a pollution level of 137 Ci / km2 and above is about 10,000 km2. In the territory of this zone (outside the resettlement zone) there are about 640 settlements with a population of more than 230 thousand people. In the first year residents of 186 settlements (116 thousand people) were evacuated from the resettlement zone, including 75 (90 thousand people) in the Ukrainian SSR, 107 (25 thousand people), the RSFSR – 4 (1 thousand people). The city of power engineers of Pripyat has been closed down and became lifeless”, (Pravda, 1989)
Mass measurements of radioactive contamination of air and soil were deployed, and then complex studies of the radioactivity of all components of the natural environment, including vegetation. A few days after the accident, a mass sampling of the soil began, followed by analysis (gamma spectrometry, radiochemistry), which allowed the construction of maps of isotope contamination of the terrain. Radionuclides of iodine and cesium precipitated, mainly in the territory of Belarus, Ukraine and the highest levels of iodine-131 contamination were observed.
The whole population was evacuated from the 30-kilometer circular zone, and the population from some Belarusian villages outside the zone was also evacuated. In the first months after the accident more than 100,000 people were evacuated, including 92,000 out of 75 settlements in the Kyiv and Zhytomyr regions.
The control of the pollution of the Pripyat River and the Kiev reservoir, the source of water supply in Kiev, was introduced. In the Kremenchug reservoir in May 1986 the concentration of strontium-90 had radioactivity, which is almost 100 times higher than the established rate. Strongly polluted were bottom soils on the site of the Kiev reservoir, adjacent to the mouth of the river Pripyat.
Special measures were taken to prevent the spread of radioactive contamination from the area of the accident with high water. Deep dams and a wall in the ground, cutting out the removal of radionuclides from the near zone of the Chernobyl nuclear power plant, and dull and filtering dams (131 structures) on small rivers to contain radionuclides were built near the Pripyat River and surrounding areas. A few hundred meters from the nuclear power plant, around it, dozens of wells were drilled to the depth of the aquifer to control and protect groundwater, when necessary, the water from them was pumped into the cooling pond. The total length of all structures, dams and lintels was 29 km. The Chernobyl tragedy cannot be reversed. Thousands of people died immediately, others developed all types of cancers incompatible with life and died shortly after.
Advances in scientific and technological progress have given man tremendous opportunities to use atomic energy, but does he have enough knowledge and common sense to ensure the reliability and safety of this process?
2017-10-26-1508993226